Possible Interaction: Calcium Channel Blockers and Epinephrine

“The organic calcium antagonist, nitrendipine, and the inorganic calcium channel blockers (Co2+, Mn2+, Cd2+, La3+) drastically inhibited rat and human platelet aggregation induced by thrombin, ADP or adrenaline in the presence of 0.32 mM Ca2+.”

“The synergistic interaction of …-5 microM) and epinephrine (0.5-2 microM) was inhibited by … blocker (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)).”

“Conclusion: A hypertensive response, following systemically absorbed topical vasoconstrictors, including both phenylephrine and epinephrine , can be associated with dire consequences when treated with a beta-adrenergic blocking drug and, possibly, calcium channel blockers.”

“3) Treatment with calcium blockers in normotensives decreases the aggregatory response to epinephrine.”

“ Calcium channel blockers and dibutyryl cAMP enhanced the activity of the pump, and exerted respectively overlapping and additive effects with epinephrine , when added simultaneously.”

“Studies on the possible involvement of secondary messengers in cell expansion indicated that (i) both 8‐bromo‐CAMP and forskolin caused cell shrinking (…, such as 1,2‐dioctanoyl‐sn‐glycerol, lysophosphatidic acid, and arachidonic acid caused cell expansion; and (iv) EGTA (calcium chelator) and nifedipine calcium channel blocker) … epinephrine.”

“The calcium channel blocker (cadmium and nifedipine) greatly blocked the effects of adrenaline on the peak and total tension of K+ contractures.”

“In preparations with prominent … plateaus, addition of epinephrine resulted in triggered activity; similarly, epinephrine caused automaticity from a depolarized … 8/9 fibers quiescent at ‐50 to ‐60 mV. Thus, the calcium channel blocking drugs bepridil and lidoflazine produced striking repolarization changes at …, but unlike quinidine, triggered activity was rare.”

“Interventions to counter the deleterious effects of adrenaline were: calcium antagonism , β-blockade, an antilipolytic agent, and a combination of calcium antagonism and an antilipolytic agent.”