A targeted synthetase inhibitor was a medication designed to target and inhibit the growth of a particular set of cells in a body.
Doctor Shenti Yisec Eres Ree injected USS Titan counselor Deanna Troi with a targeted synthetase inhibitor to stunt the growth of her second aborted fetus in 2381 after she refused to have it removed. The daily injections allowed the fetus to continue to draw sustenance from her body but prevented it from rupturing her uterine lining. (ST - Destiny novel: Gods of Night)