Tesis sobre el tema "Inhalation Aerosols"

PhD
Electrostatics of aerosols for inhalation is a relatively new research area. Charge properties of these particles are largely unknown but electrostatic forces have been proposed to potentially influence lung deposition. Investigation on the relationship between formulation and aerosol charging is required to understand the fundamental mechanisms. A modified electrical low pressure impactor was employed to measure the particles generated from metered dose inhalers and dry powder inhalers. This equipment provides detailed size and charge information of the aerosols. The particles were sized by impaction onto thirteen stages. The net charges in twelve of the size fractions were detected and recorded by sensitive electrometers. The drug deposits were quantified by chemical assay. The aerosol charge profiles of commercial metered dose inhalers were product-dependent, which was due to differences in the drug, formulation, and valve stem material. The calculated number of elementary charges per drug particle of size ≤ 6.06 μm ranged from zero to several ten thousands. The high charge levels on particles may have a potential effect on the deposition of the aerosol particles in the lung when inhaled. New plastic spacers marketed for use with metered dose inhalers were found to possess high surface charges on the internal walls, which was successfully removed by detergent-coating. Detergent-coated spacer had higher drug output than the new ones due to the reduced electrostatic particle deposition inside the spacer. Particles delivered from spacers carried lower inherent charges than those directly from metered dose inhalers. Those with higher charges might be susceptible to electrostatic forces inside the spacers and were thus retained. The electrostatic low pressure impactor was further modified to disperse two commercial Tubuhaler® products at 60 L/min. The DPIs showed drug-specific responses to particle charging at different RHs. The difference in hygroscopicity of the drugs may play a major role. A dual mechanistic charging model was proposed to explain the charging behaviours. The charge levels on drug particles delivered from these inhalers were sufficiently high to potentially affect deposition in the airways when inhaled. Drug-free metered dose inhalers containing HFA-134a and 227 produced highly variable charge profiles but on average the puffs were negatively charged, which was thought to be due to the electronegative fluorine atoms in the HFA molecules. The charges of both HFAs shifted towards neutrality or positive polarity with increasing water content. The spiked water might have increased the electrical conductivity and/or decreased the electronegativity of the bulk propellant solution. The number of elementary charges per droplet decreased with decreasing droplet size. This trend was probably due to the redistribution of charges amongst small droplets following electrostatic fission of a bigger droplet when the Raleigh limit was reached.

The aim of this work was to gain a better understanding of the physiochemical factors which affect the formulation of suspension inhalation aerosols. This has been attempted by applying the principles of colloid science to aerosol formulation. Both a drug system and a model colloid system have been used. The adsorption of six nonionic and cationic surfactants onto Spherisorb has been investigated. The results were analysed by calculating the area occupied by one adsorbed molecule at the surface and by comparing these values for each surfactant. The amount of each surfactant adsorbed was correlated with the number of sites on that surfactant molecule which could interact with the surface. The stability of suspensions, produced by both the model colloid Spherisorb, and by the drug isoprenaline sulphate, after adsorption of the surfactants, has been assessed by measuring settling times and rising times. The most stable suspensions were found to be those which had the greatest amounts of long chain fatty acid surfactant adsorbed on their surface. A comparison was made between the effective stabilising properties of Span 85 and oleic acid on various drug suspensions. It was found that Span 85 gave the most stable suspensions. Inhalation aerosol suspensions of isoprenaline sulphate were manufactured using the same surfactants used in the adsorption and suspension stability studies and were analysed by measuring the particle size distributions of the suspension and the emitted doses. The results were found to correlate with the adsorption and suspension stability studies and it was concluded that a deflocculated suspension was preferable to a flocculated suspension in inhalation aerosols provided that the drug density was less than the propellant density. The application of this work to preformulation studies was also discussed.

In asthma therapy, the use of theophylline to prevent bronchial spasm and glucocorticoids to decrease inflammation is widely indicated. Apart from the acute asthma attack oral theophylline is treated for chronic therapy in order to minimize inflammation and to enhance the efficiency of corticosteroids and recover steroids’ anti-inflammatory actions in COPD treatment. The preferred application route for respiratory disease treatment is by inhalation, such as dry powder inhalers (DPI) being the delivery systems of first choice. As shown recently, there is an advantageous effect if the drugs are given simultaneously which is caused by a synergistic effect at the same target cell in the lung epithelia. Therefore, it seems rational to combine both substances in one particle. This type of particle has the advantage over a combination product containing both drugs in a physical mixture which occurs rather randomly deposition leading to API segregation and non-dose-uniformity. Dry powder inhalers (DPIs) is a type of therapeutic pharmaceutical formulations usually present in the solid form. Due to the nature of the solid-state, an understanding of chemical and physical properties must be established for acquiring optimum performance of the active pharmaceutical ingredients (APIs). In recent year, generation of DPIs is a destructive procedure to meet the micron size. Such processes are inefficient and difficult to control. Moreover, according to current researches on combination APIs formulation, this type of DPIs performed a greater variability in does delivery of each active, leading to poor bioavailability and limit clinical efficient. This result suggest that combination formulations require advanced quality and functionality of particles with suitable physicochemical properties. Hence, in order to production of binary and combination DPIs products, the aim of this study was to develop the spray drying and ultrasonic process for engineering of combination drug particles that will be delivered more efficiently and independently of dose variations to the lung. Microparticles were produced by spray drying or/and ultrasonic technique. The processing parameters and addition of excipients (polymers) were optimized using a full factorial design such that microparticles were produced in a narrow size range suitable for inhalation. Employing excipients resulted in high saturation environment leading to minimized sphere particles when compared to conventional solvent. Solid state characterization of microparticles using powder x-ray diffraction and differential scanning calorimetry indicated that the particles contained crystalline but no cocrystal. The combination particles comparable to or better than micronized drug when formulated as a powder blended with lactose. It was concluded that the use of HPMC enhanced crystallinity suitable for inhalation; and combination particles improved uniform distribution on the stage of NGI.

Thesis (M.S.)--West Virginia University, 2003.
Title from document title page. Document formatted into pages; contains vii, 112 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 109-112).

The aim of the work was to design, manufacture, and characterize targeted multi-component dry powder aerosols of (non-destructive) mucolytic agent (mannitol), antimicrobial drug (tobramycin or azithromycin), and lung surfactant mimic phospholipids (DPPC:DPPG=4:1 in molar ratio). The targeted dry powder for inhalation formulation for deep lung delivery with a built-in rationale of specifically interfering several disease factors of chronic infection diseases in deep lungs such as cystic fibrosis, pneumonia, chronic bronchitis, and etc. The dry powder aerosols consisting of selected chemical agents in one single formulation was generated by using spray drying from organic solution. The physicochemical properties of multi-component dry powder inhaler (DPI) formulation were characterized by a number of techniques. In addition, the in vitro aerosol dispersion performance, storage stability test, and in vitro drug release of selected spray-dried (SD) multi-component systems were conducted. The physicochemical study revealed that multi-component aerosol particles possessed essential particle properties suitable for deep lung delivery. In general, the multi-component particles (typically 0.5 to 2 µm) indicated that the designed SD aerosol particles could potentially penetrate deep lung regions (such as respiratory bronchiolar and alveolar regions) by sedimentation and diffusion, respectively. The essential particle properties including narrow size distribution, spherical particle and smooth surface morphologies, and low water content (or water vapor sorption) could potentially minimize interparticulate interactions. The study of in vitro aerosol dispersion performance showed that majority of SD multi-component aerosols exhibited low values (less than 5µm) of MMAD, high values (approximately above 30% up to 60.4%) of FPF, and high values (approximately above 90%) of ED, respectively. The storage stability study showed that azithromycin–incorporated multi-component aerosol particles stored at 11 and 40% RH with no partial crystallization were still suitable for deep lung delivery. Compared to SD pure azithromycin particles, the azithromycin-incorporated multi-component particles exhibited an enhanced initial release. The targeted microparticulate and nanoparticulate multi-component dry powder aerosol formulations with essential particle properties for deep lung pulmonary delivery were successfully produced by using spray drying from organic solution. The promising experimental data suggest the multi-component formulations could be further investigated in in vivo studies for the purpose of commercialization.

The toxicology of aerosols in occupational settings is often performed through particle collection on a filter followed by reconstitution into cell culture media which can alter the biological effects. Current in vitro exposure systems require additional instruments to control temperature and humidity, making the system bulky and difficult to take to the field. The Portable In Vitro Exposure Cassette (PIVEC) was designed for personal monitoring, characterized using copper nanoparticles, tested with alveolar cells, and set-up for real-time monitoring. Three differently sized copper nanoparticles, 40-800 nm, were dispersed as a dry aerosol and measured gravimetrically and on a number concentration basis to determine the deposition efficiency of the PIVEC. A549 cells, a human alveolar adenocarcinoma epithelial line, were exposed to the aerosols and oxidative stress and cell viability were monitored post-exposure. The deposition efficiency ranged from 0.5% to 18% depending on method of analysis and size of particle. Oxidative stress increased within the first two hours post exposure, however there was no significant difference in cell viability at the four hour time point at deposited doses up to 1.63 mg/cm2. Validation of the PIVEC was done in the laboratory using diesel exhaust. Metal oxide fuel additives are used to reduce emissions; however, additives have been shown to increase emitted nanoparticles. The PIVEC was used to determine the potential cytotoxicity and oxidative activity changes in A549 cells after exposure to either model particles or exhaust generated with or without a commercial, nano-cerium oxide based additive. Acellular experiments suggest a correlation between the deposition and the type of fuel used for the newly designed PIVEC. Cellular results suggest a decrease in cytotoxicity and no statistically significant effect on reactive oxygen species generation with the use of the nano-cerium oxide additive. Rapid monitoring of oxidative stress was performed using an enzyme-based biosensor. The functionalized biosensor uses cytochrome c to measure reactive oxygen species through electrochemical detection during aerosol exposures. When compared to a traditional biological assay, the biosensor response was similar. The PIVEC is a unique device, designed to monitor aerosols using air-liquid interface in vitro techniques including a real-time monitor for oxidative stress.

