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Nitrate (vasodilator) Pregnancy: Use with caution. Sublingual for acute angina — limited data.

Glyceryl Trinitrate (GTN)

Brand names: Nitrolingual, GTN 400 Spray, Nitro-Dur, Minitran

Adult dose

Dose: Angina: 400–800 micrograms sublingual/spray; IV (ACS/APO): 10–200 micrograms/min
Route: Sublingual (tablet/spray), IV infusion, or transdermal patch
Frequency: SL: as needed; IV: continuous titrated infusion
Max: 800 micrograms per SL dose; IV titrated to response
Acute angina: 1–2 puffs (400–800 mcg) sublingual, repeat after 5 min. If no relief after 3 doses in 15 min — call 999. STEMI: IV GTN for ongoing ischaemia or APO. APO (acute pulmonary oedema): 400–800 mcg SL every 5 min then IV infusion at 10–20 mcg/min up to 200 mcg/min.

Paediatric dose

Route: IV infusion
Frequency: Continuous infusion
Max: 10 micrograms/kg/min
Concentration: 100 micrograms/ml
Paediatric IV (specialist): 0.5–1 micrograms/kg/min, increasing to max 10 mcg/kg/min. Titrate to effect. Specialist paediatric cardiology/ICU use.

Dose adjustments

Renal

No dose adjustment required.

Hepatic

Use with caution in severe hepatic impairment.

Clinical pearls

  • Ask about sildenafil/tadalafil/vardenafil BEFORE giving GTN — 24h (sildenafil) or 48h (tadalafil) contraindication
  • SL spray more stable than tablets — preferred for acute use
  • Tolerance with continuous IV infusion: always allow GTN-free interval (patch off overnight)
  • If headache intolerable — paracetamol can be given
  • IV GTN: titrate based on BP — target systolic >90 mmHg

Contraindications

  • Hypotension (SBP <90 mmHg)
  • PDE5 inhibitors (sildenafil, tadalafil) within 24–48 hours — severe hypotension
  • Severe aortic stenosis
  • Hypertrophic obstructive cardiomyopathy
  • Closed-angle glaucoma

Side effects

  • Headache (most common — due to meningeal vasodilation)
  • Flushing
  • Hypotension
  • Tachycardia (reflex)
  • Tolerance (with continuous use — GTN-free interval 8–12 hours required)

Interactions

  • PDE5 inhibitors — CONTRAINDICATED (potentially fatal hypotension)
  • Antihypertensives and vasodilators — additive hypotension
  • Ergotamine — reduced anti-anginal effect

Monitoring

  • Blood pressure every 5 min (IV use)
  • Symptoms
  • Headache

Reference: BNFc; BNF; NICE NG185 ACS; ESC STEMI/NSTE-ACS Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways