What is Imdur Used For?
Imdur (isosorbide mononitrate extended-release) is primarily indicated for the prevention of angina pectoris due to coronary artery disease. 1
Primary Indication: Angina Prevention
- Imdur is FDA-approved specifically for preventing anginal episodes in patients with chronic stable angina caused by coronary artery disease. 1
- The medication works by dilating coronary arteries (both normal and atherosclerotic), enhancing collateral blood flow, and redistributing coronary blood flow to ischemic regions. 2
- It is NOT effective for aborting acute anginal attacks due to insufficient rapidity of onset—patients need sublingual nitroglycerin for acute episodes. 1
Dosing and Administration
- The most commonly studied and effective dose is 60 mg once daily, which provides antianginal protection for approximately 1 to 12 hours after administration. 3, 4
- Once-daily morning administration provides effective prophylaxis throughout the day while allowing a nitrate-free interval overnight to prevent tolerance. 3, 4
- Higher doses (120-240 mg daily) may be used for more severe symptoms, with evidence showing maintained efficacy at 6 weeks compared to lower doses. 3
Combination Therapy
- Imdur is particularly effective when added to beta-blocker therapy, significantly increasing exercise capacity and reducing anginal attacks beyond beta-blockade alone. 5
- The combination of isosorbide mononitrate with beta-blockers provides superior antianginal protection compared to either agent alone. 5
Secondary Use: Heart Failure (Specific Populations)
While not the primary FDA indication for Imdur specifically, isosorbide mononitrate (as part of the broader nitrate class) has an important role in heart failure:
- In African American patients with NYHA class III-IV heart failure with reduced ejection fraction, the combination of hydralazine plus isosorbide dinitrate (which includes mononitrate formulations) reduces mortality. 6, 2
- This combination should be added to standard heart failure therapy (ACE inhibitors/ARBs, beta-blockers, mineralocorticoid receptor antagonists) in symptomatic African American patients. 6
- The benefit is presumed related to enhanced nitric oxide bioavailability. 6, 2
- For patients intolerant of ACE inhibitors or ARBs (due to hypotension or renal insufficiency), the hydralazine-nitrate combination may be considered, though evidence is limited in this population. 6
Important Safety Considerations
Absolute Contraindications
- Never use with phosphodiesterase-5 inhibitors (sildenafil, tadalafil, vardenafil) due to risk of profound hypotension, myocardial infarction, and death. 6, 2
- Avoid in patients with systolic blood pressure <90 mmHg or >30 mmHg below baseline. 6, 2
Use With Caution
- Patients with aortic stenosis may experience marked hypotension following nitrate administration. 2
- Headache is the most common side effect but typically resolves within 5-6 days and rarely requires discontinuation. 3, 7
Tolerance Prevention
- A nitrate-free interval of at least 10 hours is essential to prevent tolerance. 6, 2
- Once-daily Imdur administration naturally provides this interval overnight, maintaining efficacy during long-term treatment. 3, 4
- Studies show no evidence of classical tolerance with once-daily Imdur 60 mg over extended periods when the nitrate-free interval is maintained. 3, 4