The purpose of this study is to evaluate the pharmacokinetics and safety of a single dose of IV azithromycin in preterm neonates and confirm that the pharmacokinetics of azithromycin is similar in the 24-<32 week and 32-<37 week neonate. The dose of 10 mg/kg has been chosen on the basis of previous pediatric pharmacokinetic studies.

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.

Inclusion Criteria:

1. 24 to 37 weeks gestational age
2. postnatal age 0 to 30 days
3. May require therapy with antibiotics/anti-infectives
4. Have baseline Hematology labs available (hemoglobin, hematocrit, white blood cell and differential and platelet count), which have been obtained within the previous 72 hours, as part of their standard of care
5. Signed informed consent by the parent or guardian

Exclusion Criteria:

1. Clinically significant hepatic disease (ALT or AST twice the normal value)
2. Clinically significant anemia (hemoglobin < 10 gm %)
3. Neutropenia (absolute neutrophil count < 500 cells/mm3)
4. Clinically significant renal disease [Creatinine clearance twice the normal value, as calculated by the Schwartz formula : Length in cms x k (a constant) / S.Cr (Values for the constant are given in Appendix 1)]
5. Cardiac rhythm abnormalities
6. Critically ill patients
7. Patients who are on or expected to be on the following concurrent medications carbamazepine, phenytoin, theophylline, digoxin, warfarin, ergot alkaloids, triazolam, cyclosporine, terfenadine, hexobarbital and antacids.