Imdur (isosorbide mononitrate) is a long-acting nitrate medication specifically formulated for the prophylactic management of angina pectoris. It belongs to the organic nitrate class of vasodilators and is indicated to reduce the frequency and severity of angina attacks in patients with coronary artery disease. By promoting venous and arterial dilation, Imdur decreases myocardial oxygen demand and improves perfusion, offering sustained cardiovascular support. This extended-release formulation ensures stable plasma concentrations, allowing for convenient once-daily dosing in appropriate patients under medical supervision.

Features

• Contains isosorbide mononitrate as the active pharmaceutical ingredient
• Extended-release tablet formulation for prolonged therapeutic effect
• Available in multiple strengths (e.g., 30 mg, 60 mg, 120 mg)
• Designed for oral administration with once-daily dosing convenience
• Bioavailability approximately 90% with consistent pharmacokinetic profile
• White to off-white, round, biconvex film-coated tablets

Benefits

• Significantly reduces frequency and severity of angina episodes
• Provides 24-hour therapeutic coverage with single daily dosing
• Decreases myocardial oxygen demand through balanced vasodilation
• Improves exercise tolerance and functional capacity in stable angina
• Offers predictable pharmacokinetics with minimal peak-trough fluctuations
• Compatible with comprehensive anti-anginal treatment regimens

Common use

Imdur is primarily prescribed for the prophylaxis of angina pectoris in patients with documented coronary artery disease. It is not intended for the acute termination of angina attacks but rather for preventive management. The medication is typically incorporated into treatment plans alongside beta-blockers, calcium channel blockers, and other anti-anginal agents when monotherapy provides insufficient symptom control. Clinical use extends to patients with stable exertional angina, vasospastic angina, and those with angina that persists despite revascularization procedures. The extended-release formulation makes it particularly suitable for patients requiring consistent nitrate coverage throughout daily activities.

Dosage and direction

The recommended initial dosage for most patients is 30 mg or 60 mg once daily, taken in the morning upon awakening. Dosage may be titrated upward at 3-day intervals based on therapeutic response and tolerability, with maximum recommended daily dose of 240 mg. Tablets should be swallowed whole with a glass of water and not crushed, chewed, or divided. Administration should occur at the same time each day to maintain consistent plasma levels. The medication may be taken with or without food, though consistent administration relative to meals is advised. For patients experiencing anginal attacks at particular times of day, dosing schedules may be adjusted under medical supervision to optimize coverage during high-risk periods.

Precautions

Patients should be advised that Imdur may cause hypotension, particularly upon initiation or dosage escalation. Caution is warranted when rising from supine or seated positions. Alcohol consumption may potentiate hypotensive effects and should be avoided. Tolerance to anti-anginal effects may develop with continuous nitrate therapy; implementing a nitrate-free interval of 10-14 hours daily (typically overnight) helps prevent tolerance development. Use with caution in patients with hypovolemia, hypotension, or compromised cerebral perfusion. Periodic assessment of blood pressure and heart rate is recommended, especially during dosage adjustments. Patients should be educated about the medication’s mechanism and advised not to use short-acting nitrates concurrently unless specifically directed.

Contraindications

Imdur is contraindicated in patients with known hypersensitivity to isosorbide mononitrate, other nitrates, or any component of the formulation. Concurrent use with phosphodiesterase-5 inhibitors (sildenafil, tadalafil, vardenafil) is absolutely contraindicated due to risk of severe hypotension and cardiovascular collapse. Additional contraindications include patients with severe anemia, increased intracranial pressure, or closed-angle glaucoma. The medication should not be used in cases of cardiogenic shock or marked hypotension (systolic pressure <90 mmHg). Patients with acute myocardial infarction with congestive heart failure or low filling pressures should not receive nitrate therapy.

Possible side effects

The most frequently reported adverse reactions involve cardiovascular and neurological systems. Headache occurs in approximately 30% of patients, often dose-related and typically diminishing with continued therapy. Dizziness and postural hypotension may affect 5-10% of users. Less common effects include nausea, vomiting, flushing, and reflex tachycardia. Approximately 2-5% of patients experience cutaneous vasodilation with flushing. Rare but serious adverse effects include syncope, severe hypotension requiring intervention, and paradoxical angina exacerbation. Dermatological reactions including rash and pruritus occur infrequently. Any persistent or severe side effects should prompt medical evaluation and possible dosage adjustment.

Drug interaction

Imdur exhibits several clinically significant interactions requiring careful management. Concomitant use with phosphodiesterase-5 inhibitors is absolutely contraindicated. Antihypertensive agents, calcium channel blockers, beta-blockers, and diuretics may potentiate hypotensive effects. Concurrent administration with riociguat may result in additive hypotensive effects. Alcohol, vasodilators, and tricyclic antidepressants may enhance orthostatic hypotension. Aspirin may increase nitrate serum concentrations. Hepatic enzyme inducers such as rifampin may reduce nitrate efficacy. Healthcare providers should conduct comprehensive medication reviews before initiation and during therapy to identify potential interactions.

Missed dose

If a dose is missed, it should be taken as soon as remembered on the same day. However, if it is near the time for the next scheduled dose, 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, so patients should be encouraged to establish routine administration practices. If multiple doses are missed, medical consultation is advised before resuming therapy, as dosage adjustment may be necessary.

Overdose

Nitrate overdose manifests primarily as vasodilation with severe hypotension, paradoxical bradycardia, syncope, methemoglobinemia, and circulatory collapse. Symptoms may include nausea, vomiting, diaphoresis, visual disturbances, and headache. Management involves immediate cardiovascular support with Trendelenburg positioning and intravenous fluid administration. Vasopressor agents may be required for refractory hypotension. Methylene blue is indicated for methemoglobinemia exceeding 30%. Hemodialysis is not effective due to extensive tissue distribution. All suspected overdoses require immediate medical attention with continuous hemodynamic monitoring for at least 24 hours due to the extended-release formulation.

Storage

Store at controlled room temperature (20-25°C or 68-77°F) with excursions permitted between 15-30°C (59-86°F). Protect from moisture and light. Keep in the original container with the lid tightly closed. Do not transfer to other containers. Keep out of reach of children and pets. Do not use if tablets appear discolored, damaged, or show signs of moisture exposure. Properly discard any unused medication after the expiration date or when no longer needed through medication take-back programs.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Individual patient responses may vary. Treatment decisions should be made by qualified healthcare professionals based on comprehensive patient assessment. The prescribing physician should be consulted for specific recommendations tailored to individual medical circumstances. Patients should not alter dosage or discontinue medication without medical supervision.

Reviews

Clinical studies demonstrate Imdur effectively reduces angina frequency by 40-60% in appropriately selected patients. The extended-release formulation maintains therapeutic nitrate levels for 12-24 hours with once-daily dosing. Patient satisfaction surveys indicate improved quality of life measures related to reduced angina limitation. Cardiology guidelines support the use of long-acting nitrates as second-line therapy for angina prophylaxis when beta-blockers are contraindicated or insufficient. Real-world evidence confirms the safety profile remains consistent with clinical trial data when used according to prescribing information.