Vasodilator and hypotensive effects of the optical isomers of nicardipine (YC-93), a new Ca2+-antagonist.
Vasodilator and hypotensive effects of (+) and (-) nicardipine were investigated in anesthetized dogs. When administered intravenously, (+) nicardipine was 3 times as potent as the (-) isomer in increasing vertebral blood flow and in lowering mean blood pressure. When injected into the vertebral artery, (+) nicardipine was also 3 times as potent as the (-) isomer in increasing vertebral blood flow. Upon both routes of administration, the duration of the action after (+) nicardipine was longer than that after the (-) isomer. However, there were no differences of plasma nicardipine levels after intravenous injection of both isomers to conscious beagle dogs. The LD50 values of (+) nicardipine in mice and rats upon intravenous injection were only 1.5-2 times smaller than those of the (-) isomer. These results indicate that there exists a stereoselectivity of vasodilator and hypotensive actions among the nicardipine isomers.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002121:Calcium Channel Blockers / Q000097:blood / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D007536:Isomerism; D007928:Lethal Dose 50; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009529:Nicardipine; D009543:Nifedipine / Q000031:analogs & derivatives / Q000097:blood / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013329:Structure-Activity Relationship; D014665:Vasodilator Agents / Q000097:blood / Q000494:pharmacology*; D014711:Vertebral Artery / Q000187:drug effects
D002121:Calcium Channel Blockers; D011725:Pyridines; D014665:Vasodilator Agents; D009529:Nicardipine; D009543:Nifedipine