ACUTE TOLERANCE TO THE CARDIOVASCULAR EFFECTS OF VOLATILIZED COCAINE FREE-BASE IN RATS

The cardiovascular effects elicited by volatilized cocaine were compar ed to those produced by i.v. drug administration. All of the subjects exposed to volatilized cocaine exhibited an initial increase in mean a rterial pressure (MAP), profound bradycardia, and heart blocks. Intrav enous administration of cocaine (1.5 mg/kg i.v.), a dose equivalent to the amount of drug subjects received from inhalation exposure, led to a transient increase in MAP but failed to produce any obvious ECG abn ormalities or bradycardia; however, increasing the dose to 4.5 mg/kg r esulted in considerable toxicity. Finally, the hemodynamic effects eli cited by inhalation cocaine were found to undergo rapid tolerance duri ng the first 5-min exposure period and the three subsequent drug expos ures.