Action And Clinical Pharmacology: The basic action of isosorbide dinitrate is the relaxation of smooth muscle. Relaxation of peripheral vascular smooth muscle and pooling results in the reduction of preload and afterload on the left ventricle. The effect of the long acting nitrate appears to be mainly peripheral. Although isosorbide dinitrate dilates the coronary arteries there is no incontrovertible evidence that it relieves ischemic heart pain by increasing coronory blood flow.
When administered sublingually, isosorbide dinitrate has an onset of action of 2 to 5 minutes and lasts 1 to 2 hours. After oral administration, relief of angina pectoris begins in 30 minutes and lasts 4 to 6 hours.
Isosorbide dinitrate is metabolized to 2-isosorbide mononitrate and 5-isosorbide mononitrate. After a single oral dose, 80 to 100% of the amount absorbed is excreted in the urine within 24 hours, chiefly as metabolites.
Indications And Clinical Uses: The prophylaxis of ischemic heart pain associated with coronary insufficiency. Isosorbide dinitrate may reduce the number, duration and severity of anginal attacks, exercise tolerance may be increased and nitroglycerin requirements curtailed.
Contra-Indications: Although isosorbide dinitrate may be used for the control of angina pectoris occurring after myocardial infarction, it is suggested that treatment be withheld in the presence of cardiogenic shock, or if there is a risk of shock developing. Hypersensitivity to isosorbide dinitrate.
Manufacturers’ Warnings In Clinical States: Data supporting the use of nitrites during the early days of the acute phase of myocardial infarction (the period during which clinical and laboratory findings are unstable) are insufficient to establish safety.
Precautions: Use isosorbide dinitrate with caution in patients with glaucoma. Isosorbide dinitrate is a potent vasodilator and causes a slight decrease in mean blood pressure (approx. 10 to 15 mm Hg) in some patients when used in therapeutic doses. Caution should be exercised in using the drug in patients who are prone to, or might be affected by, hypotension. In patients with renal insufficiency, isosorbide dinitrate should be used with caution since the hypotensive effect may cause a dangerous reduction in renal blood flow.
Tolerance to this drug and cross tolerance to other nitrites and nitrates may occur.
Adverse Reactions: As with nitroglycerin and other nitrates, vascular headache occurs and it may be severe and persistent. This adverse effect occurs most frequently at the beginning of therapy. Headache usually can be controlled by temporary dosage reduction, concomitant administration of suitable analgesics or by administering the drug during meals. These headaches usually disappear within 1 week of continuous, uninterrupted therapy. It is usually best to advise the patient of their possible occurrence and of their importance in regard to the prevention of angina. Drug and/or exfoliative dermatitis occasionally occur. Signs of cerebral ischemia associated with postural hypotension such as weakness, transient episodes of dizziness may occasionally develop. Cutaneous vasodilatation with flushing may occur. Rarely, a marked sensitivity to the hypotensive effects of the drug and severe response (nausea, vomiting, restlessness, perspiration and collapse) can occur and alcohol may enhance this effect. Isosorbide dinitrate can antagonize the effects of histamine or epinephrine, acetylcholine and similar agents.
Symptoms And Treatment Of Overdose: Symptoms: Related to vasodilatation; cutaneous flushing, headache, nausea, dizziness and hypotension. tag_Treatment
Treatment: Gastric lavage. Symptomatic and supportive therapy should include ventilation with oxygen and vasopressor amines if indicated (norepinephrine is suitable).
Dosage And Administration: Sublingual Tablets (tablets dissolve in 20 seconds in the mouth): 5 to 10 mg sublingually, every 2 to 4 hours for the prophylaxis of acute angina; may be supplemented by a dose of 5 to 10 mg sublingually prior to stressful situations likely to provoke an attack of angina.
Oral Titradose Tablets: 5 to 30 mg orally 4 times daily, according to therapeutic and patient response.
Availability And Storage: 5 mg: Each pink, sublingual tablet with a depressed dot, contains: isosorbide dinitrate 5 mg. Nonmedicinal ingredients: cornstarch, FD&C Red Aluminum Lake, lactose, magnesium stearate and microcrystalline cellulose. Energy: 0.50 kJ (0.12 kcal)/tablet. Gluten- and tartrazine-free. Bottles of 100.
10 mg: Each white, scored, titradose tablet, imprinted ISORDIL 10, contains: isosorbide dinitrate 10 mg. Nonmedicinal ingredients: lactose, magnesium stearate, microcrystalline cellulose and polacrilin potassium. Energy: 2.72 kJ (0.65 kcal). Gluten- and tartrazine-free. Bottles of 100, 500 and 2 500.
30 mg: Each white, scored titradose tablet, imprinted ISORDIL 30, contains: isosorbide dinitrate 30 mg. Energy: 3.85 kJ (0.92 kcal). Nonmedicinal ingredients: magnesium stearate, microcrystalline cellulose and polacrilin potassium. Gluten- and tartrazine-free. Bottles of 100, 500 and 2 500.
ISORDIL® Wyeth-Ayerst Isosorbide Dinitrate Coronary Vasodilator