Glycerylnitrat (Glyceryl Trinitrate)

Glycerylnitrat is employed in several acute cardiovascular conditions where rapid vasodilation is required.

• Management of acute angina pectoris episodes
• Treatment of acute heart failure with pulmonary congestion
• Control of hypertensive emergencies resistant to standard therapy
• Adjunct therapy during cardiac catheterisation procedures
• Relief of coronary artery spasm (Prinzmetal angina)

Side effects of Glycerylnitrat vary in frequency and severity.

Common

• Headache, often described as throbbing
• Flushing or warmth in the face and neck
• Hypotension leading to dizziness or light‑headedness
• Tachycardia or reflex heart rate increase
• Nausea or mild gastrointestinal discomfort

Serious

• Severe hypotension with syncope
• Methemoglobinemia, a rare blood disorder
• Acute myocardial infarction precipitated by rapid blood pressure drop
• Allergic reactions such as rash, itching, or anaphylaxis
• Persistent chest pain unresponsive to therapy

When prescribing Glycerylnitrat, clinicians consider several safety factors.

• Assess baseline blood pressure; avoid use in patients with severe hypotension.
• Use cautiously in patients with recent phosphodiesterase‑5 inhibitor use due to risk of profound hypotension.
• Monitor for signs of methemoglobinemia, especially in patients with G6PD deficiency.
• Adjust dose in elderly patients or those with hepatic impairment.
• Ensure proper intravenous line placement to prevent extravasation and local tissue injury.
• Educate patients about the possibility of headache and advise appropriate management.

Glycerylnitrat can interact with several drug classes, influencing its safety profile.

Avoid

• Phosphodiesterase‑5 inhibitors (e.g., sildenafil, tadalafil) because combined use may cause severe hypotension.
• Other potent vasodilators such as hydralazine or other nitrates, which increase the risk of additive blood pressure lowering.
• Certain antihypertensive agents (e.g., ACE inhibitors, ARBs) when used concurrently without monitoring.

Use with caution

• Beta‑blockers, as they may mask tachycardia reflex.
• Diuretics, which can exacerbate volume depletion and hypotension.
• Alcohol, which may enhance vasodilatory effects.
• General anaesthetics during surgery, requiring close haemodynamic monitoring.