From the Guidelines
Isosorbide mononitrate is generally preferred over isosorbide dinitrate due to its less frequent dosing and more predictable absorption and bioavailability, with standard dosing being 20 mg twice daily for immediate-release formulations 1. The key differences between isosorbide mononitrate (IMN) and isosorbide dinitrate (ISDN) lie in their dosing frequency, absorption, and bioavailability.
- Isosorbide mononitrate requires less frequent dosing, typically once or twice daily, whereas isosorbide dinitrate requires more frequent administration, usually 2-4 times daily.
- The dosing for isosorbide mononitrate is 20 mg twice daily for immediate-release formulations, as indicated in the guidelines 1.
- Isosorbide dinitrate, on the other hand, is typically administered at doses of 10-40 mg per dose, with the last dose taken no later than 7 PM to avoid nitrate tolerance. Both medications work by dilating blood vessels, reducing cardiac workload and oxygen demand, which is crucial for managing angina symptoms.
- Isosorbide mononitrate is the active metabolite of isosorbide dinitrate, explaining its more direct action and improved pharmacokinetic profile. Common side effects for both include headache, dizziness, and hypotension, and a nitrate-free period of 10-14 hours daily is recommended for both medications to prevent tolerance.
- Neither should be used with phosphodiesterase inhibitors like sildenafil due to the risk of dangerous hypotension, as highlighted in the guidelines 1. It's essential to consider these differences and guidelines when selecting a nitrate medication for angina treatment, prioritizing the patient's morbidity, mortality, and quality of life outcomes.
- The most recent and highest quality study, such as the 2013 ACCF/AHA focused update 1, should be prioritized when making a definitive recommendation.
- The guidelines emphasize the importance of individualizing treatment and considering the patient's specific needs and medical history when choosing between isosorbide mononitrate and isosorbide dinitrate.
From the FDA Drug Label
Isosorbide mononitrate (ISMN), an organic nitrate and the major biologically active metabolite of isosorbide dinitrate (ISDN), is a vasodilator with effects on both arteries and veins. The chemical name for isosorbide mononitrate is 1,4:3,6-dianhydro-,D-glucitol 5-nitrate; The chemical name for isosorbide dinitrate is 1,4:3,6-dianhydro-D-glucitol 2,5-dinitrate.
The main difference between Isosorbide Mononitrate (IMN) and Isosorbide Dinitrate (ISDN) is their chemical structure, with IMN being the major biologically active metabolite of ISDN. Key differences include:
- Chemical name: Isosorbide mononitrate is 1,4:3,6-dianhydro-,D-glucitol 5-nitrate, while isosorbide dinitrate is 1,4:3,6-dianhydro-D-glucitol 2,5-dinitrate.
- Molecular weight: IMN has a molecular weight of 191.14, while ISDN has a molecular weight of 236.14 2, 3.
From the Research
Difference between Isosorbide Mononitrate (IMN) and Isosorbide Dinitrate (ISDN)
- Isosorbide Mononitrate (IMN) and Isosorbide Dinitrate (ISDN) are both nitrates used in the treatment of angina pectoris, but they have some differences in terms of their efficacy, dosage, and tolerance development 4, 5, 6, 7, 8.
- IMN is a sustained-release formulation that can be administered once daily, providing effective antianginal prophylaxis for up to 12 hours without inducing tolerance 5, 6, 8.
- ISDN, on the other hand, is often administered multiple times a day, and its efficacy can be limited by the development of tolerance 4, 7.
- Studies have shown that IMN is at least as effective as ISDN in reducing anginal attacks and improving exercise tolerance, and may even be more cost-effective due to its lower required dosage 7.
- The choice between IMN and ISDN may depend on individual patient needs and responses to treatment, as well as considerations such as dosage convenience and potential side effects 5, 8.
- Both IMN and ISDN have been shown to be safe and well-tolerated, with common side effects including headache and dizziness 5, 7, 8.