Indications

Nitroglycerin is indicated for acute relief of an attack or prophylaxis of angina pectoris due to coronary artery disease.

Composition

Pharmacology

The principal pharmacological action of nitroglycerin is relaxation of vascular smooth muscle, producing a vasodilator effect on both peripheral arteries and veins with more prominent effects on the latter. Dilation of the post-capillary vessels, including large veins, promotes peripheral pooling of blood and decreases venous return to the heart, thereby reducing left ventricular enddiastolic pressure (pre-load). Arteriolar relaxation reduces systemic vascular resistance and arterial pressure (after-load). Nitroglycerin forms free radical nitric oxide (NO), which activates guanylate cyclase, resulting in an increase of guanosine 3’5’-monophosphate (cyclic GMP) in smooth muscle and other tissues. This eventually leads to dephosphorylation of myosin light chains, which regulates thecontractile state in smooth muscle and results in vasodilation. Absorption : Nitroglycerin is rapidly absorbed and is often used in emergency situations for this reason. Distribution : The volume of distribution of Nitroglycerin is 3 L/kg. Metabolism : Nitroglycerin is rapidly metabolized in the liver by hepatic enzymes to di-nitrates and mononitrates. Elimination : Nitroglycerin is excreted by the renal route, primarily as the 2 di-nitro-metabolites.

Dosage & Administration

Sublingual tablet : One tablet (0.5 mg) should be dissolved under the tongue at the first sign of an acute anginal attack. The dose may be repeated approximately every five minutes, until relief is obtained. If the pain persists after a total of 3 tablets in a 15-minute period, prompt medical attention is recommended. Sustained release tablet : Dosage should always to be adjusted according to the requirement and response obtained by the individual patient and the severity of the anginal pain. 2.6 mg: 1 tablet 2 times a day before meal (in the morning, at noon). If necessary the doses may be raised gradually 2 or 3 tablets 2 times daily. 6.4 mg: One tablet twice daily. Or as directed by the registered physician Spray : At the onset of an attack, one metered dose spray or two metered dose sprays should be administered under the tongue. A spray may be repeated approximately every 5 minutes as needed. Maximum of 3 metered sprays are recommended within a 15-minute period. If chest pain persists after a total of 3 sprays, prompt medical attention is recommended. May be used prophylactically 5 minutes to 10 minutes before engaging in activities that might precipitate an acute attack.

Contraindications

It is contraindicated for patients who are using PDE5 inhibitors (Sildenafil, Vardenafil & Tadalafil), patients who have severe anemia, increased intracranial pressure, hypersensitivity to it or to other nitrates or nitrites & acute circulatory failure or shock.

Side Effects

Most common adverse reactions are headache, flushing and hypotension.

Pregnancy & Lactation

There is no evidence relating to the safety of nitrates in pregnancy and lactation. Nitrates should be administered to pregnant women and nursing mothers unless considered essential by the physician. It is not known whether Nitroglycerin is excreted in human milk.

Precautions & Warnings

Only the smallest dose is required for effective control of the acute anginal attack. Excessive use may lead to the development of tolerance. This drug should be used with caution in patients who may be volume-depleted or are already hypotensive.

Therapeutic Class

Nitrates: Coronary vasodilators

Storage Conditions

Keep out of reach of children. Store in a dry place, below 25°C temperature and protected from light.