isosorbide dinitrate

INDICATIONS AND USAGE Isosorbide Dinitrate Tablets, USP 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.

DOSAGE AND ADMINISTRATION 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 tablets 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.

CONTRAINDICATIONS Isosorbide dinitrate tablets are contraindicated in patients who are allergic to isosorbide dinitrate or any of its other ingredients. Do not use isosorbide dinitrate tablets in patients who are taking certain drugs for erectile dysfunction (phosphodiesterase inhibitors), such as sildenafil, tadalafil, or vardenafil. Concomitant use can cause severe hypotension, syncope, or myocardial ischemia. Do not use isosorbide dinitrate tablets in patients who are taking the soluble guanylate cyclase stimulator riociguat. Concomitant use can cause hypotension.

ADVERSE REACTIONS 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. To report SUSPECTED ADVERSE REACTIONS contact AvKARE at 1-855-361-3993; email drugsafety@avkare.com ; or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .

Drug Interactions The vasodilating effects of isosorbide dinitrate may be additive with those of other vasodilators. Alcohol, in particular, has been found to exhibit additive effects of this variety. Concomitant use of isosorbide dinitrate with phosphodiesterase inhibitors in any form is contraindicated (see Error! Hyperlink reference not valid. ). Concomitant use of isosorbide dinitrate with riociguat, a soluble guanylate cyclase stimulator, is contraindicated (see Error! Hyperlink reference not valid. ).

DESCRIPTION Isosorbide dinitrate (ISDN) is 1,4:3,6-dianhydro-D-glucitol 2,5-dinitrate, an organic nitrate whose structural formula is and whose molecular weight is 236.14. The organic nitrates are vasodilators, active on both arteries and veins. Isosorbide dinitrate is a white, crystalline powder compound which is stable in air and in solution, has a melting point of 69°C to 72°C and optically active. Isosorbide dinitrate is very soluble in acetone, sparingy soluble in alcohol and very slightly soluble in water. Each Isosorbide dinitrate tablet contains 5 mg, 10 mg, 20 mg, 30 mg or 40 mg of isosorbide dinitrate. The inactive ingredients in each tablet are microcrystalline cellulose, colloidal silicon dioxide, and magnesium stearate. The 5mg, 10 mg, 20 mg and 30 mg dosage strengths also contain anhydrous lactose and sodium starch glycolate Type A. Additionally 5 mg contains FD & C red 40 Al lake. 10 mg, 20mg, 30 mg and 40 mg contains FD & C Blue 1 Al lake and D & C Yellow 10 Al lake. FDA approved dissolution test specifications differ from USP. Isosorbide Dinitrate Chemical Structure

