Controlled release in inhalation

Increasingly complicated medication regimens associated with the necessity of the repeated dosing of multiple agents used in treating pulmonary disease has been shown to compromise both disease management and patient convenience. In this study the viability of spray drying to introduce controlled release vectors into dry powders for inhalation was investigated. The first experimental section highlights the use of leucine in producing highly respirable spray dried powders, with in vitro respirable fractions (Fine particle fraction, FPF: F < 5µm) exceeding 80% of the total dose. The second experimental chapter introduces the biocompatible polymer chitosan (mw 190 – 310 kDa) to formulations containing leucine with findings of increased FPF with increasing leucine concentration (up to 82%) and the prolonged release of the active markers terbulataline sulfate (up to 2 hours) and beclometasone dipropionate (BDP: up to 12 hours) with increasing chitosan molecular weight. Next, the thesis details the use of a double emulsion format in delivering the active markers salbutamol sulfate and BDP at differing rates; using the polymers poly-lactide co-glycolide (PLGA 50:50 and PLGA 75:25) and/or chitosan incorporating leucine as an aerosolisation enhancer the duration of in vitro release of both agents reaching 19 days with FPF exceeding 60%. The final experimental chapter involves dual aqueous and organic closed loop spray drying to create controlled release dry powders for inhalation with in vitro sustained release exceeding 28 days and FPF surpassing 55% of total loaded dose. In conclusion, potentially highly respirable sustained release dry powders for inhalation have been produced by this research using the polymers chitosan and/or PLGA as drug release modifiers and leucine as an aerosolisation enhancer.

Physicochemical characteristics of chlorofluorohydrocarbon based inhalation aerosols

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.

Development of a co-culture model of the human lungs for toxicity testing and identification of biomarkers of inhalation toxicity

The airway epithelium is the first point of contact in the lung for inhaled material, including infectious pathogens and particulate matter, and protects against toxicity from these substances by trapping and clearance via the mucociliary escalator, presence of a protective barrier with tight junctions and initiation of a local inflammatory response. The inflammatory response involves recruitment of phagocytic cells to neutralise and remove and invading materials and is oftern modelled using rodents. However, development of valid in vitro airway epithelial models is of great importance due to the restrictions on animal studies for cosmetic compound testing implicit in the 7th amendment to the European Union Cosmetics Directive. Further, rodent innate immune responses have fundamental differences to human. Pulmonary endothelial cells and leukocytes are also involved in the innate response initiated during pulmonary inflammation. Co-culture models of the airways, in particular where epithelial cells are cultured at air liquid interface with the presence of tight junctions and differentiated mucociliary cells, offer a solution to this problem. Ideally validated models will allow for detection of early biomarkers of response to exposure and investigation into inflammatory response during exposure. This thesis describes the approaches taken towards developing an in vitro epithelial/endothelial cell model of the human airways and identification biomarkers of response to exposure to xenobiotics. The model comprised normal human primary microvascular endothelial cells and the bronchial epithelial cell line BEAS-2B or normal human bronchial epithelial cells. BEAS-2B were chosen as their characterisation at air liquid interface is limited but they are robust in culture, thereby predicted to provide a more reliable test system. Proteomics analysis was undertaken on challenged cells to investigate biomarkers of exposure. BEAS-2B morphology was characterised at air liquid interface compared with normal human bronchial epithelial cells. The results indicate that BEAS-2B cells at an air liquid interface form tight junctions as shown by expression of the tight junction protein zonula occludens-1. To this author’s knowledge this is the first time this result has been reported. The inflammatory response of BEAS-2B (measured as secretion of the inflammatory mediators interleukin-8 and -6) air liquid interface mono-cultures to Escherichia coli lipopolysaccharide or particulate matter (fine and ultrafine titanium dioxide) was comparable to published data for epithelial cells. Cells were also exposed to polymers of “commercial interest” which were in the nanoparticle range (and referred to particles hereafter). BEAS-2B mono-cultures showed an increased secretion of inflammatory mediators after challenge. Inclusion of microvascular endothelial cells resulted in protection against LPS- and particle- induced epithelial toxicity, measured as cell viability and inflammatory response, indicating the importance of co-cultures for investigations into toxicity. Two-dimensional proteomic analysis of lysates from particle-challenged cells failed to identify biomarkers of toxicity due to assay interference and experimental variability. Separately, decreased plasma concentrations of serine protease inhibitors, and the negative acute phase proteins transthyretin, histidine-rich glycoprotein and alpha2-HS glycoprotein were identified as potential biomarkers of methyl methacrylate/ethyl methacrylate/butylacrylate treatment in rats.

