Isosorbide Mononitrate

Isosorbide Mononitrate is employed in the management of coronary artery disease‑related angina and related pathways.

• Stable angina pectoris: reduces the frequency of angina attacks.
• Chronic stable angina: improves exercise tolerance and daily activity capacity.
• Angina prophylaxis: maintains myocardial oxygen balance during physical stress.

• Isosorbide Mononitrate acts as a nitric oxide donor. After oral absorption, it is metabolized to nitric oxide, which activates guanylate cyclase in vascular smooth muscle, increasing cyclic GMP levels. Elevated cGMP leads to relaxation of arterial and venous smooth muscle, 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 throbbing pain.
• Dizziness or light‑headedness.
• Flushing of the face or neck.
• Hypotension: transient drop in blood pressure.
• Nausea or gastrointestinal discomfort.
• Palpitations or tachycardia.

Serious or Rare Side Effects

• Severe hypotension leading to syncope.
• Acute myocardial infarction in susceptible patients.
• Allergic reactions such as rash, pruritus, or angioedema.
• Methemoglobinemia.
• Life‑threatening arrhythmias.
• Hepatic dysfunction in rare cases.

Before initiating therapy, clinicians should evaluate cardiovascular status and consider potential interactions.

• Assess cardiovascular status: confirm diagnosis of stable angina.
• Monitor blood pressure: watch for symptomatic hypotension.
• Avoid abrupt discontinuation: taper to prevent rebound angina.
• Caution in hepatic impairment: dose adjustment may be required.
• Avoid concomitant use with other nitrates or PDE5 inhibitors: risk of additive hypotension.
• Store at room temperature: keep in the original pack, protect from moisture and direct sunlight.

Isosorbide Mononitrate can interact with several drug classes, requiring careful management.

Major Interactions (Avoid)

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

Moderate Interactions (Monitor Closely)

• Antihypertensives (ACE inhibitors, beta‑blockers): may enhance blood‑pressure‑lowering effect.
• Azole antifungals (e.g., ketoconazole): can increase plasma concentrations of the nitrate.
• Alcohol: may potentiate hypotensive response.
• Diuretics: may augment orthostatic hypotension.