Calcium channel blockers

Calcium channel blockers (CCB’s) – (calcium antagonists):
Drugs that prevent calcium ions from entering cells  decrease in afterload by relaxing vascular smooth muscle and cause vasodilaton
Used to treat hypertension (moderate to severe), angina pectoris and dysrhythmias

Calcium channels are gated pores in cytoplasmic membrane – role is to regulate the movement of calcium ions into the cells  play role in initiating contractile process of smooth muscle. If channels blocked  contraction prevented  vasodilation

Three types:
• dihydropyridines (eg nifedipine, amlodipine, felodipine) – act primarily on arterioles
• phenylakylamines (eg verapamil) – act on arterioles and heart
• benzothiazepines (eg diltiazem) – act on arterioles and heart