Nicorandil

Common indications

• For prevention and treatment of chest pain in people with stable angina. 
• First choice treatments for stable angina are β-blockers and calcium channel blockers, individually or in combination. 
• Nicorandil (or a long-acting nitrate) may be used if these drugs are insufficient or not tolerated.

 

Mechanisms of action

• Nicorandil causes both arterial and venous vasodilatation through its actions as a nitrate (see Nitrates) and by activating K+-ATP channels. 
• Efflux of K+ through activated K+-ATP channels leads to hyperpolarisation of the cell membrane and subsequent inactivation of voltage-gated Ca2+ channels. The net effect is a decrease in free intracellular calcium. As calcium is required for smooth muscle contraction, relaxation and vasodilatation occur. 
• The effect of this is to reduce cardiac preload and systemic and coronary vascular resistance. 
• This improves myocardial perfusion, and decreases myocardial work and oxygen demand. 
• Clinically, this reduces the frequency and severity of angina attacks.

 

Important adverse effects

• Unwanted effects of vasodilatation include flushing, dizziness and headache. 
• Nicorandil can also cause nausea, vomiting and hypotension. 
• Less frequently, it can cause gastrointestinal, skin or mucosal ulceration, which only responds to withdrawal of treatment.

 

Warnings

• You should not routinely prescribe nicorandil for patients with poor left ventricular function, hypotension or pulmonary oedema, as it can worsen these conditions.

 

Important interactions

• As with nitrates, the hypotensive side effects of nicorandil are significantly enhanced by phosphodiesterase inhibitors (e.g. sildenafil). 
• They should not be prescribed together.