Dry powder inhalation of macromolecules using novel PEG-co-polyester microparticle carriers

This study investigated optimizing the formulation parameters for encapsulation of a model mucinolytic enzyme, a-chymotrypsin (a-CH), within a novel polymer; poly(ethylene glycol)-co-poly(glycerol adipate-co-?-pentadecalactone), PEG-co-(PGA-co-PDL) which were then applied to the formulation of DNase I. a-CH or DNase I loaded microparticles were prepared via spray drying from double emulsion (w(1)/o/w(2)) utilizing chloroform (CHF) as the organic solvent, l-leucine as a dispersibility enhancer and an internal aqueous phase (w(1)) containing PEG4500 or Pluronic(®) F-68 (PLF68). a-CH released from microparticles was investigated for bioactivity using the azocasein assay and the mucinolytic activity was assessed utilizing the degradation of mucin suspension assay. The chemical structure of PEG-co-(PGA-co-PDL) was characterized by (1)H NMR and FT-IR with both analyses confirming PEG incorporated into the polymer backbone, and any unreacted units removed. Optimum formulation a-CH-CHF/PLF68, 1% produced the highest bioactivity, enzyme encapsulation (20.08±3.91%), loading (22.31±4.34µg/mg), FPF (fine particle fraction) (37.63±0.97%); FPD (fine particle dose) (179.88±9.43µg), MMAD (mass median aerodynamic diameter) (2.95±1.61µm), and the mucinolytic activity was equal to the native non-encapsulated enzyme up to 5h. DNase I-CHF/PLF68, 1% resulted in enzyme encapsulation (17.44±3.11%), loading (19.31±3.27µg/mg) and activity (81.9±2.7%). The results indicate PEG-co-(PGA-co-PDL) can be considered as a potential biodegradable polymer carrier for dry powder inhalation of macromolecules for treatment of local pulmonary diseases.

Pharmaceutical inhalation aerosols: their delivery and therapeutic applications

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Synchronous Oral Paracoccidioidomycosis And Pulmonary Tuberculosis In An Immunocompetent Patient.

Paracoccidioidomycosis (PCM) and tuberculosis (TB) are chronic granulomatous infectious diseases, in which the main form of contraction is through inhalation of the microorganism-Paracoccidioides brasiliensis and Mycobacterium tuberculosis. Oral involvement of PCM is observed in up to 70 % of the cases and usually presents clinically as ulcerations with granular surface showing tiny hemorrhagic areas. Oral presentation of TB is rare with prevalence smaller than 0.5 % of all cases. Clinical presentation of oral TB mainly consists of single ulcers with irregular limits and necrotic base. A 70-year-old immunocompetent man presented simultaneously oral PCM and pulmonary TB. Medical history revealed a previous diagnosis of pulmonary TB; however, even under treatment for TB, the patient remained with oral lesions and intense pulmonary fibrosis. The physician requested P. brasiliensis serological analysis, which resulted positive. Although the combination of PCM and TB has been reported in the literature, it is still considered an uncommon condition and their diagnosis may represent a challenge to healthcare professionals because of the similarity between their clinical and radiological presentations.

