Calcium channel blockers

Question 1

MOA

Cause smooth muscle relaxation by blocking the binding of calcium to its receptors, preventing contraction

Subsequent dilation of peripheral arteries decreases afterload, leading to a decrease in BP & a reduction in myocardial workload & O2 demand

Question 2

Contraindications/precautions

• Hypersensitivity, acute MI, pulm congestion
• WPW syndrome, severe hypotension, cardiogenic shock
• Sick sinus syndrome, 2/3rd deg AV block

Question 3

Food/drug interactions

• Inc effect w/other antihypertensive drugs, cimetidine, & ranitidine
• Dec effect w/phenytoin & rifampin
• Grapefruit juice may inc serum levels

Answer 3

• Possible toxicity of anesthetics, doxorubicin, benzodiazepines, buspirone, carbamazepine, digoxin statins, steroids, tacrolimus, sirolinus, theophylline, & vincristine when given concurrently w/a CCB

Question 4

Adverse effects

• Hypotension, palps, bradycardia
• HF, constipation, nausea, dermatitis
• Dyspnea, rash, flushing, peripheral edema, & wheezing

Question 5

Nursing

• Hold med per parameters
• IV infusion needs continuous ECG monitoring - may prolong PR interval or AV block
• Assess for toxicity - hypotension, bradycardia, HF, & conduction disorders

Answer 5

• Eval effectiveness as evidenced by dec chest discomfort & fatigue, improved VS, skin color, & urinary output
• Monitor I&O’s & report >2 lbs wt gain/day or 5 lbs/wk
• Avoid concurrent use of antacids & grapefruit juice

Question 6

Examples

• Diltiazem
• Nifedipine
• Verapamil