Primary Prophylaxis of Cerebral Toxoplasmosis in HIV-Infected Patients

To evaluate the effectiveness of pyrimethamine (given with leucovorin calcium versus placebo (an inactive substance) for the primary prophylaxis (prevention) of cerebral toxoplasmosis in HIV-infected patients. Cerebral toxoplasmosis is one of the most frequently encountered opportunistic infections in the course of AIDS. The mortality (death) rate is estimated to be greater than 50 percent. Pyrimethamine is a drug that appears promising for the primary prevention of cerebral toxoplasmosis in HIV-infected patients. Cerebral toxoplasmosis is one of the most frequently encountered opportunistic infections in the course of AIDS. The mortality (death) rate is estimated to be greater than 50 percent. Pyrimethamine is a drug that appears promising for the primary prevention of cerebral toxoplasmosis in HIV-infected patients. AMENDED: 04-04-91 On the first day of therapy, a loading dose is given. After the first day, patients take pyrimethamine or placebo 3 times a week. Patients also take leucovorin calcium orally three times weekly. Enrollment occurs over approximately 12 months. All patients are followed on study until a common study close-out date and final analysis of the study. It is anticipated that this common close-out will occur when the mean duration of time on study therapy will be 3 years (approximately in January, 1994). ORIGINAL design: On the first day of treatment, patients receive a loading dose of pyrimethamine or placebo, plus of leucovorin calcium. After the first day, patients take pyrimethamine or placebo three times a week. Patients also take folinic acid orally three times weekly. The mean duration of study participation is 3 years.