Isoket Retard (Isosorbide Dinitrate)

Isoket Retard belongs to the organic nitrate class and is used in cardiovascular conditions that benefit from vasodilation.

• Angina pectoris: reduces the frequency and severity of chest pain episodes.
• Chronic heart failure: improves symptoms and exercise tolerance by lowering cardiac workload.
• Angina prophylaxis: prevents recurrence of anginal attacks during physical exertion or stress.

• Isosorbide dinitrate 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, decreasing preload and afterload, and ultimately reducing myocardial oxygen demand.

Isoket Retard may cause a range of adverse reactions, most of which are dose‑related and reversible.

Common Side Effects

• Headache: throbbing pain often occurring shortly after dosing.
• Dizziness or light‑headedness: related to blood pressure lowering.
• Flushing: warmth and redness of the face or neck.
• Hypotension: mild to moderate drop in blood pressure.
• Nausea: occasional upset stomach.
• Tachycardia: compensatory increase in heart rate.

Serious or Rare Side Effects

• Severe hypotension: marked blood pressure fall requiring medical attention.
• Syncope: sudden loss of consciousness.
• Myocardial infarction: rare but reported in susceptible individuals.
• Allergic reactions: rash, itching, or swelling.
• Life‑threatening bradycardia: markedly slow heart rate.

Before prescribing Isoket Retard, clinicians should consider several safety measures.

• Dose titration: start with a low dose and increase gradually to minimise hypotension.
• Concomitant nitrates: avoid simultaneous use with other nitrate preparations to prevent additive vasodilation.
• Phosphodiesterase‑5 inhibitors: do not combine with sildenafil, tadalafil, or similar agents.
• Severe anemia or hypovolemia: monitor haemodynamic status closely.
• Pregnancy and lactation: use only if the potential benefit outweighs the risk and after professional consultation.
• Store at room temperature: keep in the original container, protect from moisture and light.

Isoket Retard can interact with several drug classes, requiring attention to avoid adverse outcomes.

Major Interactions (Avoid)

• Sildenafil, tadalafil, and other PDE‑5 inhibitors: risk of profound hypotension.
• Other nitrates (e.g., nitroglycerin, isosorbide mononitrate): additive vasodilatory effect.
• Strong antihypertensive agents (ACE inhibitors, beta‑blockers): may exaggerate blood pressure lowering.

Moderate Interactions (Monitor Closely)

• Diuretics: increased likelihood of orthostatic hypotension.
• Alcohol: potentiates vasodilatory response and dizziness.
• Certain antifungal agents (e.g., ketoconazole): may affect nitrate metabolism.