Characteristics influencing the effective administration of drugs as inhalation aerosols

Clinical Considerations in the Use of Inhalation Delivery Devices

Medications delivered through oral inhalation represent the cornerstone of pharmacotherapy for asthma and chronic obstructive pulmonary diseases. Several options exist as methods of delivering aerosols to the lung, including metered-dose inhalers, metered-dose inhalers attached to spacers or valved holding chambers, dry powder inhalers, and nebulizers. Delivery of aerosols to the lung is affected by numerous factors including characteristics of aerosol particles, patients’ ventilatory patterns, and physical condition of the lung. It has become increasingly clear that the device used to deliver the medication is an important factor in the extent of deposition and the ultimate therapeutic effect. Further, the same therapeutic agent may exhibit differing effects depending on which delivery device is used. Each inhalation device has specific instructions for use, and the techniques for use vary significantly among the available products. In each case, patients should be instructed and observed to ensure that they have the proper technique of use to achieve an optimal effect.

Efficacy of inhaled fluticasone propionate in asthma results from topical and not from systemic activity

The objective of this study was to determine whether the therapeutic benefits of inhaled fluticasone propionate are mediated through topical or systemic effects. Two hundred seventy-four patients with asthma receiving beclomethasone dipropionate or triamcinolone acetonide during a 2-wk, single-blind, run-in period were randomized to inhaled fluticasone propionate powder 100 or 500 micrograms twice daily, oral fluticasone propionate 20 mg once daily, or placebo during a 6-wk treatment period. Patients receiving inhaled fluticasone propionate had a significantly greater probability of remaining in the study over time compared with patients receiving oral fluticasone propionate or placebo (p = 0.001). FEV1 and PEF rates at end point were significantly higher with inhaled fluticasone propionate treatment regimens than with oral fluticasone propionate (with the exception of PEF rates for inhaled fluticasone propionate 100 micrograms) or placebo treatments (p < or = 0.004). Systemic exposure to fluticasone propionate as assessed by trough plasma concentrations and/or 12-hr plasma concentration area under the curve analyses (AUC12) was higher with the oral fluticasone propionate than with the two inhaled fluticasone propionate treatment groups. The results of this study suggest that the therapeutic benefits of inhaled fluticasone propionate are mediated through topical effects in the lungs and not through systemic effects.