To compare the uptake of azithromycin in white cells relative to plasma concentrations in HIV-infected patients.

Patients are randomized to receive azithromycin orally or intravenously, with crossover to the alternate treatment after a 21-day wash-out period.

Inclusion Criteria

Concurrent Medication:

Allowed:

• Antiretroviral agents, provided regimen has been stable for at least 1 month.

Patients must have:

• HIV infection.
• CD4 count <= 200 cells/mm3.
• No active opportunistic infection (pending discussion with Pfizer Clinician).

Prior Medication:

Allowed:

• Prior antiretroviral agents.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Active intercurrent illness (pending discussion with the Pfizer Clinician).
• Allergies to macrolide antibiotics.
• Signs and symptoms of severe illness that would preclude treatment.

Patients with the following prior conditions are excluded:

• History of clinically significant allergic, hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, or neurological disease.
• Clinically important change in baseline status within 4 weeks prior to study entry.
• Condition affecting drug absorption (e.g., ulcers, gastrectomy, HIV-associated enteropathies) within 4 weeks prior to study entry.

Prior Medication:

Excluded:

• Investigational drugs including treatment IND drugs within 4 weeks prior to study entry.

Known drug or alcohol dependence.