Dosing regimen of gentamicin and the effect of antenatal steroids on clearance in preterm infants

ObjectiveDetermine the gentamicin pharmacokinetic and pharmacodynamic (PK/PD) profiles of once daily dosing (ODD) versus every 18-hour (q18h) regimens and to characterize the effect of antenatal steroid on gentamicin clearance (GentCL).nnStudy DesignRetrospective cohort of preterm infants ([≤]34 weeks gestation; [≤]7 days) who received gentamicin for >48 hours from January 2005 to June 2007. Serum gentamicin peak and trough concentrations were determined, and PK/PD profiles calculated using standard noncompartmental methods.nnResult122 (63%) infants received ODD and 73 (37%) received q18h regimen. Desired gentamicin peak (5 to 12 mcg/mL) and trough ( 72 mcg/mL/hr) was achieved in 73% (89/122) of infants on ODD vs. 22% (16/73) on q18h (p 0.86).nnConclusionPK/PD profile of gentamicin is improved by ODD in preterm infants. GentCl was significantly less in infants exposed to antenatal steroids but not in those treated with indomethacin.