Pharmacokinetics and pharmacodynamics of famotidine in infants

The pharmacokinetics and pharmacodynamics of intravenous famotidine were ev aluated in 10 infants ranging from 5 to 19 days of age who had a therapeuti c indication for the prophylactic treatment of str ess ulceration. After a 0.5-mg/kg infusion of famotidine, timed serum (n = 6), urine (24-hour colle ction), and repeated measurements of gastric pH were obtained. The mean +/- standard deviation maximum plasma concentration (C-max) was 640.66 +/- 250 .66 ng/mL, the elimination half-life (t(1/2 beta)) was 10.51 +/- 5.43 hours , and the apparent volume of distribution at steady state (Vd(ss)) was 0.82 +/- 0.29 L/kg. Plasma clearance (Cl) and renal clearance (Cl-R) were 0.132 +/- 0.061 L/hr/kg and 0.093 +/- 0.056 L/hr/kg, respectively. No significan t correlations were found between t(1/2 beta), Vd(ss), Cl, and Cl-R and age . Six of the nine infants who had intragastric pH monitoring maintained a g astric pH > 4 until the final 24-hour sampling point. In this study, the t( 1/2 beta) of famotidine was prolonged and the Vd(ss), Cl, Cl-R were reduced compared with corresponding parameters in previously reported studies of c hildren older than one year of age and adults. (C) 1998 The American Colleg e of Clinical Pharmacology.