From the Guidelines
Imdur (Isosorbide mononitrate) is a nitrate medication used to prevent angina attacks.
Key Characteristics of Imdur
- Route of Administration: Oral
- Dose: 20 mg twice daily or 60 to 240 mg once daily (slow release) 1
- Duration of Effect: 12 to 24 hours
Mechanism of Action
Nitrates, including Isosorbide mononitrate, work by dilating blood vessels to reduce myocardial oxygen demand and increase oxygen delivery to the heart muscle 1.
Clinical Use
Imdur is used to prevent angina attacks, which are characterized by chest pain or discomfort due to transient myocardial ischemia. It is often prescribed for patients with a history of angina to reduce the frequency and severity of attacks.
Important Considerations
- Contraindications: Nitrates, including Imdur, are contraindicated in patients who have taken phosphodiesterase inhibitors (e.g., sildenafil, tadalafil) within a certain time frame, as this can cause severe hypotension 1.
- Side Effects: Common side effects of nitrates include headache, dizziness, and hypotension.
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 isosorbide mononitrate extended-release tablet is an oral extended-release formulation of ISMN, the major active metabolite of isosorbide dinitrate; most of the clinical activity of the dinitrate is attributable to the mononitrate
Imdur (Isosorbide mononitrate) is a vasodilator with effects on both arteries and veins, and it is the major active metabolite of isosorbide dinitrate 2 2.
From the Research
Definition and Composition of Imdur
- Imdur is a sustained-release isosorbide 5-mononitrate preparation used for the treatment of chronic stable angina pectoris 3.
- It contains isosorbide-5-mononitrate (IS-5-MN) in a controlled-release (Durules) formulation 4.
Mechanism of Action and Efficacy
- Imdur has significant antianginal and anti-ischaemic effects compared to placebo after 2 weeks of treatment 3.
- The anti-anginal effect of Imdur persists during long-term treatment without the development of tolerance 4.
- Imdur provides effective antianginal prophylaxis for up to 12 hours and does not seem to be associated with rebound phenomena at the end of the dosage interval 3.
Dosage and Administration
- The most widely studied dosage of Imdur is 60 mg once daily 3.
- Imdur 60 mg once daily has been shown to be more effective than isosorbide dinitrate 30 mg 4 times daily and similar to or better than isosorbide dinitrate 20 mg 3 times daily 3.
- Imdur 60 mg once daily has similar efficacy to diltiazem 60 mg 3 times daily 3.
Safety and Tolerability
- Imdur is generally well tolerated, with the most frequently reported adverse event being headache, which is usually mild to moderate and improves with long-term therapy 3.
- Headache is the only significant side-effect reported in studies 5, 6.
- Patient compliance is better with once-daily administration of Imdur than with twice-daily administration of conventional isosorbide 5-mononitrate 3.