The goal of inhaled corticosteroid therapy is the targeted delivery of drug into the lung to achieve distinct pulmonary effects with reduced systemic side effects. Pharmacokinetic/pharmacodynamic assessment of pulmonary delivery suggests that an ideal inhaled corticosteroid and/or its delivery system should have the following characteristics: high pulmonary deposition efficiency, low oral bioavailability, high systemic clearance, optimized pulmonary residence time, and selective binding to the glucocorticoid receptor. Therefore, future developments will focus on improved delivery devices with higher pulmonary deposition; drugs or drug formulations providing prolonged pulmonary residence time (e.g., use of liposomes, microspheres, and nanothin coatings, or use of biological systems that achieve prolonged pulmonary residence time by ester formation and reactivation); drugs with efficient systemic clearance (e.g., soft drugs/hydrolyzable drugs); and/or improved pharmacodynamic selectivity.