In vitro antiproliferative effects of tricyclic psychopharmaceutical agents and synergism with some resistance modifiers.

: Some of the phenothiazines and dibenz[b,f]azepines exert an antiproliferative effect on HEp-2 and rat prolactinoma cells. The same compounds also have effects on different membrane-bound biochemical events, such as H2O2 formation and the peroxide-generated chemiluminescence of polymorphonuclear leukocytes. The superoxide dismutase inhibition by 7,8-dioxochlorpromazine and 6,9-dioxochlorpromazine have some relation to the growth inhibitory action on the growth of HEP-2 and prolactinoma cells in vitro. The antiproliferative effects of phenothiazines were synergized with resistance modifiers like verapamil, omeprazole and tubulozole-C, due to increased drug-influx or decreased drug-efflux and due to possible action on the cytoskeleton.