The purpose of this study is to examine the safety and tolerability of ZDV when given to premature infants born to HIV-positive women to prevent HIV infection.

ZDV has been used successfully to prevent the transmission of HIV from mother to child during pregnancy and birth. However, ZDV has been given to very few premature babies, and the best dose to use has not yet been determined.

In the preliminary group of premature infants, those receiving q 6h dosing had an average trough concentration of 7.3 uM (18%). However, the premature infants in the preliminary pharmacokinetic study did not have long term follow-up to assess toxicity. Due to the potential for altered ZDV pharmacokinetics and increased toxicity in this population, an evaluation of ZDV pharmacokinetics in premature infants is proposed.

Premature infants less than or equal to 34 weeks gestational age at birth and begun on ZDV by their clinical caregivers will be entered into the protocol within the first 5 days of life. Upon entry, ZDV will be administered every 12 hours intravenously or orally. The study will require 9 serum samples for ZDV assay collected over 30 days, some additional clinical laboratory tests collected over 12 weeks, collection of 3 spot urine samples, and collection of routine clinical data.

Inclusion Criteria

Your baby may be eligible for this study if he/she:

• Requires ZDV (as decided by your doctor) because you are HIV-positive.
• Is 1-5 days old and was born prematurely.

Exclusion Criteria

Your baby will not be eligible for this study if he/she:

• Is not expected to live 6 weeks because of severe illness.
• Is having problems with blood pressure or is not urinating enough.