The purpose of this study was to characterize and evaluate the performance of a whole-body human exposure chamber for controlled test atmospheres of gases and particulates. The chamber was constructed from Plexiglass, has a volume of 75 ft 3, operated at a flowrate of 33.8 CFM, and both the makeup and exhaust air are HEPA filtered. Fly ash dust was generated using a Wright Dust Feeder. An elutriator was used to eliminate particles larger 8 μm aerodynamic diameter from the airstream. A direct reading instrument, the Rupprecht and Patashnick PM-10 TEOM, was used for determination of particle concentration. Particle size distributions were determined by a QCM cascade impactor. Data from gravimetric analysis were used to test for the evenness of dust concentrations in the chamber. CO2 is used as a representative gas and its concentration was measured using the Metrosonics aq-5000. Total dust concentrations as measured by the TEOM, in μg/m 3, at 0.2, 0.4, 0.6 and 1.6 RPMs of the Wright Dust Feeder, were 110 + 2.8, 173 + 8.5, 398 + 20 and 550 + 17, respectively. For these RPMs, particle size distributions were associated with a MMD of 1.27 μm and a GSD of 2.35, a MMD of 1.39 and a GSD of 2.22, a MMD of 1.46 and a GSD of 2.08, a MMD of 1.15 and a GSD of 2.2, respectively. Total dust concentrations as measured by gravimetric analysis, in μg/m3 for the respirable fraction. Dust concentrations measured at different points within the chamber showed uniform distribution with a variability less than 10%. Similarly, the particle size distributions were found to be consistent across the different RPMs settings. Regarding carbon dioxide, its concentration was straightforward and the measured and theoretical maximum concentration levels were in agreement. The performance of this whole-body human exposure chamber has been characterized and evaluated for low levels of particles and gases and now it is a valuable research tool for inhalation challenge studies.

Class of 2017 Abstract
Objectives: Milk protein allergy is estimated to affect 1.2% to as much as 17% of people of all ages. Advair® Diskus® (FP/SX) utilizes lactose as an excipient which limits the utility of this product for this population. Furthermore, Advair® Diskus® is formulated as an interactive physical mixture via a micronization process. Alternatively, spray dried engineering achieves narrow particle size distribution, allowing greater deposition in the targeted respiratory bronchioles. The purpose of this dry powder inhaler (DPI) study was to conduct an in vitro comparative analysis of the aerodynamic performance of a co-spray dried lactose-free formulation of FP/SX with a mannitol excipient as a molecular mixture versus the Advair® Diskus® 250/50 (FP/SX) interactive physical mixture product. Methods: Utilizing mannitol as an excipient, a co-spray dried FP/SX powder was prepared using the Buchi Mini-Spray Dryer B-290 under closed system configuration. The resulting feed solution was spray dried at pump rates of 25%, 50%, and 100% with all other parameters remaining constant (aspiration, atomization rate, nitrogen gas rate). The primary outcome measure, aerodynamic performance, was assessed using the Copley Next-Generation Impactor (NGI). NGI data for the DPIs was used to calculate mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD), and fine particle fraction (FPF) of each powder, including the Advair® Diskus®. Residual water content was quantified by Karl Fischer titration. Particle characteristics were visualized by scanning electron microscopy. Results: FPF, MMAD, and GSD were calculated from NGI data; Wolfram Alpha software was used to calculate MMAD and GSD. T-test regression was used for comparative analysis of spray-dried and Advair® Diskus® powders. MMAD for each spray dried sample was analyzed using a t-test regression against the MMAD values from the Advair® Diskus®. Using aerodynamic analysis studies triplicated for each powder, there was no significant difference between the spray dried powder and Advair® Diskus® for MMAD and GSD (p-values >0.05). The 50% and 100% pump rate samples had similar FPF to the Advair® Diskus® (p-values >0.05). However, the 25% pump rate sample had a significantly improved FPF compared to the Advair® Diskus® (p <0.01). Conclusions: A co-spray-dried lactose-free formulation of FP/SX with a mannitol excipient demonstrated similar aerodynamic performance to the Advair® Diskus® which consists of a physical mixture of two drugs with lactose. Of significance, 25% pump rate spray-dry conditions demonstrated an improved FPF compared to the Advair® Diskus®.

Introdução: A pneumonia associada à ventilação mecânica (PAV) causada por Staphylococcus aureus resistente à meticilina (SARM) é uma infecção nosocomial frequente em pacientes críticos. A vancomicina é o tratamento de escolha, porém tem apresentado altas taxas de falha terapêutica, sendo uma das possíveis causas a baixa penetração no tecido pulmonar após administração intravenosa. Diversos estudos experimentais têm demonstrado que a administração de antibióticos por nebulização possibilita a obtenção de altas concentrações no tecido pulmonar e maior efeito bactericida que a obtida por infusão intravenosa. Entretanto, até o momento, a literatura carece de estudos comparando a utilização de vancomicina por via intravenosa com a via inalatória. Objetivo: O objetivo principal deste estudo foi comparar a concentração de vancomicina atingida no tecido pulmonar saudável após a administração de dose única via intravenosa ou por nebulização, em suínos anestesiados e submetidos à ventilação mecânica. Métodos: Vinte e quatro suínos foram submetidos à anestesia intravenosa, intubação e ventilação mecânica e aleatorimanete distribuidos: Doze animais receberam uma dose única de vancomicina por infusão intravenosa (15 mg.Kg-1), dos quais seis animais foram eutanasiados uma hora após término da administração e seis animais foram eutanasiados após 12 horas e doze animais receberam uma dose única de vancomicina por nebulização com nebulizador de placa vibratória (37,5 mg.Kg-1), dos quais seis animais foram eutanasiados uma hora após término da administração e seis animais foram eutanasiados após 12 horas. Foram coletadas amostras de sangue para dosagem sérica de vancomicina antes da administração em 30\', 1, 2, 4, 6, 8 e 12h após o término da administração. Após a eutanásia, foram coletadas amostras de tecido pulmonar de regiões dependentes e não dependentes para dosagem tecidual de vancomicina. Nos animais que receberam a vancomicina por nebulização, a deposição extrapulmonar deste antibiótico foi calculada após da lavagem das partes do circuito ventilatório e da câmara de nebulização. A dosagem de vancomicina foi realizada por meio de cromatografia líquida de alta eficiência (CLAE-UV). Resultados: A concentração de vancomicina no tecido pulmonar obtida no grupo nebulizado de uma hora foi aproximadamente treze vezes maior que a concentração pulmonar obtida no grupo intravenoso de uma hora; (mediana e intervalo interquartílico) 161 (71-301) vs. 12 (4-42) Mig.g-1 (p < 0,05), respectivamente. A concentração pulmonar de vancomicina no grupo nebulizado de 12 horas foi 63 (23-119) Mig.g-1 e níveis indetectáveis de vancomicina foram obtidos no grupo intravenoso de 12 horas; 0 (0-19) Mig.g-1 (p < 0,05). Houve ausência de um pico sérico de vancomicina após o término da administração por nebulização no grupo de doze horas comparado ao grupo intravenoso. Conclusão: A administração de vancomicina por nebulização apresentou maiores concentrações pulmonares do que pela via intravenosa. Os resultados sugerem uma passagem lentificada da vancomicina pela barreira alvéolo-capilar após nebulização
Introduction: Ventilator-associated pneumonia caused by Staphylococcus aureus methicillin resistant is a frequent nosocomial infection in critically ill patients. Vancomycin is the treatment of choice, but it has presented high rates of therapeutic failure, possibly due to its low penetration in lung tissue following intravenous administration. Many studies have shown that lung tissue deposition and antibacterial efficiency of nebulized antibiotics were greater than by intravenous administration. However, to date, the literature lacks studies comparing the use of vancomycin intravenously with the inhalation route Objective: The aim of this study was to compare vancomycin concentration in healthy lungs after a single dose nebulized or intravenously administered in anesthetized and ventilated piglets. Methods: Twenty four piglets were anesthetized, intubated and submitted to mechanical ventilation. Twelve animals received a single dose of vancomycin by intravenous infusion (15 mg.kg-1), of which six animals were euthanized one hour after the end of administration and six animals were euthanized after 12 hours and twelve animals received a single dose of vancomycin using a vibrating plate nebulizer (37,5 mg.kg-1), of which six animals were euthanized one hour after the end of administration and six animals were euthanized after 12 hours. Blood samples were collected for serum vancomycin dosage before and at 30\', 1, 2, 4, 6, 8 and 12 hours after the end of administration. After euthanasia, tissue samples from dependent and non-dependent lung tissue were collected for tissue dosage of vancomycin. In animals receiving vancomycin by nebulization, the extrapulmonary deposition of this antibiotic was calculated after washing the parts of the ventilator circuit and the nebulization chamber. The dosage of vancomycin was performed using high performance liquid chromatography (HPLC-UV). Results: Vancomycin lung tissue concentrations in one-hour aerosol group were thirteen times greater than pulmonary concentration in one-hour intravenous group (median and interquartile range): 161 (71-301) Mig.g-1 vs. 12 (4-42) Mig.g-1 (p < 0.05). Vancomycin lung tissue concentration in twelve-hour aerosol group was 63 (23-119) ?g.g-1 and it was undetectable in twelve-hour intravenous group; 0 (0-19) Mig.g-1 (p < 0.05). There was no vancomycin serum peak following the end of administration by nebulization in the 12-hour group compared to intravenous administration. Conclusion: Administration of vancomycin by nebulization showed higher lung tissue concentrations than intravenous route. The results suggest a slower passage of vancomycin through alveolar capillary barrier after nebulization

Epidemiological studies have consistently shown an association between elevated quantities of ambient airborne particulate matter (PM) and acute health effects. The focus here is on health effects of primary PM and is intended to provide insight into the roles of particulate speciation on inhalation toxicity. PM considered consisted of combustion generated ash particles from (1) coal, (2) coal/municipal sewage sludge (MSS) mixture, (3) MSS burned with natural gas assist, (4) coal/refuse derived fuel (unstaged and staged), (5) residual fuel oil (ROFA), (6) combustion generated zinc particles, with and without sulfur, and (7) combustion generated zinc which had been sequestered by sorbent particles. In each case, health effects were investigated in-vivo by direct inhalation by a mouse model. An aerosol re-suspension system that produces aerosol concentrations of ∼1000μg/m³ was designed, and characterized. Particles were characterized with respect to size, elemental composition, leachability, and pH of supernatant. Measured alterations in lung permeability, along with pulmonary functions were used as measurements of lung injury. One-hour exposures were conducted for periods lasting from 1 to 24 days. The validity of assumptions used in the lung permeability measurement technique, was explored using a new mathematical model. In-vivo results indicate two types of lung permeability behavior. Inhalation of ash particles from coal, MSS, residual fuel oil, ZnO, and Zn sequestered by kaolinite caused an initial decrease in lung permeability followed by a "recovery" to control mice values (Type 1 behavior). In contrast, the exposure to ash from coal plus MSS, coal plus RDF, and zinc plus sulfur, triggered an increase in lung permeability (Type 2 behavior). This work demonstrates the value of health effects engineering, combining both combustion engineering and toxicology. Particle speciation is extremely important and sulfated zinc has been identified as a "bad actor". Ash aerosol from either coal or MSS combustion alone produces Type 1 behavior in lung permeability, while ash aerosol from combustion of a mixture of coal and MSS produces Type 2 behavior. The high temperature capture of zinc vapor on kaolinite sorbent greatly mitigates lung injury allowing permeability behaviors to change from Type 2 to Type 1.

