Question | Answer |
normal physiology of calcium channel | is COUPLED with B-1 receptors---epi/nor/agonist binds B-1---cAMP 2nd messenger opens Ca channel---Ca influx |
once Ca in cell, what are heat targets/actions | SA node/HR-----AV node/conduction velocity-----myocardium/force of contraction |
B-1 receptors/Ca channels also located in artery smooth muscle, what is their action | in arteries, normal action is to vasocon periph arteries/inc bp--------vasoCON coronary arteries/dec perfusion |
so, when we BLOCK Ca channels, what is that effect on the heart | Ca can't get in--> SA/DECREASED HR-----AV/DECREASED force of conduction-----myocardium/DECREASED force of contraction |
when we BLOCK Ca channels in arteries, what is effect | arteries vasoDIL--> increased coronary perfusion---peripheral vasoDIL/dec bp |
two classes of calcium channel blockers | dihydropyridines ---- other class (verapamil, diltiazem) |
MOA of verapamil (other class, drug 1) | blocks Ca channels in BOTH artery VSM (vascular smooth muscle) AND heart. net effect to dec bp/inc cardiac perfusion and dec HR/conductivity/force of contraction |
verapamil indiacted for | indicated for essential HTN, CAD, angina pectoris, dysrhyth, tachy, migraine prophylaxis |
compliance limiting SE verapamil | constipation - also blocks GI Ca channels |
SEs we would expect from verapamil based on MOA | expect CARDIAC SEs ----overshoot if too high of dose-------brady----heart block (too little conduction) |
Lesser SEs expected from verapamil | vasodil--> flushing/diz/HA/mild periph edema-------GINGIVAL HYPERPLASIA |
MOA of diltiazem (other class, drug 2) | MOA is similar to verapamil with less potent effects on heart -----sim action on VSM to dec bp, inc coronary perfusion |
are verapamil and diltiazem safe for RF pts | yes, they are metabilized in the liver |
MOA of dihydriopyridienes = DHPs----AKA dipines | they ONLY act on B-1/Calcium channels on VSM. NO, NONE, NADA, ZIP action on heart except baroreceptor reflex which I am not getting into |
DHP - dihydropyridine indicated for | HTN and angina pectoris. No indications for cardiac |
ADRs DHP dihydropyridine | ANKLE EDEMA-----flush/HA/dizz ---some reflex tachy bwo inotropic effects, which we are not discussing |
Name 6 DHPs ---dihydropyridines | meet the dipine family---clevidipine---nisoldipine---felodipine---amlodipine---isradipine---nicardipine |
what 1 DHP is ONLY, ONLY, ONLY to be used to prevent cerebral vasospasm in subarachnoid bleeds | nimodipine |
primary MOA of DHPs | major role block B-1/Ca Channels in VSM. Virtualy no direct effect on heart (indirect, but I am so not talking about it) |
DHP given IV only | clevidipine |
DHP 5% bioavailability | nisoldipine |
DHP 20% bioavailability | felodipine |
DHP very long acting | amlodipine |
DHPs - 2 - nothing remarkable | isradipine, nicardipine |
DHP that can't be used for HTN | nimodipine - only subarachnoid bleed-prevent vasospasm |
What CCB has MOST ADRs | verapimil wins this prize |
which CCB has middle ADRs | diltiazem is runner up |
which CCB class has least ADRs | DHP class of dihydropiridines = dipines has fewest ADRs |
which CCB is most likely to cause ADR of heart block | verapamil, followed by diltiazepam |
which CCB is most likely to cause constipation | verapamil, less likely diltiazepam |
which CCB is most likely to cause ankle edema | any DHP dipipine . . .except nimodipine which is only used for . . .you know it already! quiz answer was nifedipine |