Sorbinate SR 60

Isosorbide-5-mononitrate.

Each uncoated sustained release tablet of Sorbinate SR 60 Tablets contains: Isosorbide-5-mononitrate 60 mg.

Pharmacology: Sorbinate-SR tablet is an oral extended-release formulation of isosorbide mononitrate, the major active metabolite of isosorbide dinitrate: most of the clinical activity of the dinitrate is attributable to the mononitrate. The principal pharmacological action of isosorbide mononitrate and all organic nitrates in general is relaxation of vascular smooth muscle, producing dilatation of peripheral arteries and veins especially the latter. Dilatation of the veins promotes peripheral pooling of blood, 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, and systolic arterial pressure and mean arterial pressure (afterload). Dilatation of the coronary arteries also occurs.
Pharmacokinetics: Isosorbide mononitrate also is readily absorbed from the GI tract. Following oral administration of extended-release isosorbide mononitrate tablets, peak plasma concentrations of isosorbide mononitrate are reached in about 3-4.5 hours onset of action occurs within 20 minutes and lasts for about 8-10 hours. Unlike isosorbide mononitrate does not undergo first pass hepatic metabolism and bioavailability is 77-80%.
Isosorbide mononitrate is widely distributed with a large apparent volume of distribution.
Isosorbide mononitrate is metabolised to inactive metabolites isosorbide mononitrate glucuronide. Only about 2% of isosorbide mononitrate is excreted unchanged in the urine. An elimination half-life about 4-5 hours has been reported.
Sorbinate SR tablet is a sustained release formulation of isosorbide-5-mononitrate. The active substance independently of pH, over a 10 hours. Compared to ordinary tablets the absorption phase of Sorbinate SR tablet is prolonged and the duration of effect is extended. The extend of Sorbinate SR tablet is about 90% compared to immediate release tablets. Absorption is not significantly affected by food intake.

Sorbinate SR 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.

The recommended starting dose of Sorbinate SR tablets is 60 mg once daily to be taken in the mornings. The dose may be increased to 120 mg daily, taken once daily in the morning. The dose can be treated to minimize the possibility of headache by initiating treatment with 30 mg for the first 3-4 days. Sorbinate SR tablets should not be chewed or crushed and should be swallowed together with a half glassful of fluid.

Symptoms of overdose which are most common include hypotension, tachycardia, flushing, headache, vertigo, palpitations, visual disturbances, diaphoresis, dizziness, syncope, nausea, vomiting, anorexia, initial hyperpnea, dyspnea, increased intracranial pressure with cerebral symptoms of confusion, fever, paralysis, tissue hypoxia due to methemoglobinemia can lead to cyanosis.
Treatment: induce emesis or perform gastric lavage followed by charcoal administration, keep patient recumbent in shock position and comfortably warm or temporarily terminate the infusion until the patient's condition stabilizes.
Treat severe hypotension and reflex tachycardia by elevating the legs and administering IV fluids. While methemoglobinemia is diagnosed, treat with high-flow oxygen and administer methylene blue, 1-2 mg/kg intravenously.

Isosorbide mononitrate is contraindicated in patients who are allergic to it.

Severe hypotension, particularly with up right posture, may occur with even small doses of isosorbide mononitrate. 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 mononitrate may be accompanied by paradoxical bradycardia and increased angina pectoris. Nitrate therapy may aggravate the angina caused by hypertrophic cardiomyopathy.
Use in children: safety and effectiveness of isosorbide mononitrate in pediatric patients have not been established.

Use in pregnancy: There are no adequate and well-controlled studies in pregnant women.
Use in lactation: It is not known whether isosorbide mononitrate is excreted in human milk, caution should be exercised when isosorbide mononitrate is administered to nursing women.

Isosorbide mononitrate may cause flushing of the face, dizziness, tachycardia, the throbbing headache and blurred vision. Large doses can cause vomiting, restlessness, blurred vision, hypotension (which can be severe syncope), and rarely cyanosis and methemoglobinemia, impairment of respiration and bradycardia may ensue.

Alcohol: severe hypotension and cardiovascular collapse may occur.
Aspirin: increase nitrate serum concentrations and actions may occur.
Calcium channel blockers: may decrease symptomatic orthostatic hypotension. Dosage adjustment of either agent may be necessary and maked decreasing the antianginal effects.
Dihydroergotamine: increase bioavailability of dihydroergotamine.
Nitroglycerin: pharmacologic effects of heparin may be decreased.

KEEP IN A COOL DRY PLACE.
PROTECT FROM LIGHT.

Anti-Anginal Drugs

C01DA14 - isosorbide mononitrate ; Belongs to the class of organic nitrate vasodilators. Used in the treatment of cardiac disease.

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