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Calcium
channel blockers: the two classes of calcium channel blockers (Dihydropyridines and
Nondihydropyridines) are generally indicated for African-Americans, diabetics,
and people who are at high risk for cornary disease.
Dihydropyridines:
Amlodipine (Norvasc), nifedipine (Procardia, Adalat), felodipine (Plendil),
nicardipine (Cardene), isradipine (DynaCirc), and nisoldipine (Sular) are most
commonly associated with lower extremity edema.
-Amlodipine
is indicated for essential hypertension, chronic stable angina, Prinzmetal’s
angina (vasospastic angina), and isolated systolic hypertenion in elderly
patients. The most common side
effect is peripheral edema. Amlodipine
is not associated with any significant AV nodal blockade or decreased
inotropic effects. -Nifedipine
and the other dihydropyridines are associated with the same general indications
as amlodipine but remember that sublingual nifedipine should not be used
for the treatment of hypertensive urgencies or emergencies since it may produce
a stroke by rapidly lowering the blood pressure. Nondihydropyridines:
Diltiazem (Cardizem, Dilacor, Tiazac) and verapamil (Isoptin, Calan,
Verelan, Covera) -Diltiazem
and verapamil are indicated for rate control of rapid atrial fibrillation,
atrial flutter, and narrow complex supraventricular tachycardia.
Additionally, diltiazem, and verapamil are indicated in patients with
cyclosporine-induced hypertension, migraines, and diabetes mellitus.
These drugs should be avoided in patients with Wolff-Parkinson-White
syndrome (WPW) and atrial fibrillation since these agents decrease conduction in
the AV node and produce increased conduction in the accessory pathway.
The increased conduction could lead to 1:1 conduction through the
accessory pathway from the atria to the ventricles and possibly produce
ventricular fibrillation. Another agent such as procainamide should be
considered for patients with WPW and atrial fibrillation.
Diltiazem and verapamil are contraindicated in second or third degree
heart block, and should be avoided in systolic congestive heart failure.
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