The purpose of this research was to evaluate the capability and performance of the University of South Florida’s (USF) Human Exposure Chamber (HEC) using aerosols in the thoracic range. The goals of this research were two-fold: to obtain an average particle size of 10 µm (thoracic-size range) inside the chamber during dust production and to test for evenness of dust concentration within the chamber. The USF HEC can be used for studies using gases and/or particulates. The chamber measurements are 4.16 ft x 2.67 ft x 6.75 ft, for a total volume of 75 ft3 or 2.13 m3. This research has public health significance since outdoor air pollution is found most commonly in the thoracic size range; future studies with the HEC could focus on the impact of outdoor air pollution on human subjects under various exposure conditions, and various particle size ranges. Soda lime glass beads were used in this study due to their uniformity in shape and size. A Wright Dust Feeder (WDF) was used to generate the glass beads aerosol in the chamber. Nitrogen gas and HEPA-filtered fresh air were used to transport the aerosol through the system and into the chamber. A total of nine different chamber configurations were made in order to increase the average particle size closer to the goal of 10 µm. Chamber reconfiguration provided statistically significant effect on increasing particle size with the exception of two intermediate settings. It was concluded that aerosol distribution within the chamber was even during operation of the chamber, and modification steps utilized in the study provided size distribution within +/- 6% of the target particle size.

La délivrance de médicaments lors de la mise en œuvre de thérapies inhalées est dépendante de nombreux facteurs. Parmi ceux-ci la morphologie des voies aériennes supérieures(VAS) et en particulier celle de la région glottique est déterminante dans les mécanismes de dépôt de particules par impaction inertielle. Dans le cadre de ce travail, il est examiné d’une part la dynamique glottique durant différentes modalités de respiration et d’autre part déterminé numériquement l’effet de ces mouvements et des conditions de respiration associées sur le dépôt des aérosols dans les VAS.Une étude clinique a été menée dans un premier temps sur un panel de 20 sujets sains (10 hommes et 10 femmes) au sein du service ORL de l’hôpital de la Timone à Marseille pour déterminer le mouvement glottique durant différentes tâches de ventilation allant d’une respiration normale avec moins de 20 cycles/min à une ventilation accélérée jusqu’à 90 cycles/min. L’acquisition des mouvements glottiques a été réalisée par imagerie numérique durant un examen de laryngoscopie avec mesure simultanée des débits associés aux différentes tâches de respiration.Les mesures expérimentales montrent que la géométrie glottique varie pendant la respiration en fonction de la tâche de respiration, du volume courant et de la fréquence respiratoire. Une étude statistique a permis d’isoler deux comportements types l’un où l’aire glottique demeure sensiblement constante durant la respiration et l’autre ou une variation de cette même aire est observée. Sur ce dernier groupe d’individus la variation d’aire maximale observée sur les hommes est de 26%, l’ouverture maximale étant atteinte durant la phase d’inspiration et l’aire minimale durant l’expiration.Ces résultats, ainsi que des données anatomiques, ont permis de construire un modèle géométrique idéalisé des VAS. Ce modèle reproduit fidèlement les principales singularités des voies extrathoraciques en apportant un grand soin à la description de la région glottique. Le transport et le dépôt d’aérosols dans ce modèle a été étudié en ayant recours à des simulations numériques3D de l’écoulement cyclique. Une étude paramétrique a permis d’évaluer l’influence sur le dépôt de l’écoulement cyclique, de la nature du gaz porteur (Air vs mélange d’hélium-oxygène), de la prise en compte de la dynamique glottique et de la taille des particules.Les résultats mettent principalement en évidence une nette diminution de la part extrathoracique du travail respiratoire lors de l’emploi du mélange He-O2 et un écoulement de type jet en aval de la glotte durant l’inspiration associé à une recirculation sous le plancher glottique. Le mécanisme de dépôt principal étant l’impaction inertielle (pour les tailles des particules 1 - 10μm)le zone principale de dépôt est situé dans l’oropahrynx, quelles que soient les conditions pendant inspiration. La fraction de dépôt augmente rapidement avec le diamètre des particules atteignant près de 80% pour les particules de 10μm et diminuer deux fois pour He-O2 en comparaison avec air.Finalement, la dynamique du dépôt ne varie pas de façon significative entre le modèle où la glotte est considérée comme statique et celle où elle est mobile. Donc, dans les conditions de respiration normal le mouvement de la glotte peut être négligé
During inhaled therapies several factors limits the amount of drug delivered to the lungs. E.g. the upper airways morphology and in particular the glottis, defined by the vocal-fold aperture, causes upper airways to narrow in a minimal cross section, which is determinant on aerosol depo­ sition by inertial impaction. This thesis aims to (i) investigate evolution of the glottal area during breathing, and (ii) predict the effects of a dynamic glottis and realistic airflow conditions on the aerosol deposition in upper airways using three-dimensional simulations.First, a clinical study was conducted on 20 healthy volunteers (10 males and 10 females) to explore the glottal motion during several specifie slow (below 20 cycles/min) and rapid breathing tasks (up to 90 cycles/min). The breathing was investigated simultaneously for the glottal area variations using laryngoscopie video recordings and for airflow rate using oral flowmeter.The experimental measurements showed that the glottal geometry observed during a breathing cycle can be extremely variable depending on the respiratory phase, tidal volume, and breathing frequency. Testing the dynamic behaviour of the glottis during breathing, two groups of subjects were identified: one with relatively constant glottal area and other with significant variations. In average, the variations for the latter group of subjects was observed for males at 26% comparing maximale and minimal glottal opening during inspiration and expiration respectively.The results of the clinical study together with anatomical morphological data served to create a madel with idealised geometry of upper airways. This madel represents the major geometrical characteristics of upper airways with special interest in the glottal region. Transport and deposition of aerosols was studied using 3D numerical cyclic simulations and parametrical analysis allowed to evaluate the influence of the cyclic flow, glottal dynamics, type of carrier gas (air or helium-oxygen mixture) and particle size on the deposition of aerosols in the upper airways.The numerical simulations demonstrated significant decrease of respiration work with He-02 and jet-like flow with recirculation zone in the oro-pharynx and downstream the glottal plane. The principal deposition mechanism is inertial impaction (for the particle diameters 1 - lOiJ.m) with most significant deposition region in the oro-pharynx. Important parameters for deposition are the particle size and the nature of carrier gas. For He-02 the deposition reaches two times smaller values than for air and the fraction of deposited particles increases significantly with diameter, reaching 80% of deposited efficiency for 10 iJ.m particles. Finally, the CFD results demonstrated negligible differences in aerosol transport and deposition between different glottal characteristics. Therefore, in normal breathing conditions the glottal motion can be neglected

Dry powder inhalers (DPIs) are commonly used to deliver drugs to the lungs. The drug particles used in these DPIs should possess a number of key properties. These include an aerodynamic particle size < 5μm and particle crystallinity for long term formulation stability. The conventionally used micronization technique to produce inhalation particles offers limited opportunities to control and optimize the particle characteristics. It is also known to induce crystalline disorder in the particles leading to formulation instability. Hence, this research project investigates and optimizes a solvent/anti-solvent crystallization process capable of directly yielding inhalation particles using albuterol sulfate (AS) as a model drug. Further, the feasibility of the process to produce combination particles of AS and ipratropium bromide monohydrate (IB) in predictable proportions and in a size suitable for inhalation is also investigated. The solvent / anti-solvent systems employed were water / ethyl acetate (EA) and water / isopropanol (IPA). Investigation and optimization of the crystallization variables with the water / EA system revealed that particle crystallinity was significantly influenced by an interaction between the drug solution / anti-solvent ratio (Ra ratio), stirring speed and crystal maturation time. Inducing a temperature difference between the drug solution and anti-solvent (Tdrug solution > Tanti-solvent) resulted in smaller particles being formed at a positive temperature difference of 65°C. IPA was shown to be the optimum anti-solvent for producing AS particles (IPA-AS) in a size range suitable for inhalation. In vitro aerosol performance of these IPA-AS particles was found to be superior compared to the conventionally used micronized particles when aerosolized from the Novolizer®. The solvent / anti-solvent systems investigated and optimized for combination particles were water / EA, water / IPA, and water / IPA:EA 1:10 (w/w). IPA was found to be the optimum anti-solvent for producing combination particles of AS and IB with the smallest size. These combination particles showed uniform co-deposition during in vitro aerosol performance testing from the Novolizer®. Pilot molecular modeling studies in conjunction with the analysis of particle interactions using HINT provided an improved understanding of the possible interactions between AS and IB within a combination particle matrix.

This research was aimed at the development and validation of new in vitro methods capable of predicting in vivo drug deposition from dry powder inhalers, DPIs, in lung-normal human adults. Three physical models of the mouth, throat and upper airways, MT-TB, were designed and validated using the anatomical literature. Small, medium and large versions were constructed to cover approximately 95% of the variation seen in normal adult humans of both genders. The models were housed in an artificial thorax and used for in vitro testing of drug deposition from Budelin Novolizer DPIs using a breath simulator to mimic inhalation profiles reported in clinical trials of deposition from the same inhaler. Testing in the model triplet produced results for in vitro total lung deposition (TLD) consistent with the complete range of drug deposition results reported in vivo. The effect of variables such as in vitro flow rate were also predictive of in vivo deposition. To further assess the method’s robustness, in vitro drug deposition from 5 marketed DPIs was assessed in the “medium” MT-TB model. With the exception of Relenza Diskhaler, mean values for %TLD+SD differed by only < 2% from their literature in vivo. The relationship between inhaler orientation and in vitro regional airway deposition was determined. Aerosol drug deposition was found to depend on the angle at which an inhaler is inserted into the mouth although the results for MT deposition were dependent on both the product and the formulation being delivered. In the clinic, inhalation profiles were collected from 20 healthy inhaler naïve volunteers (10M, 10F) before and after they received formal inhalation training in the use of a DPI. Statistically significant improvements in Peak Inhalation Flow Rate (PIFR) and Inhalation Volume (V) were observed following formalized training. The shapes of the average inhalation profiles recorded in the clinic were found to be comparable to the simulated profiles used in the in vitro deposition studies described above. In conclusion, novel in vitro test methods are described that accurately predict both the average and range of aerosol airway drug deposition seen from DPIs in the clinic.

