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Glyceryl Trinitrate (GTN) 💊
📚 Related Subjects: Cardiogenic Pulmonary Oedema
📖 About
Always check the BNF link here before prescribing. Glyceryl Trinitrate (GTN) is a cornerstone drug in acute cardiovascular care.
- 💊 A useful drug to be familiar with in both acute and chronic cardiac emergencies.
⚡ Action
- 🩸 Potent systemic venodilator → reduces preload, easing cardiac workload.
- ❤️ Coronary vasodilation → improves myocardial perfusion.
- 🩻 Mild arteriolar dilation → reduces afterload.
- 🔬 Acts by increasing nitric oxide (NO) and stimulating cGMP pathways.
🩺 Indications & Dose (⚠️ can precipitate syncope)
| Indication / Formulation | Details |
|---|---|
| 🚑 Acute Coronary Syndromes | Relief of chest pain with sublingual GTN (spray or tablet) |
| 💔 Left Ventricular Failure | Reduces preload and improves symptoms |
| 📈 Hypertensive Crises | Parenteral GTN infusion titrated to BP |
| 💨 GTN Spray | 1–2 sprays (400–800 mcg/dose) under the tongue as required |
| 💊 Sublingual Tablets | 500 mcg, 1–2 as required
⚠️ Sit down before use to avoid syncope |
| 🩹 Transdermal Patches | 5–20 mg per 24 h |
| 💉 IV Infusion | Start at 0.5 mg/hour; titrate to BP and symptoms (only if SBP >90 mmHg) |
| 💉 Syringe Driver | 50 mg GTN in 50 mL 0.9% NaCl → 0.5–10 mL/hour |
| 💉 Infusion Pump | 50 mg GTN in 500 mL 0.9% NaCl → 5–100 mL/hour |
| 🛑 Stop Criteria | Stop infusion if SBP <100 mmHg or patient becomes symptomatic with hypotension |
⚠️ Interactions
- ❌ Dangerous hypotension with Sildenafil (Viagra) and other PDE5 inhibitors.
🚫 Contraindications
- Severe Aortic or Mitral Stenosis.
- Hypertrophic Obstructive Cardiomyopathy (HOCM).
- Constrictive Pericarditis or Cardiac Tamponade.
- ❗ Caution in conditions where RV filling is vital (e.g. PE, inferior MI).
💥 Side Effects
- 🤕 Headache (very common).
- ⬇️ Hypotension, dizziness, syncope.
- ⚡ Tolerance develops with prolonged use, reducing efficacy.
📑 References
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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