displayName: DESCRIPTION SECTION
FDA Article Code: 34089-3
Isosorbide dinitrate, an organic nitrate, is a vasodilator with effects on both arteries and veins. The chemical name for isosorbide dinitrate is 1,4:3,6-dianhydro-D-glucitol 2, 5-dinitrate. The compound has the following structural formula:
Isosorbide dinitrate is a white, crystalline, odorless compound which is stable in air and in solution, has a melting point of 70°C and has an optical rotation of +134° (c=1.0, alcohol, 20°C). Isosorbide dinitrate is freely soluble in organic solvents such as acetone, alcohol, and ether, but is only sparingly soluble in water.
Isosorbide dinitrate tablets are available for oral administration as 5 mg, 10 mg, 20 mg, or 30 mg tablets.
Each tablet contains the following inactive ingredients: lactose anhydrous, magnesium stearate, microcrystalline cellulose, sodium starch glycolate and stearic acid. In addition, the 20 mg tablet contains D&C Yellow #10, FD&C Blue #1, and FD&C Yellow #6; the 30 mg tablet contains FD&C Blue #1.
displayName: CLINICAL PHARMACOLOGY SECTION
FDA Article Code: 34090-1
The principal pharmacological action of isosorbide dinitrate is relaxation of vascular smooth muscle and consequent dilatation of peripheral arteries and veins, especially the latter. Dilatation of the veins promotes peripheral pooling of blood and decreases venous return to the heart, thereby reducing left ventricular end-diastolic pressure and pulmonary capillary wedge pressure (preload). Arteriolar relaxation reduces systemic vascular resistance, systolic arterial pressure, and mean arterial pressure (afterload). Dilatation of the coronary arteries also occurs. The relative importance of preload reduction, afterload reduction, and coronary dilatation remains undefined.
Dosing regimens for most chronically used drugs are designed to provide plasma concentrations that are continuously greater than a minimally effective concentration. This strategy is inappropriate for organic nitrates. Several well-controlled clinical trials have used exercise testing to assess the anti-anginal efficacy of continuously-delivered nitrates. In the large majority of these trials, active agents were no more effective than placebo after 24 hours (or less) of continuous therapy. Attempts to overcome nitrate tolerance by dose escalation, even to doses far in excess of those used acutely, have consistently failed. Only after nitrates have been absent from the body for several hours has their anti-anginal efficacy been restored.
INDICATIONS AND USAGE
displayName: INDICATIONS & USAGE SECTION
FDA Article Code: 34067-9
Isosorbide dinitrate tablets are indicated for the prevention of angina pectoris due to coronary artery disease. The onset of action of immediate-release oral isosorbide dinitrate is not sufficiently rapid for this product to be useful in aborting an acute anginal episode.
displayName: CONTRAINDICATIONS SECTION
FDA Article Code: 34070-3
Allergic reactions to organic nitrates are extremely rare, but they do occur. Isosorbide dinitrate is contraindicated in patients who are allergic to isosorbide dinitrate or any of its other ingredients.
displayName: WARNINGS SECTION
FDA Article Code: 34071-1
Amplification of the vasodilatory effects of isosorbide dinitrate by sildenafil can result in severe hypotension. The time course and dose dependence of this interaction have not been studied. Appropriate supportive care has not been studied, but it seems reasonable to treat this as a nitrate overdose, with elevation of the extremities and with central volume expansion.
The benefits of immediate-release oral isosorbide dinitrate in patients with acute myocardial infarction or congestive heart failure have not been established. If one elects to use isosorbide dinitrate in these conditions, careful clinical or hemodynamic monitoring must be used to avoid the hazards of hypotension and tachycardia. Because the effects of oral isosorbide dinitrate are so difficult to terminate rapidly, this formulation is not recommended in these settings.
displayName: PRECAUTIONS SECTION
FDA Article Code: 42232-9
Severe hypotension, particularly with upright posture, may occur with even small doses of isosorbide dinitrate. This drug should therefore be used with caution in patients who may be volume depleted or who, for whatever reason, are already hypotensive. Hypotension induced by isosorbide dinitrate may be accompanied by paradoxical bradycardia and increased angina pectoris.
Nitrate therapy may aggravate the angina caused by hypertrophic cardiomyopathy.
As tolerance to isosorbide dinitrate develops, the effect of sublingual nitroglycerin on exercise tolerance, although still observable, is somewhat blunted.
Some clinical trials in angina patients have provided nitroglycerin for about 12 continuous hours of every 24-hour day. During the daily dose-free interval in some of these trials, anginal attacks have been more easily provoked than before treatment, and patients have demonstrated hemodynamic rebound anddecreasedexercise tolerance. The importance of these observations to the routine, clinical use of immediate-release oral isosorbide dinitrate is not known.
