Simpler Gentamicin Dosing
Once-daily Gentamicin Dosing for the Preterm and Term Newborn: Proposal for a Simple Regimen that Achieves Target Levels. Hansen A, Forbes P, Arnold A, et al. Journal of Perinatology (2003) 23, 635-639.
Objectives:
Based on recent safety and efficacy data, combined with the known
pharmacokinetic parameters of aminoglycosides in the newborn, once-daily
gentamicin should be preferable to the many other dosing regimens currently in
use. Although there are growing data to support its use in term newborns,
experience with preterm infants is more limited. In our Neonatal Intensive
Care Unit, we experienced difficulties regarding complicated dosing regimens,
actual dosing errors, and the tendency to check trough and peak levels around
the third dose for infants receiving only a 48 hour course. Therefore, we
conducted a quality improvement initiative in which we developed and tested a
clinical practice guideline for the use of once-daily gentamicin for preterm
and term infants that we hoped would yield trough and peak levels in our
target range.
Methods: We combined a review of the published English language
literature with pharmacokinetic analysis of our own data prior to initiation
of this new regimen to design the following dosing regimen: <35 weeks
gestation: 3 mg/kg q 24 hours, 
35
weeks gestation: 4 mg/kg q 24 hours. Our goal serum levels were a trough 
2
g/ml
and a peak between 6 and 12 g/ml.
We collected and analyzed trough and peak levels from all infants receiving
this dosing regimen in the first week of life for at least 72 hours between
3/1/99 and 12/31/00.
Results: In
total, 214 babies met our inclusion criteria, 75 of whom were <35 weeks
gestation. 100% of babies of all gestational ages had a nontoxic trough level.
For infants <35 weeks gestation, 79% had a therapeutic peak level, with a mean
value of 6.8 g/ml.
For infants of at least 35 weeks gestation, 93% had a therapeutic peak level,
with a mean value of 8.4 g/ml.
92% of nontherapeutic peaks were too low.
Conclusions: This study of once-daily gentamicin represents the
largest sample size of pre-term infants published to date. The proposed
regimen is simple and yields a high proportion of desirable levels. We
recommend it for use in preterm and term newborns.
Comments: I really like the simplicity of this dosing
regimen for gentamicin. And for neonates who are only going to be treated
for 48-72 hours, please resist the impulse to check gentamicin levels. If
the baby has limited renal function, I would pick a different antibiotic.
ABK.