Isosorbidmononitrat

Isosorbidmononitrat, also known as isosorbide mononitrate, is a nitrate ester used as a long-acting vasodilator to prevent angina pectoris associated with coronary artery disease. It is the mononitrate metabolite of isosorbide dinitrate and is available in oral immediate-release and sustained-release formulations.

The medication works by releasing nitric oxide in vascular smooth muscle, which increases cyclic guanosine monophosphate and causes relaxation of the smooth muscle. The resulting venodilation reduces preload, and at higher doses can lower afterload. Together, these effects decrease myocardial oxygen demand and help prevent anginal episodes when taken regularly.

Isosorbide mononitrate is indicated for the long-term prevention of angina rather than for acute relief. It is commonly used as part of a broader antianginal regimen, sometimes in combination with beta-blockers or calcium channel blockers. Dosing and formulation vary, with different products designed for once-daily or twice-daily administration.

Common adverse effects include headache, dizziness, flushing, and hypotension. Tolerance may develop with continuous use, so clinical regimens often include a nitrate-free interval to maintain effectiveness. Cautions include potential severe hypotension when combined with phosphodiesterase-5 inhibitors (such as sildenafil or tadalafil), and use is generally avoided in patients with significant hypotension or certain intracranial pressure conditions.

Pharmacokinetically, oral isosorbide mononitrate is absorbed with formulation-dependent bioavailability and is metabolized in the liver, with renal excretion of metabolites. Onset of action varies by formulation, with immediate-release forms acting within an hour and sustained-release forms providing prolonged effect suitable for daily dosing.