Inclusion Criteria

Inclusion Criteria

Concurrent Medication:

Allowed:

- Aerosolized pentamidine for Pneumocystis carinii pneumonia prophylaxis.

- Isoniazid not initiated during study period.

- Methadone maintenance.

Required:

- Stable prescribed dose of zidovudine (AZT) of at least 500 mg/day.

Exclusion Criteria

Co-existing Condition:

Patients with the following conditions or symptoms are excluded:

- Prior history of toxoplasmic encephalitis.

- Unable to take oral medication reliably or have a malabsorption syndrome (i.e., 3 or
more loose stools/day for at least 4 weeks associated with an unintentional weight
loss of = or > 10 percent of body weight).

- History of sensitivity to the study medications.

Concurrent Medication:

Excluded:

- Maintenance therapy for opportunistic infections with macrolides or sulfonamides,
immunomodulators, rifampin, amphotericin, dapsone, ganciclovir, antifolates,
probenecid, benzodiazepines, nephrotoxins, and experimental cytotoxic chemotherapy.

- Medications such as aspirin, benzodiazepines, cimetidine, indomethacin, morphine, and
sulfonamides should be avoided.

Concurrent Treatment:

Excluded:

- Lymphocyte replacement.

Patients with the following are excluded:

- Any medical or social condition that, in the opinion of the investigator, would
adversely affect either participation or compliance in the study.

- Diagnosis of AIDS and febrile and have evidence of another serious opportunistic
infection or central nervous system impairment.

Prior Medication:

Excluded:

- Maintenance therapy for opportunistic infections with macrolides or sulfonamides,
immunomodulators, rifampin, amphotericin, dapsone, ganciclovir, antifolates,
probenecid, benzodiazepines, nephrotoxins, and experimental cytotoxic chemotherapy
within past 14 days.

Prior Treatment:

Excluded:

- Lymphocyte replacement within past 14 days.

Patients have the following symptoms and conditions:

- Laboratory evidence of HIV infection.

- Serological evidence of exposure to Toxoplasma gondii, but no clinical evidence of
active toxoplasmic infection.

- Able to understand and sign a written informed consent.

- Either homosexual male or intravenous drug user.

Required:

- Stable prescribed dose of zidovudine (AZT) of at least 500 mg/day for 4 weeks.

Intravenous drug abuse.