limaprost and Thrombocytopenia

A chemically stable prostacyclin analog, KP-10614 [(4z,16s)-4,5,18,18,19,19-hexadehydro-16,20-dimethyl-delta 6(9;alpha)-9(o)- methano-PGI1], has been compared with two other prostacyclin derivatives (Iloprost and TEI-7165) and one prostaglandin E1 derivative (OP-1206) with respect to ADP-induced in vitro aggregation of human platelets and ex vivo platelet aggregation in rats and dogs, given by bolus injection and i.v. infusion. These compounds were also tested on the systemic arterial blood pressure of rats and dogs. KP-10614 was the most potent inhibitor of in vitro platelet aggregation induced by ADP with IC50 of 1 nM among the compounds studied in this report, and it also showed ex vivo effectiveness at doses much lower than the other three compounds. KP-10614 was also orally active. At oral doses of 25, 50 and 100 micrograms/kg, this new compound caused a dose-dependent inhibition of ex vivo platelet aggregation in rats, whereas the other three compounds were effective only at 500 micrograms/kg or more. In addition, KP-10614 showed definite antithrombotic effects at a dose range of 0.1 to 1 microgram/kg i.v. in various thrombosis models in which platelet aggregation was mainly involved. These results indicate that KP-10614 possesses therapeutic potential in thrombotic diseases.

Topics: Administration, Oral; Alprostadil; Animals; Arachidonic Acid; Arachidonic Acids; Blood Pressure; Collagen; Dogs; Epoprostenol; Female; Fibrinolytic Agents; Heart Rate; Humans; Iloprost; Infusions, Intravenous; Injections, Intravenous; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Pulmonary Embolism; Rats; Rats, Inbred Strains; Thrombocytopenia; Vasodilator Agents

Effects of OP 1206 were studied on the cardiovascular system and platelet functions to assess OP 1206 as an antianginal agent. OP 1206 given orally at more than 100 micrograms/kg relieved vasopressin-induced ST depression of rat electrocardiogram (ECG), an animal model of angina pectoris, concomitant with slight hypotension. Intra-coronary injection of OP 1206 (1-100 ng/kg) in dogs resulted in a remarkable increase of coronary blood flow without any influence on heart rate, blood pressure, myocardial oxygen consumption and redox potential. Resistance in both large and small vessels of dog coronary artery was decreased by intravenous injection of OP 1206 (1-3 micrograms/kg). Platelet aggregation, adhesiveness, bleeding time, and thrombocytopenia induced by ADP and collagen infusion in guinea-pigs were inhibited by oral administration of OP 1206 at the same doses or doses less than those relieving vasopressin-induced ST depression of ECG. These results suggest that OP 1206 contributes to the improvement of cardiac imbalance between oxygen demand and supply, and suppression of thrombus formation in atherosclerotic heart.

Topics: Alprostadil; Angina Pectoris; Animals; Blood Platelets; Dogs; Electrocardiography; Female; Hemodynamics; Male; Myocardium; Oxygen Consumption; Platelet Adhesiveness; Platelet Aggregation; Prostaglandins E, Synthetic; Rats; Thrombocytopenia; Vascular Resistance