Isosorbide Mononitrato Eg (Isosorbide Mononitrate)

Isosorbide Mononitrate is an organic nitrate used in the management of coronary artery disease‑related angina.

• Prevention of angina pectoris: reduces the frequency of angina attacks in patients with stable coronary disease.
• Treatment of angina pectoris: relieves chest pain during episodes of exertional angina.
• Chronic stable angina: improves exercise tolerance and quality of life in patients with chronic stable angina.

• Isosorbide mononitrate is a prodrug that is metabolized to release nitric oxide (NO). NO activates soluble guanylate cyclase in vascular smooth muscle, increasing cyclic GMP levels, which leads to relaxation of smooth muscle, vasodilation of veins and arteries, reduction of preload and afterload, and consequently lower myocardial oxygen demand. The effect is sustained over 24 hours, providing stable anti‑anginal control.

Isosorbide mononitrate may cause a range of adverse reactions, varying in frequency and severity.

Common Side Effects

• Headache: throbbing headache often occurring at treatment initiation.
• Dizziness: light‑headed sensation, especially when standing quickly.
• Flushing: warm sensation and reddening of the skin.
• Nausea: mild stomach upset.

Serious or Rare Side Effects

• Severe hypotension: marked drop in blood pressure that can cause fainting or shock.
• Allergic reaction: rash, itching, swelling, or difficulty breathing indicating possible hypersensitivity.
• Palpitations: awareness of rapid or irregular heartbeat.
• Syncope: temporary loss of consciousness due to low cerebral perfusion.
• Methemoglobinemia: rare blood disorder causing reduced oxygen delivery.

When prescribing isosorbide mononitrate, clinicians should consider several safety measures.

• Dose titration: start with low dose and increase gradually to minimize headache.
• Concomitant nitrates: avoid using with other nitrate preparations to prevent severe hypotension.
• Phosphodiesterase‑5 inhibitors: do not combine with sildenafil, tadalafil, or vardenafil due to risk of profound hypotension.
• Renal impairment: use caution and monitor blood pressure in patients with reduced kidney function.
• Pregnancy and lactation: safety not established; prescribe only if benefit outweighs risk.
• Store at ambient temperature: keep below 25 °C, protect from moisture and light in original container.

Isosorbide mononitrate interacts with several drug classes; awareness of these interactions helps maintain patient safety.

Major Interactions (Avoid)

• Other nitrates (e.g., nitroglycerin): additive vasodilatory effect causing severe hypotension.
• Phosphodiesterase‑5 inhibitors (sildenafil, tadalafil, vardenafil): risk of profound hypotension.
• Sodium nitroprusside: synergistic vasodilation leading to dangerous blood pressure fall.

Moderate Interactions (Monitor Closely)

• Antihypertensives (ACE inhibitors, ARBs, beta‑blockers): may enhance blood‑pressure‑lowering effect, monitor BP.
• Diuretics: additive effect on volume depletion, watch for orthostatic symptoms.
• Alcohol: can increase vasodilatory response, advise moderation.