title: Effect of Ca2+-antagonistic vasodilators, diltiazem, nifedipine, perhexiline and verapamil, on platelet aggregation in vitro.
abstract: Ca2+-Antagonistic vasodilators, diltiazem, nifedipine, perhexiline and verapamil, showed inhibitory activity on platelet aggregation in human platelet-rich plasma (PRP) induced with ADP, adrenaline and collagen. Preincubation of PRP with one of the drugs effectively prevented the aggregation induced by ADP, ID50s being 2.1 x 10(-4), 3.5 x 10(-5), 3.4 x 10(-5) and 2.3 x 10(-4) g/ml for diltiazem, nifedipine, perhexiline and verapamil, respectively. Nifedipine and perhexiline were equipotent and about 10 times as potent as diltiazem and verapamil. In addition, PRP maximally aggregated with 9.1 mumol/l ADP was disaggregated by administration of any of these drugs. The mechanism of action was considered to be Ca2+-antagonism because, with the exception of perhexiline, the potency ratio of the anti-aggregating activity had a close resemblance to that of the vasodilator activity of these drugs previously reported in the literature. Perhexiline showed the most potent anti-aggregating activity but has been reported to be the least potent vasodilator among the Ca2+-antagonists studied. This further studies are necessary to elucidate the mechanism of perhexiline's inhibition of platelet aggregation.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D002118:Calcium / Q000037:antagonists & inhibitors*; D003094:Collagen / Q000494:pharmacology; D004110:Diltiazem / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D010480:Perhexiline / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D014665:Vasodilator Agents; D000244:Adenosine Diphosphate; D003094:Collagen; D014700:Verapamil; D004110:Diltiazem; D009543:Nifedipine; D010480:Perhexiline; D002118:Calcium; D004837:Epinephrine