Protocol For the Treatment of Cryptosporidiosis in AIDS Patients With Diclazuril (R64,433)

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.