Imdur (isosorbide mononitrate) is a long-acting nitrate vasodilator prescribed for the prevention of angina pectoris, the chest pain associated with coronary artery disease. It works by relaxing and widening blood vessels, which reduces the heart’s workload and improves blood flow to the heart muscle. This medication is designed for prophylactic use, significantly decreasing the frequency and severity of angina attacks and enhancing exercise tolerance in patients with chronic stable angina. Its extended-release formulation provides sustained therapeutic effects, supporting consistent daily management of cardiac symptoms.

Features

• Active ingredient: Isosorbide mononitrate
• Pharmacological class: Organic nitrate vasodilator
• Formulation: Extended-release tablets (30 mg, 60 mg, 120 mg)
• Mechanism of action: Venous and arterial dilation, reducing preload and afterload
• Duration of effect: Up to 12 hours with once-daily dosing
• Bioavailability: Nearly 100% following oral administration
• Prescription status: Rx-only medication

Benefits

• Significantly reduces the frequency of angina attacks
• Increases exercise capacity and tolerance in patients with chronic angina
• Provides consistent, long-lasting coronary vasodilation for all-day protection
• Helps decrease myocardial oxygen demand through hemodynamic unloading
• Supports improved quality of life through reliable symptom management
• Offers convenient once-daily dosing for enhanced adherence

Common use

Imdur is primarily indicated for the prophylactic management of angina pectoris in patients with coronary artery disease. It is not intended for the acute relief of angina attacks but rather for the long-term prevention of these episodes. The medication is typically prescribed as part of a comprehensive cardiac management plan that may include beta-blockers, calcium channel blockers, antiplatelet therapy, and lifestyle modifications. Healthcare providers often recommend Imdur for patients who experience frequent angina despite optimal medical therapy or for those who cannot tolerate other antianginal medications.

Dosage and direction

The recommended initial dosage of Imdur is 30 mg or 60 mg once daily, taken in the morning. The dosage may be titrated upward at 3-day intervals based on therapeutic response and tolerability. The typical maintenance dose ranges from 60 mg to 120 mg once daily, with 120 mg representing the maximum recommended daily dosage. Tablets should be swallowed whole with a glass of water and should not be crushed, chewed, or divided. Administration with food may help minimize potential headache side effects. It is crucial to maintain a consistent dosing schedule and avoid evening doses to prevent the development of tolerance.

Precautions

Patients should be advised that Imdur may cause dizziness or lightheadedness, particularly upon standing quickly from a sitting or lying position. Alcohol consumption should be limited as it may exacerbate these effects. Abrupt discontinuation of therapy should be avoided due to the risk of rebound angina. A drug-free interval of 10-14 hours is recommended daily to maintain sensitivity to nitrate therapy. Patients with hypovolemia, hypotension, or increased intracranial pressure should use Imdur with extreme caution. Regular monitoring of blood pressure and heart rate is advised, especially during dosage adjustments.

Contraindications

Imdur is contraindicated in patients with known hypersensitivity to isosorbide mononitrate, other nitrates, or any component of the formulation. It must not be used concurrently with phosphodiesterase type 5 inhibitors (such as sildenafil, tadalafil, or vardenafil) due to the risk of severe hypotension. Additional contraindications include severe anemia, increased intracranial pressure, and circulatory failure associated with marked hypotension or shock. The medication is not recommended for use in patients with acute myocardial infarction or congestive heart failure with low filling pressures.

Possible side effects

The most common side effect of Imdur is headache, which typically diminishes in frequency and intensity with continued therapy. Other frequently reported adverse reactions include dizziness, lightheadedness, nausea, and flushing. Less common side effects may include orthostatic hypotension, tachycardia, syncope, and cutaneous vasodilation with flushing. Rare but serious adverse effects include severe hypotension, methemoglobinemia (particularly with overdose), and paradoxical angina exacerbation. Patients should report persistent or severe side effects to their healthcare provider promptly.

Drug interaction

Imdur exhibits significant interactions with several medication classes. Concomitant use with phosphodiesterase-5 inhibitors is absolutely contraindicated due to potentially life-threatening hypotension. Concurrent administration with other vasodilators, antihypertensive agents, or calcium channel blockers may result in additive hypotensive effects. Alcohol consumption may enhance the vasodilatory and hypotensive effects of Imdur. The medication may reduce the efficacy of heparin, and its effects may be diminished by ergot alkaloids. Healthcare providers should conduct thorough medication reconciliation before initiating therapy.

Missed dose

If a dose of Imdur is missed, the patient should take it as soon as remembered unless it is nearly time for the next scheduled dose. In that case, the missed dose should be skipped, and the regular dosing schedule resumed. Patients should never double the dose to make up for a missed administration. Consistent daily dosing is important for maintaining therapeutic effects, but occasional missed doses are unlikely to cause significant clinical deterioration due to the medication’s extended-release properties.

Overdose

Imdur overdose manifests primarily as vasodilation leading to severe hypotension, reflex tachycardia, headache, dizziness, syncope, and flushing. Methemoglobinemia may occur with substantial overdosage, presenting as cyanosis, fatigue, and dyspnea. Management includes supportive care with Trendelenburg positioning, intravenous fluid administration, and oxygen therapy. Severe hypotension may require vasopressor agents, while methemoglobinemia exceeding 30% may necessitate methylene blue administration. Hemodialysis is not effective for nitrate removal due to extensive extravascular distribution.

Storage

Imdur tablets should be stored at controlled room temperature (20-25°C or 68-77°F) in their original container with the lid tightly closed. The medication must be protected from moisture, light, and excessive heat. Tablets should be kept out of reach of children and pets. Unused or expired medication should be disposed of properly through medication take-back programs or according to FDA-recommended disposal methods. Do not flush medications down the toilet unless specifically instructed to do so.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Imdur is a prescription medication that should be used only under the supervision of a qualified healthcare professional. Patients should not initiate, discontinue, or modify their dosage without consulting their physician. The prescribing information provided here may not include all possible uses, directions, precautions, or interactions. Always refer to the official prescribing information and discuss any questions with your healthcare provider.

Reviews

Clinical studies have demonstrated Imdur’s efficacy in reducing angina frequency and improving exercise tolerance. In randomized controlled trials, patients receiving Imdur experienced 40-50% fewer angina attacks compared to placebo and showed significant improvement in time to onset of angina during exercise testing. Many patients report improved quality of life and reduced limitation of physical activities. Some users note that initial headaches typically subside within the first week of therapy. Healthcare providers appreciate the once-daily dosing regimen for its positive impact on patient adherence compared to multiple-daily nitrate regimens.