Pharmacokinetics of budesonide in children with asthma.
The pharmacokinetics of the glucocorticoid budesonide was studied in 6 children with asthma after i.v. injection of 0.5 mg and oral inhalation of 1 mg as an aerosol. Budesonide is a 1:1 mixture of the epimers 22 S and 22 R, which were assayed separately by HPLC combined with RIA. All pharmacokinetic parameters of the epimers differed except the half-life of about 1.5 h. It was significantly shorter than that reported in adults. Plasma clearance averaged 103 l X h-1 for epimer 22 R and 74 l X h-1 for epimer 22 S; calculated per kg body weight these values were about 50% higher than in adults. The difference was about 40% when calculated per m2 of body surface area. Since budesonide is a high-clearance drug, the data indicate higher liver blood flow X kg-1 body weight and m2 of body surface area in children. The systemic availability of the aerosol was approximately 30% of nominal dose, i.e. the same as in adults. The high clearance and short half-life of budesonide in children are advantageous in reducing the risk of possible systemic side-effects of prophylactic treatment of asthma in childhood.
D000280:Administration, Inhalation; D000293:Adolescent; D001249:Asthma / Q000097:blood / Q000188:drug therapy*; D001682:Biological Availability; D019819:Budesonide; D002648:Child; D002986:Clinical Trials as Topic; D005938:Glucocorticoids / Q000008:administration & dosage / Q000097:blood* / Q000627:therapeutic use; D006207:Half-Life; D006801:Humans; D007262:Infusions, Intravenous; D007700:Kinetics; D008297:Male; D011282:Pregnenediones / Q000008:administration & dosage / Q000097:blood*
D005938:Glucocorticoids; D011282:Pregnenediones; D019819:Budesonide