Overview
Nicorandil is a potassium channel activator with nitrate-like properties used for the prevention and treatment of angina pectoris. It combines the effects of nitrate vasodilation (acting on venous capacitance vessels) and potassium channel opening (acting on arterial resistance vessels), resulting in reduced preload and afterload while increasing coronary blood flow.
Mechanism of Action
Dual mechanism: (1) Activates ATP-sensitive potassium channels in vascular smooth muscle, causing hyperpolarization and vasodilation of coronary and peripheral arteries (reduces afterload). (2) Contains a nitrate moiety that stimulates guanylate cyclase, increasing cyclic GMP and causing venous and coronary vasodilation (reduces preload).
Indications
- Prevention and treatment of chronic stable angina pectoris
- Variant (Prinzmetal's) angina
Dosage
Initial: 5 mg twice daily (morning and evening). Maintenance: 10-20 mg twice daily. Maximum: 40 mg daily. Tablets should be swallowed whole with water, not chewed or crushed.
Contraindications
- Hypersensitivity to nicorandil or any component
- Cardiogenic shock
- Hypotension (systolic BP <90 mmHg)
- Left ventricular failure with low filling pressures
- Concomitant use with phosphodiesterase-5 inhibitors (sildenafil, tadalafil, vardenafil)
Side Effects
- Headache (most common)
- Dizziness
- Flushing
- Nausea, vomiting
- Weakness, fatigue
- Hypotension
- Palpitations
- Gastrointestinal ulceration (rare but serious)
- Skin/mucosal ulceration
- Tachycardia
Interactions
- Phosphodiesterase-5 inhibitors (sildenafil, tadalafil, vardenafil): Contraindicated due to risk of severe hypotension
- Other vasodilators (nitrates, calcium channel blockers, ACE inhibitors): Additive hypotensive effects
- Alcohol: May enhance hypotensive effects
- Antihypertensive agents: Enhanced blood pressure lowering