Combination of Drugs Promising for Treatment of Toxoplasmosis

National Institute of Allergy and Infectious Diseases Update EMBARGOED FOR RELEASE NATIONAL INSTITUTES OF HEALTH Mon, y, July 20, 1992 Greg Folkers 1:00 p.m. (7:00 a.m. EDT) [phone] Combination of Drugs Promising for Treatment of Toxoplasmosis A combination of the drugs 566C80 and pyrimethamine shows promise in fighting toxoplasmosis in people with AIDS, according to preliminary results of a small National Institute of Allergy and Infectious Diseases study. Data from the same study suggest that a second experimental treatment for patients with AIDS-related toxoplasmosis, azithromycin taken alone, may be ineffective. Joseph A. Kovacs, M.D., senior investigator at the NIAID/Clinical Center AIDS Program, plans to present the findings in a poster session at the VI International Conference on AIDS in Amsterdam from July 20 to 24. Approximately 40 to 60 percent of AIDS patients with toxoplasmosis cannot tolerate the side effects of the standard treatment, a combination of pyrimethamine and sulfadiazine. "New therapies are needed urgently to combat toxoplasmosis, which afflicts up to a third of all people with AIDS," says Anthony S. Fauci, M.D., NIAID director. "The combination of 566C80 and pyrimethamine has shown promise, both in animal studies and now in humans, but wil require further evaluation to determine long-term benefits and side effects." Toxoplasmosis is a life-threatening infection of the brain caused by a protozoan parasite. Although 30 to 40 percent of the general adult population are infected with the parasite, those with normal immune systems have few or no symptoms of the disease. In persons whose immune (more) 5571095.0291.013

systems have been weakened by HIV infection or other causes, however, the parasite can reactivate and cause damage to the central nervous system, leading to coma and death. The most common symptoms of the infection are confusion, headaches, fever, paralysis, seizures and difficulty seeing, speaking and walking. Once symptoms occur, treatment must be continued for life in order to prevent recurrences. In the study, Dr. Kovacs and his colleagues enrolled eight patients with toxoplasmosis who could not tolerate the standard therapy. They gave two of the patients 1,200 milligrams of azithromycin a day. After two weeks, X-rays showed that their toxoplasmosis was worsening, and these patients were taken off the study and switched to another treatment. Six other patients have been given a combination of 750 milligrams of 566C80, four times a day, plus 50 milligrams of pyrimethamine, once a day. Three of the patients remain in the study and their condition has improved or stabilized. One person appeared to be responding to the drug, but died from other AIDS-related complications, and two others did not seem to benefit from the drug. Two patients on the 566C80/pyrimethamine regimen had a decline in the number of white blood cells, but the treatment was otherwise well-tolerated. In addition to Dr. Kovacs, the study investigators include Michael A. Polis, M.D., M.P.H., Barbara F. Baird, R.N., Irwin M. Feuerstein, M.D., Judith Falloon, M.D., Robert E. Walker, M.D., Richard T. Davey, M.D., H. Clifford Lane, M.D., and Henry Masur, M.D. NIAID and the Clinical Center are components of the National Institutes of Health in Bethesda, Md. NIAID supports research on allergy, immunology and infectious diseases, including an extensive AIDS clinical research program at the Clinical Center, a 500-bed hospital on the NIH campus.