Nitrosid Retard (Isosorbide Dinitrate)

Isosorbide Dinitrate is an organic nitrate used in cardiovascular disease management.

• Angina pectoris: reduces frequency of chest pain episodes by improving myocardial oxygen supply during exertion.
• Chronic heart failure: decreases cardiac workload and improves exercise tolerance in patients with reduced ejection fraction.
• Prophylaxis of angina: maintains symptom control during physical activity or emotional stress by sustaining vasodilation.

• Isosorbide Dinitrate is metabolized to release nitric oxide, which activates guanylate cyclase in vascular smooth muscle. The resulting increase in cyclic GMP leads to relaxation of coronary and systemic arteries, lowering preload and afterload, and consequently reducing myocardial oxygen consumption and alleviating ischemic symptoms.

Isosorbide Dinitrate may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Headache: throbbing pain often occurring shortly after dosing.
• Dizziness: sensation of light‑headedness, especially upon standing.
• Flushing: warmth and redness of the face or neck.
• Hypotension: measurable drop in blood pressure.
• Tachycardia: increased heart rate as a compensatory response.
• Nausea: mild gastrointestinal upset.

Serious or Rare Side Effects

• Severe hypotension: marked blood pressure reduction requiring medical attention.
• Syncope: sudden loss of consciousness.
• Myocardial infarction: rare but possible worsening of ischemia.
• Allergic reactions: rash, angioedema, or anaphylaxis.
• Methemoglobinemia: abnormal hemoglobin affecting oxygen transport.
• Life‑threatening arrhythmias: irregular heart rhythms that may be fatal.

When prescribing or dispensing Nitrosid Retard, consider the following precautions:

• Dose titration: start with a low dose and adjust under medical supervision.
• Avoid concurrent use of phosphodiesterase‑5 inhibitors: may cause profound hypotension.
• Monitor blood pressure: check regularly, especially after dose changes.
• Use with caution in patients with severe anemia or recent myocardial infarction.
• Pregnancy and lactation: safety not established; prescribe only if benefit outweighs risk.
• Store at ambient temperature: keep in original container, protect from moisture and light.

Isosorbide Dinitrate can interact with several drug classes.

Major Interactions (Avoid)

• Sildenafil and other PDE‑5 inhibitors: risk of severe hypotension.
• Other organic nitrates or nitroglycerin: additive vasodilatory effect.
• Antihypertensive agents (e.g., ACE inhibitors, beta‑blockers): may cause excessive blood pressure drop.

Moderate Interactions (Monitor Closely)

• Diuretics: may enhance hypotensive effect.
• Alcohol: can increase vasodilatory response.
• Azole antifungals (e.g., ketoconazole): may increase plasma levels of isosorbide dinitrate.