In industrial workers who have had long-term exposure to unknown (presumably high) doses of organic nitrates, tolerance clearly occurs. Chest pain, acute myocardial infarction, and even sudden death have occurred during temporary withdrawal of nitrates from these workers, demonstrating the existence of true physical dependence.
displayName: ADVERSE REACTIONS SECTION
FDA Article Code: 34084-4
Adverse reactions to isosorbide dinitrate are generally dose-related, and almost all of these reactions are the result of isosorbide dinitrate’s activity as a vasodilator. Headache, which may be severe, is the most commonly reported side effect. Headache may be recurrent with each daily dose, especially at higher doses. Transient episodes of lightheadedness, occasionally related to blood pressure changes, may also occur. Hypotension occurs infrequently, but in some patients it may be severe enough to warrant discontinuation of therapy. Syncope, crescendo angina, and rebound hypertension have been reported but are uncommon.
Extremely rarely, ordinary doses of organic nitrates have caused methemoglobinemia in normal-seeming patients. Methemoglobinemia is so infrequent at these doses that further discussion of its diagnosis and treatment is deferred (see OVERDOSAGE).
Data are not available to allow estimation of the frequency of adverse reactions during treatment with isosorbide dinitrate tablets.
DOSAGE AND ADMINISTRATION
displayName: DOSAGE & ADMINISTRATION SECTION
FDA Article Code: 34068-7
As noted under “CLINICAL PHARMACOLOGY,” multiple-dose studies with isosorbide dinitrate and other nitrates have shown that maintenance of continuous 24-hour plasma levels results in refractory tolerance. Every dosing regimen for isosorbide dinitrate tablets must provide a daily dose-free interval to minimize the development of this tolerance. With immediate-release isosorbide dinitrate, it appears that one daily dose-free interval must be at least 14 hours long.
As also noted under “CLINICAL PHARMACOLOGY,” the effects of the second and later doses have been smaller and shorter-lasting than the effects of the first.
Large controlled studies with other nitrates suggest that no dosing regimen with isosorbide dinitrate tablets should be expected to provide more than about 12 hours of continuous anti-anginal efficacy per day.
As with all titratable drugs, it is important to administer the minimum dose which produces the desired clinical effect. The usual starting dose of isosorbide dinitrate is 5 mg to 20 mg, two or three times daily. For maintenance therapy, 10 mg to 40 mg, two or three times daily is recommended. Some patients may require higher doses. A daily dose-free interval of at least 14 hours is advisable to minimize tolerance. The optimal interval will vary with the individual patient, dose and regimen.
displayName: HOW SUPPLIED SECTION
FDA Article Code: 34069-5
Isosorbide dinitrate tablets, USP are available as follows:
30 mg oral, blue, round, bisected tablets, debossed “PAR 009” on one side and supplied in blisterpacks of 30 tablets.
Store at room temperature, approximately 25°C (77°F). Protect from light. Keep bottles tightly closed.
Dispense in a light-resistant, tight container.
displayName: CLINICAL STUDIES SECTION
FDA Article Code: 34092-7
In clinical trials, immediate-release oral isosorbide dinitrate has been administered in a variety of regimens, with total daily doses ranging from 30 mg to 480 mg. Controlled trials of single oral doses of isosorbide dinitrate have demonstrated effective reductions in exercise-related angina for up to 8 hours. Anti-anginal activity is present about 1 hour after dosing.
Most controlled trials of multiple-dose oral isosorbide dinitrate taken every 12 hours (or more frequently) for several weeks have shown statistically significant anti-anginal efficacy for only 2 hours after dosing. Once-daily regimens, and regimens with one daily dose-free interval of at least 14 hours (e.g., a regimen providing doses at 0800, 1400 and 1800 hours), have shown efficacy after the first dose of each day that was similar to that shown in the single-dose studies cited above. The effects of the second and later doses have been smaller and shorter-lasting than the effect of the first.
From large, well-controlled studies of other nitrates, it is reasonable to believe that the maximal achievable daily duration of anti-anginal effect from isosorbide dinitrate is about 12 hours. No dosing regimen for isosorbide dinitrate, however, has ever actually been shown to achieve this duration of effect. One study of 8 patients, who were administered a pretitrated dose (average 27.5 mg) of immediate-release isosorbide dinitrate at 0800, 1300, and 1800 hours for 2 weeks, revealed that significant anti-anginal effectiveness was discontinuous and totaled about 6 hours in a 24 hour period.
PAR PHARMACEUTICAL, INC.
Spring Valley, NY 10977
PRINCIPAL DISPLAY PANEL
displayName: PACKAGE LABEL.PRINCIPAL DISPLAY PANEL
FDA Article Code: 51945-4
Isosorbide Dinitrate Tablets