Calcium channel blockers are effective in treating hypertension because they reduce peripheral resistance.

Amlodipine and felodipine have relatively little effects on reducing myocardial contractility compared to verapamil or diltiazem.

Arteriolar vascular tone depends on free intracellular Ca²⁺ concentration:

• Calcium channel blockers reduce transmembrane movement of Ca²⁺

• Reduce the amount reaching intracellular sites and therefore

• Reduce vascular smooth muscle tone.

All calcium channel blocks appear similarly effective for management of mild to moderate hypertension.

For low-renin hypertensive patients (elderly and African-American groups), Ca²⁺ channel blockers appear good choices for monotherapy (single drug) control.

 Adverse Effects

• SA nodal inhibition may lead to bradycardia or SA nodal arrest. This effect is more prominent if beta adrenergic antagonists are concurrently administered.

• GI reflux.

• Negative inotropic effects are augmented if beta-adrenergic receptor antagonists are concurrently administered.

• Calcium channel blockers should not be administered if the patient has SA or AV nodal abnormalities or in patients with significant congestive heart failure.