Diltiazem (Calcium Channel Blocker) 
  • Calcium channel blockers are effective in treating hypertension because they reduce peripheral resistance.
  • 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.
  • Diltiazem has a direct negative chronotropic effect on the heart sufficient to block reflex-mediated tachycardia secondary to the decrease in peripheral resistance.
  • The reflex-mediated adrenergic stimulation tends to counteract negative inotropic properties of diltiazem.
 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 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.