Isoket (Isosorbide Dinitrate)

Isoket (isosorbide dinitrate) is used in the management of coronary artery disease, specifically angina syndromes.

• Angina pectoris: provides rapid relief of chest pain by reducing myocardial oxygen demand.
• Prophylaxis of angina: maintains vasodilation to prevent angina episodes during exertion.
• Chronic stable angina: improves exercise tolerance through sustained nitrate effect.
• Coronary artery spasm: alleviates vasospastic episodes by relaxing vascular smooth muscle.

• Isosorbide dinitrate is metabolized to release nitric oxide, which activates guanylate cyclase in vascular smooth muscle cells. The resulting increase in cyclic GMP leads to relaxation of arterial and venous smooth muscle, producing vasodilation, lowering preload and afterload, and consequently reducing myocardial oxygen consumption and relieving ischemic chest pain.

Isoket may cause a range of adverse reactions, which vary in frequency and severity.

Common Side Effects

• Headache: throbbing pain often occurring shortly after dosing.
• Dizziness or light‑headedness: due to transient blood pressure reduction.
• Flushing: warm sensation and reddening of the skin.
• Hypotension: noticeable drop in blood pressure, especially when standing.
• Nausea: mild gastrointestinal upset.
• Tachycardia: compensatory increase in heart rate.

Serious or Rare Side Effects

• Severe hypotension: marked blood pressure fall requiring medical attention.
• Syncope: fainting episodes related to sudden pressure changes.
• Myocardial infarction: rare but possible in patients with unstable coronary disease.
• Allergic reaction: rash, itching, or swelling indicating hypersensitivity.
• Methemoglobinemia: rare blood disorder causing reduced oxygen delivery.

Before initiating Isoket therapy, clinicians should evaluate patient-specific factors and monitor for potential risks.

• Assess cardiovascular status: check baseline blood pressure and heart rate.
• Review concomitant nitrate use: avoid additive hypotensive effects.
• Counsel on orthostatic changes: advise patients to rise slowly from sitting or lying positions.
• Monitor for tolerance development: periodic drug‑free intervals may be needed.
• Educate on signs of severe hypotension: advise immediate medical review if symptoms occur.
• Store at ambient temperature below 25°C: keep in the original pack, protect from moisture and light.

Isoket can interact with several drug classes, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Sildenafil and other PDE5 inhibitors: may cause profound hypotension.
• Other organic nitrates or nitroglycerin: additive vasodilatory effect leading to severe blood pressure drop.
• Alcohol: enhances vasodilatory response and can precipitate dizziness.

Moderate Interactions (Monitor Closely)

• Antihypertensive agents: may require dose adjustment to avoid excessive hypotension.
• Diuretics: monitor electrolytes and renal function.
• Beta‑blockers: can mask tachycardia, necessitating careful heart rate monitoring.
• Calcium channel blockers: may increase nitrate levels, requiring observation.