Glyceryl Trinitrate Pfizer Healthcare Ireland (Glyceryl Trinitrate)

Glyceryl trinitrate intravenous solution is indicated for several acute cardiovascular conditions where rapid vasodilation is required.

• Acute angina pectoris that requires rapid symptom relief when oral nitrates are ineffective.
• Acute decompensated heart failure where reduction of preload and afterload can improve cardiac output.
• Hypertensive emergencies, especially in patients with coronary artery disease, to achieve prompt blood pressure control.
• Induction of controlled hypotension during operative or diagnostic procedures to reduce bleeding risk.
• Adjunct therapy for myocardial ischemia during cardiac catheterisation or angioplasty to limit ischemic injury.

Side‑effect profile of intravenous glyceryl trinitrate reflects its potent vasodilatory action; patients may experience both frequent, generally mild reactions and rarer, potentially serious events that require clinical attention.

Common

• Headache, often described as throbbing, due to cerebral vasodilation.
• Flushing or a sensation of warmth, typically affecting the face and neck.
• Transient hypotension accompanied by dizziness or light‑headedness, especially after rapid infusion.

Serious

• Marked hypotension leading to syncope or loss of consciousness, requiring immediate intervention.
• Myocardial ischemia caused by coronary steal, which may present as chest discomfort despite vasodilation.
• Allergic reactions ranging from skin rash to anaphylaxis, necessitating prompt medical management.

When using intravenous glyceryl trinitrate, clinicians should observe several precautions to minimise risk and ensure therapeutic effectiveness.

• Assess baseline blood pressure; avoid use in patients with severe hypotension (systolic <90 mmHg).
• Monitor heart rate and rhythm continuously, as reflex tachycardia may occur.
• Use cautiously in patients with recent myocardial infarction or unstable coronary artery disease.
• Adjust dose or discontinue if signs of methemoglobinemia develop.
• Avoid abrupt discontinuation after prolonged infusion to prevent rebound hypertension.
• Consider pregnancy status; safety data are limited, so use only if benefit outweighs potential risk.
• Ensure proper intravenous line patency to prevent extravasation and local tissue injury.

Intravenous glyceryl trinitrate may interact with several drug classes; awareness of these interactions helps maintain hemodynamic stability.

Avoid

• Other potent vasodilators (e.g., hydralazine, other nitrates) that can cause additive hypotension.
• Phosphodiesterase‑5 inhibitors (sildenafil, tadalafil) which markedly increase the risk of severe hypotension.

Use with caution

• Beta‑blockers, which may blunt reflex tachycardia and affect blood pressure control.
• Calcium channel blockers, especially dihydropyridines, that can enhance vasodilatory effects.
• Diuretics, which may predispose to volume depletion and hypotension.
• Antihypertensive agents such as ACE inhibitors or ARBs, requiring close blood pressure monitoring.
• Inhaled nitric oxide therapy, which may potentiate the vasodilatory response.