Imdur (Isosorbide 5 Mononitrate)

Imdur belongs to the organic nitrate class and is employed in the management of coronary artery disease‑related chest pain.

• Prevention of angina pectoris: reduces the frequency of anginal episodes in patients with known coronary artery disease.
• Chronic stable angina: improves exercise tolerance and decreases myocardial oxygen demand.
• Exercise‑induced angina: helps prevent chest pain triggered by physical activity.

• Isosorbide mononitrate is metabolized to release nitric oxide, which activates guanylate cyclase in vascular smooth muscle. The resulting increase in cyclic GMP causes relaxation of arterial and venous walls, producing vasodilation, lowering preload and afterload, and ultimately reducing myocardial oxygen consumption.

Common Side Effects

• Headache: mild to moderate, often transient.
• Dizziness or light‑headedness, especially on standing.
• Flushing of the face or neck.
• Nausea or upset stomach.
• Palpitations or tachycardia.
• Low blood pressure (hypotension).

Serious or Rare Side Effects

• Severe hypotension leading to syncope.
• Allergic reactions such as rash, itching, or swelling.
• Methemoglobinemia, a rare blood disorder.
• Chest pain that worsens despite therapy.
• Rapid or irregular heart rhythms.
• Persistent vomiting or severe abdominal pain.

Before starting Imdur, clinicians should evaluate cardiovascular status and consider potential contraindications.

• Assess blood pressure: ensure baseline values are adequate to tolerate vasodilation.
• Review concurrent nitrate therapy: avoid additive effects.
• Monitor for signs of hypotension: advise patients to rise slowly.
• Caution in patients with severe hepatic impairment: dose adjustment may be required.
• Store at ambient temperature below 25°C: keep in the original pack, protect from moisture and light.

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

Major Interactions (Avoid)

• Phosphodiesterase‑5 inhibitors (e.g., sildenafil, tadalafil): risk of profound hypotension.
• Other organic nitrates or nitrites: additive vasodilatory effect may cause severe blood pressure drop.
• Strong antihypertensive agents (e.g., intravenous nitroprusside): may lead to excessive hypotension.

Moderate Interactions (Monitor Closely)

• Beta‑blockers: may require blood pressure monitoring and dose adjustment.
• Diuretics: can enhance the hypotensive response.
• Alcohol: may increase vasodilatory side effects such as dizziness and flushing.