psy·cho·phar·ma·col·o·gy 
(sī′kō-fär′mə-kŏlə-jē)
(sī′kō-fär′mə-kŏlə-jē)n.
The branch of pharmacology that deals with the study of the actions, effects, and development of psychoactive drugs.
psy′cho·phar′ma·co·logic (-kə-lŏjĭk), psy′cho·phar′ma·co·logi·cal (-ĭ-kəl) adj.
psy′cho·phar′ma·colo·gist n.