Imdur (Isosorbide Mononitrate)

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

• Angina pectoris (stable): reduces the frequency and severity of chest pain episodes.
• Chronic stable angina: improves exercise tolerance by decreasing myocardial oxygen demand.
• Ischemic heart disease: helps prevent angina attacks during physical or emotional stress.

• 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 consequently reducing myocardial oxygen consumption.

Imdur may cause a range of adverse reactions, most of which are mild and transient.

Common Side Effects

• Headache: throbbing pain often occurring shortly after the first dose.
• Dizziness or light‑headedness, especially when standing quickly.
• Flushing: warm sensation and reddening of the skin.
• Nausea or mild gastrointestinal discomfort.
• Palpitations or rapid heartbeat.

Serious or Rare Side Effects

• Severe hypotension leading to fainting or shock.
• Syncope (sudden loss of consciousness).
• Allergic reactions such as rash, itching, or swelling of the face and throat.
• Methemoglobinemia, a rare blood disorder causing reduced oxygen delivery.

Before initiating Imdur, several safety considerations should be reviewed.

• Discontinuation: avoid abrupt stopping to prevent rebound angina.
• Hypotension: use cautiously in patients with low blood pressure or volume depletion.
• Hepatic impairment: dose adjustment may be required in severe liver disease.
• Concomitant PDE‑5 inhibitors: increased risk of profound hypotension; avoid co‑administration.
• Pregnancy: safety not established; prescribe only if potential benefit outweighs risk.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Isosorbide mononitrate can interact with several drug classes, altering its safety profile.

Major Interactions (Avoid)

• Other nitrates (e.g., nitroglycerin): additive vasodilatory effect may cause severe hypotension.
• Phosphodiesterase‑5 inhibitors (e.g., sildenafil, tadalafil): risk of profound blood pressure drop.

Moderate Interactions (Monitor Closely)

• Antihypertensive agents (e.g., ACE inhibitors, beta‑blockers): may enhance blood‑pressure‑lowering effect.
• Diuretics: can increase the likelihood of orthostatic hypotension.
• Alcohol: may potentiate vasodilatory side effects such as dizziness and flushing.