Since gentamicin is one of the most commonly prescribed antibiotics for culture-proven or suspected sepsis in neonates, interest has increased in refining dosing regimens for improved efficacy and decreased toxicity. Usually, 2.5 mg gentamicin/kg is infused twice daily, but its large volume of distribution, slow renal clearance and concentration-dependent character, suggests longer dosing intervals would be more appropriate. From a previous study, 22% of neonates who received a once-daily gentamicin dosage of 5 mg/kg/day had unacceptably high trough levels (i.e. > 2 μg/mL). The authors studied 105 neonates (of > 34 wk gestational age or > 2,000 g body weight) admitted to the Neonatal Unit, Srinagarind Hospital, Khon Kaen University; at risk, or with clinical features of sepsis, receiving a once-daily gentamicin dosing of 4 mg/kg intravenously. Peak (i.e. efficacy) and trough (i.e. toxicity) serum gentamicin concentrations were collected on day 3 of therapy. On days 1 and 3, nephrotoxicity was evaluated from serum creatinine and ototoxicity by a hearing test. Neonates treated with 4 mg gentamicin/kg once-daily had a mean steady-state peak vs trough concentration of 7.33 (+ 2.77) vs 0.99 (+ 0.57) μg/mL, respectively. The peak serum concentration achieved a therapeutic level > 4 μg/mL in 102 neonates (97%), while 7 (6.67%) had an undesirable trough level (viz. >2 μg/mL); notwithstanding, no nephrotoxic or ototoxic effects were identified. Gentamicin once-daily at 4 mg/kg/dose in neonates at >34 wk gestation achieved appropriate trough levels: the regimen was convenient and did not increase renal or ototoxicity.

Keywords: Once-daily, Gentamicin, Neonate