Effect of Certain Antiprotozoal Drugs on Toxoplasma In Vitro and In Vivo ∗

Abstract

Summary

In a search for a chemothera-peutic agent against toxoplasma a large number of drugs of known effectiveness against other protozoa were tested in vitro and in vivo. In the in vitro tests, heparin-ized peritoneal exudate, containing about 10,000 M.L.D. of toxoplasma, was mixed with certain concentrations of the compounds under investigation and after incubation at 37 °C in a water bath for periods of 3, 6, and 24 hr, aliquot portions were injected intraàbdominally in mice to test for the survival of the toxoplasma. In this type of test atabrin in a concentration of 1:50,000 yielded a noninfective mixture in less than 3 hr; trypaflavin, rivanol lactate, potassium antimony tartrate, optochin (in concentrations of 1:10,000) and mapharsen (1:20,000) required more than 3 but less than 6 hr, and neosalvarsan (1:20.000), tryparsamide (1:10,000), and quinine HCl (1:10,000) required more than 6 but less than 24 hr to produce the same effect. Stibosan (1:10,000), 4:4′ diamidino stilbene (1:10,000), sulfanilamide (1:4,000), sodium sulfathiazole (1:4,000) and sodium sulfa-pyridine (1:4,000) were without effect on the toxoplasma even after 24 hr. All these and a number of other compounds had no therapeutic effect when they were administered parenterally to mice and rabbits immediately after injection of the toxoplasma and once or twice daily thereafter.