Nitrong (Glyceryl Trinitrate)

Glyceryl trinitrate is used in the anti‑anginal pathway to relieve myocardial ischemia.

• Angina pectoris: provides rapid relief of chest pain by reducing cardiac workload.
• Acute coronary syndrome: improves coronary blood flow and limits ischemic injury.
• Heart failure: decreases preload and afterload, aiding symptomatic improvement.

• Glyceryl trinitrate is enzymatically converted to nitric oxide, which activates guanylate cyclase in vascular smooth muscle. The resulting increase in cyclic GMP leads to relaxation of both veins and arteries, producing vasodilation that lowers myocardial oxygen consumption and improves coronary perfusion.

Adverse reactions may occur with oral nitrate therapy.

Common Side Effects

• Headache: throbbing pain often triggered by vasodilation.
• Dizziness: due to transient blood pressure reduction.
• Flushing: warm sensation and reddening of skin.
• Hypotension: mild to moderate drop in blood pressure.
• Nausea: occasional gastrointestinal upset.

Serious or Rare Side Effects

• Severe hypotension: marked blood pressure fall requiring medical attention.
• Syncope: fainting episodes related to abrupt pressure changes.
• Methemoglobinemia: rare blood disorder impairing oxygen delivery.
• Allergic reaction: rash, itching, or swelling.
• Tachycardia: rapid heart rate in response to vasodilation.

When prescribing or dispensing Nitrong, consider the following safety measures.

• Dose titration: start with the lowest effective dose as directed by the prescriber.
• Concomitant phosphodiesterase inhibitors: avoid use due to risk of profound hypotension.
• Hypotension monitoring: regularly assess blood pressure, especially after dose changes.
• Cardiovascular surgery: discontinue prior to operative procedures to prevent intra‑operative hypotension.
• Pregnancy and lactation: safety not established; use only if benefits outweigh potential risks.
• Store at ambient temperature: keep in the original container, protect from moisture and light.

Glyceryl trinitrate may interact with several drug classes.

Major Interactions (Avoid)

• Sildenafil and other PDE5 inhibitors: can cause severe hypotension.
• Other nitrates (e.g., isosorbide dinitrate): additive vasodilatory effect may be dangerous.
• Strong antihypertensive agents (e.g., beta‑blockers, ACE inhibitors): increase risk of excessive blood pressure drop.

Moderate Interactions (Monitor Closely)

• Alcohol: may enhance vasodilatory response and dizziness.
• Diuretics: can potentiate hypotensive effects.
• Other antihypertensives: require careful blood pressure monitoring.