– Nicorandil (SG-75)(Ikorel) acts by relaxing the smooth muscle of the blood vessels, especially those of the venous system. It undertakes 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 cGMP leading to both arterial and venous vasodilatation by de-phosphorylation of the myosin light chain.