Pulmonary drug delivery deposition

An ideal in vitro model for the characterization of aerosol formulations would incorporate cell types from various regions of the lung (tracheal, bronchial, and alveolar) and would facilitate simulation of deposition mechanisms by impaction, sedimentation, and diffusion of a high-metered singlebolus inhalation. In the future, such systems may reduce the need for animal studies and may offer to correlate in a predictive way the results from such in vitro tests to clinical bioavailability data after pulmonary drug delivery in vivo. 

During normal nose breathing the majority of inhaled environmental particles are deposited in the nose and pharynx, as described in Chapter 9 (Section 9.2). Hence for pulmonary drug delivery, the aerosols are inhaled via the mouth. 

Fig. 16 shows representative scintigraphic images from both the DPI and the EHD pulmonary drug delivery device. It can be seen that the EHD pulmonary drug delivery device produced a uniform deposition distribution through the lung field with only... 

The pharmacokinetic/dynamic parameters involved in pulmonary drug delivery of glucocorticoids have been reviewed. Among these, low oral bioavailability, high pulmonary deposition, pronounced clearance, and sustained pulmonary release are the most important parameters to be considered. 

Deposition mechanisms Inhalation manoeuvre Pulmonary administration Pulmonary drug delivery Therapeutic aerosol Biopharmaceutics Particle size Dry powder inhaler Metered-dose inhaler Nebuhser Novel liquid inhaler... 

Drug delivery to the respiratory tract has been characterized in the past decade by an increase in knowledge of drug droplet or particle manufacture, behavior, aerosol dispersion, lung deposition and clearance. The number of diseases for which aerosol therapy may be applicable has increased dramatically. The pharmaceutical scientist is no longer limited to pulmonary diseases as therapeutic targets. Substantial progress has been made in every area of pharmaceutical aerosol science, and it is anticipated that this will ultimately lead to many new therapies. 

J. Talton, G. Hochhaus, J. Fitz-Gerald, and R. Singh. Pulsed laser deposited polymer films onto pulmonary dry powders for improved drug delivery. MRS 1998 Fall Meeting, Boston, 1998, p. 597. 

Taylor, G. Colthorpe, P. Farr, S.J. Pulmonary absorption of proteins influence of deposition site and competitive elimination processes. In Respiratory Drug Delivery /V Byron, P.R., Dalby, R.N., Farr, S.J., Eds. Interpharm Press, Inc. Buffalo Grove, IL, 1994 25-30. 

In humans, the pulmonary drug deposition of HFA-beclometasone is superior to CFC-beclometasone and is improved by 10-fold in some studies (Sears 1995). Equivalent improvements in asthma control are seen with half of the daily dose of HFA-beclometasone compared with CFC-beclometasone. The greater systemic availability of HFA-beclometasone does not increase adrenal suppression the adrenal effects and acute local tolerability are comparable to that of the CFC formulation at the same dose. Equivalent efficacy at a lower dose and equivalent safety at the same dose indicate a more favorable risk-benefit ratio for HFA-beclometasone. Comparative studies of HFA- and CFC-beclometasone have not been performed in horses. In theory, the enhanced drug delivery and efficacy of HFA-beclometasone may explain, in part, why relatively low doses of beclometasone are therapeutically effective in heaves-affected horses, compared with standard therapeutic doses in asthmatic humans. 

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