Professional view

isosorbide mononitrate: prescribing and clinical use

Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.

isosorbide mononitrate: clinical details

Prescribing considerations

Not suitable for terminating an acute angina episode; ensure the patient understands their rapid-acting angina plan.
Headache and postural symptoms are common during initiation or treatment changes.
Continuous nitrate exposure can produce tolerance.
Use particular caution in older or volume-depleted patients and those susceptible to hypotension.
Check formulation-specific excipients, including lactose and sucrose.

Contraindications and cautions

Hypersensitivity to isosorbide mononitrate, other nitrates or product excipients
PDE-5 inhibitor treatment
Riociguat treatment
Severe hypotension, severe hypovolaemia, shock or circulatory collapse
Acute myocardial infarction with low filling pressure
Hypertrophic obstructive cardiomyopathy, constrictive pericarditis or cardiac tamponade
Significant aortic or mitral stenosis
Severe anaemia
Raised intracranial pressure, including after head trauma or cerebral haemorrhage
Closed-angle glaucoma is listed for several selected products; verify the product-specific SmPC

Monitoring

Angina frequency, exercise tolerance and use of rapid-acting rescue treatment
Sitting and standing blood pressure when clinically indicated
Pulse and symptoms of tachycardia, bradycardia, dizziness or syncope
Headache burden and treatment adherence
Evidence of reduced anti-anginal effect that could indicate nitrate tolerance

Clinical pharmacology

Isosorbide mononitrate is an active nitrate and metabolite of isosorbide dinitrate. It has high oral bioavailability because it avoids substantial first-pass metabolism. Venodilation predominates, reducing preload; arterial and coronary vasodilation can additionally reduce afterload and improve myocardial oxygen balance.

Formulation and product differences

UK products include standard-release tablets and prolonged- or modified-release tablets and capsules; their release profiles are not automatically interchangeable.
Modified-release products should be swallowed whole and not chewed or crushed.
Divisibility is product-specific; some selected scored tablets may be split, while capsules must remain intact.
With some matrix modified-release tablets, an apparently empty tablet remnant may occasionally be visible in the stool after the medicine has been released.
Lactose and sucrose content varies between products.