Gentamicin kinetics in the neonate.

Gentamicin serum levels were measured and elimination half-life was calculated in a group of neonates with postconceptual ages ranging between 25-42 weeks. Infants were receiving intravenous gentamicin (2.5 mg/Kg/dose) at various dosage intervals and t 1/2e was calculated using a one-compartment open model. Evidence of gentamicin accumulation was present in 82% of infants 34 weeks. T 1/2e was 8.8 +/- .7 hours in infants 30 weeks, 7.8 +/- 1.1 hour in infants between 30-34 weeks and 6.2 +/- .5 in infants greater than 34 weeks. The results of the study suggest that gentamicin elimination is related to postconceptual age and that infants treated with recommended dosage regimens may have possible gentamicin tissue accumulation and nephrotoxicity. Therefore, the dosage interval may have to be lengthened to 18 hours in infants less than 34 weeks with close gentamicin plasma level monitoring.