Isomonit (Isosorbide Mononitrate)

Isosorbide Mononitrate is a nitrate vasodilator used in the management of coronary artery disease.

• Angina pectoris (stable): reduces the frequency of angina attacks.
• Chronic stable angina: improves exercise tolerance by maintaining consistent nitrate levels.
• Prevention of angina episodes: provides long‑acting nitrate therapy to lessen myocardial oxygen demand.

• Isosorbide Mononitrate is metabolized to release nitric oxide, which activates soluble guanylate cyclase in vascular smooth muscle. The resulting increase in cyclic GMP leads to relaxation of arterial and venous vessels, lowering preload and afterload, and thereby decreasing myocardial oxygen consumption.

Isosorbide Mononitrate may cause a range of adverse reactions.

Common Side Effects

• Headache: often mild to moderate and may improve with continued therapy.
• Dizziness or light‑headedness: especially on standing.
• Flushing: transient warmth and redness of the skin.
• Nausea: occasional upset stomach.
• Palpitations: awareness of heartbeat.
• Hypotension: mild drop in blood pressure.

Serious or Rare Side Effects

• Severe hypotension: marked blood pressure fall requiring medical attention.
• Syncope: fainting episodes.
• Tachycardia: rapid heart rate.
• Allergic reactions: rash, itching, or swelling.
• Methemoglobinemia: rare blood disorder causing cyanosis.

Before initiating therapy, clinicians should evaluate patient‑specific factors and counsel on safety measures.

• Assess cardiovascular status: monitor blood pressure and heart rate prior to and during treatment.
• Avoid concurrent nitrates: combined use can cause profound hypotension.
• Do not combine with phosphodiesterase‑5 inhibitors: risk of severe blood pressure reduction.
• Adjust in renal impairment: use caution in patients with severe renal dysfunction.
• Educate on orthostatic dizziness: advise rising slowly from sitting or lying positions.
• Store at ambient temperature: keep below 25°C in the original container, protect from moisture.

Isosorbide Mononitrate interacts with several drug classes; some combinations should be avoided while others require monitoring.

Major Interactions (Avoid)

• Phosphodiesterase‑5 inhibitors (e.g., sildenafil): may cause profound hypotension.
• Other nitrates (e.g., nitroglycerin): additive vasodilatory effect leading to severe blood pressure drop.
• Alcohol: can enhance hypotensive response.

Moderate Interactions (Monitor Closely)

• Antihypertensives (ACE inhibitors, beta‑blockers): may increase overall blood pressure‑lowering effect.
• Diuretics: can contribute to electrolyte imbalance and orthostatic hypotension.
• Azole antifungals (e.g., ketoconazole): may raise plasma concentrations of isosorbide mononitrate.