Cocaine and cocaethylene (a psychoactive metabolite of concurrent coca
ine and ethanol consumption) were studied in the anesthetized vervet m
onkey. The ability of each to elevate extracellular DA in the caudate
nucleus was assessed using microdialysis probes acutely lowered throug
h chronic guide cannulae. Blood samples were also collected to determi
ne plasma levels of the two drugs. Doses of 1.5 mu mol/kg cocaine (equ
ivalent to 0.5 mg/kg cocaine-HCl) and cocaethylene were administered i
ntravenously. Microdialysis and blood samples were collected at 5-min
intervals immediately following drug administration. Both drugs caused
a maximal four-fold increase in extracellular DA during the 5- to 10-
min period following drug administration. This is the first report of
cocaine (and cocaethylene) induced alterations in extracellular DA in
primates. The abilities of cocaine and cocaethylene to produce euphori
a are being compared in ongoing clinical research studies. The potenti
al use of these results for interpreting the neurochemical basis of an
y differences in those studies is discussed.