Isomex (Isosorbide Mononitrate)

Isosorbide mononitrate is used in the management of ischemic heart disease, primarily to prevent angina attacks.

• Angina pectoris (stable): reduces the frequency of chest‑pain episodes.
• Chronic coronary artery disease: improves exercise tolerance and functional capacity.
• Prevention of myocardial ischemia: lowers myocardial oxygen demand during physical stress.

• Isosorbide mononitrate is metabolized to release nitric oxide, which activates guanylate cyclase in vascular smooth muscle. The resulting increase in cyclic GMP leads to relaxation of arterial and venous vessels, producing vasodilation, reduced preload and afterload, and consequently a lower myocardial oxygen requirement.

Isosorbide mononitrate may cause a range of adverse reactions, most of which are dose‑related and reversible.

Common Side Effects

• Headache: throbbing or pressure‑type pain, often transient.
• Dizziness or light‑headedness, especially upon standing.
• Flushing: warm sensation and reddening of the skin.
• Nausea or mild gastrointestinal upset.
• Palpitations: awareness of heartbeat acceleration.

Serious or Rare Side Effects

• Severe hypotension: marked drop in blood pressure leading to fainting.
• Syncope: sudden loss of consciousness.
• Allergic reaction: rash, itching, swelling, or difficulty breathing.
• Myocardial infarction (rare): chest pain not relieved by medication.
• Life‑threatening tachyarrhythmia.

Before initiating therapy, clinicians should consider several safety measures.

• Dose titration: start with the lowest effective dose and adjust based on tolerance.
• Concomitant nitrates: avoid using other nitrate preparations to prevent additive hypotensive effects.
• Blood pressure monitoring: check supine and standing pressures regularly.
• Hepatic impairment: use with caution; dose may need adjustment.
• Pregnancy and lactation: safety not established; prescribe only if benefits outweigh potential risks.
• Store at ambient temperature: keep in the original container, protect from moisture and light.

Isosorbide mononitrate can interact with several drug classes, requiring clinical vigilance.

Major Interactions (Avoid)

• Other nitrates (e.g., nitroglycerin): may cause profound hypotension.
• Phosphodiesterase‑5 inhibitors (e.g., sildenafil, tadalafil): risk of severe blood‑pressure fall.

Moderate Interactions (Monitor Closely)

• Antihypertensives (beta‑blockers, ACE inhibitors, calcium‑channel blockers): additive blood‑pressure lowering.
• Diuretics: may increase dehydration and orthostatic symptoms.
• Alcohol: can enhance vasodilatory effects and dizziness.