Calcium Channel Blockers

Question 1

Drugs that are Calcium Channel Blockers

Answer 1

Prototype: Nifedipine (Adulate, Procardia); Diltiazem (Cardizem); Verapamil (Calan)

Question 2

Expected Pharmacological Action

Answer 2

Nifedipine: Blocking of calcium
 channels in blood vessels
 leading to vasodilation of
 peripheral arterioles and
 arteries/arterioles of the heart.
Verapmil, diltiazem: Same as
 above, but also calcium channels
 in the myocardium, SA & AV
 node leading to a decreased
 force of contraction.

Question 3

Side and Adverse Effects

Answer 3

Nifedipine: Reflex tachycardia,
 Peripheral edema, Acute toxicity
Verapamil, diltiazem: Orthostatic
 hypertension, constipation,
 bradycardia, dysrhythmias

Question 4

Intervention

Answer 4

-Monitor ECG, pulse, rhythm
-Observe for swelling in lower
extremities
-Prescribe diuretics to control
edema.
-For toxicity, administer
norepinephrine, calcium,
isoproterenol, lidocaine and IV
fluids.

Question 5

Administration

Answer 5

-No chewing or crushing
sustained-release tablets.
-IV Verapamil, inject slowly 2-3
mins.

Question 6

Patient Instruction

Answer 6

-Monitor for excessive slowing of heart rate.
-Avoid drinking grapefruit juice.
-Notify provider of swelling in
lower extremities.
-Instruct about signs of
lightheadedness, dizziness. If
occur, sit or lie down.
-if constipated, intake high fiber
and fluids.

Question 7

Contraindications

Answer 7

-Pregnancy risk category C
-Nifedipine in acute MI, unstable
angina, aortic stenosis, shock
and intestinal obstruction.
-Verapamil in heart block,
digoxin toxicity, severe HF, &
lactation.

Question 8

Precautions

Answer 8

Older adults, pts who have renal or liver disorders, mild to moderate HF, or GERD.

Question 9

Interactions

Answer 9

-Nifedipine/grapefruit juice can
 lead to toxicity.
-Verapamil increase digoxin levels.
-Concurrent use w/ beta-blocker 
 can lead to HF, AV block,
 bradycardia.