Pharmacodynamics and pharmacokinetics of budesonide: a new nebulized corticosteroid

Underutilization of anti-inflammatory agents in the treatment of asthma has received widespread attention. Inhaled glucocorticosteroids are important agents for the management of asthma in children and adults. Budesonide has a high ratio of topical anti-inflammatory to systemic activity and is one of the most extensively used inhaled glucocorticoids. Budesonide inhalation suspension is the first formulation designed to deliver budesonide by way of nebulization for infants and children under 8 years of age with persistent asthma. Budesonide decreases airway hyperresponsiveness and reduces the number of inflammatory cells and mediators present in the airways of patients with asthma. Budesonide appears to be retained within cells, allowing for a once-daily treatment regimen in certain patient groups. After inhalation of nebulized budesonide, absorption is rapid. Data suggest that plasma concentrations of budesonide are similar in adults and children after inhalation of the same nominal dose from a nebulizer. In children 3 to 6 years of age, total systemic availability of budesonide after dosing with a jet nebulizer was approximately 6% of the labeled dose. Budesonide is highly protein bound, undergoes extensive first-pass hepatic metabolism, is metabolized by the liver cytochrome P450 system, and is primarily excreted in the urine as metabolites. In children 3 to 6 years of age, the volume of distribution at steady state of budesonide inhalation suspension is approximately 3 L/kg, with a terminal elimination half-life of 2.3 hours; systemic clearance is approximately 30 mL/kg. The pharmacodynamic and pharmacokinetic properties of budesonide inhalation suspension allow for potent local anti-inflammatory activity with limited systemic exposure.