368 EVALUATION OF POTENTIAL NEPHROTOXICITY OF AMIKACIN AND TOBRAMYCIN IN PREMATURE INFANTS

The nephrotoxicity(NT) of aminoglycosides in premature infants is a still disputed problem. To assess and compare this possible side-effect of two widely used compounds, tobramycin (TB) and amikacin (AK) we determined serum creatinine (SCr), urine content of N-acetyl-beta-glucosaminidase (NAG) and blood drug levels in 28 prematures with proven or suspected infections. Fourteen infants(mean gest.age:32.1±2.1wK;mean weight: 1.650)were treated with TB,4 mg/Kg/day, and 14(inean gest.age:31.7±1.8wK; mean weight: 1.690±351 g)with AK, 15 mg/Kg/day, both divided in two doses i.m. Blood and urine samples were collected on days 1 and 8 of therapy and 5 days after its suspension. NT was defined as a rise in SCr of 0.3 mg% and/or a significant increase in urine NAG excretion on day 8 of therapy (early NT) or on day 5 after suspension (late NT). Mean trough and 1 hr postdose serum levels of TB on day 8 of therapy were 1.60±0.8 and 6.6±2 ug/ml, respectively. For AK they were 8.2±3.1 and 27.1±5.2 ug/ml. Neither drug was detected in infant sera 5 days after cessation. Both groups had similar baseline SCr and urine NAG content. No infant developed early or late NT. These data indicate that at our doses TB or AK do not result in increased levels of SCr or enzymuria in premature newborns. In addition, our results do not show any significant difference in the 2 groups and therefore, the choice between TB and AK should depend on other consideration, such as susceptibility of the pathogen or therapy cost.