A Study of the Safety and Efficacy of Chronically Administered MDL 28,574A in the Treatment of HIV-Infected Patients

Inclusion Criteria Patients must have: * HIV infection. * Asymptomatic or mildly symptomatic. * CD4 count 100 - 300 cells/mm3. Prior Medication: Allowed: * Prior antiretroviral agents for up to 6 months per agent. Exclusion Criteria Co-existing Condition: Patients with the following condition are excluded: Unable or unwilling to comply with study procedures. Concurrent Medication: Excluded: * Chemoprophylactic therapy for mycobacterial infection. * Any nonstudy prescription medications without approval of investigator. Patients with the following prior conditions are excluded: * History of grade 3 or 4 toxicity to \<= 600 mg/day AZT. * History of intolerance to lactose. * Chronic diarrhea within 6 months prior to study entry. * Unexplained intermittent or chronic fever, defined as temperature \>= 38.5 C for any 7 days within the 30 days prior to study entry. Prior Medication: Excluded: * Antiretroviral therapy within 2 weeks prior to study entry. * Prior HIV vaccines. * Biological response modifiers within 30 days prior to study entry. * Prior foscarnet. * Any investigational drug with a washout \< 5 half-lives prior to study entry. * Any medications known to alter renal, hepatic, or hematologic / immunologic function (such as barbiturates, phenothiazines, cimetidine, immunomodulators, etc.) within 14 days prior to study entry. Recent history of alcohol and/or drug abuse.