What is Imdur (isosorbide mononitrate) used for?

Isosorbide Mononitrate (Imdur) Uses

Imdur (isosorbide mononitrate) is primarily indicated for the prevention of angina pectoris due to coronary artery disease. 1

Primary Indication

• Imdur is a sustained-release formulation of isosorbide mononitrate that is FDA-approved for the prevention of angina pectoris due to coronary artery disease 1
• It is not indicated for acute anginal episodes as its onset of action is not sufficiently rapid to abort an acute attack 1

Mechanism of Action

• Isosorbide mononitrate is a nitrate vasodilator that works by:
  • Dilating normal and atherosclerotic epicardial coronary arteries 2
  • Dilating smaller arteries that constrict with certain stressors (cold, mental or physical exercise) 2
  • Promoting dilation of large coronary arteries, enhancing collateral flow and redistributing coronary blood flow to ischemic regions 2
  • Inhibiting platelet aggregation, though the clinical significance of this action is not well defined 2

Formulation and Dosing

• Imdur is available as a sustained-release (Durules) formulation that allows for once-daily dosing 3
• The most widely studied dosage is 60 mg once daily, which provides effective prophylaxis of symptoms throughout the day 3
• The controlled-release mechanism is achieved using an insoluble matrix embedding principle (Durules) 3
• Efficacy is generally observed approximately 1 to 12 hours after administration 3

Clinical Applications

Stable Angina Pectoris

• Imdur provides effective antianginal prophylaxis for up to 12 hours in patients with chronic stable angina 3
• Once-daily administration in the morning provides effective symptom prevention throughout the day 3
• It can be used as monotherapy or in combination with other anti-anginal medications 4
• When combined with beta-blocker treatment, Imdur provides superior anti-anginal protection compared to beta-blocker treatment alone 4

Heart Failure

• In heart failure patients, hydralazine plus isosorbide dinitrate (including mononitrate formulations) may be beneficial in specific populations:
  • Particularly effective in African American patients with NYHA class III or IV heart failure with reduced ejection fraction 2
  • This combination has been shown to reduce mortality in African American patients with advanced heart failure 2
  • The benefit is presumed to be related to enhanced nitric oxide bioavailability 2

Advantages of Imdur

• Once-daily dosing improves patient compliance compared to multiple daily dosing regimens 3
• Maintains effectiveness during long-term treatment without significant development of tolerance when properly dosed 3, 4
• The plasma nitrate profile is high enough to provide anti-anginal protection during the daytime but low enough during the latter part of the dosage interval to minimize tolerance development 4

Important Precautions and Contraindications

• Contraindicated with phosphodiesterase inhibitors:
  • Should not be used within 24 hours after sildenafil or within 48 hours after tadalafil 2
  • Concomitant use can cause profound hypotension, myocardial infarction, and even death 2
• Should be avoided in patients with severe hypotension (systolic BP <90 mmHg) 2
• Use with caution in patients with aortic stenosis as they may demonstrate marked hypotension following nitrate administration 2
• Abrupt discontinuation after long-term treatment may exacerbate anginal symptoms in some patients 3, 5

Side Effects

• The most common adverse effect is headache, which is usually mild to moderate and typically improves with continued therapy 3
• Other potential side effects include hypotension and dizziness 2
• Tolerance may develop with continuous use, but can be minimized by providing a "nitrate-free interval" of at least 10 hours 2

In conclusion, Imdur (isosorbide mononitrate) is primarily used for the prevention of angina pectoris in patients with coronary artery disease, with specific applications in heart failure management for certain patient populations.