General pharmacology of beraprost sodium. 2nd communication: effect on the autonomic, cardiovascular and gastrointestinal systems, and other effects.

Beraprost sodium (sodium (+/-)-(1R*,2R*,3as*,8bS*)-2,3,3a,8b-tetrahydro-2- hydroxy-1-[(E)-(3S*)-3-hydroxy-4-methyl-1-octen-6-ynyl]-1H- cyclopenta[b]benzofuran-5-butyrate, TRK-100) is an orally active epoprostenol (prostaglandin I2, PGI2) analogue. Its general pharmacological effects on peripheral organs were studied. 1. In isolated organs, beraprost sodium relaxed the trachea and increased atrial beating rate (2.4 x 10(-5) mol/l). It also dose-dependently contracted the stomach, aorta, ileum and uterus (2.4 x 10(-7)-2.4 x 10(-4) mol/l). These effects of beraprost sodium were similar, but inferior to those of PGI2 and PGE1. 2. Intravenous administration of beraprost sodium produced a dose-related decrease in blood pressure (BP), its potency being about 1/3 times that of PGI2 in anesthetized rats and dogs. Beraprost sodium and PGI2 had no effects on heart rate (HR), and enhanced respiration in conjugation with a decrease in BP. Oral administration of beraprost sodium in high doses (1-3 mg/kg in rats and 0.3 mg/kg in dogs) caused a decrease in BP. A compensatory tachycardia and an elevated plasma renin activity (PRA) occurred after low doses (0.1-0.3 mg/kg) in rats. In contrast, a change of HR and PRA in rabbits and dogs was mild. 3. Beraprost sodium produced suppression of digestive organs: markedly, gastric motility and secretion and intestinal transport; slightly, but significantly, biliary secretion. On the other hand, it enhanced ileal motility at a high dose (300 micrograms/kg i.v.). 4. Oral administration of beraprost sodium caused a decrease in urinary volume and electrolyte excretion in rats. 5. Oral administration of beraprost sodium prolonged bleeding time in mice, while it had no effect on the blood coagulation system in vitro. In addition, beraprost sodium had no hemolytic action. 6. The other effects of beraprost sodium were weak. Beraprost sodium had no local anesthetic activity and no effect on salivation, pupil size and neuromuscular transmission in the skeletal muscle. Beraprost sodium slightly contracted the uterus of non-pregnant rats in situ and dose-independently inhibited carrageenin-induced paw edema. In conclusion, beraprost sodium produced various effects on the autonomic, cardiovascular, and gastrointestinal systems. Probably, these effects may be based on its own action like PGI2.