Imdur

Imdur (isosorbide mononitrate) is a long-acting nitrate vasodilator prescribed for the prophylactic management of angina pectoris. It works by relaxing and widening blood vessels, which reduces the heart’s workload and improves oxygen supply to the myocardium. This medication is not intended for the acute relief of angina attacks but serves as a foundational therapy in the long-term prevention of ischemic symptoms. It is typically integrated into a comprehensive cardiovascular management plan that may include lifestyle modifications and other antianginal agents.

Features

• Active ingredient: Isosorbide mononitrate
• Pharmacologic class: Organic nitrate vasodilator
• Available in extended-release tablet formulations (e.g., 30 mg, 60 mg, 120 mg)
• Designed for once-daily dosing to support adherence
• Hemodynamic effects include venous and arterial dilation, reducing preload and afterload

Benefits

• Reduces the frequency and severity of angina episodes
• Decreases myocardial oxygen demand through balanced vasodilation
• Supports improved exercise tolerance and functional capacity in patients with chronic stable angina
• Offers convenient once-daily dosing to minimize dosing complexity and support long-term compliance
• May contribute to enhanced quality of life by allowing greater physical activity with reduced symptom burden

Common use

Imdur is indicated for the prevention of angina pectoris due to coronary artery disease. It is used in patients with chronic stable angina who require prophylactic therapy to minimize symptomatic episodes. It is not indicated for use in acute anginal attacks or in patients with acute myocardial infarction or congestive heart failure where specific nitrate therapy is required. It may be used as monotherapy or in combination with other antianginal agents such as beta-blockers or calcium channel blockers, under clinical guidance.

Dosage and direction

The usual starting dose of Imdur is 30 mg or 60 mg orally once daily. Dosage may be titrated upward based on therapeutic response and tolerability, with maximum recommended doses typically not exceeding 120 mg once daily. Tablets should be swallowed whole and must not be crushed, chewed, or divided. Administration in the morning is standard to minimize potential tolerance development and align with circadian patterns of angina occurrence. Dose adjustments should be made under medical supervision, particularly in elderly patients or those with hepatic impairment.

Precautions

Patients should be advised that Imdur can cause hypotension, especially upon standing. Alcohol, hot environments, and vigorous activity may exacerbate this effect. Headache is common initially and often diminishes with continued therapy. abrupt discontinuation may precipitate rebound angina. Tolerance to the antianginal and hemodynamic effects may develop with continuous dosing; a nitrate-free interval of 10–12 hours is recommended to reduce this risk. Use with caution in patients with hypovolemia, hypertrophic cardiomyopathy, or increased intracranial pressure.

Contraindications

Imdur is contraindicated in patients with known hypersensitivity to nitrates or any component of the formulation. It must not be used concurrently with phosphodiesterase type 5 (PDE5) inhibitors such as sildenafil, tadalafil, or vardenafil, due to the risk of severe hypotension and cardiovascular collapse. Additional contraindications include severe anemia, closed-angle glaucoma, and cardiogenic shock. It is also contraindicated in patients with marked hypotension (systolic BP <90 mmHg).

Possible side effects

Common side effects include headache (often dose-related), dizziness, lightheadedness, and flushing. Less frequently, nausea, vomiting, or orthostatic hypotension may occur. Syncope, reflex tachycardia, or dermatitis have been reported in some patients. Although rare, severe hypotension, methemoglobinemia, or paradoxical angina may develop. Patients should be instructed to report persistent or severe adverse reactions to their healthcare provider.

Drug interactions

Concomitant use with PDE5 inhibitors is absolutely contraindicated. Hypotensive effects may be potentiated by antihypertensives, calcium channel blockers, beta-blockers, alcohol, or tricyclic antidepressants. Aspirin may increase nitrate bioavailability. Ergot alkaloids may antagonize the vasodilatory effects of Imdur. Use with riociguat is not recommended due to additive hypotensive effects. Always review the patient’s full medication list before initiation.

Missed dose

If a dose is missed, it should be taken as soon as remembered on the same day. If it is near the time of the next dose, the missed dose should be skipped. Doubling the dose is not recommended. Patients should maintain their regular dosing schedule and contact their prescriber if multiple doses are missed or if angina symptoms recur.

Overdose

Symptoms of overdose may include severe hypotension, throbbing headache, vertigo, palpitations, visual disturbances, nausea, vomiting, syncope, air hunger, diaphoresis, and skin flushing. Methemoglobinemia may occur with massive overdose. Management includes keeping the patient recumbent in a shock position, administering IV fluids, and considering vasopressors if needed. Methylene blue may be indicated for methemoglobinemia. Hemodialysis is not effective.

Storage

Store at room temperature (20–25°C/68–77°F), in a tightly closed container, away from light, moisture, and heat. Keep out of reach of children and pets. Do not store in bathrooms or damp places. Discard any unused medication after the expiration date or as directed.

Disclaimer

This information is intended for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting, changing, or stopping any medication. Do not disregard professional medical advice based on content provided here.

Reviews

Clinical trials and post-marketing surveillance indicate that Imdur is effective in reducing angina frequency and improving exercise tolerance in a majority of patients. Some users report significant improvement in daily activities with once-daily convenience. Headache is a frequently noted side effect but often subsides with continued use. Adherence is generally high due to the simplified dosing regimen. Healthcare providers emphasize the importance of the nitrate-free interval to maintain efficacy. Individual responses may vary; discuss your experience with your cardiologist.