OVERDOSAGE Hemodynamic Effects The ill effects of isosorbide dinitrate overdose are generally the results of isosorbide dinitrate’s capacity to induce vasodilatation, venous pooling, reduced cardiac output, and hypotension. These hemodynamic changes may have protean manifestations, including increased intracranial pressure, with any or all of persistent throbbing headache, confusion, and moderate fever; vertigo; palpitations; visual disturbances; nausea and vomiting (possibly with colic and even bloody diarrhea); syncope (especially in the upright posture); air hunger and dyspnea, later followed by reduced ventilatory effort; diaphoresis, with the skin either flushed or cold and clammy; heart block and bradycardia; paralysis; coma; seizures; and death. Laboratory determinations of serum levels of isosorbide dinitrate and its metabolites are not widely available, and such determinations have, in any event, no established role in the management of isosorbide dinitrate overdose. There are no data suggesting what dose of isosorbide dinitrate is likely to be life-threatening in humans. In rats, the median acute lethal dose (LD 50 ) was found to be 1100 mg/kg. No data are available to suggest physiological maneuvers (e.g., maneuvers to change the pH of the urine) that might accelerate elimination of isosorbide dinitrate and its active metabolites. Similarly, it is not known which, if any, of these substances can usefully be removed from the body by hemodialysis. No specific antagonist to the vasodilator effects of isosorbide dinitrate is known, and no intervention has been subject to controlled studies as a therapy for isosorbide dinitrate overdose. Because the hypotension associated with isosorbide dinitrate overdose is the result of venodilatation and arterial hypovolemia, prudent therapy in this situation should be directed toward increase in central fluid volume. Passive elevation of the patient’s legs may be sufficient, but intravenous infusion of normal saline or similar fluid may also be necessary. The use of epinephrine or other arterial vasoconstrictors in this setting is likely to do more harm than good. In patients with renal disease or congestive heart failure, therapy resulting in central volume expansion is not without hazard. Treatment of isosorbide dinitrate overdose in these patients may be subtle and difficult, and invasive monitoring may be required. Methemoglobinemia Nitrate ions liberated during metabolism of isosorbide dinitrate can oxidize hemoglobin into methemoglobin. Even in patients totally without cytochrome b 5 reductase activity, however, and even assuming that the nitrate moieties of isosorbide dinitrate are quantitatively applied to oxidation of hemoglobin, about 1 mg/kg of isosorbide dinitrate should be required before any of these patients manifests clinically significant (greater than or equal to 10%) methemoglobinemia. In patients with normal reductase function, significant production of methemoglobin should require even larger doses of isosorbide dinitrate. In one study in which 36 patients received 2 to 4 weeks of continuous nitroglycerin therapy at 3.1 mg/hr to 4.4 mg/hr (equivalent, in total administered dose of nitrate ions, to 4.8 mg to 6.9 mg of bioavailable isosorbide dinitrate per hour), the average methemoglobin level measured was 0.2%; this was comparable to that observed in parallel patients who received placebo. Notwithstanding these observations, there are case reports of significant methemoglobinemia in association with moderate overdoses of organic nitrates. None of the affected patients had been thought to be unusually susceptible. Methemoglobin levels are available from most clinical laboratories. The diagnosis should be suspected in patients who exhibit signs of impaired oxygen delivery despite adequate cardiac output and adequate arterial pO 2 . Classically, methemoglobinemic blood is described as chocolate brown, without color change on exposure to air. When methemoglobinemia …

HOW SUPPLIED Isosorbide dinitrate tablets, USP are available as follows: Isosorbide dinitrate tablets USP, 5 mg, light pink to pink colored, spotted, round shaped, biconvex, uncoated tablets debossed with "1148" on one side and score on other side. NDC 70710-1148-1 in bottles of 100 tablets with child-resistant closure NDC 70710-1148-0 in bottles of 1000 tablets Isosorbide dinitrate tablets USP, 10 mg, white to off white colored, round shaped, biconvex, uncoated tablets debossed with "1149" on one side and score on other side. NDC 70710-1149-1 in bottles of 100 tablets with child-resistant closure NDC 70710-1149-0 in bottles of 1000 tablets Isosorbide dinitrate tablets USP, 20 mg, light green to green colored, spotted, round shaped, biconvex, uncoated tablets debossed with "1150" on one side and score on other side. NDC 70710-1150-1 in bottles of 100 tablets with child-resistant closure NDC 70710-1150-0 in bottles of 1000 tablets Isosorbide dinitrate tablets USP, 30 mg, light blue to blue colored, spotted, round shaped, biconvex, uncoated tablets debossed with "1151" on one side and score on other side. NDC 70710-1151-1 in bottles of 100 tablets with child-resistant closure NDC 70710-1151-0 in bottles of 1000 tablets Isosorbide dinitrate tablets USP, 40 mg, light green to green colored, spotted, round, biconvex, uncoated tablets, debossed with "1152" on one side and score on other side. NDC 70710-1152-1 in bottles of 100 tablets with child-resistant closure Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature]. Protect from Light. Dispense in a light-resistant, tight container. Keep bottles tightly closed. Manufactured by: Zydus Lifesciences Ltd., Baddi, India Distributed by: Zydus Pharmaceuticals (USA) Inc. Pennington, NJ 08534 Rev. 12/22