NITRO-TIME

INDICATIONS AND USAGE: Nitroglycerin Extended-Release Capsules are indicated for the prevention of angina pectoris due to coronary artery disease. The onset of action of oral nitroglycerin is not sufficiently rapid for this product to be useful in aborting an acute anginal episode.

DOSAGE AND ADMINISTRATION: As noted above (CLINICAL PHARMACOLOGY) , careful studies with other formulations of nitroglycerin have shown that maintenance of continuous 24-hour plasma levels of nitroglycerin result in tolerance (i.e. loss of clinical response). Every dosing regimen for Nitroglycerin Extended-Release Capsules should provide a daily nitrate-free interval avoid the development of this tolerance. The minimum necessary length of such an interval has not been defined, but studies with other nitroglycerin formulations have shown that 10-12 hours is sufficient. Large controlled studies with other formulations of nitroglycerin show that no dosing regimen with Nitroglycerin Extended-Release should be expected to provide more than about 12 hours of continuous anti-anginal efficacy per day. The pharmacokinetics of Nitroglycerin Capsules and the clinical effects of multiple-dose regimens, have not been well studied. In clinical trials, the initial regimen of nitroglycerin has been 2.5 to 6.5 mg three to four times a day, with subsequent upward dose adjustment guided by symptoms and side effects. In one trial, 5 of the 18 subjects were titrated up to a dose of 26 mg four times a day.

CONTRAINDICATIONS: Allergic reactions to organic nitrates are extremely rare, but they do occur. Nitroglycerin is contraindicated in patients who are allergic to it.

WARNINGS: Amplification of the vasodilatory effects of nitroglycerin by sildenafil can result in severe hypotension. The time course and dose dependence of this interaction have not been studied. Appropriate supportive care has not been studied, but it seems reasonable to treat this as a nitrate overdose, with elevation of the extremities and with central volume expansion. The benefits of oral nitroglycerin in patients with acute myocardial infarction or congestive heart failure have not been established. If one elects to use nitroglycerin in these conditions, careful clinical or hemodynamic monitoring must be used to avoid the hazards of hypotension and tachycardia. Because the effects at capsules are so difficult to terminate rapidly, that are not recommended in these settings. PRECAUTIONS: General: Severe hypotension, particularly with upright posture, may occur with even small doses of nitroglycerin. 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 nitroglycerin may be accompanied by paradoxical bradycardia and increased angina pectoris. Nitrate therapy may aggravate the angina caused by hypertrophic cardiomyopathy. As tolerance in other forms of nitroglycerin develops, the effect of sublingual nitroglycerin on exercise tolerance, although still observable, is somewhat blunted. In industrial workers who have had long-term exposure to unknown (presumably high) doses of organic nitrates, tolerance clearly occurs. Chest pain, acute myocardial infarction, and even sudden death have occurred during temporary withdrawal of nitrates from these workers, demonstrating the existence of true physical dependence. Some clinical trials in angina patients have provided nitroglycerin for about 12 continuous hours of every 24-hour day. During the nitrate-free intervals in some of these trials, anginal attacks have been more easily provoked than before treatment, and patients have demonstrated hemodynamic rebound and decreased exercise tolerance. The importance of these observations to the routine, clinical use at oral nitroglycerin is not known.

Drug interactions: The vasodilating effects of nitroglycerin may be additive with those of other vasodilators. Alcohol, in particular, has been found to exhibit additive effects of this variety. Marked symptomatic orthostatic hypotension has been reported when calcium channel blockers and organic nitrates were used in combination. Dose adjustments of either class of agents may be necessary.

ADVERSE REACTIONS: Adverse reactions to nitroglycerin are generally dose-related, and almost all of these reactions are the result of nitroglycerin'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 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 cases 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 nitrates have caused methemoglobinemia in normal seeming patients; for further discussion of its diagnosis and treatment see OVERDOSAGE. Data are not available to allow estimation of the frequency of adverse reactions during treatment with Nitroglycerin Extended-Release Capsules.

Pregnancy Category C: Animal reproduction studies have not been conducted with nitroglycerin. It is also not known whether nitroglycerin can cause fetal harm when administered to a pregnant woman or whether it can affect reproductive capacity. Nitroglycerin should be given to a pregnant women only if clearly needed.