Clinical Pharmacology of Gentamicin in Infants 2 to 24 Months of Age

Twenty-two infants 2 to 24 months old received gentamicin sulfate intramuscularly in dosages of 1.5 to 2.5 mg/kg every eight hours for from three to ten days. Peak serum gentamicin levels following 2.0 or 2.5 mg/kg doses were equal to or greater than minimal inhibitory concentrations of most gram-negative pathogens of infancy; antibiotic levels persisted in serum for at least eight hours. Half-life values in serum were inversely related to age, and values of 2.5 hours in older infants were similar to adult values. Gentamicin concentrations in urine were 3μg to 478μg/ml and excretion of gentamicin directly correlated with creatinine clearance rates. Acute hematologic or renal toxicity was not evident. Gentamicin doses of 2.0 or 2.5 mg/kg administered every eight hours to infants up to 2 years of age are safe and adequate to treat infections caused by susceptible gram-negative enteric bacteria and Pseudomonas.