Sir.—We read with interest the article by Naqvi et al1 regarding vancomycin pharmacokinetics in neonates. We would like to focus on the important effect of indomethacin use on vancomycin disposition in neonates. We have treated numerous neonates with vancomycin for Staphylococcus epidermidis infections. Each neonate receives a vancomycin loading dose of 15 to 20 mg/kg administered intravenously over one hour. A postloading dose peak and trough serum concentration value are obtained before the first maintenance dose is given. Pharmacokinetic variables, volume of distribution, and half-life are then calculated using a one-compartment pharmacokinetic model.
Eleven neonates with postconceptional ages of less than 35 weeks are the subject of this letter. The group was subdivided into six neonates with patent ductus arteriosus (PDA) treated with indomethacin and five control neonates without PDA who did not receive indomethacin. The characteristics of the neonates and their vancomycin pharmacokinetic variables are summarized in