Several types of
calcium antagonists (CA) (
verapamil,
diltiazem,
nifedipine and related drugs) may be used as
antihypertensives. In practice, the
dihydropyridines (
nifedipine and related drugs) are the CA used most frequently as
antihypertensives. Apart from the lowering of blood pressure CA may lead to other, theoretically beneficial, effects: regression of left ventricular and vascular
hypertrophy, renal protection, weak natriuretic, weak antiplatelet, anti-ischaemic and antiatherogenic activity. Several new
dihydropyridine CA have been introduced in recent years. The advantages of the newer compounds, such as
amlodipine,
felodipine,
isradipine,
lacidipine and
lercanidipine, may include: vasoselectivity, hence little or no cardiodepressant activity; an improved kinetic profile, resulting in a slow onset and long duration of action, fewer side-effects such as reflex
tachycardia and
headache, owing to the slow onset of the
antihypertensive action. For a few newer CA a predominant effect on specialized circulatory beds (renal, coronary and cerebral) has been claimed. The new CA, which are clearly lipophilic, deserve special attention. Owing to the lipophilic character of such compounds considerable concentration occurs in
lipid-containing membrane depots. The CA thus concentrated are slowly released from these depots and, subsequently, reach their targets, the
L-type calcium channels. This phenomenon explains both the slow onset and the long duration of action of these CA. Owing to the slow onset of action reflex
tachycardia is virtually absent. The long duration of action allows satisfactory control of blood pressure in hypertensives by means of a single daily dose. A few lipophilic
dihydropyridine CA are vasoselective. This property implies that at therapeutic, vasodilatory dosages no cardiodepressant activity occurs.
Lercanidipine is a recently introduced example of a lipophilic and vasoselective
dihydropyridine CA. It is an effective
vasodilator/
antihypertensive drug, with a slow onset and long duration of action, which is associated with neither reflex
tachycardia nor cardiodepressant activity. Other examples of recently introduced lipophilic CA are
lacidipine,
barnidipine and
manidipine.