Pharmacokinetics and nephrotoxicity of continuous intravenous infusion of gentamicin in low birth weight infants

We evaluated the pharmacokinetics and renal effects of continuous intravenous infusion of gentamicin compared with multiple-dose therapy given in equivalent daily amounts. Nine infants (mean gestational age 34.7 weeks, mean birth weight 2107 gm) were given intermittent injections of gentamicin and 10 infants (mean gestational age 34.8 weeks, mean birth weight 2078 gm) received gentamicin by continuous infusion. Comparison of gentamicin pharmacokinetic data revealed a larger volume of distribution and AUC, prolonged terminal 1 1/2, and slower total body clearance of the drug in those infants receiving gentamicin by continuous infusion. During and after therapy the fractional excretion of sodium was significantly increased in the continuous infusion group. After treatment the creatinine clearance and excretion of β₂-microglobulin were significantly lower in the continuous therapy group. Our results indicate that infants receiving gentamicin by constant infusion are at higher risk of nephrotoxicity. The extent of this nephrotoxic hazard remains to be determined.