Ciprostene (free base) is a synthetic, chemically stable analog of prostacyclin (PGI2). In animal models, administration of ciprostene resulted in dose-dependent hypotension, tachycardia, and inhibition of ex vivo ADP-induced platelet aggregation. Ciprostene was evaluated in clinical trials in patients with peripheral vascular disease. It was found to reduce restenosis in patients with coronary artery disease undergoing therapeutic percutaneous transluminal coronary angioplasty.

Ciprostene is the 9β-methyl analog of carbaprostacyclin and a stable analog of PGI2. Ciprostene exhibits biological activity similar to PGI2, but is 30-fold less potent. In patas monkeys, ciprostene induces hypotension and causes tachycardia when administered at a dose of 0.16 μg/kg/min. In addition, ciprostene inhibits ADP-induced platelet aggregation ex vivo and in vitro with ID50 values of 9.1 μg/kg/min and 60 ng/ml, respectively.