Browsing by Subject "Pulmonary drug delivery"
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Item Dry powder antibiotics for inhaled anti-tuberculosis therapy(2010-12) Son, Yoen Ju; McConville, Jason Thomas; McGinity, James W.; Williams, Robert O.; Wiederhold, Nathan; Roy, KrishnenduThe aim of this research was to develop and fully investigate a novel method of antibiotic drug delivery to the lung that will address problems with current therapeutic regimens for treatment of airway infections. To demonstrate the performance of prepared formulations, the design of suitable characterization methods were also aimed. A novel dissolution method for evaluating the in vitro dissolution behavior of inhalation formulations was developed. The membrane holder was designed to enclose previously air-classified formulations so that they could be uniformly tested in the dissolution apparatus. Dissolution procedures, the apparatus, the dose collection, the medium, and test conditions were developed and the dissolution behaviors of test compounds were evaluated by experimental and mathematical analysis. It was proved that the aerodynamic separation of formulation prior to dissolution assessment have a significant influence on the dissolution profiles. The optimized test method using the membrane holder was applied to evaluate in vitro dissolution profiles of the manufactured formulations of rifampicin (RF). The carrier/excipient-free RF dry powder formulation was investigated. The rifampicin dihydrate (RFDH) powders having MMAD of 2.2 um were prepared using a simple recrystallization process. The RFDH powders have a thin flaky structure, and this unique morphology provides improved aerosolization properties at maximal API loading. The manufactured RFDH formulation showed 80% drug release within 2 hours. To retard the release rate of RF, the prepared RFDH crystals were coated with hydrophobic polymer, PLA or PLGA, using spray-dryer equipped with multi-channel spray nozzles. The multi-channel spray nozzle used in this study has two separate nozzles for aqueous solution and one for gas fluid. The RFDH crystals and the coating solutions were sprayed through the two separate liquid nozzles at the same time. The coated RFDH formulations were prepared using multi-channel spray nozzles. The coated formulations contained at least 50% w/w of RF with no change of their flaky morphology. The initial RF release was lowered by coating; the lowest initial RF release was observed from the coated powders with PLA polymer as 32% among the coated formulations. Overall, the 80% of RF was released within 8 hours. The RFDH and coated RFDH formulations delivered via the pulmonary route would be anticipated to provide higher local (lung) drug concentrations than that of orally delivered powders. Particularly, the coated RFDH powders deposited in the alveolar region may prolong the drug residence time in the site of infections. Additionally, it was proved that the RFDH and coated RFDH formulations provided much better stability than the amorphous RF.Item Influence of carrier particle size and surface roughness on the aerosol performance of DPI formulations(2011-08) Donovan, Martin Joseph; Smyth, Hugh D. C.The influence of the size and morphology of carrier particles on drug dispersion performance from passive dry powder inhalers has been extensively studied topic, and a consensus has been reached regarding the adverse effect that larger carrier particle diameters impart to aerosol performance. However, previous studies have generally employed only a few carrier particle size fractions, generally possessing similar surface characteristics. Accordingly, theories developed to explain the influence of the physical characteristics of carrier particles on performance relied heavily on both extrapolation and interpolation. To fill in the gaps from the literature and simultaneously evaluate the influence of carrier particle size and morphology, a comprehensive study was undertaken using 4 lactose grades, each sieved into 13 contiguous sizes, to prepare 52 formulations incorporating a unique lactose grade-size population. The aerosol performance results indicated that large carrier particles possessing extensive surface roughness can improve drug dispersion, in contrast to what has been previously reported. It is proposed that this may be attributed to mechanical detachment forces arising from collisions between the carrier particle and inhaler during actuation. Based on these observations, a novel dry powder inhaler platform was developed, employing carrier particles much larger (> 1 mm) than previously explored in both the scientific and patent literature. Optimization of this technology required the judicious selection of a carrier material, and following an extensive screening process, low-density polystyrene was selected as a model candidate. Given its low mass, diameters in excess of 5-mm could be employed as carriers while still generating high detachment forces. To minimize drug particle aggregation, a novel drug-coating method employing piezo-assisted particle dispersion was developed to compensate for the reduced surface area of the novel carrier particles. In addition, the selection of a suitable inhalation device prototype was instrumental to the overall performance of the technology. In vitro testing of the novel large carrier particles yielded emitted fractions in excess of 85%, and overall drug delivery of up to 69% of the nominal dose.