The Lethal Effect of Certain Antimalarial Drugs on Tetrahymena Pyriformis

Carl F. ClancyDepartment of Microbiology, Jefferson Medical College, Philadelphia, Pennsylvania 19107

Search for other papers by Carl F. Clancy in
Current site
Google Scholar
Restricted access


The ciliated protozoon, Tetrahymena pyriformis W, was used as a test animal for determining the lethal effect of certain antimalarial drugs.

Quinacrine, proguanil, primaquine, and quinine have a definite lethal effect for Tetrahymena. Quinacrine is lethal in amounts as small as 16 µg per ml or less, the other three being somewhat less toxic. Samples of drugs, from different lots of quinacrine and primaquine, yielded results comparable to those originally tested, and samples of primaquine from two different manufacturers yielded similar results. Chloroquine is mainly inhibitory at room temperature, but has some lethal activity when incubated at 37°C for 1 hour before the usual room-temperature incubation.

Eight other antimicrobial agents had little or no activity with the exception of chlortetracycline and minocycline. Chlortetracycline had slight lethal and moderate inhibitory activity for Tetrahymena; minocycline was both a strong lethal and inhibitory agent.