Powder delivery system

Developing an appropriate drug delivery system for a given drug can completely alter the drug s unfavorable properties, such as improve its effectiveness or reduce its side effects. Dry powder delivery systems such as microspheres are of special interest. In the last two decades they have been extensively studied with respect to nasal delivery and a considerable number of studies have been reported on that subject [3,23],... 

Microspheres intended for nasal administration need to be well characterized in terms of particle size distribution, since intranasal deposition of powder delivery systems is mostly determined by their aerodynamic properties and particle sizes. Commonly used methods for particle size determinations described in the literature are sieving methods [108], light microscopy [58], photon correlation spectroscopy [66], and laser diffractometry [25,41,53,93], The morphology of the microparticles (shape and surface) has been evaluated by optical, scanning, and transmission electron microscopy [66, 95],... 

Potential solutions to these challenges to ensure effective inhalation drug treatment include active dry powder delivery systems, active liquid blister technology, and hydrofiuorocarbon (HFC) propellant nebulization systems. 

Pulmonary delivery of insulin for systemic absorption in the treatment of diabetes has been studied extensively since the early days of insulin discovery almost a century ago. Colthorpe et al. and Pillai et al. demonstrated in rabbit and monkey models, respectively, that the deeper into limg the dose of insulin was delivered, the higher was the bioavailability. The work of Laube, Benedict, and Dobs showed the need to achieve deep pulmonary deposition of this molecule for efficient absorption in humans. Handheld liquid and dry powder delivery systems have been developed to generate insulin-containing aerosols with the majority of the particles in the aerodynamic size range 1-3 pm. The relative bioavailability compared with subcutaneous injection based on the insulin contained in the dosage form was 110/ [52] powder system and for the aqueous-based... 

The development of multidose DPIs was pioneered by A. B. Draco (now a division of AstraZeneca) with their Turbuhaler [53]. This device is truly a metered-dose powder delivery system. The drug is contained within a storage reservoir and can be dispensed into the dosing chamber by a simple back-and-forth twisting action on the base of the unit (Fig. 7). The device is capable of working at moderate flowrates and also delivers carrier-free particles [54]. However, one of the drawbacks of the Turbuhaler has been the fact that it has... 

Muddle, A.G., Longridge, D.J., Sweeney, P.A., Burkoth, XL. and Bellhouse, B.J. (1997) Transdermal delivery of testosterone to conscious rabbits using powderject (R) a supersonic powder delivery system . Proc. Int. Symp. Control. Release. Bioact. Mat. 24, 713. 

Typical Class I devices include powder delivery systems to the lungs such as the Spinhaler, Rotahaler, Diskhaler, spacers which are used in conjunction with a drug and are part of a drug submission. Typical Class Ha devices include power operated nebuliser systems which are usually sold separate to the drug. 

Shock Tube as Vaccine Delivery System A unique form of powder delivery system, a biolistic system, has been developed [19]. This novel technology accelerates microparticles by a gas flow behind a traveling shockwave, so that they can attain sufficient momentum to penetrate the skin and thus achieve a pharmacological effect. One of the most recent developments is a mouse biolistic system, used in immunological studies. These studies require powdered vaccine to be delivered into the epidermis of the mouse with a narrow and highly controllable velocity distribution and a uniform spatial distribution. The preliminary results demonstrate the overall capability of a newly designed supersonic nozzle to deliver the particles to the skin targets with a more uniform velocity and spatial distribution. CTD has been utihzed to characterize the complete operation of a prototype mouse biolistic system. 

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