[Pharmacological study of mequitazine (LM-209) (III). Action on the central nervous system (author's transl)]

The action of an anti-histaminic agent, Mequitazine (LM-209) on the central nervous system was investigated. We found that LM-209 did not affect the spontaneous and co-operative movement in mice, did not induce muscle relaxation, analgesic effects or anti-convulsant effect in micr or hypothermic effects in rats. The anti-oxotremorine effect of LM-209 in mice was about 10 times more potent than clemastine fumarate (CL) and the same as promethazine. The activity and duration of the action were also superior to diethazine and orphenadrine used as an anti-Parkinson drug. LM-209 prolonged by 50% the hypnotic time induced by hexobarbital at 50 mg/kg (p.o.) in mice, while CL prolonged 50 and 100% it at 25 and 50 mg/kg (p.o.) respectively. In the EEG of rabbits, LM-209 produced a resting pattern, inhibited the arousal responses and recruiting responses and the effect was the same as CL and less potent than promethazine. From these results, the activity of LM-209 on the central nervous system (except for the anti-oxotremorine effect) seems to be the same as or somewhat less potent than CL. Therefore LM-209 should be an effective and anti-histaminic agent for clinical application.