A COMPARISON OF SOME OF THE CARDIOVASCULAR ACTIONS OF METHYLPHENIDATE AND COCAINE

¹ Research Department, CIBA Pharmaceutical Products Inc., Summit, New Jersey

Cocaine and methylplmenidate, which have been reported elsewhere to produce a differential effect on the actions of a series of pressor amines of time phenylalkyhamine type, have been shown to possess the capacity to negate the phentolamine- induced blockade of norepinephrine while not affecting the blockade induced by doses of Dibenamine producing completely irreversible blockade of norepinephrine. Experiments indicate that cocaine and methylphenidate do not produce a generalized release of endogenous catecholamines. As has been demonstrated for methylphenidate, cocaine antagonizes carotid occlusion reflex pressor responses when administered intravenously. As also reported for methylphmenidate, this blockade is not at the carotid sinus nor is a blocking effect of cocaine in the efferent sympathetic periphery demonstrable. It is concluded that as for methylphenidate, the blocking action of cocaine on carotid occlusion responses is centrally induced. These results are discussed in relation to certain cardiovascular effects of reserpine and hexahydro-1-azepinepro-pionamidoxime (Su-4029) and the suggestion is made that an important action of cocaine and methylphenidate may be occurring at the smooth muscle motor receptor site.