IMPROVED DELIVERY OF INHALED STEROIDS TO THE LARGE AND SMALL AIRWAYS

The reformulation of asthma medications with non-ozone depleting prope llants such as hydrofluoroalkane-134a (HFA) has provided the opportuni ty to apply new knowledge and inhaler technology to improve significan tly the delivery of aerosol drugs to the respiratory tract. Beclometha sone dipropionate (BDP), the most commonly prescribed inhaled corticos teroid for asthma therapy, is effective therapy; however, currently av ailable chlorofluorocarbon (CFC)-BDP metered desk inhalers typically d eliver no more than 10% of the inhaled drug to the lungs with the rema inder deposited in the oropharynx. Compared with an average particle s ize of 3.5-4.0 mu m for CFC-BDP, the new HFA-BDP formulation has an av erage particle size of 1.1 mu m and a respirable fraction of approxima tely 60%. The lung deposition of Tc-99m-radiolabelled HFA-BDP has been investigated in healthy volunteers and patients with asthma. Results showed that the HFA-BDP formulation reverses the pattern of distributi on seen with CFC-BDP products, delivering most of the dose of inhaled steroid directly to the lungs rather than to the oropharynx and gut wh ere it may lead to unwanted side-effects. As such, HFA-BDP is likely t o achieve equivalent efficacy to existing CFC-BDP formulations with lo wer doses and with reduced potential for local adverse effects.