Effect of formulation parameters on hydrofluoroalkane-beclomethasone dipropionate drug deposition in humans

Chlorofluorocarbon metered dose inhalers (MDIs) and dry powder inhalers currently deliver drug that deposits primarily in the oropharynx and secondarily in the large central airways. Chlorofluorocarbon-beclomethasone dipropionate (CFC-BDP) MDIs deliver more than 90% of the drug in the oropharynx and less than 10% in the lungs. The elimination of chlorofluorocarbons from MDIs provided the opportunity to more optimally target corticosteroids directly to all inflammatory sites. Hydrofluoroalkane-BDP (HFA-BDP) MDIs (QVAR(trade mark)) deliver 50% to 60% of the drug to the lungs with approximately 30% delivered to the mouth. Additionally, the amount of drug delivered to the lungs is distributed throughout the large, intermediate, and small airways. Radiolabeled deposition studies have shown that the HFA-BDP MDI is a "forgiving" aerosol in that even the extreme discoordinated use of the press and breathe MDI still resulted in more than 30% lung deposition. The breath-actuated Autohaler inhaler provided the same lung deposition as an optimally used press and breathe MDI. The dose delivered from either the press and breathe HFA-BDP MDI or the Autohaler was consistent across a wide range of inspiratory flows (eg, flows of 26-137 L/min). Clinical studies have shown that the improvements in lung deposition of HFA-BDP result in equivalent efficacy at approximately one half of the total daily dose compared with current CFC-BDP products.