The onset of action is not sufficiently rapid for this form to be useful in aborting an acute anginal episode.

Clinical Pharmacology
The principal pharmacologic action of nitroglyerin is relaxation of vascular smooth muscle, producing a vasodilator effect on both peripheral arteries and veins with more prominent effects on the later. 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 end-diastolic pressure (preload). Arteriolar relaxation reduces systemic vascular resistance and arterial pressure (afterload). The mechanism by which nitroglycerin relieves angina pectoris is not fully understood. Myocardial oxygen consumption or demand (as measured by the pressure-rate product, tension-time index and stroke-work index) is decreased by both the arterial and venous effects of nitroglycerin, and a more favorable supply-demand ratio is achieved. In coronary circulation, the nitrates redistribute circulating blood flow along collateral channels, improving perfusion to the ischaemic myocardium. While large epicardial coronary arteries are also dilated by nitroglycerin, the extent to which this action contributes to relief of exertional angina is unclear. Therapeutic doses of nitroglycerin reduces systolic, diastolic and mean arterial blood pressures. Effective coronary perfusion pressure is usually maintained, but can be compromised if blood pressure falls excessively or increased heart rate decreased diastolic filling time. Evaluated central venous and pulmonary capillary wedge pressures, pulmonary vascular resistance and systemic vascular resistance are also reduced by nitroglycerin therapy. Heart rate is usually slightly increased, presumably a reflex response to the fall in blood pressure. Cardiac index may be increased, decreased or unchanged. Patients with elevated left ventricular filling pressure and systemic vascular resistance values in conjunction with a depressed cardiac index are likely to experience an improvement in cardiac index. On the other hand, when filling pressures and cardiac index are normal cardiac index may be slightly reduced by intravenous nitroglycerin.

Dosage & Administration
Dosage should always to adjusted according to the requirement and response obtained by the individual patient and the severity of the anginal pain.
Adults: One NITROX-XL tablet 2.6 mg in morning and evening.
The tablets should be taken empty stomach. If the symptoms have not been adequately controlled after a week on this regimen, the dosage should be increased to one 6.4 mg tablet morning and evening.
Children: Not recommended.
Elderly: Normal adult dose.

Contraindications
Allergic reactions to organic nitrates are extremely rare, but they do occur. Nitroglycerin should not be administered to individual with a known hypersensitivity or idiosyncrasy reaction to nitroglycerin, other organic nitrates, or nitrites or to the excipients of the medicine.
NITROX-XL tables should not be used in patients with acute myocardial infarction, marked anaemia, head trauma, cerebral haemorrhage, or closed angle glaucoma.
Sildenafil has been shown to potentiate the hypotensive effects of nitrates, and its co-administration with nitrates or nitric oxide donors is therefore contraindicated.

Warning & Precautions As with other drugs for the treatment of angina pectoris, abrupt discontinuation of therapy may lead to exacerbation of symptoms. When discontinuing long-term treatment, the dosage should be reduced gradually over several days, and the patient carefully monitored.

Side Effects
Adverse reactions to nitroglycerin are generally dose-related, and almost all of these reactions are the results of nitroglycerin’s activity as a vasodilator. Headache is the most commonly reported side effect. Headache may be recurrent with each daily dose, especially at higher doses. Transient episodes of light-headedness, occasionally related to blood pressure charges 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.

Allergic reactions to nitroglycerin are also uncommon, and the great majority of those reported have been caused of contact dermatitis or fixed drug eruptions in patients receiving nitroglycerin in ointments or patches. There have been a few reports of genuine anaphylactoid reactions, and these reactions can probably occur in patients receiving nitroglycerin by any route. Extremely rarely, ordinary doses of organic nitrated have caused methaemoglobinaemia in normal-seeming patients. Methaemoglobinaemia is so infrequent at these doses that further discussion of its diagnosis and treatment is deferred. Other adverse reactions occurring in less than 1% of patients are the following tachycardia, nausea, vomiting, apprehension, restlessness, muscle twitching, retrosternal discomfort, palpitation, dizziness and abdominal pain. However, such side-effects are virtually absent or substantially diminished with NITROX-XL tablets therapy due to the controlled release system

Overdose & Its Treatment
Symptoms of overdosage include vomiting hyptension, restlessness, syncope, cyanosis and methaemoglobinaemia. Treatment should include gastric lavage, respiratory and circulatory support and attention to circulatory signs and symptoms. In severe cases, oxygen and other symptomatic and supportive respiratory and cardiovascular measures should be provided. Methaemoglobinaemia may also be treated with intravenous methylene blue. Keep unconscious patients horizontal and lower head. Physicians should be aware that tablets in the intestine will release the drug for a period of hours.

Information for Patients
Daily headaches sometime accompany treatment with nitroglycerine. In patients who get these headaches, the headaches may be a marker of the activity of the drug. Patients should resist the temptation to avoid headaches by altering the schedule of their treatment with nitroglycerin. Treatment with nitroglycerin may be associated with light-headedness on standing, especially just after rising form a recumbent or seated position. This effect may be more frequent in patients who have also consumed alcohol. Physician should discuss with patients the contraindication of nitroglycerin with concurrent Sidenafil.