The pharmacological actions of benzoyl peroxide were investigated using the screening methods of general pharmacology. The results obtained in the present study were as follows: (1) In in vivo study, benzoyl peroxide did not exhibit analgesic, anti-convulsive, muscle-relaxant or hypnotic effects in mice. (2) Benzoyl peroxide did not affect the twitch response to electrical stimulation in isolated phrenic nerve-diaphragm preparation of rats. (3) Benzoyl peroxide did not affect the contractile response to acetylcholine in the isolated bronchus of rats, but significantly depressed the contractile responses to acetylcholine and Ba^ in isolated ileum of rats. (4) Benzoyl peroxide did not exhibit diuretic effects or hemolytic effects in rabbits. The in vivo results indicated that benzoyl peroxide has no effect on the central nervous system or the somatic nervous system of rats. However, at higher concentrations benzoyl peroxide depressed the contractile response of ileal smooth muscles. Therefore, our results suggest that excess benzoyl peroxide changes some physiological functions of smooth muscle tissue without changing the behavior or external appearance in vivo experiments
