Age-dependent dose response to gentamicin.

Serum gentamicin concentrations were measured 30 minutes after 140 intravenous doses in 60 children and nine adults with normal renal function. Distinct interpatient variation was observed but individual patients tended to have similar pharmacokinetics with repeated doses. Age had a significant effect in that mean peak serum concentrations were 1.58 mug/ml per 1 mg/kg dose in children between 6 months and 5 years, 2.03 mug/ml per 1 mg/kg in those between 5 and 10, and 2.86 mug/ml per 1 mg/kg in children 10 to 15 years of age. The mean calculated single dose of gentamicin necessary to achieve a peak serum concentration between 4 and 5 mug/ml is 2.5 mg/kg for ages 0.5 to 5 years, 2.0 mg/kg for ages 5 to 10 years, and 1.5 mg/kg for individuals over 10 years of age.