L'objectif de ce travail de thèse a été d'élaborer et de caractériser des systèmes de nanovecteurs de nature lipidique, encapsulant le dipropionate de beclomethasone (DPB), adaptés à l'administration pulmonaire par nébulisation. Deux types de nanovecteurs lipidiques : des liposomes et des nanoparticules lipidiques incluant les nanoparticules solides (SLN) et les nanoporteurs lipidiques (NLC), ont été développés. Les liposomes ont été préparés par la technique d'injection d'éthanol. La technique appliquée pour la préparation des nanoparticules lipidiques était l'homogénéisation à haute vitesse. La taille, l'efficacité d'encapsulation du DPB ainsi que les profils de libération ont été satisfaisants. De plus la nébulisation de ces systèmes et la modélisation mathématiques de la déposition in vitro ont révélé des résultats prometteurs. Finalement, une technique de production des liposomes utilisant un réacteur membranaire a été étudiée pour une production à grande échelle
The objective of this work was to prepare and to characterize lipidic nanocarriers systems encapsulating the beclomethasone dipropionate (BDP) and adapted to the nebulized pulmonary drug delivery. Two types of lipidic carriers: the liposomes and the lipidic nanoparticles including the solid lipid nanoparticles (SLN) and the nanostructured lipid carriers (NLC) were developed. Liposomes were prepared by the optimised ethanol injection based technology. The lipid nanoparticles were prepared by using the high shear homogenization process. Small sized particles, with high BDP encapsulation efficiency as well as a prolonged release effect in vitro were successfully obtained. Furthermore, the nebulized suspensions characteristics and deposition mathematical simulation in vitro revealed promising results. Finally, a liposomes production technique using a membrane contactor was investigated in order to produce large batches

I händelse av ett radioaktivt utsläpp är det viktigt att ha bra beredskap med skyddsåtgärder som bidrarmed det bästa skyddet för den utsatta delen av befolkningen. Direkt efter ett utsläpp utgör exponering viainandning det största problemet eftersom partiklar och gaser ännu inte hunnit deponerats på mark, imoln och så vidare. Byggnader bidrar med ett skydd mot inhalation eftersom luften utanför och inutibostaden byts ut relativt långsamt. Hur stor del av föroreningen som tar sig in till inomhusluften och hurlång tid detta tar är viktig information för att avgöra om befolkningen är tillräckligt skyddade inutibyggnader eller om evakuering bör ske. I detta arbete har kunskap från befintlig litteratur samtmodellering använts för att beskriva generella förhållanden med vilka en förorening kan ta sig in i och utur en byggnad. Differentialekvationer med huvudprocesser och ingående parametrar har studerats för attge en uppfattning om vilket skydd en byggnad kan ge mot inhalation av partiklar och gaser i ettradioaktivt moln. Olika typer av ventilationssystem med eller utan tillhörande partikelfilter diskuteras ochinhalationsdos för olika åldersklasser och aktivitetsnivåer undersöks.Genom att jämföra mängd förorening i luften utanför mot inuti en byggnad talar man om byggnadensskyddskoefficient. De tre huvudprocesser som styr transporten är ventilation, penetration samtdeponering. Ventilationen uppkommer av luftutbytet mellan inomhus‐ och utomhusluften. Ventilationenstyrs antingen mekaniskt eller naturligt. Penetrationen beskriver hur stor andel av partiklarna ellergaserna som tar sig in över byggnadens fasad och deponeringen hur partiklar och gaser tenderar attfastna på de ytor de passerar under transporten. Deponeringen sker även på samtliga ytor inutibyggnaden. Efter att ämnen deponerats kan de resuspendera och åter komma upp till luften vilketmöjliggör för inandning innan de åter kan deponera på tillgängliga ytor. Deponeringen ses som en sänkamedan resuspensionen fungerar som en källa för inomhuskoncentrationen.En av de faktorer som påverkar skyddskoefficienten till störst del är partikeldiametern eftersomdeponerings‐ och penetrationsprocessen är starkt storleksberoende. Stora och små partiklar deponeraslättare och kvar finns den så kallade mellanfraktionen, 0,2‐1 μm i diameter, som håller sig i luften längsttid. Gaser rör sig lätt in och ut ur byggnaden och hindras inte av partikelfilter. Däremot finns särskildafilter att installera som hindrar gaser att ta sig in, exempelvis kolfilter. Sönderfallshastigheten hos de olikaradionukliderna påverkar även skyddsfaktorn. Då ämnena sönderfaller minskar koncentrationen i luften,sönderfallet är då en sänka för koncentrationen inomhus. Ventilationshastigheten har en viss påverkan påskyddskoefficienten. En ökad ventilationshastighet leder till att koncentrationen inomhus kommer att gåmot penetrationsfaktorn. Detta gäller om ventilationshastigheten kan antas vara mycket större ändepositionshastigheten. Ventilationssystem utrustade med partikelfilter kan hålla en stor del avföroreningen utanför byggnaden. Partikelfiltren har olika effektivitet och klassificeras som grov‐, mediumsamtfinfilter. En hög filtereffektivitet har stor påverkan på skyddskoefficienten. Ett filter skall däremotses som en färskvara. De kräver underhåll och bör bytas ut i tid för att kunna fungera som de ska.Inhalationsdosen beror av partikelstorlek eftersom deponeringen som sker i luftvägarna fungerar påliknande sätt som i transporten in och ut ur byggnaden. Mellanfraktionen har tendens att tränga djupt nedi lungorna efter inandning. Effekten från inhalation beror på en individs ålder, storlek och fysisk aktivitet.
In case of a radioactive release, it is important to have good preparedness with the right actions to contribute the best protection for the vulnerable section of the population. Immediately after a release theexposure through inhalation will be the biggest problem, since particles and gases have not beendeposited on land, clouds and so on. Buildings contribute to protection against inhalation. The reason forthis is that the air outside and inside the dwelling is changed relatively slowly. How much of the pollutionthat enter the indoor air and how long time it takes is important information to determine if thepopulation is sufficiently protected inside buildings or if evacuation is needed. In this work knowledgefrom existing literature and modelling has been used to describe general conditions with which apollutant moves in and out of a building. Differential equations with main processes and parameters havebeen studied to give a estimation as to the protection a building can provide against exposure throughinhalation of particles and gases in a radioactive cloud. Different types of ventilation systems, with orwithout associated particle filter are discussed and inhalation dose for different age groups and activitylevels are examined.A buildings protection coefficient is defined by comparing the amount of pollution in the air outside withthe air inside a building. The three main processes that control the transport of the pollution in and outfrom a building are ventilation, penetration and deposition. Ventilation arises of air exchange betweenindoor and outdoor air. Ventilation is controlled either mechanically or naturally. Penetration describesthe proportion of the particles or gases that enter trough the buildings shell. Deposition of particles andgases accurse due to the fact that they tend to stick to the surfaces they pass in transit. The deposition alsooccurs on all surfaces inside the building. After the particles and gases have become deposited, they mayre‐suspend and come back up into the air permitting inhalation before they once more deposit onavailable surfaces. The deposit is seen as a sink while re‐suspension acts as a source for indoor airconcentration.One of the factors that have a large impact of a buildings protection factor is the particle diameter, due tothe deposition and penetration process strongly dependent on particles size. Large and small particlesdeposited easier and the remaining fraction, the midfraction (0.2 to 1 micron in diameter), remains. Thisfraction will stay in the air longer since the deposition process does not affect it strongly. Gases moveeasily in and out of the building and are not prevented by the particle filter. However, there are specialfilters to install that prevent gases to penetrate, such as carbon filters. The rate of decay of the variousradionuclides also affects the protection factor. When nuclides decay the concentration in the airdecreases, the decay is then a sink of the concentration indoors. Ventilation rate has a certain influence onprotection coefficient. An increased ventilation rate leads to the concentration inside approaching thepenetration factor; this is applied if the ventilation rate can be assumed to be much higher than thedeposit rate. Ventilation system equipped with a particle filter can keep a large part of the pollutantoutside the building. Particle filters have different efficiency and are classified as coarse, medium and finefilter. High filter efficiency has a major impact on the protection coefficient. For a filter to functionproperly it demands maintenance and should be replaced in time.Inhalation dose depends on the particle size, since the deposition process affected in respiratory functionis similar to the transport in and out of a building. The midfraction tends to penetrate deep into the lungsafter inhalation. The effect of inhalation is due to an individual's age, size, and physical activity.

Compte tenu de ses aspects multiples, de sa dangerosité potentielle et du taux de

survie considérablement bas qui lui est associé dans ses formes les plus graves, l’aspergillose

pulmonaire est encore à l’heure actuelle dévastatrice sur le plan clinique. L’approche

médicamenteuse conventionnelle consiste en l’administration par voie orale ou

intraveineuse (IV) d’agents antifongiques. Ces voies classiques requièrent l’administration de

doses très élevées qui sont nécessaires à l’obtention de concentrations systémiques

suffisantes pour obtenir un effet thérapeutique au niveau pulmonaire. Cependant, ces

concentrations systémiques sont également la cause d’effets secondaires indésirables et

d’interactions médicamenteuses importantes. Une alternative thérapeutique à ces voies

classiques serait de localiser ces antifongiques dans le poumon, en utilisant la voie inhalée.

Cela permettrait d’augmenter le taux de succès thérapeutique en déposant et en

concentrant directement la dose au niveau du site d’infection tout en minimisant les

concentrations systémiques.

Pour ce faire, nous avons choisi de développer des poudres sèches pour inhalation à

base d’itraconazole (ITZ), un antifongique actif à l’égard des souches d’aspergillus. Celles-ci

sont administrable via un inhalateur à poudre sèche pour les avantages que présente ce

mode d’administration comparativement aux nébuliseurs et aux inhalateurs pressurisés. Le

développement des formulations implique entre autres l’obtention de caractéristiques

aérodynamiques appropriées, c’est-à-dire, ayant, après décharge à partir d’un dispositif

d’inhalation, un profil de déposition pulmonaire permettant d’atteindre des doses

pulmonaires pharmacologiquement efficaces. Toutefois, l’ITZ présente une solubilité

aqueuse extrêmement faible (solubilité aqueuse à pH 7 ~ 4 ng/ml à 25°C). Or, une fois

déposée dans le poumon, la dose inhalée doit se solubiliser pour exercer son action

pharmacologique. Nous avons donc inclus dans les concepts de formulation, une stratégie

permettant l’amélioration du profil de dissolution et l’augmentation de la solubilité de l’ITZ.

Cela permettrait en effet d’en potentialiser au maximum l’action pharmacologique au sein

des lésions fongiques avant qu'il ne soit éliminé sous sa forme non dissoute par les

mécanismes de clairance non absorptifs du poumon. De plus, le poumon étant un organe ne

tolérant qu’un nombre limité de substances administrables par inhalation, nous nous

sommes focalisés sur l’utilisation d’excipients présentant un faible potentiel toxique ou bien

tolérés après inhalation. Enfin, nous avons gardé à l’esprit lors du développement des procédés de fabrication qu’ils pouvaient être sujets à la mise à l’échelle industrielle. Nous

avons donc privilégié des procédés de fabrication simples incluant des technologies

transposables telles que l’atomisation par la chaleur et l’homogénéisation à haute pression.

Une attention particulière lors de la caractérisation des poudres a été portée sur les

propriétés d’écoulement des formulations, toujours dans l’optique de faciliter une

potentielle future manutention à plus grande échelle.

