In vitro studies with azithromycin show good inhibitory activity against U. urealyticum. Pharmacokinetic studies of azithromycin in older children show better tolerance, higher tissue concentration, fewer side effects, and fewer drug interactions, when compared to erythromycin. Thus far, there have been no published data on the pharmacokinetic profile of azithromycin in neonates including low birth weight infants. However, the clinical pharmacology profile suggests a substantial therapeutic advantage of this drug in the newborn. To date, there are no data on the PK profile of IV Azithromycin from whence rational dosing can be derived.