chapter 45: calcium channel blockers Flashcards
what are three overall therapeutic uses of calcium channel blockers
hypertension, angina pectoris and cardiac dysrhythmias
what do calcium channel blockers have the greatest effect on
heart and vascular smooth muscle
what are calcium channels
gated pores in cytoplasmic membrane that regulate entry of calcium into cells
what do calcium channels regulate in the VSM
contraction
what do calcium channels act on in the VSM
peripheral arterioles and arterioles in the heart
action potential causes calcium channels to do what
calcium channels open and ions move inward which causes contraction
what do calcium channels do in the heart
helps regulate function of the myocardium, SA and AV
what are calcium channels coupled to
beta1 adrenergic receptors
what happens if calcium channels are blocked
relaxation
what do calcium channel blockers do to inotropic effect, force of contractility, heart rate and dromotopic effect?
all are decreased
what type of chronotropic effect does calcium have?
positive
what type of inotropic effect does calcium have?
positive
what type of dromotropic effect does calcium have?
positive
what CCB works on arterioles at therapeutic doses?
nefedipine
if nifedipine dose becomes toxic, what effects could it produce?
significant cardiac suppression
what could nifedipine help with
coronary perfusion
what effect does nifedipine have on heart rate and force of contractility?
normally does not effect these two in any way
what CCBs work on arterioles and the heart?
verapamil and diltiazem
what is an indirect effect seen with verapamil and diltiazem
reflex tachycardia
what are the three net effects seen with verapamil and diltiazem?
vasodilation, reduced arterial pressure, increased coronary perfusion
where does blockade occur with verapamil and diltiazem?
peripheral arterioles that result in dilation, arteries and arterioles in heart, SA node, AV node, myocardium
what does blockade on peripheral arterioles lead to?
decreased arterial pressure and decreased vascular resistance
blockade on arteries and arterioles in heart has what effect?
improving coronary perfusion
blockade in SA and AV node has what two effects?
decreased heart rate and decreased AV impulses
the blockade on myocardium of the heart produces what effect?
decreased contractility
a patient comes into the clinic complaining of constipation and headache. during your assessment you notice flushing and slight edema in their ankles. what CCB do you suspect they may be taking?
verapamil or diltiazem
what are the effects that verapamil/diltiazem can have on the heart
symptomatic bradycardia (SA node blocked), partial or complete AV block or decreased contractility (myocardium blocked)
what drug should you not use a BB with?
verapamil/diltiazem
what are 3 drug-drug interactions with verapamil/diltiazem?
digoxin, beta-adrenergic blockers, grapefruit juice
what can concurrent use of verapamil and metaprolol cause?
massive cardiac suppressions
what are the therapeutic uses for nifedipine
hypertension and angina pectoris
what can nifedipine NOT be used for?
cardiac dysrhythmias
where are nifedipine direct effects located?
VSM
what does nifedipine help increase?
force of contractility
what drug can nifedipine be given concurrently with?
beta-adrenergic blocker
nifedipine has no opposition for what?
reflex tachycardia
what formulation of nifedipine safer to use?
sustained release rather than immediate release
a rapid decrease in BP with nifedipine can cause what?
will stimulate the baroreceptor reflex which can cause reflex tachycardia
what are the direct effects experienced with nifedipine
peripheral vasodilation and increased coronary perfusion
what is the one ADR seen with verapamil that is NOT seen with nifedipine?
constipation
what is a positive drug interaction with nifedipine
beta-adrenergic blockers
what is nifedipine the preferred drug for?
AV heart block, heart failure, or bradycardia
