Double-Blind Comparison of the Efficacy of Continued Zidovudine Versus 2',3'-Dideoxyinosine (ddI) (BMY-40900) for the Treatment of Patients With AIDS or AIDS-Related Complex and Increasing Symptomatology Despite Treatment With Zidovudine

Inclusion Criteria Concurrent Medication: Allowed for Hematologic toxicity: * Erythropoietin. * Colony-Stimulating Factors. * Allowed for prophylaxis of Pneumocystis carinii pneumonia (PCP): * Aerosolized pentamidine. * Trimethoprim/sulfamethoxazole. * Dapsone. * NOTE: * If intravenous pentamidine is required for treatment of PCP, study drug should be suspended until one week after completion of intravenous pentamidine. * Allowed: * Prophylactic or suppressive therapy begun prior to study entry with the exception of neurotoxic agents (as defined in the protocol). Concurrent Treatment: Allowed: * Transfusions for hematologic toxicity. Exclusion Criteria Co-existing Condition: Patients with the following conditions or symptoms are excluded: * Active acute AIDS defining infection. * Clinical evidence of acute pancreatitis in the last two years or chronic pancreatitis. * Dementia of such severity that patient cannot give informed consent. * Grade 2 or worse peripheral neuropathy as defined by Targeted Neuropathy Score (Schaumberg). * Prior Cytomegalovirus disease requiring ongoing systemic ganciclovir therapy. * Extensive Kaposi's sarcoma or other malignancy requiring systemic cytotoxic myelosuppressive or neurotoxic chemotherapy. * Cardiomyopathy or the need for antiarrhythmic therapy. * Inability to tolerate at least 600 mg per day of zidovudine (AZT). * Seizures within the last 6 months or the need for anticonvulsant therapy. Concurrent Medication: Excluded: * Ganciclovir (DHPG). * Myelosuppressive or neurotoxic chemotherapy. * Antiarrhythmic therapy. * Anticonvulsant therapy. * Neurotoxic agents (as defined in the protocol). * NOTE: * If intravenous pentamidine is required for treatment of Pneumocystis carinii pneumonia (PCP), study drug should be suspended until 1 week after completion of intravenous pentamidine. Patients with the following are excluded: * Symptoms and conditions defined in the Patient Exclusion Co-Existing Conditions field. * Average of two sequential CD4 counts from SciCor Clinical Laboratories in the 30 days prior to study entry \> 300 cells/mm3. Prior Medication: Excluded, participation in studies using: * Dideoxyinosine (ddI). * 2',3'-Dideoxy-2',3'-didehydrothymidine (d4T). * Dideoxycytidine (ddC). * Excluded within one month of study entry: * Any other experimental antiretroviral compounds. Patients must: * Have documented HIV positivity via ELISA. * Meet CDC criteria for AIDS or AIDS related complex (ARC). * Have received zidovudine (AZT) for = or \> 6 months and tolerated a dose of at least 500 mg per day without significant hematologic toxicity. * Have no acute AIDS defining opportunistic infection, but may be receiving suppressive therapy for such infections. * Demonstrate at least one of the following criteria for clinical deterioration despite AZT therapy within 4 weeks prior to study entry (8 weeks prior for weight loss): * involuntary weight loss of more than 5 percent of the body weight occurring over the 8 week period prior to study entry, Karnofsky score = or \> 50 but demonstrating a fall = or \> 20 from previous level of functioning (assessment must be persistent on two occasions at least 14 days apart), unexplained fever of = or \> 38 degrees C (despite evaluation defined in protocol) for more than 7 days, appearance of newly diagnosed oral hairy leukoplakia or oral candidiasis, or recurrence of a previously quiescent multidermatomal varicella-zoster, appearance of dermatologic afflictions (e.g. psoriasis, molluscum contagiosum, or newly diagnosed seborrheic dermatitis), appearance of chronic herpetic ulcers not responsive to acyclovir therapy. Required: * Zidovudine (AZT) for = or \> 6 months prior to study entry.