Use of netilmicin once or twice daily in preterm newborns: evaluation of nephrotoxicity by urinary alpha1-microglobulin and retinol binding protein

Since aminoglycoside efficacy is proportional to serum peak/MIC ratio and linked to post antibiotic effect, use of netilmicin once rather than twice a day has been proposed. On the other hand netilmicin might play a role in drug-induced nephrotoxicity, mainly on proximal tubule. Urinary retinol binding protein (RBP) and alpha1 microglobulin (alpha1m) are early and specific indicators of tubular damage and dysfunction. 21 preterm neonates (GA < 37 weeks) were divided in two groups on the basis of netilmicin administration modality (1: once a day, 2: twice a day, both for 7 days, at 5 mg/kg/die) and differences in netilmicin tolerability were assessed by evaluation of alpha1m and RBP levels by immunonephelometric method. No significant differences were found between the two groups either considering levels at time 1 and at time 2, or considering the difference between time 1 and 2 (Delta1/2). In our study once-daily dosing schedule shows similar low rates of nephrotoxicity, compared with multiple daily dosing schedule: this result may support the general adoption of once-daily dosing of netilmicin in clinical practice.