Prostacyclin (PGI2) is a cyclooxygenase metabolite with antithrombotic properties found in vascular endothelial cells. The half-life is short both in vivo and in vitro, ranging from 30 seconds to a few minutes. CG 4305 is a stable carbacyclic analog of PGI2 that inhibits ADP-induced platelet aggregation 25% at a concentration of 50 nM. Doses of 10 mg/kg (oral) or 1 mg/kg (intraduodenal) have been shown to prevent rabbit carotid artery thrombosis.