Inclusion Criteria

Concurrent Medication:

Allowed:

• Anti-diarrheal and antiemetic medications.
• Anti-HIV agents such as zidovudine, ddI, and ddC if dosing regimens were stable for at least 3 weeks prior to start of study drug.

Patients must have:

• AIDS.
• Chronic diarrhea with presence of Cryptosporidium oocysts in a stool specimen.
• CD4 count < 150/mm3 (not required if patient has had cryptosporidiosis for a minimum of 4 weeks).
• Life expectancy of at least 1 month.

Prior Medication:

Allowed:

• Anti-HIV agents such as zidovudine, ddI, and ddC if dosing regimens were stable for at least 3 weeks prior to start of study drug.
• Anti-diarrheal and antiemetic medications.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Grade 4 hematologic toxicity or grade 3 other toxicity ( patients with grade 3 hepatic toxicity may be enrolled if abnormalities are considered to be caused by biliary cryptosporidiosis).
• Presence of other diarrhea-causing pathogens.
• Active (defined as newly diagnosed, progressive, or requiring therapeutic intervention) opportunistic infection that requires antimicrobial therapy (patients receiving maintenance or prophylactic antimicrobial therapy for opportunistic infection may be enrolled if the dosing regimen has been stable for at least 3 weeks).
• Evidence of cytomegalovirus retinitis or colitis.

Concurrent Medication:

Excluded:

• Ganciclovir, cancer chemotherapy, or interferon-alpha or other immunomodulating agents.
• Any investigational drug (drugs available under an FDA-authorized expanded access program will not be considered investigational).

Prior Medication:

Excluded:

• Any investigational drug within 1 month prior to start of study drug (drugs available under an FDA-authorized expanded access program will not be considered investigational).
• Ganciclovir, cancer chemotherapy, or interferon-alpha or other immunomodulating agents within 7 days prior to start of study drug.