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.
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.