The pharmacokinetics of oral ranitidine in children and adolescents with cystic fibrosis

The pharmacokinetics of oral ranitidine were studied in 9 patients (ages 9. 9 to 19.6 years) with cystic fibrosis (CF). patients were evaluated at stea dy-state conditions, and the mean maximum serum concentration (C-max) was 8 45.7 +/- 448.2 ng/mL. To adjust for the variable drug dosing used among stu dy patients both C-max and area under the concentration curve (AUC) were st andardized to dose (C-maxST and AUC(ST), respectively) and were 217.9 +/- 8 7.9 ng/ml and 1038.0 +/- 242.2 ng/mL . h. The elimination half-life (t(1/2) ) was 2.7 +/- 1.4 hours, and the apparent steady-state volume of distributi on (Vd(SS)) was 4.6 +/- 1.7 L/kg. The plasma clearance was 1.022 +/- 0.290 L/kg/h. The Vd(SS) in this study was greater than that previously reported in children with peptic ulcer disease. Statistically significant relationsh ips between pharmacokinetic parameters and measures of disease severity wer e not observed in the study population. The pharmacokinetics of ranitidine in children and adolescents with CF may differ from those in children and a dolescents without CF. (C) 1999 the American College of Clinical Pharmacolo gy.