Pour répondre à ces critères, durant la première partie de ce travail, nous avons

imaginé deux concepts de formulation qui ont pour but de former des microparticules de

mannitol dans lesquelles est dispersé l’ITZ sous forme « modifiée ».

Le premier concept de formulation qui a été développé consistait à former une

dispersion solide (DS) entre l’ITZ, si possible amorphe pour en augmenter la solubilité, et un

agent matriciel en utilisant le procédé d’atomisation par la chaleur d’une solution contenant

tous les ingrédients sous forme dissoute. Lors de tests préliminaires, nous avons évalué trois

types d’agents matriciels, deux agents hydrophiles (le mannitol et le lactose) et un agent

hydrophobe (le cholestérol). Sur base de la faisabilité, des résultats préliminaires de

solubilité, de dissolution et de déposition pulmonaire in vitro, le mannitol a été retenu.

Après une optimisation des conditions d’atomisation, les formulations ont été produites en

vue d’être caractérisées. Il a été observé, par diffraction de rayons X sur poudre (PXRD) et

par calorimétrie différentielle à balayage (DSC), qu’après atomisation, l’ITZ était obtenu sous

forme amorphe et le mannitol sous forme cristalline. Les tests d’évaluation des propriétés

aérodynamiques ont été réalisés à l’aide d’un impacteur liquide multi-étages (MsLI) en

suivant les recommandations pratiques de la Pharmacopée européenne. Ce type de

compositions, atomisées dans les conditions optimales, permettait d’obtenir des poudres

sèches présentant les caractéristiques de taille (diamètre médian < 5 μm, mesuré par

diffraction laser) et les propriétés aérodynamiques appropriées à l’administration

pulmonaire (fraction de particules fines (FPF) déterminées lors des tests d’impaction

comprises entre 40 % et 70 %). La formation d’une DS avec le mannitol était nécessaire afin

d’augmenter la solubilité et d’accélérer la cinétique de dissolution de l’ITZ comparativement

à son homologue micronisé sous forme cristalline ou encore à sa forme amorphe atomisée

sans mannitol. Par exemple, dans sa configuration amorphe atomisée sans excipient ou sous

sa forme cristalline initiale, l’ITZ présentait une solubilité à saturation (mesurée dans un tampon phosphate contenant 0,02% de dipalmytoyl phosphatidyl choline) inférieure à 10

ng/ml. Après formation d’une DS avec le mannitol suivant notre procédé de formulation,

nous sommes parvenus à des valeurs de solubilité atteignant 450 ng/ml. Il s’est avéré que

l’ajout à la composition d’un surfactant, le tocopherol polyethylène glycol 1000 succinate

(TPGS), permettait d’accélérer la cinétique de dissolution du principe actif. Toutefois,

l’utilisation du TPGS induisait une diminution des performances aérodynamiques des

formulations. Etant donné que cette augmentation de la cinétique de dissolution pouvait

être un avantage après administration pulmonaire, nous avons considéré un autre type de

surfactant, les phospholipides (PL). L’utilisation de la lécithine de soja hydrogéné s’est

révélée être très efficace. Les performances aérodynamiques des formulations ont été

préservées et même améliorées. Leur incorporation à la DS permettait également d’obtenir

une accélération du profil de dissolution de l’ITZ. De plus, l’augmentation de la quantité de

PL dans nos formulations, dans la gamme des concentrations utilisées, était corrélée avec

une amélioration d’autant plus marquée du profil de dissolution de l’ITZ. En outre, les

solubilités de l’ITZ en présence de PL furent considérablement améliorées avec, par

exemple, des concentrations mesurées de 870 ng/ml et 1342 ng/ml pour les formulations

contenant respectivement 10 % (m/mpoudre) et 35 % (m/mpoudre) d’ITZ, ainsi que 10 % de PL

exprimés par rapport à la quantité d’ITZ.

Le deuxième concept de formulation développé consistait à produire des

microparticules de mannitol dans lesquelles étaient dispersées des nanoparticules (NP)

cristallines d’ITZ. Le procédé de fabrication était le suivant. Une suspension de nanocristaux

d’ITZ produite par homogénéisation à haute pression (HPH) était re-suspendue dans une

solution de mannitol qui était par la suite atomisée pour obtenir les microparticules de

poudres sèches. Après optimisation des conditions d’homogénéisation, nous sommes

parvenus à produire des nanosuspensions d’ITZ dont les particules présentaient un diamètre

médian inférieur à 250 nm. Nous avons alors évalué l’influence qu’avait l’ajout du mannitol

et du taurocholate sodique sur l’état d’agrégation des NP avant l’étape d’atomisation et sur

les performances des formulations sous forme sèche. Il a été observé que l’ajout de

mannitol était nécessaire à la production de solutions sursaturées en ITZ avec une solubilité

maximale d’ITZ mesurées à 96 ng/ml dans le tampon phosphate précédemment cité. L’ajout

de mannitol s’est avéré nécessaire afin de minimiser le phénomène d’agrégation des NP durant l’étape d’atomisation. De plus, l’ajout de taurocholate de sodium permettait

également d’inhiber leur agrégation. La cristallinité des NP d’ITZ a été confirmée par PXRD et

DSC. Ce type de formulation présentait des tailles et des performances aérodynamiques

compatibles à l’administration pulmonaire (tailles des particules < 5 μm et FPF entre 35 % et

46 %). Néanmoins, comparativement aux DS précédemment décrites, ces formulations à

base de NP s’avèrent sensiblement moins performantes. En effet, au niveau des

caractéristiques aérodynamiques, les formulations à base de NP présentent des FPF

nettement inférieures à celles obtenues pour les DS (FPF de ~40 % pour les formulations

nanoparticulaires contre ~70 % pour les DS d’ITZ amorphe). De plus, à partir des

formulations à bases de NP, les taux de sursaturation en ITZ atteints étaient nettement

inférieurs à ceux obtenus avec les DS (~100 ng/ml Vs > 1000 ng/ml pour les meilleurs DS). En

outre, la production des nanosuspensions nécessitait l’étape supplémentaire d’un minimum

de 300 cycles d’homogénéisation, ce qui représente un désavantage considérable en termes

de rendement économique en cas de transposition à échelle industrielle comparativement à

l’étape unique nécessaire pour la fabrication des DS. Pour ces raisons, seules les DS ont été

évaluées in vivo.

Après la mise au point des formulations, la seconde partie de ce projet consistait à

évaluer les DS développés dans un système biologique complet, la souris. Nous avons en

premier lieu réalisé une pharmacocinétique (PK) après administration pulmonaire pour

déterminer l’effet de l’augmentation de la solubilité observée in vitro et de l’ajout de PL dans

la formulation. Ensuite, nous avons entrepris une étude d’activité sur un modèle murin

d’aspergillose pulmonaire invasive (API) permettant de comparer l’efficacité thérapeutique

ou prophylactique de nos formulations comparativement à une thérapie standard par voie

orale. Pour effectuer ces deux études, nous avons préalablement validé une méthode

d’administration des poudres sèches chez la souris à l’aide d’un insufflateur (DP-4M®, Penn

Century, Wyndmoor, USA) en utilisant la voie endotrachéale. Le premier point de cette

investigation avait pour objet de déterminer si l’intervalle de taille particulaire généré lors de

la décharge de nos formulations au sortir de l’insufflateur permettait une répartition

homogène dans les poumons ainsi qu’une pénétration profonde des particules jusqu’aux

alvéoles pulmonaires. Le deuxième point sur lequel nous nous sommes également attardés était la reproductibilité des doses pulmonaires générées après insufflation, facteur

déterminant lors de la réalisation d’une étude PK.

Sur base des observations constatées durant la validation du dispositif

d’administration, nous avons entrepris une étude PK après administration pulmonaire d’une

dose de 0,5 mg/kg d’ITZ, représentant une quantité inhalable par l’homme et pouvant

garantir des taux pulmonaires en antifongiques théoriquement adéquats. Cette étude a

permis de comparer les concentrations pulmonaires et plasmatiques en ITZ après

l’administration de poudres sèches à base d’une DS de mannitol et d’ITZ qui était soit

cristallin soit amorphe, avec ou sans PL. Après administration de la DS à base d’ITZ sous sa

forme amorphe, une augmentation de la quantité d’ITZ absorbée vers le compartiment

systémique a été observée. En effet, il a été observé une augmentation d’un facteur 2,7 de

l’aire sous la courbe des concentrations plasmatiques en ITZ de 0 à 24 heures (AUC0-24h)

comparativement à celle obtenue après administration de la DS à base d’ITZ sous sa forme

cristalline. Le temps pour atteindre la concentration plasmatique maximale (tmax) était

également plus court pour la formulation à base ITZ sous sa forme amorphe (tmax de 10 min

vs 30 min pour la formulation cristalline). De plus, dans cette configuration amorphe, les

temps de rétention pulmonaire en ITZ étaient considérablement plus élevés (t1/2

d’élimination de 6,5 h pour l'ITZ cristallin vs 14 ,7 h pour l’ITZ amorphe) permettant de

maintenir une concentration pulmonaire en ITZ supérieure à la CMI de la souche

d’aspergillus la plus fréquente (A. fumigatus ;2 μg/gpoumon) pendant plus de 24h. L’ajout de

PL dans un rapport ITZ:PL:mannitol (1:3:97) dans la DS influençait le profil PK de l’ITZ

amorphe en accentuant et accélérant d’avantage la phase d’absorption initiale de l’ITZ

observée (Cmax et tmax plasmatique supérieur et inférieur à ceux obtenus pour l’ITZ amorphe,

respectivement). Toutefois, cette formulation a été éliminée plus rapidement des poumons

(t1/2 d’élimination pulmonaire de l’ITZ de 4,1h pour les formulations avec PL vs 14,7h sans

PL). Pour cette raison, nous avons décidé d’évaluer l’efficacité des formulations à base d’ITZ

sous forme amorphe sans phospholipides dans un modèle murin d’aspergillose pulmonaire

invasive (API) que nous avons développé.

Nous ne sommes pas parvenus à mettre en évidence un effet thérapeutique de

l’administration des poudres sèches administrées dans ce modèle murin neutropénique

d’API. Nous justifions ce manque d’activité par une agressivité du modèle trop prononcée et par l’impossibilité de pouvoir administrer de manière plus fréquente le traitement par

inhalation en raison de l’anesthésie nécessaire pour la procédure d’administration

endotrachéale. Toutefois, des essais complémentaires vont être envisagés (modification de

la charge fongique, administration des poudres par une tour d’inhalation, optimisation du

dosage et de la fréquence d’administration). En revanche, il a été mis en évidence que

l’administration prophylactique (début des administrations 2 jours avant l’infection) d’une

dose de 5 mg/kg/48h d’une DS d’ITZ amorphe augmentait significativement le taux de survie

de 12 jours après l’infection par A. fumigatus comparativement aux animaux non traités

(taux de survivants :50 % vs 0 %). A titre de comparaison, le pourcentage de survie obtenu

après prophylaxie quotidienne d’une dose de 12,5 mg/kg/12h de solution orale de VCZ (la

thérapie recommandée pour l’API) n’était que de 25 %.

