Isoket (Isosorbide Dinitrate)

Isosorbide Dinitrate is employed in cardiovascular conditions where vasodilation reduces myocardial oxygen demand.

• Angina pectoris: decreases frequency and severity of chest pain episodes.
• Heart failure: improves symptoms and exercise tolerance by lowering cardiac preload.
• Chronic coronary artery disease: provides symptomatic relief through sustained 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 arterial and venous smooth muscle, producing vasodilation, reduced preload and afterload, and consequently lower myocardial oxygen consumption.

Isosorbide dinitrate may cause a range of adverse reactions, most of which are dose‑related and transient.

Common Side Effects

• Headache: throbbing pain often occurring shortly after administration.
• Hypotension: noticeable drop in blood pressure, sometimes with dizziness.
• Flushing: warm, reddened skin, typically on the face and neck.
• Nausea: mild to moderate upset stomach.
• Tachycardia: compensatory increase in heart rate.
• Dizziness: sensation of light‑headedness, especially when standing.

Serious or Rare Side Effects

• Severe hypotension: marked blood pressure fall requiring medical intervention.
• Syncope: transient loss of consciousness due to inadequate cerebral perfusion.
• Myocardial infarction: rare but possible in patients with unstable coronary disease.
• Allergic reaction: rash, itching, or anaphylaxis in hypersensitive individuals.
• Methemoglobinemia: rare disorder causing reduced oxygen delivery.
• Persistent tachyarrhythmia: sustained rapid heart rhythms needing evaluation.

Careful assessment and monitoring are required when using intravenous nitrates.

• Blood pressure monitoring: check systolic and diastolic values before and during infusion.
• Concomitant PDE5 inhibitors: avoid co‑administration due to risk of profound hypotension.
• Alcohol consumption: limit intake as it may enhance vasodilatory effects.
• Anemia or hypovolemia: use cautiously, adjusting dose as needed.
• Renal or hepatic impairment: consider dose reduction and close observation.
• Store at room temperature: keep in original container, protect from moisture and light.

Isosorbide dinitrate interacts with several drug classes; some require avoidance while others need monitoring.

Major Interactions (Avoid)

• Sildenafil, tadalafil, vardenafil: combined use can cause severe hypotension.
• Other organic nitrates (e.g., nitroglycerin): additive vasodilatory effect leading to dangerous blood pressure drops.
• Alcohol: potentiates hypotensive response.

Moderate Interactions (Monitor Closely)

• Antihypertensive agents (ACE inhibitors, ARBs, calcium channel blockers): may enhance blood pressure lowering.
• Diuretics: risk of volume depletion and excessive hypotension.
• Beta‑blockers: may mask tachycardia, requiring careful heart rate monitoring.