TREATMENT OF TOXOPLASMOSIS.

Screening tests were carried out for the purpose of obtaining new and effective drugs against toxoplasmosis. Compounds tested were 14 pyrimidine derivatives, 17 triazine derivatives, 9 sulfonamide derivatives, 2 thiourea derivatives, 1 purine derivative, and 1 guanidine derivative. The compounds to be tested were given intraperitoneally for five days successively, starting one day before infection. The daily dosage was 115 of the LD50 of each compound, the effects of which were evaluated by the differences in survival between the experimental and the control mice. Of the compounds tested, pyrimethamine has been shown to be the single most effective drug. After administration of pyrimethamine to RH infected mice, no mouse died within 21 days and no toxoplasmas were found in the tissues of the surviving mice, based on subinoculation procedures. Treatment with a sulfone-pyridazine combination revealed distinct therapeutic advantages over treatment with the sulfones alone. Showing even greater synergistic effects were the drugs pyrimethamine and pyridazine. Spiramycine and pyridazine, although individually showing only slight killing effects on Toxoplasma, greatly prolonged the period of survival of the treated mice. In combination however, the two drugs were almost equivalent, therapeutically, to pyrimethamine. Author