Isosorbide Dinitrate: Price, Dosage & Where to Buy

Isosorbide dinitrate is an organic nitrate medicine that widens blood vessels. It is mainly prescribed to prevent angina pectoris, which is chest pain caused by coronary artery disease.

The medicine requires a prescription in the United Kingdom. No generic version is available according to the product information.

Isosorbide dinitrate belongs to the organic nitrate group of medicines. In the body, it releases substances that relax the muscle in blood vessel walls. This widens the vessels, particularly the veins, so less blood returns to the heart.

The heart then has less work to do and needs less oxygen. Widening the arteries that supply the heart may also help improve blood flow to the heart muscle. These effects can reduce the strain that contributes to angina.

Because the blood-vessel effects can lower blood pressure, lightheadedness or fainting may occur. Continued exposure can lead to tolerance, meaning the medicine may become less effective. The label therefore describes a daily dose-free interval as part of its dosing regimens.

Isosorbide dinitrate tablets are indicated for the prevention of angina pectoris caused by coronary artery disease. Angina is chest pain or discomfort that can happen when the heart muscle does not receive enough oxygen-rich blood. This immediate-release oral medicine is intended for prevention rather than stopping an acute angina episode.

Its onset is not sufficiently rapid for aborting an acute episode. The label does not establish benefits for acute myocardial infarction or congestive heart failure, and oral isosorbide dinitrate is not recommended in those settings because its effects are difficult to stop rapidly.

The label lists 5 mg, 10 mg, 20 mg, and 30 mg oral tablets. The usual starting dose is 5 mg to 20 mg, two or three times daily. The label lists 10 mg to 40 mg, two or three times daily for maintenance therapy.

The label states that some patients may require higher doses. The label lists a daily dose-free interval of at least 14 hours to minimise tolerance with immediate-release tablets. The optimal interval varies with the individual patient, dose, and regimen.

The label states that continuous 24-hour blood levels can cause refractory tolerance and that no regimen should be expected to provide more than about 12 hours of continuous anti-anginal effect per day. These are label facts for prescribers and do not replace individual medical advice.

Store at room temperature, approximately 25°C (77°F), and protect from light. Keep bottles tightly closed. Dispense in a light-resistant, tight container to maintain quality.

A missed dose can reduce protection against angina. General pharmacy advice is to follow the prescribed schedule when the missed dose is remembered, unless it is close to the next scheduled dose. In that situation, the missed dose is usually omitted rather than doubled.

The label describes a planned daily dose-free interval, so changing the schedule can affect tolerance and protection. A pharmacist or prescriber can advise on the individual regimen.

There are no adequate, well-controlled studies in pregnant women. Animal studies showed a dose-related increase in embryotoxicity in rabbits at oral doses 35 and 150 times the maximum recommended human daily dose.

The label states that isosorbide dinitrate should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. The label does not specify lactation data, so discuss use with a doctor or pharmacist.