Tianantang Isosorbide Mononitrate Tablets

1. Indications and Usage
Chronic Angina: Indicated for the prophylactic treatment of angina pectoris.
Acute Attacks: It is not indicated for the termination of an acute anginal attack; short-acting nitrates (e.g., sublingual nitroglycerin) should be used instead.
2. Dosage and Administration
Standard Dose: The recommended starting dose is 20 mg once daily or 10 mg twice daily (with a 4–6 hour interval between doses). This interval helps prevent nitrate tolerance.
Administration: Can be taken with or without food. The dose may be increased to 40 mg once daily or 20 mg twice daily based on patient response.
Discontinuation: The dose should not be stopped abruptly in patients with unstable angina; it should be gradually reduced to minimize the risk of rebound angina.
3. Mechanism of Action
Nitric Oxide Donor: Isosorbide mononitrate is metabolized to release nitric oxide (NO), which activates guanylyl cyclase in vascular smooth muscle cells.
Vasodilation: This leads to increased intracellular cyclic GMP, causing relaxation of vascular smooth muscle. It predominantly dilates veins, reducing preload and myocardial oxygen demand.
4. Safety and Warnings
Hypotension: The most common adverse effect is hypotension, which may cause dizziness or syncope.
Contraindications: Contraindicated in patients with severe hypotension, hypovolemia, or right ventricular infarction.
Cerebral Hemorrhage: Use with extreme caution in patients with increased intracranial pressure, as vasodilation may worsen the condition.
5. Adverse Reactions and Clinical Research
Common Adverse Reactions: Headache (often transient), dizziness, lightheadedness, and flushing. These are dose-dependent and usually diminish with continued therapy.
Tachyphylaxis: Continuous exposure can lead to tolerance (nitrate tolerance), reducing the drug’s efficacy. A daily “nitrate-free interval” is essential to maintain effectiveness.
6. Drug Interactions
Sildenafil: Concomitant use with phosphodiesterase-5 (PDE5) inhibitors (e.g., sildenafil, tadalafil) is contraindicated due to the risk of severe, life-threatening hypotension.
Alcohol: May potentiate the hypotensive effects of nitrates.
Antihypertensives: Can enhance the blood pressure-lowering effects of other antihypertensive agents.
7. Pharmaceutical Information
Active Ingredient: Isosorbide Mononitrate.
Strengths: Typically available as 10 mg, 20 mg, and 40 mg tablets (including immediate-release and extended-release formulations).
Appearance: White or off-white tablets.
Storage: Store below 30°C in a tight, light-resistant container.