SEX-DIFFERENCES IN PLASMA COCAINE LEVELS AND SUBJECTIVE EFFECTS AFTERACUTE COCAINE ADMINISTRATION IN HUMAN VOLUNTEERS

Gender differences after acute cocaine administration have received li ttle attention in spite of the fact that males and females respond dif ferently to many drugs. Seven male and seven female occasional cocaine users received both an intranasal dose of cocaine hydrochloride (0.9 mg/kg) and placebo powder in a randomized order and reported subjectiv e effects via an instrumental joystick device and various questionnair es. Blood samples were withdrawn at 5-min intervals to assess pharmaco kinetic differences. Male subjects achieved the highest peak plasma co caine levels (144.4 +/- 17.5 ng/ml), detected cocaine effects signific antly faster than females and also experienced a greater number of epi sodes of intense good and bad effects. Women studied during the follic ular phase of their menstrual cycle had peak plasma cocaine levels of 73.2 +/- 9.9 ng/ml, which was significantly higher than when they were studied during their luteal phase (54.7 +/- 8.7 ng/ml), but there wer e no differences in their subjective reports of cocaine effects. In sp ite of the different cocaine blood levels and subjective effects, peak heart rate increases did not differ between males and females suggest ing that women may be more sensitive than males to the cardiovascular effects of cocaine. These data suggest that there are significant gend er and menstrual cycle differences in the response to acute intranasal cocaine administration and these differences may have implications fo r the differential abuse of this drug.