T-type Ca2+ channels have properties different from those of the L-type and are involved|
in cardiac pacemaking and regulation of blood flow, but not in myocardial contraction.
Efonidipine is an antihypertensive and antianginal drug with dihydropyridine
structure that was recently found to block both L- and T-type Ca2+ channels. In isolated
myocardial and vascular preparations, efonidipine has potent negative chronotropic and
vasodilator effects but only a weak negative inotropic effect. In experimental animals and
patients, reduction of blood pressure by the drug was accompanied by no or minimum
reflex tachycardia leading to improvement of myocardial oxygen balance and maintenance
of cardiac output. Efonidipine increased glomerular filtration rate without increasing
intraglomerular pressure. By relaxing both the afferent and efferent arterioles,efonidipine markedly reduced proteinuria. Thus, efonidipine, an L- and T-type dual Ca2+
channel blocker, appears to have an ideal profile as an antihypertensive and antianginal
drug with organ-protective effects in the heart and kidney.