Nicorandil is a potassium channel activator with a nitrate component. Nicorandil is thought to have two antianginal effects:

• Activation of the potassium channels resulting in relaxation of arterial smooth muscle, arterial dilation and reduced cardiac afterload
• Nitrate mediated relaxation of venous smooth muscle resulting in a reduction in preload (see symptom relief)

Nicorandil is suitable only for use in patients who either cannot tolerate beta blockers or calcium channel blockers or in combination with beta blockers, calcium channel blockers or other anti-anginal drugs where monotherapy does not adequately control symptoms.

As with the nitrates headache is a commonly experienced side effect of nicorandil. To minimise the severity and occurrence of this side effect patients may be initiated on doses as low as 5mg twice daily. These doses are then titrated to a maximum daily dose of 60mg, in two divided doses, to provide control of anginal symptoms.

In order to provide a complete 24 hour effect it is important that nicorandil is administered at 12 hour intervals.

Ulceration is a rare side effect of nicorandil that can start at any time during or after treatment, including years after starting treatment. This form of ulceration presents as gastrointestinal and oromucosal ulcers although it can cause serious skin and eye ulceration.

Pharmacists should be alert to patients requesting treatment for mouth ulcers who are prescribed nicorandil as these ulcers are refractory to treatment but respond to withdrawal of the nicorandil.¹¹

Concomitant use of nicorandil and phosphodiesterase type 5 inhibitors is contraindicated by the manufacturer because of the nitrate component and the risk of profound hypotension - see previous information.

¹¹ Medicines and Healthcare products Regulatory Agency. Drug Safety Update: Nicorandil: risk of gastrointestinal ulceration. June 1, 2008; 1(11): 5. https://www.gov.uk/drug-safety-update/nicorandil-risk-of-gastrointestinal-ulceration.