Nitronal (Glyceryl Trinitrate)

Nitronal (glyceryl trinitrate) is used in the management of cardiovascular conditions where rapid vasodilation is required.

• Acute angina pectoris: provides rapid relief of chest pain by dilating coronary arteries and improving myocardial oxygen delivery.
• Acute heart failure: decreases cardiac preload and afterload through venous and arterial dilation, supporting hemodynamic stabilization in decompensated patients.
• Hypertensive emergencies: produces prompt reduction of systemic vascular resistance, aiding in the rapid control of severely elevated blood pressure.

• Glyceryl trinitrate is enzymatically converted to nitric oxide within vascular smooth‑muscle cells. The released nitric oxide activates soluble guanylate cyclase, increasing cyclic GMP levels, which leads to relaxation of smooth‑muscle fibers in veins and arteries. This vasodilatory effect reduces both preload and afterload, improving coronary blood flow and lowering arterial pressure. The process is dose‑dependent and occurs within seconds after intravenous administration.

Glyceryl trinitrate may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Headache: a throbbing headache that may be severe, resulting from cerebral vasodilation, often worsens with dose escalation and may require analgesic therapy.
• Flushing: a warm sensation and visible redness of the face, neck, or upper chest, typically transient and self‑limiting.
• Hypotension: a transient decrease in arterial pressure, particularly when the infusion rate is high, which may cause light‑headedness.

Serious or Rare Side Effects

• Methemoglobinemia: increased methemoglobin in the blood causing cyanosis, reduced oxygen delivery, and may present with chocolate‑colored blood.
• Severe hypotension: a profound fall in blood pressure that can lead to dizziness, syncope, or shock, requiring immediate medical intervention.
• Allergic reaction: hypersensitivity manifestations such as rash, pruritus, bronchospasm, or anaphylactic shock, necessitating prompt discontinuation and emergency treatment.

When using Nitronal, several precautions should be observed to ensure patient safety and product stability.

• Blood pressure monitoring: continuously assess arterial pressure before and during infusion.
• Titration: adjust infusion rate gradually to avoid abrupt hypotension.
• Concomitant nitrates: avoid using with other nitrate preparations to prevent additive vasodilation.
• Phosphodiesterase inhibitors: contraindicated in patients taking sildenafil or similar agents due to risk of severe hypotension.
• Cardiovascular status: use cautiously in patients with severe aortic stenosis or recent myocardial infarction.
• Store at ambient temperature: keep below 25°C, protect from light and moisture, and retain in original container.

Glyceryl trinitrate can interact with several medicines, altering its effect or increasing risk.

Major Interactions (Avoid)

• Phosphodiesterase‑5 inhibitors: may cause life‑threatening hypotension.
• Other nitrates or nitroglycerin: additive vasodilatory effect leading to severe hypotension.
• Sodium nitroprusside: combined use can result in excessive vasodilation.

Moderate Interactions (Monitor Closely)

• Antihypertensives (ACE inhibitors, beta‑blockers): may enhance blood pressure‑lowering effect.
• Diuretics: can potentiate volume depletion and hypotension.
• Alcohol: may increase vasodilatory response and dizziness.