Efeito da oxigenoterapia hiperbárica: relato de caso de paciente com síndrome hepato-pulmonar em lista de espera para transplante hepático

INTRODUÇÃO: As doenças hepáticas apresentam índices de morbidade e mortalidade elevados e quando em estágio avançado têm o transplante do fígado como forma de tratamento potencialmente curativo e eficaz, embora este não possa ser oferecido a todos os pacientes. Isso faz com que essas doenças sejam consideradas problema de saúde pública em todo o mundo. Os cuidados clínicos para manter o paciente com condições de esperar e suportar o transplante continua um desafio. RELATO DO CASO: Mulher com 65 anos de idade, procedente do Recife, com diagnóstico de cirrose hepática secundária a vírus C apresentava dispnéia importante aos mínimos esforços tendo PaO2 de repouso de 60 mmHg e O2 de 90%, com espirometria normal. Realizou eco-Doppler que evidenciou shunt pulmonar importante. Durante a triagem em lista de transplante (MELD de 16 em agosto de 2006) foi optado pelo início de sessões de oxigenioterapia em câmara hiperbárica a fim de melhorar a sintomatologia respiratória da síndrome hepato-pulmonar. Apresentava melhora substancial da tolerância ao exercício após a terapia hiperbárica, assim como os valores do PaO2 à gasometria. Realizou 10 sessões de oxigenioterapia em câmara hiperbárica. Realizou transplante hepático em outubro de 2007 e vem em acompanhamento ambulatorial com boa evolução e melhora substancial da dispnéia. CONCLUSÃO: Constatou-se melhora da condição hepato-pulmonar após oxigenoterapia hiperbárica. Desta forma, ela surge como mais uma ferramenta para o tratamento das doenças hepáticas, devendo ser realizados outros estudos que avaliem sua utilização clínica.

Drug consumption among medical students in São Paulo, Brazil: influences of gender and academic year

OBJECTIVE: To analyze alcohol, tobacco and other drug use among medical students. METHOD: Over a five-year period (1996-2001), we evaluated 457 students at the Universidade de São Paulo School of Medicine, located in São Paulo, Brazil. The students participated by filling out an anonymous questionnaire on drug use (lifetime, previous 12 months and previous 30 days). The influence that gender and academic year have on drug use was also analyzed. RESULTS: During the study period, there was an increase in the use of illicit drugs, especially inhalants and amphetamines, among the medical students evaluated. Drug use (except that of marijuana and inhalants) was comparable between the genders, and academic year was an important influencing factor. DISCUSSION: Increased inhalant use was observed among the medical students, especially among males and students in the early undergraduate years. This is suggestive of a specific behavioral pattern among medical students. Our findings corroborate those of previous studies. CONCLUSION: Inhalant use is on the rise among medical students at the Universidade de São Paulo School of Medicine. Because of the negative health effects of illicit drug use, further studies are needed in order to deepen the understanding of this phenomenon and to facilitate the development of preventive measures.

Infecção por C. psittaci: uma revisão com ênfase em psitacídeos

A clamidiose ou ornitose é uma doença infecciosa, causada pela bactéria Chlamydophila psittaci, que acomete aves e mamíferos. Trata-se de uma das principais zoonoses de origem aviária. A transmissão ocorre principalmente por inalação de secreções contaminadas. Os sinais clínicos mais comuns incluem alterações no sistema gastrointestinal, respiratório e ocular, porém é possível encontrar aves infectadas sem sinais aparentes, dificultando a identificação da doença. O diagnóstico definitivo em aves vivas pode ser difícil, devido às características da infecção pela bactéria. Há duas principais abordagens para o diagnóstico, a primeira envolve a detecção direta da bactéria e a segunda implica a detecção de anticorpos anti-Chlamydophila sp. O tratamento é longo e envolve o uso de tetraciclinas, quinolonas ou macrolídeos, durante 21-45 dias, dependendo da espécie e do fármaco de escolha. Atualmente, o Brasil não dispõe de medidas padronizadas que visam a guiar o clínico na identificação, manejo e tratamento para a doença. Tais medidas tornam-se necessárias, bem como a pesquisa de novos métodos diagnósticos e auxiliares para a doença.