En conclusion, les DS d’ITZ destinées à être administrées par inhalation constituent

une approche thérapeutique prometteuse dans le cadre de la prévention et du traitement

de l’aspergillose pulmonaire.
Doctorat en Sciences biomédicales et pharmaceutiques
info:eu-repo/semantics/nonPublished

Although, pulmonary drug delivery is a well established means for targeting of drugs to the lungs for the treatment of respiratory diseases as well as for the systemic delivery of volatile anesthetic agents, drug absorption kinetics in the lung have not been subjected to extensive research. The main objective of this thesis was to investigate drug absorption characteristics of the lung barrier, using the isolated and perfused rat lung model and in vivo pharmacokinetic studies in rats. Physicochemically diverse drugs (i.e. atenolol, budesonide, cromolyn, cyanocobalamin, enalapril, enalaprilate, formoterol, imipramine, losartan, metoprolol, propranolol, talinolol, terbutaline, and the tetrapeptide TArPP) were used as model compounds. In connection to these investigations, a nebulization catheter device was successfully adapted and evaluated as a new technique for delivery of defined aerosol doses to the rat lung. In addition, a physicochemical profile of the inhaled drugs on the market worldwide during 2001 was made.

The pulmonary first-order absorption rate constant and bioavailability were found to correlate to the drug lipophilicity, the molecular polar surface area, and the apparent permeability of Caco-2 cell monolayers. In contrast to the intestinal mucosa and the blood-brain barrier, the pulmonary epithelium was highly permeable to drugs with a high molecular polar surface area. Accordingly, a small hydrophilic tetrapeptide (oral bioavailability ~0.5%) showed a complete bioavailability after pulmonary delivery to rats in vivo. Regional differences in bioavailability, absorption rate, and first-pass metabolism of the peptide was demonstrated after targeted delivery to different regions of the respiratory tract in rats in vivo. The high pulmonary bioavailability of the efflux transporter substrates losartan and talinolol provides functional evidence for an insignificant role of efflux transporters such as P-glycoprotein in limiting the absorption of these drugs from the rat lung.

The results of this thesis demonstrate that the lung efficiently absorbs drugs with a wide range of lipophilicity. The pulmonary route should thus be regarded as a potential alternative for administration of drugs with low oral bioavailability. In addition, drug inhalation present an opportunity to attain a more rapid onset of drug action than can be attained by the oral route.

Liu Hua.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references (leaves 139-143).
Abstracts in English and Chinese.
Table of Contents --- p.I
Acknowledgement --- p.VII
Abstract --- p.VIII
Abstract (Chinese) --- p.X
List of Tables --- p.XV
List of Figures --- p.XXIV
List Symbols and Abbreviations
Chapter Chapter One --- Introduction
Chapter 1.1. --- Rationale of study --- p.2
Chapter 1.2. --- Drug Delivery to the lungs --- p.5
Chapter 1.3. --- Particle transport and deposition mechanisms --- p.8
Chapter 1.4. --- Factors affecting particulate interactions --- p.9
Chapter 1.4.1. --- Particle size --- p.9
Chapter 1.4.2. --- Particle shape --- p.10
Chapter 1.4.3. --- Surface texture --- p.10
Chapter 1.4.4. --- Surface energy --- p.11
Chapter 1.4.5. --- Contact area --- p.12
Chapter 1.4.6. --- Relative humidity --- p.12
Chapter 1.4.7. --- Electrical properties --- p.13
Chapter 1.5. --- Fine powder production technologies applicable to dry powder inhalation formulations --- p.13
Chapter 1.5.1. --- Batch crystallization and micronization --- p.14
Chapter 1.5.2. --- Spray drying --- p.15
Chapter 1.5.3. --- Supercritical fluid crystallization --- p.17
Chapter 1.6. --- Physical characterization of aerosol powders --- p.18
Chapter 1.6.1. --- Microscopy and particle size analysis --- p.19
Chapter 1.6.2. --- Powder X-ray diffractometry --- p.19
Chapter 1.6.3. --- Thermal analysis --- p.20
Chapter 1.6.4. --- In-vitro deposition assessment --- p.20
Chapter 1.6.5. --- Surface energy measurement by inverse gas chromatography (IGC) --- p.21
Chapter 1.7. --- Scope of study --- p.22
Chapter Chapter Two --- Materials and Methods
Chapter 2.1. --- Materials --- p.25
Chapter 2.2. --- Equipment --- p.25
Chapter 2.3. --- Methods --- p.27
Chapter 2.3.1. --- Determination of aqueous solubility of salbutamol sulphate in water --- p.27
Chapter 2.3.2. --- Preparation of spray-dried salbutamol sulphate powders under different operating conditions --- p.27
Chapter 2.3.3. --- Preparation of spray-dried salbutamol sulphate powders at various lecithin concentrations --- p.30
Chapter 2.3.4. --- Preparation of spray-dried salbutamol sulphate powders at various oleic acid concentrations --- p.32
Chapter 2.3.5. --- Physical characterization of spray-dried salbutamol sulphate powders --- p.34
Chapter 2.3.5.1. --- Scanning electron microscopy --- p.34
Chapter 2.3.5.2. --- Specific surface area determination --- p.34
Chapter 2.3.5.3. --- Particle size distribution measurements --- p.35
Chapter 2.3.5.4. --- Water content determination --- p.36
Chapter 2.3.5.5. --- Isothermal water vapour sorption studies --- p.37
Chapter 2.3.5.6. --- Powder X-ray diffraction --- p.37
Chapter 2.3.5.7. --- Thermal analysis --- p.38
Chapter 2.3.5.8. --- Surface energy measurement by inverse gas chromatography --- p.39
Chapter 2.3.5.8.1. --- Calculation of surface thermodynamic parameters --- p.40
Chapter 2.3.5.8.1.1. --- Standard Free Energy of Adsorption and Related Thermodynamic Parameters --- p.40
Chapter 2.3.5.8.1.2. --- Dispersive Component of Surface Free Energy and Related Thermodynamic Parameters --- p.41
Chapter 2.3.5.8.1.3. --- Specific Interactions and Associated Acid-Base Properties --- p.42
Chapter 2.3.5.9. --- In-vitro deposition measurement by multi-stage liquid impinger --- p.43
Chapter Chapter Three --- Results and discussion
Chapter 3.1. --- Influence of spray drying operating parameters --- p.46
Chapter 3.1.1. --- Drying temperature --- p.46
Chapter 3.1.1.1. --- "Particle size, particle morphology, and specific surface area" --- p.46
Chapter 3.1.1.2. --- "Crystallinity, moisture sorption and thermal behaviour" --- p.53
Chapter 3.1.1.3. --- Surface thermodynamic properties --- p.60
Chapter 3.1.1.4. --- Aerodynamic properties and in-vitro deposition --- p.64
Chapter 3.1.2. --- Feed solution concentration --- p.67
Chapter 3.1.2.1. --- "Particle size, particle morphology and specific surface area" --- p.69
Chapter 3.1.2.2. --- "Crystallinity, moisture sorption and thermal behaviour" --- p.69
Chapter 3.1.2.3. --- Surfacethermodynamicproperties --- p.70
Chapter 3.1.2.4. --- Aerodynamic properties and in-vitro deposition --- p.70
Chapter 3.1.3. --- Feed speed --- p.72
Chapter 3.1.3.1. --- "Particle size, particle morphology, and specific surface area" --- p.72
Chapter 3.1.3.2. --- "Crystallinity, moisture sorption and thermal behaviour" --- p.73
Chapter 3.1.3.3. --- Surfacethermodynamicproperties --- p.73
Chapter 3.1.3.4. --- Aerodynamic properties and in-vitro deposition --- p.73
Chapter 3.2. --- Influence of formulation additives --- p.78
Chapter 3.2.1. --- Influence of lecithin as additive --- p.78
Chapter 3.2.1.1. --- "Particle morphology, particle size and specific surface area" --- p.79
Chapter 3.2.1.2. --- "Crystallinity, moisture sorption and thermal behaviour" --- p.84
Chapter 3.2.1.3. --- Surfacethermodynamicproperties --- p.90
Chapter 3.2.1.4. --- Aerodynamic properties and in-vitro deposition --- p.94
Chapter 3.2.2. --- Influence of oleic acid as additive --- p.101
Chapter 3.2.2.1. --- "Particle morphology, particle size and specific surface area" --- p.101
Chapter 3.2.2.2. --- "Crystallinity, moisture sorption and thermal behaviour" --- p.106
Chapter 3.2.2.3. --- Surfacethermodynamicproperties --- p.123
Chapter 3.2.2.4. --- Aerodynamic properties and in-vitro deposition --- p.127
Chapter Chapter Four --- Conclusion and Future Work
Chapter 4.1. --- Conclusion --- p.134
Chapter 4.1.1. --- Influence of spray drying operating parameters --- p.134
Chapter 4.1.2. --- Influence of formulation additives --- p.135
Chapter 4.2. --- Future Work --- p.137
References --- p.139

