EFFICACY OF PYRIMETHAMINE SULFADOXINE IN THE PREVENTION OF TOXOPLASMIC ENCEPHALITIS RELAPSES AND PNEUMOCYSTIS-CARINII PNEUMONIA IN HIV-INFECTED PATIENTS

The efficacy and safety of 25 mg pyrimethamine plus 500 mg sulfadoxine given twice a week in preventing relapses of AIDS-related toxoplasmic encephalitis was evaluated in an open study. The 56 HIV-infected pati ents evaluated had responded to intensive treatment with pyrimethamine /clindamycin prior to starting the present prophylactic regimen. Four patients (7 %) experienced relapse while on pyrimethamine/sulfadoxine. The probability of freedom from relapse was > 90 % for 12 months and > 80 % for 24 months. Side effects comprised mild or moderate allergic reactions which occurred in 23 patients (41 %), leading to discontinu ation in four patients (7%). Forty-nine of the 56 patients did not hav e a history of Pneumocystis carinii pneumonia and did not receive anti parasitic prophylaxis other than pyrimethamine/sulfadoxine; two of the m (4 %) developed pneumocystosis. The probability of freedom from pneu mocystosis was about 90 % for 24 months. Pyrimethamine/sulfadoxine twi ce a week appears to be a promising regimen for prevention of toxoplas mic encephalitis, and also appears to provide protection against Pneum ocystis carinii pneumonia. Although allergic reactions are usually mil d and disappear on continuation, they may limit the value of this regi men.