Calcium Channel Blockers

Definition
Medications that disrupt the movement of calcium through calcium channels
Antihypertensives
Effective against large vessel stiffness

Uses
High Blood Pressure
Coronay Artery Disease
Arrhythmia
To reduce chest pain due to angina pectoris
To prevent cerebral vasospasm
Some circulatory conditions like Raynaud's disease

Available Preparations
Amlodipine
Felodipine
Nicardipine
Isradipine
Nisoldipine
Nifedipine
Nimodipine - can pass the blood brain barrier and prevents cerebral vasospasm
Nitridipine

Phenyalkylamine - selective for myocardium, reduce myocardial oxygen demand and reverse coronay vasospasm - used in angina - less reflex tachycardia
Verapamil (Isoptin)
Gallopamil
Fendiline

Benzothiazepine - Diltiazem

Gabapentin
Pregabalin
Selective blockers of 2Õ Subunit. contain voltage-gated calcium channels - used to treat epilepsy and neuropathic pain

Adverse Effects
Vasodilation and hypotension can lead to reflex tachycardia may affectpatients with ischaemic symptoms due to increased myocardial oxygen demand
May worsen proteinuria in nephropathy
Dizziness, headache, redness in the face
Pedal edema
Rapid heart rate
Slow heart rate
Constipation
Gingival overgrowth
Because of the negative inotropic effects to be avoided in cardiomyopathy

Interactions
Certain calcium channel blockers interact with grapefruit products

Mechanism of Action
Reduce aldosterone production: Directly influence the biosynthesis of aldosterone in adrenocortical cells with consequent impact on the clinical treatment of hypertension
Reduce systemic vascular resistance and arterial pressure
Act on vascular smooth muscle (arterial, not venous) vasodilation
Reduce the force of contraction of heart
Slow down the conduction of electrical activity within the heart slow down heart beat

Heart afterload decreases
Calcium channel blockers maintain blood pressure better than betablockers since they do not decrease the effect of sympathetic nervous system
Negative inotropic and chronotropic effects






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