Isosorbide Dinitrate Management for Angina Pectoris
Mechanism of Action and Effects
- Isosorbide dinitrate promotes vasodilation of veins, arteries, and arterioles through nitric oxide release, reducing right and left ventricular preload through peripheral vasodilation, decreasing afterload through arterial vasodilation, and reducing cardiac work and myocardial oxygen requirements 1
Tolerance Management and Precautions
- Tolerance to hemodynamic effects typically develops after 24 hours of continuous therapy, and providing a nitrate-free interval of at least 14 hours daily helps minimize tolerance, with lower doses and intermittent dosing also helping to prevent tolerance development 2
- The American College of Cardiology recommends that sildenafil should not be used within 24 hours of nitrate administration, and tadalafil should not be used within 48 hours of nitrate administration, due to the risk of profound hypotension 2, 3
Special Populations and Considerations
- The American Heart Association suggests that African American patients with heart failure may benefit from combination therapy with hydralazine and isosorbide dinitrate, starting at 37.5 mg hydralazine/20 mg isosorbide dinitrate three times daily 4
- Isosorbide dinitrate should be used with caution in patients with right ventricular infarction, as they depend on adequate RV preload to maintain cardiac output, and exercise caution is advised in patients with inferior wall MI with RV involvement due to the risk of profound hypotension 1
Isosorbide Dinitrate Dosing to Prevent Tolerance
Introduction to Dosing Regimens
- The American College of Cardiology and American Heart Association guidelines recommend dosing regimens that provide at least a 14-hour nitrate-free interval to prevent tolerance, with a typical dosing schedule of 5mg twice-daily 5, 6
Clinical Efficacy and Tolerance Prevention
- The 5mg twice-daily dose represents the lower end of the therapeutic range, with guidelines recommending 5-80mg given 2-3 times daily, and is appropriate for patients requiring minimal nitrate therapy or those at risk for hypotension, according to the American College of Cardiology and American Heart Association 5, 6