Phase II Randomized Open-Label Trial of Atovaquone Plus Pyrimethamine and Atovaquone Plus Sulfadiazine for the Treatment of Acute Toxoplasmic Encephalitis
Phase II Randomized Open-Label Trial of Atovaquone Plus Pyrimethamine and Atovaquone Plus Sulfadiazine for the Treatment of Acute Toxoplasmic Encephalitis
To evaluate the efficacy, safety, and tolerance of atovaquone with either pyrimethamine or
 sulfadiazine in AIDS patients with 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.
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.
Inclusion Criteria

 Concurrent Medication:

 Allowed:

 -  Aerosolized pentamidine for PCP prophylaxis.

 PER AMENDMENT 4/3/96:

 -  History of treatment limiting toxicity to pyrimethamine. Patients with a history of
 treatment limiting toxicity to both pyrimethamine and sulfonamides will be assigned to
 receive atovaquone plus clarithromycin.

 Patients must have:

 -  Documented HIV infection or diagnosis of AIDS (except for CD4 count < 200 cells/mm3).

 -  Toxoplasmic encephalitis.

 -  Ability to give informed consent or legal designee who could give consent.

 PER AMENDMENT 4/3/96:

 -  NOTE - A history of treatment limiting toxicity to both pyrimethamine and sulfonamides
 will result in the patient being enrolled in the atovaquone plus clarithromycin arm.

 Exclusion Criteria

 Co-existing Condition:

 Patients with the following symptoms or conditions are excluded:

 -  Coma.

 -  Opportunistic infection that requires either acute or maintenance treatment with
 disallowed medications.

 -  Any infections or neoplasms of the central nervous system other than Toxoplasma, HIV
 encephalopathy, or syphilis.

 -  Unable to take oral study drugs.

 -  Malabsorption (i.e., three or more episodes of diarrhea per day that has caused >= 10
 percent loss of body weight over the past 4 weeks).

 -  Positive CSF or serum for Cryptococcus antigen or culture (a positive serum antigen
 only is acceptable, provided patient received prior antifungal therapy and is on
 maintenance, and the likelihood of recurrence is low).

 -  Malignancy requiring use of cytotoxic chemotherapy.

 -  Medical or social condition that would adversely affect study participation or
 compliance.

 Concurrent Medication:

 Excluded:

 -  Trimethoprim-sulfamethoxazole.

 -  Primaquine.

 -  Sulfonamides.

 -  Antifolates.

 -  Dapsone.

 -  Clarithromycin (except for patients in the cohort to receive this drug).

 -  Azithromycin.

 -  Clindamycin.

 -  Other macrolides.

 -  Gamma interferon.

 -  Metoclopramide.

 -  G-CSF or GM-CSF.

 Excluded in patients receiving clarithromycin as study drug:

 -  Terfenadine, astemizole, or any other long-acting, non-sedating antihistamines.

 PER AMENDMENT 4/3/96:

 -  Cisapride - may increase GI motility and may increase drug absorption.

 Patients with the following prior conditions are excluded:

 -  History of treatment-limiting toxicity to atovaquone.

 -  Receipt of > 96 hours (per amendment) of treatment prior to study entry for the
 current episode of toxoplasmic encephalitis.