Potassium channel activators in vasospastic angina.

Activation of potassium channels induces relaxation of vascular smooth muscle, and experimental studies have demonstrated that potassium channel activators have potent coronary vasodilator properties. In humans, nicorandil, a potassium channel blocker, causes vasodilatation not only in angiographically normal segments but also at sites of dynamic coronary stenosis, where coronary spasm has been provoked by methylergometrine as well as at sites of spontaneous spasm. The efficacy of nicorandil in relieving ergometrine-induced spasm is comparable to that of nifedipine. Oral administration of nicorandil significantly reduces the frequency of anginal episodes in patients with vasospastic angina, and either as monotherapy, or in conjunction with other agents is a novel therapeutic option in patients with vasospastic angina.