There are three different groups of calcium channel blockers:
- dihydropyridine group e.g. nifedipine. This group acts primarily as arterial vasodilators. They are effective in the management of angina - however side-effects such as flushing and tachycardia may be troublesome - particularly with short-acting preparations. There is some observational evidence that the use of high doses or short acting dihyropyridines may be associated with adverse morbidity and mortality. Although the evidence currently available falls short of proof, it appears prudent to use longer acting agents.
- verapamil acts primarily to reduce the force of myocardial contraction and to limit heart rate. This drug is contraindicated in patients with ventricular impairment. Extreme caution is required if combining verapamil with a beta-blocker - in general this combination should be avoided.
- diltiazem - has properties intermediate between verapamil and the dihydropyridines.
Mibefradil, a new class of calcium channel blocker with rate - limiting properties was withdrawn (1).
Reference:
- notification from Roche Products Ltd (5/6/98)
- Factfile (3/97). British Heart Foundation