Chan, Pui.
"November, 2009."
Thesis (M.Phil.)--Chinese University of Hong Kong, 2010.
Includes bibliographical references (leaves 108-114).
Abstracts in English and Chinese.
Table of Contents --- p.i
Acknowledgement --- p.vi
Abstract --- p.vii
Abstract (Chinese) --- p.ix
Chapter Chapter One --- Introduction
Chapter 1.1. --- Pulmonary Route for Drug Delivery --- p.2
Chapter 1.2. --- Factors Affecting the Performance of Inhaled Formulations --- p.3
Chapter 1.2.1. --- Particle Aerodynamic Diameter --- p.4
Chapter 1.2.2. --- Dispersibility of Particles --- p.5
Chapter 1.2.3. --- Clearance Mechanism in Lung and Dissolution of Particles --- p.6
Chapter 1.3. --- Production of Dry Powder Inhalation by Spray Drying --- p.7
Chapter 1.4. --- Approaches to Enhance Aerosol Performance of Spray Dried Particles --- p.8
Chapter 1.4.1 --- Porous/Hollow Particles --- p.9
Chapter 1.4.2 --- Non-Porous Corrugated Particles --- p.10
Chapter 1.4.3 --- Blends and Ternary Systems --- p.10
Chapter 1.4.4 --- Surface Energy and Crystallinity Modification --- p.11
Chapter 1.4.5 --- Other Approaches to Enhancing Aerosol Performance --- p.12
Chapter 1.5 --- Objectives and Rationale of the Present Study --- p.13
Chapter 1.6 --- Scope of Present Study and Particle Characterization Techniques Employed --- p.14
Chapter 1.6.1 --- Microscopy and Particle Density Measurements --- p.14
Chapter 1.6.2 --- Particle Size Analysis and Particle Dispersibility --- p.15
Chapter 1.6.3 --- Thermal Analysis and Particle Crystallinity --- p.15
Chapter 1.6.4 --- Particle Surface Characterization --- p.16
Chapter 1.6.5 --- Inverse Gas Chromatography --- p.18
Chapter 1.6.6 --- Fractal Analysis --- p.19
Chapter 1.6.6.1 --- Background and Origin of Fractal Analysis --- p.19
Chapter 1.6.6.2 --- Use of Fractal Analysis in Pharmaceutical Research --- p.20
Chapter 1.6.6.3 --- Methods for fractal analysis --- p.21
Chapter 1.6.7 --- Atomic Force Microscopy --- p.23
Chapter 1.6.7.1 --- Background of Atomic Force Microscopy --- p.23
Chapter 1.6.7.2 --- Characterization of Surface Topography by Atomic Force Microscopy --- p.23
Chapter 1.6.7.3 --- Measurement of Interaction Forces by Colloid Probe 226}0Ø Microscopy --- p.25
Chapter 1.6.7.4 --- Use of Atomic Force Microscopy in Pharmaceutical Research --- p.27
Chapter Chapter Two --- Materials and Methods
Chapter 2.1. --- Materials --- p.30
Chapter 2.2. --- Equipment --- p.31
Chapter 2.3. --- Methods --- p.33
Chapter 2.3.1. --- Powder Preparation --- p.33
Chapter 2.3.1.1 --- Preparation of Salbutamol Sulphate Samples --- p.33
Chapter 2.3.1.2 --- Preparation of Disodium Cromoglycate Samples --- p.33
Chapter 2.3.1.3 --- Preparation of ß-Galactosidase (BG) Samples --- p.34
Chapter 2.3.2. --- Determination of Aerosol Performance --- p.35
Chapter 2.3.3. --- Determination of Protein Activity for BG Samples --- p.36
Chapter 2.3.3.1. --- Enzyme Assay Procedure --- p.37
Chapter 2.3.3.2. --- Calculation of Enzyme Activity --- p.38
Chapter 2.3.3.3. --- Determination of Enzyme Activity Retained in Spray-dried Samples --- p.38
Chapter 2.3.4. --- Physicochemical Characterization of Particles --- p.39
Chapter 2.3.4.1. --- Scanning Electron Microscopy --- p.39
Chapter 2.3.4.2. --- Particle Density Determination --- p.39
Chapter 2.3.4.3. --- Particle Size Analysis --- p.40
Chapter 2.3.4.4. --- Thermal analysis --- p.41
Chapter 2.3.4.5. --- Powder X-ray Diffraction --- p.42
Chapter 2.3.4.6. --- Surface Area Determination --- p.42
Chapter 2.3.4.7. --- Surface Composition Characterization --- p.43
Chapter 2.3.4.8. --- Surface Tension Measurement --- p.44
Chapter 2.3.4.9. --- Inverse Gas Chromatography --- p.45
Chapter 2.3.4.9.1. --- Calculation of Standard Free Energy of Adsorption --- p.46
Chapter 2.3.4.9.2. --- Calculation of Dispersive Component of Surface Free Energy --- p.47
Chapter 2.3.4.9.3. --- Determination of Specific Interactions and Associated Acid-Base Properties --- p.48
Chapter 2.3.4.10. --- Fractal Analysis --- p.49
Chapter 2.3.4.11. --- Atomic Force Microscopy --- p.49
Chapter Chapter Three --- Results
Chapter 3.1. --- In vitro Aerosol Performance --- p.52
Chapter 3.2. --- Enzyme Activity Retained in BG Samples --- p.55
Chapter 3.3. --- Scanning Electron Microscopy (SEM) --- p.56
Chapter 3.3.1. --- SEM of Salbutamol Sulphate Formulations --- p.56
Chapter 3.3.2. --- SEM of DSCG Formulations --- p.59
Chapter 3.3.3. --- SEM of BG Formulations --- p.61
Chapter 3.4. --- Density Measurements --- p.65
Chapter 3.4.1. --- Densities of Salbutamol Sulphate Formulations --- p.65
Chapter 3.4.2. --- Densities of DSCG Formulations --- p.66
Chapter 3.4.3. --- Densities of BG Formulations --- p.67
Chapter 3.5. --- Particle Size Analysis by Laser Diffraction --- p.68
Chapter 3.5.1. --- Volume Mean Diameter Measurements --- p.68
Chapter 3.5.2. --- Particle Size Distributions and Dispersion Patterns of Formulations --- p.70
Chapter 3.6. --- Thermal Analysis --- p.75
Chapter 3.7. --- Powder X-ray Diffraction --- p.80
Chapter 3.8. --- Surface Area Measurements --- p.84
Chapter 3.9. --- Surface Composition Characterization --- p.85
Chapter 3.9.1. --- Surface Composition of Salbutamol Sulphate Formulations --- p.85
Chapter 3.9.2. --- Surface Composition of DSCG Formulations --- p.88
Chapter 3.9.3. --- Surface Composition of BG/BSA Formulations --- p.89
Chapter 3.10. --- Surface Tension Measurements --- p.91
Chapter 3.11. --- Inverse Gas Chromatography --- p.92
Chapter 3.12. --- Fractal Analysis --- p.93
Chapter 3.13. --- Atomic Force Microscopy --- p.94
Chapter Chapter Four --- Discussion
Chapter 4.1. --- Influence of BSA on Aerosol Performance and Protein Integrity --- p.98
Chapter 4.2. --- Influence of BSA on Physicochemical Properties of Particles --- p.98
Chapter 4.2.1. --- Influence of BSA on surface corrugation --- p.98
Chapter 4.2.2. --- Influence of BSA on particle size and dispersion behavior --- p.99
Chapter 4.2.3. --- Influence of BSA on crystallinity and thermal properties of particles --- p.100
Chapter 4.2.4. --- Influence of BSA on surface energetics of particles --- p.100
Chapter 4.3. --- Relationship between Surface Corrugation and Aerosol Performance --- p.101
Chapter 4.4. --- Mechanism of Surface Modification for BSA on Spray-dried Particles --- p.103
Chapter Chapter Five --- Conclusions and Future Work
Chapter 5.1. --- Conclusions --- p.106
Chapter 5.1.1. --- General Aerosolization-Enhancing Effect of BSA --- p.106
Chapter 5.1.2. --- Surface Modifying Effect of BSA --- p.106
Chapter 5.1.3. --- Relationship between Surface Corrugation and Aerosol Performance --- p.106
Chapter 5.2. --- Future Work --- p.107
References --- p.108

No
Previously, dose emission below 30 L min(-1) through DPI has not been routinely determined. However, during routine use some patients do not achieve 30 L min(-1) inhalation flows. Hence, the aim of the present study was to determine dose emission characteristics for low inhalation flows from terbutaline sulphate Turbuhaler. Total emitted dose (TED), fine particle dose (FPD) and mass median aerodynamic diameter (MMAD) of terbutaline sulphate Turbuhaler were determined using inhalation flows of 10-60 L min(-1) and inhaled volume of 4 L. TED and FPD increase significantly with the increase of inhalation flows (p <0.05). Flows had more pronounced effect on FPD than TED, thus, faster inhalation increases respirable amount more than it increases emitted dose. MMAD increases with decrease of inhalation flow until flow of 20L min(-1) then it decreases. In vitro flow dependent dose emission has been demonstrated previously for Turbuhaler for flow rates above 30 L min(-1) but is more pronounced below this flow. Minimal FPD below 30 L min(-1) suggests that during routine use at this flow rate most of emitted dose will impact in mouth. Flow dependent dose emission results suggest that Pharmacopoeias should consider the use variety of inhalation flows rather than one that is equivalent to pressure drop of 4 KPa.

碩士
國立臺灣大學
生理學研究所
88
It was demonstrated previously that inhalation of citric acid aerosol induced noncholinergic airway constriction, which was suppressed by antioxidants, in guinea pigs. In this study, we attempted to examine the direct relationship between oxygen radicals and noncholinergic airway constriction. Guinea pigs were divided into two groups: control and dimethylthiourea (DMTU, 250 mg/kg, ip. ×3 days). DMTU is a hydroxyl radical scavenger. Each animal was anesthetized, cannulated, paralyzed, and artificially ventilated. Animals in each group were further separated into four subgroups: baseline, recovery 2-3 min, recovery 10 min, and recovery 20 min. In the first subgroup, we measured pulmonary function and collected bronchoalveolar lavage (BAL) fluid after surgical preparation. In the other three subgroups, we gave each animal citric acid aerosol inhalation (0.6 M, 4 ml/breath, 50 breaths) after measuring the baseline function, then we measured function again and collected BAL samples during 2-3, 10, or 20 min into the recovery period. Citric acid inhalation caused decreases in both dynamic compliance and maximal expiratory flow at 30 % vital capacity, two indices of bronchoconstriction, for at least 20 min in the control group. This airway constriction was totally blocked by DMTU. In addition, we detected significant increases in luminol-amplified t-butyl hydroperoxide-initiated chemiluminescence counts, an index of oxidative stress, in the BAL samples during the whole recovery period (at least 20 min) in the control group, but not in the DMTU group. On the contrary, substance P (SP) levels, an index of tachykinin releasing, in the BAL samples revealed an increasing tendency (without statistical significance) only during the early recovery period (2-3 min) in the control group. In addition, we found that the total cell numbers in the BAL were larger in the late recovery period (20 min) than either the baseline or the early recovery period, and differential cell counts revealed significant increase in neutrophil infiltration after citric acid aerosol inhalation. This inflammatory cell infiltration phenomenon was prevented by DMTU pretreatment. These results suggest that citric acid inhalation may induce an initial tachykinin release which, in turn, augments oxygen radicals production. We speculate that oxygen radicals cause a further neutrophil infiltration, which lead to continuous oxygen radical generation. Therefore, the continuous increase in oxygen radicals may be essential for the extended noncholinergic airway constriction.

