Calcium+channel+blocker+recall

= Calcium channel blocker recall =

[|Amlodipine] [|Felodipine] [|Lercanidipine] [|Nifedipine] [|Nimodipine] [|Diltiazem] [|Verapamil]
 * Dihydropyridine**
 * Benzothiazepine**
 * Phenylalkylamine**

Block inward current of calcium into cells in vascular smooth muscle, myocardium and cardiac conducting system via L-type calcium channels. Calcium channel blockers differ in their chemical nature, sites of action and therapeutic effects. Dihydropyridines act mainly on vascular smooth muscle to reduce peripheral vascular resistance, and have minimal effect on normal myocardial cells at therapeutic doses. Nimodipine may prevent cerebral ischaemic damage from reactive vasospasm after subarachnoid haemorrhage, by dilating cerebral vessels and increasing blood flow. Verapamil has greater cardiac effects, reducing contractility, heart rate and conduction with less effect on vascular smooth muscle. Diltiazem acts on both cardiac and vascular smooth muscle, but it has less effect on cardiac cells than verapamil.
 * Mode of action**


 * Indications**
 * Hypertension
 * Angina


 * C****omparative Information**

//Hypertension//
 * Their effect on arterial pressure is similar to that of other antihypertensives, eg diuretics, beta-blockers, ACE inhibitors.
 * In large randomised trials, diltiazem and verapamil had no advantage over diuretics or beta-blockers in terms of overall prevention of cardiovascular events (less stroke and more MI with diltiazem, more heart failure with verapamil) or the total incidence of adverse effects.
 * Felodipine and long acting nifedipine products are as effective as diuretics or beta-blockers in the elderly (in trials with limited statistical power); a difference in preventive efficacy cannot be ruled out. In the ALLHAT trial, amlodipine had similar efficacy to thiazide diuretics, but it was associated with an increased risk of heart failure based on clinical diagnosis.
 * Verapamil and diltiazem are contraindicated in patients with heart failure and can be combined with beta-blockers only under close surveillance and only in patients without ventricular dysfunction. Amlodipine and felodipine have been shown not to increase morbidity in chronic heart failure.

//Prevention of angina//
 * Their symptomatic efficacy is similar to that of beta-blockers; however, only controlled release verapamil has been shown to decrease the incidence of cardiovascular events in people with stable angina, and may reduce the risk of reinfarction and death after MI.

//Other indications//
 * Verapamil is useful for the prevention and treatment of SVTs and for ventricular rate control in AF and atrial flutter.
 * Nimodipine is used to prevent and treat ischaemic neurological deficits following subarachnoid haemorrhage.
 * Nifedipine is used for threatened preterm labour.

//Duration of action//
 * The duration of action of dihydropyridines differ depending on pharmacokinetics and formulation used.
 * Nifedipine and felodipine are absorbed rapidly and have relatively short half-lives. Controlled release products are available to prolong their duration of action and facilitate once daily dosing.
 * Amlodipine and lercanidipine have a longer half-life, and can be administered once daily. They have a slower onset of effect which may take longer to be fully established.


 * Practice Points**
 * dihydropyridine-induced peripheral oedema does not require treatment with diuretics, which may put patient at risk of volume depletion

Resources
[|AMH - Calcium channel blockers]