Mononit (Isosorbide Mononitrate)

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

• Prophylaxis of angina pectoris: reduces the frequency of angina attacks during physical exertion or stress.
• Chronic stable angina: improves exercise tolerance and decreases episodes of chest pain.
• Angina pectoris in patients with coronary artery disease: provides sustained nitrate therapy to maintain myocardial oxygen balance.

• 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 that lowers preload and afterload, thereby improving myocardial oxygen supply and reducing cardiac workload.

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

Common Side Effects

• Headache: mild to moderate, often transient.
• Dizziness or light‑headedness: especially on standing.
• Flushing: warm sensation of skin.
• Nausea or abdominal discomfort.
• Palpitations: awareness of heartbeat.
• Hypotension: low blood pressure, particularly with rapid dose escalation.

Serious or Rare Side Effects

• Severe hypotension: may lead to syncope.
• Methemoglobinemia: abnormal hemoglobin affecting oxygen transport.
• Allergic reactions: rash, pruritus, or angioedema.
• Chest pain worsening: paradoxical increase in angina.
• Liver enzyme elevation: rare hepatic involvement.
• Renal impairment: worsening kidney function in susceptible patients.

Before initiating therapy, clinicians should assess patient history and comorbid conditions.

• Cardiovascular assessment: evaluate for recent myocardial infarction or unstable angina.
• Concomitant nitrates: avoid combined use to prevent severe hypotension.
• Phosphodiesterase‑5 inhibitors: contraindicated due to risk of profound blood pressure drop.
• Hepatic or renal dysfunction: dose adjustment may be required.
• Pregnancy and lactation: safety not established; use only if benefit outweighs risk.
• Store at ambient temperature: keep below 25°C, retain in original packaging, protect from moisture and direct sunlight.

Isosorbide Mononitrate interacts with several drug classes; awareness helps prevent adverse events.

Major Interactions (Avoid)

• Other nitrates (e.g., nitroglycerin): may cause additive hypotensive effects.
• Phosphodiesterase‑5 inhibitors (e.g., sildenafil): risk of severe blood pressure reduction.
• Antihypertensive agents (e.g., ACE inhibitors, beta‑blockers): can amplify hypotension.

Moderate Interactions (Monitor Closely)

• Diuretics: may enhance orthostatic hypotension.
• Alcohol: can increase vasodilatory response.
• Antacids containing aluminum or magnesium: may affect absorption, monitor efficacy.