Inclusion Criteria

Concurrent Medication:

Allowed:

• Any medications not listed as excluded will be permitted on study.

[ AS PER AMENDMENT 4/11/97:PCP prophylaxis is permitted if initiated after the Day 21 evaluation has been completed.]

Patients must have:

• Documented HIV infection.
• Documented PCP.
• On a room air ABG, the PO2 value greater than or equal to 70 mm Hg and the (A-a) DO2 less than 35 mm Hg.
• Signed informed consent from parent or legal guardian for those patients less than 18 years of age.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Known hypersensitivity to quinolines.
• If patient is unwilling or unable to discontinue other medications with anti-PCP activity during the treatment period of this study.

Concurrent Medication:

Excluded:

• Any patient unwilling or unable to discontinue other medications with anti-PCP activity during the treatment period of this study (e.g., TMP/SMX, sulfonamides, dapsone, pentamidine, trimetrexate, atovaquone, clindamycin, azithromycin, pyrimethamine, primaquine).
• Methemoglobinemia-producing agents (dapsone, primaquine, sulfonamides, chloroquine, nitrofurantoin, nitrates and nitrites).

Patients with the following prior conditions or symptoms are excluded:

• History of G6PD deficiency, hemoglobin M abnormality, or NAD methemoglobin reductase deficiency.

Prior Medication:

Excluded:

• More than 24 hours receipt of anti-PCP treatment for the current episode of PCP. Receipt of prior PCP prophylaxis is permitted, as long as it is discontinued at study entry.