Monopront Retard (Isosorbide Mononitrate)

Isosorbide Mononitrate is used in the management of coronary artery disease‑related conditions, primarily acting to relieve anginal symptoms.

• Chronic stable angina: reduces the frequency and severity of chest pain episodes, improving patient activity tolerance.
• Angina pectoris: enhances exercise capacity and decreases the need for short‑acting nitrate rescue medication.
• Ischemic heart disease: helps maintain myocardial oxygen balance by decreasing cardiac preload and afterload.

• Isosorbide Mononitrate is metabolized to release nitric oxide, which activates soluble guanylate cyclase in vascular smooth muscle. The resulting increase in cyclic guanosine monophosphate causes relaxation of both venous and arterial vessels, lowering preload and afterload. This vasodilatory effect improves coronary blood flow and reduces myocardial oxygen demand, thereby alleviating anginal pain. The drug’s long‑acting nitrate profile provides sustained nitric oxide delivery over 12‑24 hours, allowing once‑daily dosing in many treatment regimens.

Isosorbide Mononitrate may be associated with several adverse reactions, ranging from mild to serious.

Common Side Effects

• Headache: throbbing pain often occurring shortly after the first dose.
• Dizziness: sensation of light‑headedness, especially when standing quickly.
• Flushing: warm sensation and reddening of the skin.
• Nausea: mild stomach upset or queasiness.
• Hypotension: low blood pressure causing faintness.

Serious or Rare Side Effects

• Severe hypotension: marked drop in blood pressure leading to syncope.
• Syncope: sudden loss of consciousness.
• Myocardial infarction: rare occurrence of heart attack.
• Allergic reaction: rash, itching, swelling, or difficulty breathing.
• Methemoglobinemia: abnormal hemoglobin causing cyanosis (very rare).

When prescribing Isosorbide Mononitrate, clinicians should observe several precautionary measures to ensure patient safety.

• Assess cardiovascular status: evaluate blood pressure and heart rate before initiating therapy.
• Review concomitant nitrate use: avoid combining with other nitrate preparations to prevent excessive vasodilation.
• Monitor for hypotension: advise patients to rise slowly from sitting or lying positions.
• Caution in hepatic impairment: dose adjustments may be required in patients with liver dysfunction.
• Educate on headache management: advise use of acetaminophen rather than aspirin which may increase bleeding risk.
• Store at ambient temperature: keep below 25 °C in the original container, protected from moisture and light.

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

Major Interactions (Avoid)

• Sildenafil and other PDE5 inhibitors: combined use may cause severe hypotension.
• Other nitrates (e.g., nitroglycerin, isosorbide dinitrate): additive vasodilatory effect leading to dangerous blood pressure drops.
• Alcohol: can potentiate hypotensive effects and increase dizziness.

Moderate Interactions (Monitor Closely)

• Antihypertensive agents (ACE inhibitors, beta‑blockers, calcium channel blockers): may require dose adjustment to avoid excessive blood pressure reduction.
• Diuretics: increased risk of dehydration and orthostatic hypotension.