Pregnancy enhances cocaine's actions on the heart and within the peripheral circulation.

Abstract

Our purpose was to determine whether cocaine's enhanced cardiovascular actions in pregnancy are cardiac alone or involve the peripheral vascular system. Six pregnant and five nonpregnant ewes chronically instrumented for heart rate, blood pressure, cardiac output, and systemic vascular resistance were given cocaine at 1.0 and 2.0 mg/kg and monitored for 60 minutes. Blood samples for cocaine levels were taken at 5, 15, 30, and 60 minutes. Cocaine initially (first 60 seconds) produced increased heart rate, decreased cardiac output, decreased stroke volume, and increased cardiac oxygen consumption, which were greater in pregnant than nonpregnant ewes. After 1 minute recovery of cardiac responses was accompanied by increased systemic vascular resistance, which was greater at each dose in pregnant than nonpregnant ewes. Cocaine levels at 5 minutes for pregnant ewes were eightfold to tenfold higher than for nonpregnant ewes. Cocaine produces cardiovascular alterations that are dose and time related but, in each case, enhanced in pregnant ewes. Cocaine metabolism may contribute to this pregnancy-related phenomenon.