IV Calcium Channel Blockers

Class IV drugs have a selective ability to block calcium entry into myocardial and vascular smooth-muscle cells. These drugs inhibit calcium influx by binding to specific channels in the cell membrane.12,15 As discussed previously, calcium entry plays an important role in the generation of the cardiac action potential, especially during phase 2. By inhibiting calcium influx into myocardial cells, calcium channel blockers can alter the excitability and conduction of cardiac tissues. 

Calcium channel blockers decrease the rate of discharge of the SA node and inhibit conduction velocity through the AV node.5 These drugs are most successful in treating arrhythmias caused by atrial dysfunction, such as supraventricular tachycardia and atrial fibrillation.15,39 

Because drugs like verapamil slow down the heart rate by inhibiting calcium entry into cardiac muscle cells, excessive bradycardia (less than 50 beats per minute) may occur in some patients receiving these drugs. Calcium channel blockers also limit calcium entry into vascular smooth muscle, which may cause peripheral 

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Category Antiarrhythmic class IV Calcium channel blocker Half-life 30-50 hours... 

Trade names Alti-Diltiazem Britiazem Calcicard Cardizem (Biovail) Cartia-XT Deltazen Dilacor XR (Watson) Dilrene Diltahexal Diltia-XT Nu-Diltiaz Presoken Teczem (Sanofi-Aventis) Tiamate Tiazac (Forest) Tilazem Tildiem Indications Angina, essential hypertension Category Antiarrhythmic class IV Calcium channel blocker Half-life 5-8 hours (for extended-release capsules)... 

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