Central action of ketotifen.

Ketotifen (4-/1-methyl-4-piperidylidene/-4H-benzo[4,5]cyclohepta[1,2-b]thiophen-10(9H)-one hydrogen fumarate) inhibited spontaneous locomotor activity and amphetamine hypermotility in mice and rats, as well as L-DOPA-induced motor stimulation in mice. It produced in mice a slight hypothermia and did not prevent reserpine-induced hypothermia; thus, it does not posses properties or tricyclic antidepressants. Ketotifen showed some features of serotoninolytic: it inhibited the head twitch response to 5-hydroxytryptophan in mice, depressed tryptamine-induced clonic convulsions in rats, antagonized fenfluramine-induced hyperthermia in rats at high ambient temperature and showed weak antiserotonin action in the flexor reflex preparation. Ketotifen did not affect spiperone- or reserpine-induced catalepsy and showed no cholinolytic activity. LD50 of ketotifen (after 24 h) was 122.5 mg/kg ip in mice and 62.6 mg/kg ip in rats.