Pharmacokinetics and Pharmacodynamics of Famotidine in Infants

The pharmacokinetics and pharmacodynamics of intravenous famotidine were evaluated in 10 infants ranging from 5 to 19 days of age who had a therapeutic indication for the prophylactic treatment of stress ulceration. After a 0.5‐mg/kg infusion of famotidine, timed serum (n = 6), urine (24‐hour collection), and repeated measurements of gastric pH were obtained. The mean ± standard deviation maximum plasma concentration (Cmax) was 640.66 ± 250.66 ng/mL, the elimination half‐life (t1/2β) was 10.51 ± 5.43 hours, and the apparent volume of distribution at steady state (Vdss) was 0.82 ± 0.29 L/kg. Plasma clearance (Cl) and renal clearance (ClR) were 0.132 ± 0.061 L/hr/kg and 0.093 ± 0.056 L/hr/kg, respectively. No significant correlations were found between t1/2β, Vdss, Cl, and ClR and age. Six of the nine infants who had intragastric pH monitoring maintained a gastric pH > 4 until the final 24‐hour sampling point. In this study, the t1/2β of famotidine was prolonged and the Vdss, Cl, ClR were reduced compared with corresponding parameters in previously reported studies of children older than one year of age and adults.