Targeting inhaled steroids

Asthma is a disease of the entire respiratory tract and successful asthma therapy requires drug delivery throughout the large and small airways. The most commonly prescribed inhaled corticosteroid for the treatment of asthma is beclomethasone dipropionate (BDP) delivered by a metered-dose inhaler (MDI) containing chlorofluorocarbons (CFCs). CFC-BDP MDIs produce relatively large particles and when used optimally deposit less than 10% of the dose in the lungs, primarily in the large airways, with more than 90% being deposited in the oropharynx. The new hydrofluoroalkane (HFA)-BDP inhaler developed by 3M Pharmaceuticals (Qvar) delivers a particle size of approximately 1.1 microns. Animal and mechanical models predict more than 50% lung deposition with this formulation. Clinical results, with radiolabelled Qvar in patients with asthma and volunteers, have demonstrated that 50-60% of the dose is deposited throughout the airways with approximately 30% being deposited in the oropharynx. 3M Pharmaceuticals have developed the breath-actuated Autohaler which provides the same lung deposition as an optimally used Qvar MDI by automatically delivering the drug very early in the inhalation. Neither device routinely requires the use of a spacer.