Nitroglycerin is a fast-acting nitrate used to treat angina, heart failure, and hypertensive emergencies. Learn about its mechanism of action, uses, dosage, side effects, brand names, and price.
Table of Contents:
1. Introduction
3. Pharmacokinetics and Dynamics
4. Indications & Drug of Choice
6. Side Effects
8. Dosage
9. Brand Names
10. Price
11. Conclusion
1. Introduction:
*Nitroglycerin* (also called *glyceryl trinitrate or GTN*) is a *rapid-acting nitrate vasodilator* used primarily in the *management of angina pectoris*, *acute coronary syndromes*, *heart failure*, and *hypertensive crises*. It is available in multiple forms, including sublingual tablets, sprays, patches, and IV infusions.
2. Mechanism of Action:
Nitroglycerin is converted into *nitric oxide (NO)* in vascular smooth muscle. NO activates guanylate cyclase, increasing cGMP, which causes:
- *Venous dilation* → ↓ preload
- *Arterial dilation (at higher doses)* → ↓ afterload
- *Coronary vasodilation* → ↑ oxygen supply to myocardium
This reduces myocardial oxygen demand and relieves anginal pain.
3. Pharmacokinetics and Dynamics:
| Onset (SL form) | 1–3 minutes
| Peak effect | 5 minutes
| Duration | 30–60 minutes (SL)
| Half-life | 1–4 minutes
| Metabolism | Liver (first-pass metabolism)
| Excretion | Urine
*Note:* Tolerance may develop with continuous use.
4. Indications & Drug of Choice:
- *Angina pectoris* (acute relief and prophylaxis)
- *Acute coronary syndrome (ACS)*
- *Heart failure with myocardial ischemia*
- *Hypertensive emergencies*
- *Controlled hypotension during surgery*
Drug of Choice for:
- *Acute angina relief* (sublingual form)
- *Hypertensive crisis with chest pain (IV form)*
5. Contraindications:
- Hypotension (SBP < 90 mmHg)
- Increased intracranial pressure
- Constrictive pericarditis or tamponade
- Use with *PDE-5 inhibitors* (e.g., sildenafil) → risk of severe hypotension
6. Side Effects:
- Headache
- Dizziness
- Hypotension
- Flushing
- Nausea
- Methemoglobinemia (rare)
7. Drug Interactions:
- *PDE-5 inhibitors (e.g., sildenafil, tadalafil)*: severe hypotension
- *Antihypertensives & alcohol*: additive hypotensive effect
- *Ergot derivatives*: may antagonize nitrate effect
- *Heparin*: IV nitroglycerin may reduce heparin efficacy
8. Dosage:
*Sublingual Tablets/Spray (Angina):*
- 0.3–0.6 mg every 5 minutes (max 3 doses in 15 minutes)
*IV Infusion (MI/HTN crisis):*
- Start at 5 mcg/min, titrate up to 100 mcg/min as needed
*Transdermal Patch/Ointment (Prophylaxis):*
- 0.2–0.8 mg/hr; apply for 12–14 hours/day to prevent tolerance
9. Brand Names:
- *Nitrostat*
- *Nitrolingual*
- *Nitro-Bid*
- *Rectiv*
- *GTN Spray*
- *Angised*
10. Price:
- *USA:* $10–25 (sublingual), IV form more expensive
- *India/Pakistan:* Rs. 10–30 per tablet/spray (generic available)
Available in sublingual, IV, transdermal, and topical forms.
11. Conclusion:
*Nitroglycerin* remains a *cornerstone in angina management* and *cardiovascular emergencies*. Its rapid onset and multiple formulations make it a flexible and lifesaving option in acute care. Patients should be educated about tolerance and proper usage, especially in acute settings.
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