Monosan (Isosorbide Mononitrate)

Isosorbide Mononitrate is indicated for conditions within the coronary artery disease and angina spectrum.

• Angina pectoris (stable): reduces frequency and severity of chest pain episodes by decreasing myocardial oxygen demand.
• Chronic stable angina: improves exercise tolerance and allows patients to engage in daily activities with fewer symptoms.
• Prophylaxis of angina attacks: provides long‑acting nitrate therapy to prevent recurrence of ischemic episodes.

• Isosorbide Mononitrate is metabolized to release nitric oxide, which activates guanylate cyclase in vascular smooth muscle. The resulting increase in cyclic guanosine monophosphate leads to relaxation of arterial and venous vessels, lowering preload and afterload. This vasodilatory effect diminishes myocardial oxygen consumption, thereby alleviating anginal symptoms. The drug’s nitrate moiety is bio‑available after oral absorption, providing a sustained plasma concentration without the need for nitrate‑free intervals.

Isosorbide Mononitrate may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Headache: throbbing pain often occurring shortly after dosing.
• Dizziness or light‑headedness: related to blood pressure reduction.
• Flushing: warm sensation and reddening of the skin.
• Nausea: mild gastrointestinal upset.
• Hypotension: orthostatic drop in blood pressure.
• Palpitations: awareness of heartbeat irregularities.

Serious or Rare Side Effects

• Severe hypotension: marked blood pressure fall requiring medical attention.
• Syncope: fainting episodes due to inadequate cerebral perfusion.
• Methemoglobinemia: rare disorder causing reduced oxygen delivery.
• Anaphylactic reaction: life‑threatening allergy with rash, swelling, airway compromise.
• Myocardial infarction: extremely rare but reported in susceptible individuals.

When prescribing Isosorbide Mononitrate, clinicians should observe several safety measures to minimize risks.

• Dose titration: start with a low dose and increase gradually to reduce the likelihood of hypotension.
• Concomitant PDE‑5 inhibitors: avoid using with sildenafil, tadalafil or similar agents because of potential profound blood pressure fall.
• Blood pressure monitoring: check for orthostatic hypotension, especially after therapy initiation.
• Hepatic or renal impairment: adjust dosing or monitor closely in patients with reduced organ function.
• Pregnancy and lactation: safety not established; use only if potential benefit justifies the risk.
• Store at room temperature: keep in the original container, protect from moisture and light.

Isosorbide Mononitrate can interact with several medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Phosphodiesterase‑5 inhibitors (e.g., sildenafil, tadalafil): may cause severe hypotension.
• Other nitrates (nitroglycerin, isosorbide dinitrate): additive vasodilatory effect leading to dangerous blood pressure drops.

Moderate Interactions (Monitor Closely)

• Antihypertensives (ACE inhibitors, beta‑blockers, calcium channel blockers): may enhance blood pressure‑lowering effect.
• Diuretics: can increase risk of electrolyte imbalance and orthostatic hypotension.
• Alcohol: may potentiate hypotensive response.