Monorem R (Isosorbide Mononitrate)

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

• Chronic stable angina pectoris: reduces the frequency of angina episodes and improves exercise tolerance.
• Prevention of angina attacks: helps maintain symptom‑free periods during daily activities.
• Effort‑induced chest pain: decreases myocardial oxygen demand by lowering preload and afterload.

• 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 smooth muscle, producing vasodilation. This reduces both preload and afterload, decreasing myocardial oxygen consumption and improving the balance between oxygen supply and demand in the heart. The effect is sustained over a 24‑hour period, allowing once‑daily dosing in most regimens.

Isosorbide mononitrate may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Headache: throbbing pain often occurring shortly after dosing.
• Dizziness or light‑headedness: due to transient blood pressure lowering.
• Flushing: warm sensation and reddening of skin.
• Nausea: mild gastrointestinal upset.

Serious or Rare Side Effects

• Severe hypotension: marked drop in blood pressure requiring medical attention.
• Syncope: fainting episodes associated with low blood pressure.
• Allergic reaction: rash, itching, swelling, or anaphylaxis in rare cases.

Before initiating therapy with isosorbide mononitrate, clinicians should consider several safety measures.

• Cardiovascular assessment: evaluate baseline blood pressure and heart rate.
• Concomitant nitrate use: avoid combining with other organic nitrates to prevent excessive vasodilation.
• PDE5 inhibitor caution: do not use with sildenafil, tadalafil or similar agents due to risk of severe hypotension.
• Hepatic impairment: adjust therapy in patients with significant liver dysfunction.
• Store at room temperature: keep in the original packaging, protect from moisture and heat.

Isosorbide mononitrate interacts with several drug classes that can modify its hemodynamic effects.

Major Interactions (Avoid)

• Sildenafil and other PDE5 inhibitors: risk of profound hypotension.
• Other organic nitrates (e.g., nitroglycerin): additive vasodilatory effect.
• Strong antihypertensive agents: may cause excessive blood pressure reduction.

Moderate Interactions (Monitor Closely)

• Diuretics: can enhance hypotensive response.
• Beta‑blockers: may mask tachycardia signs.
• Alcohol: may increase dizziness and hypotension.