Pharmacokinetics of inhaled corticosteroids

Abstract

The inhaled corticosteroids have improved asthma therapy significantly. The inhaled route allows the delivery of relatively small doses directly to the airway, providing a high local concentration and minimizing systemic adverse effects. Knowledge of pharmacokinetic properties of inhaled corticosteroids (deposition in respiratory system, rate of absorption, first-pass effect oral bioavailability, distribution and elimination) is a prerequisite for successful asthma therapy. Inhaled corticosteroids show various levels of oral bioavailability and significant differences in the rate of absorption. Rate of absorption is one of the most relevant properties of inhaled corticosteroids as it reflects pulmonary residence time and therefore duration of availability in the lungs. Significant hepatic first-pass metabolism of the swallowed dose of some corticosteroids (fluticasone propionate, budesonide) reduces oral bioavailability and systemic adverse effects. Pharmacokinetic properties could also be applied to predict and explain the systemic adverse effect profiles of inhaled corticosteroids. Taking into consideration the revealed differences in pharmacokinetic properties of inhaled corticosteroids enable individual therapeutic approach, better efficacy and safety of asthma treatment.