Background: A temporal relationship has been established between cocai
ne ingestion and myocardial infarction, and a cocaine-induced increase
in platelet aggregation has been suggested as a possible explanation.
However, the mechanisms of cocaine associated coronary thrombosis hav
e yet to be completely elucidated. For this reason, we examined the in
vitro effect of cocaine and its metabolites on platelet aggregation.
Methods: Platelet aggregation was tested by obtaining platelet rich pl
asma from 42 healthy volunteers and incubating the platelet rich plasm
a in six concentrations of cocaine (ranging from 1.47 to 2940 nmol) fo
r 10 minutes prior to aggregation with ADP 1 mu M. The same procedure
was used to test the effect of two cocaine metabolites, benzoylecgonin
e and ecgonine methyl ester, on platelet aggregation. Abnormal results
were confirmed by inducing aggregation with ADP at higher concentrati
ons (2.4 and 10 mu M) and with arachidonic acid (624 mu M). Results: A
t increasing concentrations, cocaine progressively inhibited ADP and a
rachidonic acid induced platelet aggregation. No effect was seen with
benzoyl ecgonine or ecgonine methyl ester as compared to saline. Concl
usions: These data suggest that under certain conditions cocaine may n
egatively affect hemostasis by decreasing platelet aggregation.