碩士
國立臺灣大學
生理學研究所
90
Citric acid inhalation causes bronchoconstriction in guinea pigs, but the mechanism of this effect has not been fully clarified. We examined the role of bradykinin, mast cells and reactive oxygen species in citric acid-induced bronchoconstriction. Guinea pigs were divided into 7 groups: saline (SA) + SA; SA + citric acid (CA); bradykinin (BK) + CA; cromolyn sodium (CS) + CA; BK + CS + CA; compound 48/80 + CA; and compound 48/80 + BK + CA. Each animal was anesthetized, cannulated, paralyzed, and artificially ventilated. Bradykinin (0.1 nmol/kg) and cromolyn sodium (10 mg/kg) were intravenously injected 15 min prior to the citric acid aerosol inhalation. Compound 48/80 (total dose of 25 mg/kg s.c.), a mast cell degranulating agent, was given to the animals for 3 days before the study. All animals were pretreated with propranolol (1 mg/kg i.v.) and atropine (1 mg/kg i.v.) to block adrenergic and cholinergic neural effects, respectively. In addition, the animals were pretreated with indomethacin (5 mg/kg i.v.) and captopril (1 mg/kg i.v.) to avoid, respectively, the indirect effects of bradykinin by producing prostaglandins and the endogenous breakdown of bradykinin via angiotensin converting enzyme. Citric acid aerosol inhalation caused decreases in dynamic respiratory compliance, forced expiratory parameters and maximal expiratory flow at 50% vital capacity, indicating bronchoconstriction. This citric acid-induced airway constriction was significantly attenuated by cromolyn sodium and compound 48/80. We detected significant increase in lucigenin-initiated chemiluminescence counts of the bronchoalveolar lavage (BAL) sample in only the BK + CA group. On the contrary, substance P (SP) levels, an index of tachykinin releasing, in the BAL samples significantly increased 3 min into the recovery period in the SA+CA, BK+CA, BK+CS+CA, 48/80+CA and BK+48/80+CA groups. In addition, we found that the total cell numbers in the BAL significantly increased at 3 and 20 min of the recovery period, with a higher value at 20 min than that at 3 min. Differential cell counts revealed significant increase in neutrophil infiltration after citric acid aerosol inhalation. On the other hand, we found that the inflammatory cell infiltration in the lung tissue samples increased in the SA+CA group. In addition, we found also that mast cell counts in the lung tissue samples increased in the SA+CA group. These results suggest that bradykinin augments citric acid-induced superoxide production which, in turn, enhances mast cell-dependent noncholinergic bronchoconstriction.

Dry Powder inhalers (DPIs) have been one of the most promising developments in pulmonary drug delivery systems. In general, DPIs are more effective than systemic administrations and convenient to use. However, delivering high-dose antibiotics through a DPI is still a challenge because high powder load may need a very large inhaler or increase the incidence of local adverse effects. Spray drying has been increasingly applied to produce DPI formulations for high-dose antibiotics; nevertheless, many spray-dried particles are amorphous and physically unstable during storage, particularly under the humid environment.

My research focuses on addressing critical challenges in physical stability of DPIs for spray-dried high-dose antibiotics. The effects of moisture-induced crystallization on physical stability and aerosol performance of spray-dried amorphous Ciprofloxacin DPI formulations stored at different humidity conditions were studied. Our study not only provided a mechanistic understanding in the impact of crystallization on aerosol performance but also developed novel approaches for improving stability of spray-dried formulations used in DPI.

Our work has shown that recrystallization of amorphous spray-dried Ciprofloxacin led to significant changes in aerosol performance of DPIs upon storage, which cause critical quality and safety concerns. These challenges have been solved through co-spray-drying Ciprofloxacin with either excipient such as leucine or synergistic antibiotic like Colistin. Co-spray-drying Ciprofloxacin with Colistin not only improved physical and aerosol stability but also enhanced antibacterial activity which is a great advantage for treating ‘difficult to cure’ respiratory infections caused by multidrug resistant bacteria.

My research work is a sincere effort to maximize the utility and efficacy of high-dose DPI, an effective delivery tool for treating severe resistant bacterial respiratory infections.

Chan, Ka Man Carmen.
"October 2009."
Thesis (M.Phil.)--Chinese University of Hong Kong, 2010.
Includes bibliographical references (leaves 160-165).
Abstracts in English and Chinese.
Table of Contents --- p.I
Acknowledgements --- p.IV
Abstract --- p.V
Abstract (Chinese version) --- p.VIII
List of Figures --- p.X
List of Tables --- p.XVIII
Chapter Chapter One. --- Introduction
Chapter 1.1 --- Pulmonary drug delivery --- p.1
Chapter 1.2 --- Inhalation drug delivery systems --- p.4
Chapter 1.3 --- Dry powder inhalation aerosols --- p.5
Chapter 1.3.1 --- Principle of operation of DPIs --- p.5
Chapter 1.3.2 --- Aerodynamic diameter --- p.6
Chapter 1.3.2.1 --- Fine particle fraction --- p.8
Chapter 1.3.3 --- Dispersibility --- p.8
Chapter 1.3.4 --- Factors that affect dispersibility --- p.9
Chapter 1.3.4.1 --- Particle Size --- p.9
Chapter 1.3.4.2 --- Particle Density and Morphology --- p.10
Chapter 1.3.4.3 --- Interparticulate interactions一Cohesion and adhesion --- p.11
Chapter 1.3.4.3.1 --- Surface energetics --- p.11
Chapter 1.3.4.3.2 --- Effect of hygroscopicity and electrostatic charges --- p.12
Chapter 1.4 --- Particle formation techniques for DPI formulation --- p.14
Chapter 1.4.1 --- Spray-drying --- p.14
Chapter 1.4.2 --- Surface modification --- p.16
Chapter 1.5 --- Physical characterization --- p.17
Chapter 1.5.1 --- Laser diffraction --- p.17
Chapter 1.5.2 --- X-ray powder diffraction --- p.18
Chapter 1.5.3 --- Thermal analysis --- p.19
Chapter 1.5.4 --- Particle morphology and surface area --- p.20
Chapter 1.5.5 --- In vitro aerosol performance --- p.21
Chapter 1.6 --- Surface characterization --- p.21
Chapter 1.6.1 --- X-ray photoelectric spectroscopy (XPS) --- p.21
Chapter 1.6.2 --- Inverse gas chromatography --- p.22
Chapter 1.7 --- Atomic force microscopy in pharmaceutical science --- p.23
Chapter 1.7.1 --- Principle of operation --- p.24
Chapter 1.7.1.1 --- Tapping mode --- p.27
Chapter 1.7.1.2 --- Contact mode --- p.27
Chapter 1.8 --- Scope of thesis --- p.29
Chapter Chapter Two. --- Materials and Methods
Chapter 2.1 --- Materials --- p.32
Chapter 2.2 --- Methods --- p.32
Chapter 2.2.1 --- Optimization of spray-drying parameters --- p.32
Chapter 2.2.2 --- Preparation of spray-dried salbutamol sulphate powders containing different concentrations of amino acid additive --- p.33
Chapter 2.2.3 --- Physical characterization of spray-dried powders --- p.34
Chapter 2.2.3.1 --- Particle size and size distribution --- p.34
Chapter 2.2.3.2 --- Specific surface area --- p.35
Chapter 2.2.3.3 --- X-ray powder diffraction --- p.35
Chapter 2.2.3.4. --- Scanning electron microscopy --- p.36
Chapter 2.2.3.5. --- Thermal analysis --- p.36
Chapter 2.2.3.5.1 --- Thermogravimetric analysis (TGA) --- p.36
Chapter 2.2.3.5.2 --- Differential scanning calorimetry (DSC) --- p.36
Chapter 2.2.3.6 --- Water vapour sorption isotherm --- p.37
Chapter 2.2.3.7 --- Density measurements --- p.37
Chapter 2.2.3.8 --- In vitro particle deposition (MSLI) --- p.38
Chapter 2.2.4 --- Surface characterization of the spray-dried powders --- p.39
Chapter 2.2.4.1 --- X-ray photoelectric spectroscopy (XPS) --- p.39
Chapter 2.2.4.2 --- Surface energy measurement by inverse gas chromatography (IGC) --- p.40
Chapter 2.2.4.2.1 --- Calculation of standard free energy of adsorption --- p.41
Chapter 2.2.4.2.2 --- Dispersive component of surface free energy and related thermodynamic parameters --- p.42
Chapter 2.2.4.2.3 --- Specific interactions and associated acid-base properties --- p.43
Chapter 2.2.5. --- Atomic Force Microscopy (AFM) --- p.43
Chapter 2.2.5.1. --- Imaging --- p.43
Chapter 2.2.5.2. --- Force measurements --- p.44
Chapter 2.2.5.2.1 --- Adhesion force measurements --- p.44
Chapter 2.2.5.2.2 --- Force curve data conversions --- p.44
Chapter Chapter Three. --- "Optimal Spray-drying Conditions, Physical Characterization and Aerosol Performance of Additive-modified Spray-dried Salbutamol Sulphate particles"
Chapter 3.1 --- Optimization of spray-drying conditions --- p.46
Chapter 3.2 --- Effect of phenylalanine on the spray-dried SS particles --- p.52
Chapter 3.2.1. --- Phenylalanine as the additive --- p.52
Chapter 3.2.1.1 --- In vitro aerosol performance --- p.53
Chapter 3.2.1.2 --- Particle morphology --- p.55
Chapter 3.2.1.3 --- Crystallinity --- p.62
Chapter 3.2.1.4 --- Particle size distribution and specific surface area --- p.63
Chapter 3.2.1.5 --- Density --- p.65
Chapter 3.2.1.6 --- Thermal analysis --- p.66
Chapter 3.2.1.7 --- Water vapour isotherm --- p.70
Chapter 3.3 --- Effect of leucine on the spray-dried SS particles --- p.77
Chapter 3.3.1. --- L-Leucine as the additive --- p.77
Chapter 3.3.1.1 --- In vitro aerosol performance --- p.78
Chapter 3.3.1.2 --- Particle morphology --- p.80
Chapter 3.3.1.3 --- Crystallinity --- p.86
Chapter 3.3.1.4 --- Particle size distribution and specific surface area --- p.87
Chapter 3.3.1.5 --- Density --- p.90
Chapter 3.3.1.6 --- Thermal analysis --- p.92
Chapter 3.3.1.7 --- Water vapour isotherm --- p.95
Chapter Chapter Four. --- Surface Characterization of Additive-modified Spray-dried Salbutamol Sulphate Particles
Chapter 4.1 --- X-ray photoelectric spectroscopy --- p.103
Chapter 4.1.1 --- Phenylalanine --- p.103
Chapter 4.1.2 --- Leucine --- p.104
Chapter 4.2 --- Inverse gas chromatography --- p.105
Chapter 4.2.1 --- Phenylalanine --- p.105
Chapter 4.2.2 --- Leucine --- p.107
Chapter 4.3 --- Atomic force microscopy --- p.109
Chapter 4.3.1 --- Surface topography --- p.109
Chapter 4.3.2 --- Adhesive force measurements --- p.118
Chapter Chapter Five. --- Conclusions and Suggestions for Future Works
Chapter 5.1 --- Conclusions --- p.139
Chapter 5.1.1 --- Physical properties --- p.139
Chapter 5.1.2 --- Surface characteristics and aerosol performance --- p.140
Chapter 5.2 --- Future studies --- p.142
Appendix --- p.143
References --- p.160