From the Guidelines
Imdur should not be used as a first-line treatment for angina, but rather as a second-line option for vasospastic angina, according to the 2023 AHA/ACC/ACCP/ASPC/NLA/PCNA guideline for the management of patients with chronic coronary disease 1. When considering the use of Imdur, it's essential to understand its role in managing angina. Imdur (isosorbide mononitrate) is a long-acting nitrate medication that works by relaxing and widening blood vessels, improving blood flow to the heart muscle and reducing its workload.
Key Points to Consider
- The guideline recommends baseline therapy for vasospastic angina, including aspirin and statin if atherosclerosis or endothelial impairment is present, sublingual nitroglycerin as needed, smoking cessation, and lifestyle changes 1.
- First-line antianginal therapy for vasospastic angina is a calcium channel blocker (CCB), such as verapamil 40 mg BID uptitrated 1.
- Imdur (isosorbide mononitrate) is considered a second-line option for vasospastic angina, with a typical dosing of 10 mg BID 1.
- It's crucial to note that Imdur should not be combined with erectile dysfunction medications like Viagra, as this combination can cause dangerous drops in blood pressure.
Important Considerations
- Patients should take Imdur on an empty stomach to minimize side effects.
- A nitrate-free period of 10-14 hours daily, usually overnight, is recommended to prevent tolerance.
- Common side effects of Imdur include headache, dizziness, and flushing, which often diminish with continued use.
- Patients should avoid sudden position changes to prevent dizziness while taking Imdur.
From the FDA Drug Label
Isosorbide mononitrate extended-release tablets are indicated for the prevention of angina pectoris due to coronary artery disease. The onset of action of oral isosorbide mononitrate is not sufficiently rapid for this product to be useful in aborting an acute anginal episode.
- Indication: Imdur (isosorbide mononitrate) is used for the prevention of angina pectoris due to coronary artery disease.
- Key point: It is not intended for aborting an acute anginal episode due to its slow onset of action 2.
From the Research
Imdur Use
- Imdur (IMD) is a sustained-release isosorbide 5-mononitrate preparation used for the treatment of chronic stable angina pectoris 3.
- The most widely studied dosage of Imdur is 60 mg once daily, which has significant antianginal and anti-ischaemic effects compared with placebo after 2 weeks' treatment 3.
- Efficacy of Imdur is generally observed approximately 1 to 12 hours after administration, indicating that once-daily administration in the morning will provide effective prophylaxis of symptoms throughout the day 3.
Mechanism of Action
- Nitrates, including Imdur, are highly effective in terminating acute attacks of angina pectoris and in the prophylaxis of symptomatic and asymptomatic myocardial ischemia 4.
- Preload reduction by venodilatation is the prevailing mechanism of nitrates in patients with chronic stable angina 4.
Efficacy and Tolerance
- Studies have shown that Imdur 60 mg once daily is more effective than isosorbide dinitrate 30 mg 4 times daily and similar to or better than isosorbide dinitrate 20 mg 3 times daily 3.
- There is no evidence of classical tolerance to Imdur 30 to 240 mg/day in a large well-designed study 3.
- A daily low-nitrate interval is required to prevent tolerance development, and a 12-h patch-free interval should prevent tolerance in most patients 4.
Combination Therapy
- The addition of Imdur once daily to beta-blockade significantly increased the anti-anginal effect in patients with stable exertional angina pectoris 5.
- Imdur in combination with a beta-blocker significantly increased the total exercise capacity and decreased the attack rate and nitroglycerin consumption 5.