Pharmacological factors that influence the choice of inhaled corticosteroids.

Local therapeutic effect relative to the risk of adverse effects of inhaled drugs, i.e. airway selectivity, is determined by the efficiency of the delivery system and the physicochemical and pharmacokinetic properties of the drug molecule. For the inhaled corticosteroid formulations, many of the pharmacokinetic prerequisites for airway selectivity have been fulfilled, but there are still differences that may influence the choice of treatment regimens. This choice should be based on disease severity, age, inhalation technique, preference and expected compliance, together with a knowledge of individual features of different corticosteroid formulations. Simple to use, hand-held pressurised or breath-actuated inhalers have favourable lung deposition properties and are appropriate for most patients. For small children or severely ill patients, nebulised treatment or spacers may be advocated. A corticosteroid formulation with a high intrinsic activity and long duration of action allows for once-daily administration in some patient groups. These properties may also partly compensate for noncompliance when more frequent administration schemes are used. The risk of adverse effects is reduced if systemic exposure is held to a minimum by rapid elimination and low tissue distribution.