Epoprostenol (Prostacyclin) in Unstable Angina

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Abstract
The purpose of this randomized, double‐blind multicenter trial was to investigate the potential therapeutic effect of epoprostenol (prostacyclin, PGI2) in patients with unstable angina, as compared with placebo, and to investigate the safety of this agent. Of the 184 patients enrolled, 28 did not fit the study criteria; of the remaining 156 patients, 30 received prostacyclin in an open‐label fashion. In the double‐blind portion of the study, 63 patients each received prostacyclin or placebo. The drug or its vehicle was infused intravenously up to 5 ng/kg/min dose for 72 hours with a tapering off period for the last 12 hours. Both treatment groups from the double‐blind portion were comparable in regard to the demographic data, length of infusion, and total dose received. There were no significant differences between the placebo and prostacyclin group in the following clinical endpoints: levels of cardiac enzymes throughout hospitalization period (with the exception of lower SGOT level in the prostacyclin group at day 2), and severity of angina (throughout the study), and at the end of the study (day 30). The number of patients who had congestive heart failure, new myocardial infarction, balloon pump insertion, coronary artery bypass grafting, or percutaneous coronary angioplasty was similar in both groups. Similar results in regard to the efficacy endpoints were also apparent in the prostacyclin group that was treated under open‐label fashion. There was also no difference in the New York Heart Association (NYHA) functional status at the end of the double‐blind study. The overall incidence of adverse drug reactions was insignificantly higher in the prostacyclin patients as compared with the placebo ones. However, the portion of patients reporting headache, flushing, nausea, and vomiting was significantly higher in the drug group. There were no clinically significant differences between the treatment groups in safety laboratory evaluations (beginning to end of study). The lack of clinical benefit of prostacyclin may be explained by heterogeneous mechanisms of unstable angina, by multiple standard medications patients were exposed to, by PGl2 inability to prevent or lyse coronary thrombus at advanced stages of unstable angina, or simply by its pharmacologic ineffectiveness in this disease.