Calcium antagonists--assessment of side effects.

Clinically used calcium antagonists are derivatives of either verapamil (verapamil), dihydropyridines (e.g. felodipine and nifedipine), or benzothiazepines (diltiazem). The principal side effects are mostly predictable, dose-dependent, and related to their main actions: vasodilatation, negative inotropic effects and antiarrhythmic effects. All calcium antagonists have demonstrated a pronounced hypotensive effect. Conduction disturbances and bradycardia are seen more often after verapamil and diltiazem, while tachycardia, headache, ankle oedema; and flush are more frequent after felodipine and nifedipine. Another side effect is constipation, which is frequent after verapamil. Important interactions have been reported with, for instance, digoxin and beta-adrenergic blocking agents. Calcium antagonists may have favourable effects on serum lipids, and there is no indication of consistent changes in basal glucose metabolism. Uric acid is unchanged or reduced. Regarding the effects on the quality of life exerted by the different calcium antagonists, very little is known since such studies have not been performed so far.