Disrupts movement of calcium through calcium channels, thereby:
Reducing BP
Slowing HR
Reducing force of contraction of the heart
Unlike beta blockers, CCB don't decrease responsiveness of heart to the SNS, hence the baroreceptor reflex. CCB's thus permit better maintenance of blood pressure than beta blockers. However, as a result, the baroreceptor thus increases sympathetic effect, increasing heart rate and contractility
N-type, L-type, and T-type voltage-dependent calcium channels are present in the zona glomerulosa of the human adrenal, and CCB's can directly influence the biosynthesis of aldosterone in adrenocortical cells, thus influencing the Tx of HTN
Indications
They are particularly effective against large vessel stiffness, one of the common causes of elevated systolic BP in elderly Pt's
Alter heart rate
Prevent cerebrovasospasm
Reduce chest pain caused by angina pectoris
Classification
Dihydropyridine (-dipine, DHP), which are used to reduce systemic vascular resistance and arterial pressure. It includes:
Amlodipine (Norvasc), used to lower BP, and prevent chest pain
Aranidipine
Azelnidipine
Barnidipine
Benidipine
Cilnidipine
Clevidipine
Isradipine
Efonidipine
Felodipine
Lacidipine
Lercanidipine
Manidipine
Nicardipine
Nifedipine (Procardia, Adalat), used as an antianginal (especially Prinzmetal's angina) and as an anti-HTN. It is also used as a tocolytic in preterm labor
Nilvadipine
Nimodipine
Nisoldipine
Nitrendipine
Pranidipine
Non-dihydropyridine, including:
Phenylalkylamine, which are relatively selective for myocardium, reducing myocardial oxygen demand, and reverse coronary vasospasm, thus often used to Tx angina. It includes:
Verapamil (Calan, Isoptin)
Gallopamil
Fendiline
Benzothiazepine, which are an intermediate class between phenylalkylamine and dihydropyridines in their selectivity for vascular calcium channels. By having both cardiac depressant and vasodilator actions, they are able to reduce arterial pressure w/o prdoucing the same degree of reflex cardiac stimulation caused by dihydropyridines. It includes:
Diltiazem (Cardizem)
Non-selective, including:
Mibefradil
Bepridil
Flunarizine
Fluspirilene
Fendiline
Side effects
Dizziness, headache, redness in the face
Peripheral edema (i.e. fluid buildup in the legs and ankle)
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