To assess the tolerance and toxicity profile of deoxy-3'-fluorothymidine (FLT) after multiple oral dosing for 16 weeks. To characterize the steady-state pharmacokinetics of FLT after multiple oral doses. To assess the effect of FLT on immunologic and virologic markers of HIV infection (CD4+ lymphocyte count, p24 antigen, viremia) in patients with AIDS or AIDS related complex (ARC) after multiple oral dosing for 16 weeks.

Inclusion Criteria

Concurrent Medication:

Allowed:

• Aerosolized pentamidine for Pneumocystis carinii pneumonia (PCP) prophylaxis.
• Up to 14 days of systemic therapy for minor opportunistic infections such as candidiasis, mucocutaneous Herpes simplex or cutaneous Herpes zoster infections.

Patients must have the following:

• AIDS or AIDS related complex (ARC) as defined by the CDC.
• Positive antibody to HIV as determined by a commercially licensed ELISA test kit, confirmed by Western blot analysis.

Exclusion Criteria

Co-existing Condition:

Patients with the following conditions or symptoms are excluded:

• Symptomatic visceral Kaposi's sarcoma or progression of Kaposi's sarcoma within the month prior to study entry (progression is defined as more than a 25 percent increase in the product of bidirectional measurement of indicator lesions and/or more than a 25 percent increase in the number of new lesions).
• Concurrent neoplasms other than Kaposi's sarcoma or basal cell carcinoma of the skin. Patients who have had a malignancy in the past that has been in complete remission for 1 year without therapy may be enrolled.
• Signs or symptoms of neuropathy and a Vibratron 2 score = or > 4 for either great toe.

Concurrent Medication:

Excluded:

• Acute therapy for AIDS-related infection.
• Systemic maintenance therapy for AIDS-defining opportunistic infection.
• Recombinant erythropoietin.
• Long term therapy with either aspirin or probenecid.

Concurrent Treatment:

Excluded:

• Blood transfusion more than once per month.

Patients with the following are excluded:

• Symptomatic visceral Kaposi's sarcoma or progression of Kaposi's sarcoma within the month prior to study entry.
• Unwilling to sign an informed consent or patients unwilling to be followed at the medical center where they were enrolled for the duration of the study and follow-up as required.
• History of intolerance to zidovudine (AZT) at any dose as demonstrated by an AZT related decrease in hemoglobin levels of at least 2 g/dl or AZT related depression of neutrophils of at least 200 cells/mm3 to < 750 cells/mm3 which required discontinuation of AZT therapy.
• Diseases or conditions listed in Exclusion Co-Existing Conditions.

Prior Medication:

Excluded:

• Antiretroviral agents within 14 days of study entry.
• Immunomodulating agents or corticosteroids within 30 days prior to study entry.
• Treatment for acute Pneumocystis carinii pneumonia within 2 weeks prior to study entry.

Prior Treatment:

Excluded:

• Blood transfusions within 7 days prior to study entry.
• Radiation therapy for Kaposi's sarcoma within 30 days prior to study entry.

Active substance abuse.