CCBs Flashcards

1
Q

What are the uses of CCBs?

A
  • angina
  • HTN
  • supraventricular arrhythmias (a fib, a flutter, paroxysmal SVT)
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2
Q

How does calcium initiate contraction in the heart? Smooth muscle?

A

Heart- binding to troponin C reduces the inhibition of actin-myosin cross-bridges

SM- binding to calmodulin activates MLCk, which phosphorylates myosin and triggers contraction

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3
Q

Where do CCBs act specifically?

A

L-type voltage dependent, slowly inactivated Ca2+ channels. Other channels and regulators of calcium throughout the body (especially nerves (N and P type channels) are not affected by this process, this giving these drugs specificity)

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4
Q

Describe the smooth muscle contraction in vasculature.

A

graded, Ca2+ dependent through L-type channels

slow and sustained

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5
Q

Describe the smooth muscle contraction in the heart.

A

rely on L-type channels for contractile cells (atria, ventricles) AND slow response (SA, AV) cells

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6
Q

What are the effects of CCBs?

A

increase the time L-type channels are closed reducing the magnitude of current (all) and slow the recovery of the channel (non-dihydropyridines)

relax ARTERIAL but not venous smooth muscle (reduce afterload not preload)

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7
Q

What are the main effects of dihydropyridine CCBs?

A

arterial and coronary vasodilation (may increase reflex tachycardia and contractility)

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8
Q

What are the main effects of non-dihydropyridine CCBs?

A

act on cardiac and smooth muscle- arterial and coronary vasodilation and reduce HR and contractility (SA and AV node reduced)

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9
Q

What is the difference in the way NDHP and DHP CCBs act?

A

NDHPs bind to channels in a use-dependent way (channels that constantly open and close)

DHPs bind in a voltage-dependent way and prefer smooth muscle because their voltage changes very slowly

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10
Q

Absorption and elimination of CCBs?

A

extensive first-pass and hepatic metabolism via CYP3A4 eliminates (also CYP3A4 inhibitors)

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11
Q

Adverse effects of DHPs?

A
  • excessive vasodilation
  • GI pain
  • peripheral edema
  • paradoxical exacerbation of angina (coronary steal)- less with new slow-release reparations
  • fetotoxic
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12
Q

Adverse effects of NDHPs?

A
  • bradycardia, asystole, AV block
  • hypotension, peripheral edema
  • constipation (verapamil only)
  • CHF worsening (verapamil only)

-fetotoxic both

Never combine with a BB

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13
Q

What is coronary steal?

A

when massive vasodilation occurs during an MI event, it can steal perfusion from the myocardium

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14
Q

CYP3A4 inhibitors?

A
  • grapefruit
  • AZOLES
  • cimetidine
  • erythromycin
  • NDHP CCBs

increase NDHP CCB effect

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15
Q

CYP3A4 inducers?

A

-rifampin

decrease NDHP CCB effect

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16
Q

Which CCBs have the most side effects?

A

DHP more than NDHPs (verapamil more than diltiazem in just about everything except hypotension and peripheral edema-same)