To evaluate the safety and efficacy of diclazuril capsules compared with placebo capsules as treatment of cryptosporidial related diarrhea in AIDS patients. Treatment efficacy will be based on the drug's clinical results and on its anti-protozoan effects. Safety will be assessed by the occurrence of side effects as reported by patients at their visits and by frequent monitoring of hematology, biochemistries, and urinalysis.

Inclusion Criteria

Concurrent Medication:

Allowed:

• Patients who require anti-diarrheal medication must have received only one anti-diarrheal medication, loperamide, for at least 7 days prior to study entry. Dose of loperamide cannot be increased during study.
• Aerosolized pentamidine.
• Ganciclovir for cytomegalovirus (CMV) retinitis only but patient must be stable at least 4 weeks prior to study entry.
• Zidovudine (AZT).
• Nystatin for oropharyngeal infections if not taken within 2 hours of diclazuril.

Patients must have:

• Diagnosis of AIDS that is confirmed HIV positive by Western blot or AIDS defined diagnosis, or CDC defined AIDS. Stool specimens positive for cryptosporidium oocysts.
• Given written informed consent after the purpose and nature of the study, as well the possible drug-related adverse effects, have been explained.
• Ability to return for all subsequent applicable visits on days 8, 15, 21, and, if necessary, 28.

Prior Medication:

Allowed:

• Aerosolized pentamidine.
• Loperamide.
• Ganciclovir for cytomegalovirus (CMV) retinitis.

Exclusion Criteria

Co-existing Condition:

Patients with the following are excluded:

• Diagnosis of cryptosporidiosis less than 4 weeks prior to study entry, unless patient has been diagnosed with AIDS for more than 4 weeks.
• Other treatable enteric pathogens including Clostridia must be treated and eradicated prior to study entry.
• Inability to swallow capsules.
• Uncontrolled vomiting.

Concurrent Medication:

Excluded:

• Trimethoprim/sulfamethoxazole (Bactrim).
• Ganciclovir for any other reason except cytomegalovirus (CMV) retinitis.
• Other antibiotics.
• Other anti-protozoal drugs.
• Anti-fungal drugs other than nystatin.
• Amphotericin B.
• Other investigational drugs.

Patients with the following are excluded:

• Diagnosis of cryptosporidiosis less than 4 weeks prior to study entry, unless patient has been diagnosed with AIDS for more than 4 weeks.
• Inability to swallow capsules.
• Uncontrolled vomiting.
• Life expectancy of < 28 days.
• Can not be depended upon to follow the instructions of the investigator.
• Participation in an investigational study within 15 days of study entry.

Prior Medication:

Excluded within 15 days of study entry:

• Another investigational drug or device (except aerosolized pentamidine).

Prior Treatment:

Excluded within 15 days of study entry:

• Participation in an investigational study.