Nicorandil

Nicorandil is a drug used to treat angina. It is marketed under the trade names Ikorel (in the United Kingdom, Australia and most of Europe), Zynicor (in India) and Sigmart (in Japan, South Korea and Taiwan). Nicorandil is not available in the United States.

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Mechanism of action

Nicorandil acts by relaxing the smooth muscle of the blood vessels, especially those of the venous system. It does this through two methods. Firstly, by activating potassium channels, and secondly by donating nitric oxide to activate the enzyme guanylate cyclase. Guanylate cyclase causes activation of GMP leading to both arterial and venous vasodilatation. As it is selective for vascular potassium channels, it has no significant action on cardiac contractility and conduction.

Although it can dilate the coronary vessels of a healthy individual, its effects on the coronary vessels of someone with ischaemic heart disease will be little as they will already be completely dilated. Instead, it dilates the venous system, reducing preload and the work of the heart.

Side effects

Common side effects include flushing, palpitation, weakness, headache, mouth ulcers, nausea and vomiting. More recently peri-anal, ileal and peri-stomal ulceration has been reported as a side effect. Anal ulceration is now recognised by the British National Formularly as a recognised side effect.

References

• Kukovetz WR et al (1992). Molecular mechanism of action of nicorandil. Journal of Cardiovascular Pharmacology 20 Suppl.3:S1–S7.

• Tripathi, K.D. Essentials of Medical Pharmacology, chapter 37, page 499.