Possible Interaction: Epinephrine and Verapamil

“High doses of verapamil (but not diltiazem) inhibited platelet aggregation and secretion in response to adrenaline.”

“The synergistic interaction of …-5 microM) and epinephrine (0.5-2 microM) was inhibited by alpha2-… (yohimbine; IC50= 0.4 microM), calcium channel blockers ( verapamil and diltiazem with IC50 of 10 and 48 mM, respectively), PLC inhibitor (…=6 microM) and nitric oxide (NO) donor, SNAP (IC50=1.6 microM)).”

“The SNAP, diltiazem and verapamil inhibited the platelet aggregation induced by A23187 and epinephrine with IC50 value of 0.5 microM, 50 microM and 22 microM respectively.”

“ Verapamil shortened the action potential duration to 355 +/- 28 ms (p < 0.01 vs. epinephrine ) and decreased the dispersion to 44 +/- 19 ms (p < 0.05 vs. epinephrine).”

“It was found that verapamil is a more potent inhibitor of platelet aggregation induced by adrenaline as compared with nifedipine inhibiting this process only at high concentrations.”

“Diltiazem and verapamil inhibited aggregation caused by adrenaline 5 microM and collagen 2 micrograms/ml, but only at concentrations far in excess of those seen in clinical use.”

“ Verapamil inhibits the epinephrine contribution to the aggregation response by blocking alpha 2-adrenergic receptor binding.”

“Perhaps a reduction in circulating adrenaline contributes to the blood pressure lowering effects of verapamil.”

“In vivo verapamil significantly decreased platelet aggregation induced by ADP and epinephrine while no changes were observed after arachidonic acid.”

“ Epinephrine sensitive phosphorylation is completely inhibited following pretreatment with verapamil or nitrendipine.”