Phase II Randomized Open-Label Trial of Atovaquone Plus Pyrimethamine and Atovaquone Plus Sulfadiazine for the Treatment of Acute Toxoplasmic Encephalitis

AIDS patients with toxoplasmic encephalitis who receive the standard therapy combination of sulfadiazine and pyrimethamine experience a high frequency of severe toxicity. Atovaquone, an antibiotic that has demonstrated efficacy against toxoplasmosis in animal models and in preclinical testing has been well tolerated, is now available as a suspension, which is more readily absorbed than the tablet form of the drug. The efficacy and safety of atovaquone in combination with sulfadiazine or pyrimethamine will be studied. Seventy patients are randomized to receive atovaquone with either pyrimethamine or sulfonamides for up to 48 weeks. Additionally, three cohorts of 10 patients each who have a history of treatment-limiting toxicity to pyrimethamine, sulfadiazine, or both drugs receive atovaquone plus the alternate drug or atovaquone plus clarithromycin. All patients receiving pyrimethamine also receive leucovorin protection. PER AMENDMENT 4/3/96: The open treatment groups are: Atovaquone plus pyrimethamine for patients with acute toxoplasmic encephalitis who have no treatment limiting toxicity to pyrimethamine, and Atovaquone plus clarithromycin for patients with acute toxoplasmic encephalitis who have treatment limiting toxicity to both pyrimethamine and sulfadiazine. The following arms closed on 12/22/95: Randomization to the atovaquone plus sulfadiazine arm for patients with acute toxoplasmic encephalitis who had no treatment limiting toxicity to pyrimethamine or sulfonamides, and Atovaquone plus sulfadiazine for patients with acute toxoplasmic encephalitis who had treatment limiting toxicity to pyrimethamine. The following arm closed on 9/26/95: Atovaquone plus pyrimethamine for patients with acute toxoplasmic encephalitis who had treatment limiting toxicity to sulfonamides. NOTE: Any patients enrolled in previous versions will continue to be treated with that same drug treatment and followed under their previous version guidelines.