Once daily dose gentamicin in neonates - is our dosing correct?

AIM

The aim of this paper is to study the safety and efficacy (measured by therapeutic level) of once daily gentamicin in neonates >or=32 weeks of gestation and <or=7 days of age.

SETTING

Level II neonatal intensive care unit.

SUBJECTS

Neonates >or=32 weeks of gestation and <or=7 days of age treated with gentamicin for presumed sepsis.

METHODS

Gentamicin was administered by intravenous injection at 4 mg/kg/day once daily. Peak and trough gentamicin levels were measured at the third dose.

RESULTS

In neonates with gestational age between 32 and 36 weeks, 14 out of 65 (22%) had trough serum concentration >2 mg/L. Only 39 (60%) had peak and trough levels within the therapeutic range. All babies who had audiometric evaluation (62 out of 65) had normal hearing. Out of the 65 babies, 60 had paired serum creatinine levels estimated and none had evidence of renal dysfunction. Among term neonates, only 2 out of 50 had the trough serum concentration of >2 mg/L. In 38 (76%) of the 50 neonates, the trough serum gentamicin concentration was <2.0 mg/L and the peak level was <10 mg/L. Forty-eight babies had audiometric evaluation which was normal.

CONCLUSION

A dose of 4 mg/kg/day produces serum gentamicin levels outside the therapeutic range in two-fifths of neonates between 32 and 36 +/- 6 weeks. A single dose of 4 mg/kg/day of gentamicin is appropriate for term babies and probably excessive for 32-36 weeks' neonates.