Nitrate / Stable Angina

Isosorbide Mononitrate (Stable Angina)

Brand names: Elantan, Imdur, Monosorb

Isosorbide mononitrate is a long-acting oral nitrate used for the prophylaxis of angina.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION The recommended regimen of isosorbide mononitrate tablets is 20 mg twice daily, with the doses seven hours apart. A starting dose of 5 mg (½ tablet of the 10 mg dosing strength) might be appropriate for persons of particularly small stature but should be increased to at least 10 mg by the second or third day of therapy. Dosage adjustments are not necessary for elderly patients or patients with altered hepatic or renal function. As noted above ( CLINICAL PHARMACOLOGY ), multiple studies of organic nitrates have shown that maintenance of continuous 24-hour plasma levels results in refractory tolerance. The asymmetric (2 doses, 7 hours apart) dosing regimen for …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2026-03-27. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It is converted to nitric oxide, causing venodilatation (reduced preload) and coronary vasodilatation, lowering myocardial oxygen demand.

Prescribing in practice

Tolerance develops with continuous exposure — use an asymmetric schedule or a modified-release form to provide a nitrate-free interval.
Headache, flushing and hypotension are common, especially initially.
It is contraindicated with PDE5 inhibitors (e.g. sildenafil).

Monitoring

Review angina frequency and blood pressure.

Counselling the patient

It prevents angina — it is not for an acute attack (use your GTN spray/tablet for that).
Headaches are common at first and usually settle.
Never take it with erectile-dysfunction tablets such as sildenafil.

Evidence & guidelines

A long-acting nitrate for angina prophylaxis, dosed to allow a nitrate-free interval to limit tolerance (NICE NG185).

Reference: ESC Stable Coronary Artery Disease Guidelines 2019; NICE CG126 (Stable Angina); SPC Elantan; SPC Imdur; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways