Nitrate / Acute Angina

Glyceryl Trinitrate (Sublingual / IV)

Brand names: GTN spray (Nitrolingual), GTN tablets (Nitrostat), IV: Nitronal

Used in: Acute Coronary Syndrome & Chest Pain

Glyceryl trinitrate is a nitrate used sublingually (tablet or spray) for rapid relief of acute angina, and intravenously in acute settings such as pulmonary oedema and unstable 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

Administer one tablet under the tongue or in the buccal pouch at the first sign of an acute anginal attack. Allow tablet to dissolve without swallowing. One additional tablet may be administered every 5 minutes until relief is obtained. No more than three tablets are recommended within a 15-minute period. If the pain persists after a total of 3 tablets in a 15-minute period, or if the pain is different than is typically experienced, seek prompt medical attention. Nitroglycerin sublingual tablets may be used prophylactically 5 to 10 minutes prior to engaging in activities that might precipitate an acute attack. For patients with xerostomia, a small sip of water prior to placing the tablet …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2024-10-15. 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 (reducing preload) and coronary vasodilatation, which lowers myocardial oxygen demand and relieves ischaemic pain.

Prescribing in practice

Headache, flushing and hypotension are common.
Tolerance develops with continuous exposure, so a nitrate-free interval is used for regular nitrate therapy.
It is contraindicated with PDE5 inhibitors (e.g. sildenafil), which together cause profound hypotension.

Monitoring

Monitor blood pressure and symptom response, particularly with intravenous use.

Counselling the patient

For an attack, sit down and use it; repeat as advised and call emergency services if pain persists after the advised doses/time.
A brief headache is common.
Never use it with erectile-dysfunction tablets such as sildenafil.

Evidence & guidelines

Standard for acute angina relief and used intravenously in acute cardiac care.

Reference: ESC Stable CAD Guidelines 2019; NICE CG126 (Stable Angina); NICE NG185 (ACS); SPC Nitrolingual; 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