nitroglycerin

INDICATIONS AND USAGE Transdermal nitroglycerin is indicated for the prevention of angina pectoris due to coronary artery disease. The onset of action of transdermal nitroglycerin is not sufficiently rapid for this product to be useful in aborting an acute attack.

DOSAGE AND ADMINISTRATION The suggested starting dose is between 0.2 mg/hr and 0.4 mg/hr. Doses between 0.4 mg/hr and 0.8 mg/hr have shown continued effectiveness for 10 to 12 hours daily for at least one month (the longest period studied) of intermittent administration. Although the minimum nitrate-free interval has not been defined, data show that a nitrate-free interval of 10 to 12 hours is sufficient (see CLINICAL PHARMACOLOGY ). Thus, an appropriate dosing schedule for nitroglycerin patches would include a daily patch-on period of 12 to 14 hours and a daily patch-off period of 10 to 12 hours. Although some well controlled clinical trials using exercise tolerance testing have shown maintenance of effectiveness when patches are worn continuously, the large majority of such controlled trials have shown the development of tolerance (i.e., complete loss of effect) within the first 24 hours after therapy was initiated. Dose adjustment, even to levels much higher than generally used, did not restore efficacy. PATIENT INSTRUCTIONS FOR APPLICATION OF SYSTEM A patient leaflet is supplied with each carton.

CONTRAINDICATIONS Nitroglycerin is contraindicated in patients who are allergic to it. Allergy to the adhesives used in nitroglycerin patches has also been reported, and it similarly constitutes a contraindication to the use of this product. Do not use Nitroglycerin Transdermal Systems in patients who are taking phosphodiesterase inhibitors (such as sildenafil, tadalafil, or vardenafil) for erectile dysfunction or pulmonary arterial hypertension. Concomitant use can cause severe drops in blood pressure. Do not use Nitroglycerin Transdermal Systems in patients who are taking the soluble guanylate cyclase stimulator riociguat. Concomitant use can cause hypotension.

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 light-headedness, occasionally related to blood pressure changes, 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 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. Methemoglobinemia is so infrequent at these doses that further discussion of its diagnosis and treatment is deferred (see OVERDOSAGE ). Application-site irritation may occur but is rarely severe. In two placebo-controlled trials of intermittent therapy with nitroglycerin patches at 0.2 to 0.8 mg/hr, the most frequent adverse reactions among 307 subjects were as follows: Placebo Patch Headache 18% 63% Light-headedness 4% 6% Hypotension, and/or syncope 0% 4% Increased angina 2% 2%

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. Concomitant use of Nitroglycerin Transdermal Systems with phosphodiesterase inhibitors in any form is contraindicated (see CONTRAINDICATIONS ). Concomitant use of Nitroglycerin Transdermal Systems with riociguat, a soluble guanylate cyclase stimulator, is contraindicated (see CONTRAINDICATIONS ). 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.

DESCRIPTION Nitroglycerin is 1,2,3-propanetriol, trinitrate, an organic nitrate whose structural formula is: and whose molecular weight is 227.09. The organic nitrates are vasodilators, active on both arteries and veins. The nitroglycerin transdermal system is a flat unit designed to provide continuous controlled release of nitroglycerin through intact skin. The rate of release of nitroglycerin is linearly dependent upon the area of the applied system; each cm 2 of applied system delivers approximately 0.026 mg of nitroglycerin per hour. Thus, the 4 cm 2 , 8 cm 2 , 16 cm 2 and 24 cm 2 systems deliver approximately 0.1 mg, 0.2 mg, 0.4 mg and 0.6 mg of nitroglycerin per hour, respectively. The remainder of the nitroglycerin in each system serves as a reservoir and is not delivered in normal use. After 12 hours, for example, each system has delivered approximately 11% of its original content of nitroglycerin. The nitroglycerin transdermal system comprises two layers as shown below. Proceeding from the visible surface towards the surface attached to the skin, these layers are: 1) a polyolefin film backing layer that is impermeable to nitroglycerin and is printed with the name of the drug and strength; 2) nitroglycerin in an acrylic pressure sensitive adhesive. Prior to use, a peelable polyester release liner, which is coated on one side with silicone, is removed from the adhesive surface. Each unit is sealed in a foil-lined pouch. Cross section of the system: Nitroglycerin Structural Formula Patch Cross Section

OVERDOSAGE Hemodynamic Effects The ill effects of nitroglycerin overdose are generally the result of nitroglycerin’s capacity to induce vasodilatation, venous pooling, reduced cardiac output, and hypotension. These hemodynamic changes may have protean manifestations, including increased intracranial pressure, with any or all of persistent throbbing headache, confusion, and moderate fever; vertigo; palpitations; visual disturbances; nausea and vomiting (possibly with colic and even bloody diarrhea); syncope (especially in the upright posture); air hunger and dyspnea, later followed by reduced ventilatory effort; diaphoresis, with the skin either flushed or cold and clammy; heart block and bradycardia; paralysis; coma; seizures; and death. Laboratory determinations of serum levels of nitroglycerin and its metabolites are not widely available, and such determinations have, in any event, no established role in the management of nitroglycerin overdose. No data are available to suggest physiological maneuvers (e.g., maneuvers to change the pH of the urine) that might accelerate elimination of nitroglycerin and its active metabolites. Similarly, it is not known which, if any, of these substances can usefully be removed from the body by hemodialysis. No specific antagonist to the vasodilator effects of nitroglycerin is known, and no intervention has been subject to controlled study as a therapy of nitroglycerin overdose. Because the hypotension associated with nitroglycerin overdose is the result of venodilatation and arterial hypovolemia, prudent therapy in this situation should be directed toward an increase in central fluid volume. Passive elevation of the patient’s legs may be sufficient, but intravenous infusion of normal saline or similar fluid may also be necessary. The use of epinephrine or other arterial vasoconstrictors in this setting is likely to do more harm than good. In patients with renal disease or congestive heart failure, therapy resulting in central volume expansion is not without hazard. Treatment of nitroglycerin overdose in these patients may be subtle and difficult, and invasive monitoring may be required. Methemoglobinemia Nitrate ions liberated during metabolism of nitroglycerin can oxidize hemoglobin into methemoglobin. Even in patients totally without cytochrome b 5 reductase activity, however, and even assuming that the nitrate moieties of nitroglycerin are quantitatively applied to oxidation of hemoglobin, about 1 mg/kg of nitroglycerin should be required before any of these patients manifests clinically significant (≥ 10%) methemoglobinemia. In patients with normal reductase function, significant production of methemoglobin should require even larger doses of nitroglycerin. In one study in which 36 patients received 2 to 4 weeks of continuous nitroglycerin therapy at 3.1 to 4.4 mg/hr, the average methemoglobin level measured was 0.2%; this was comparable to that observed in parallel patients who received placebo. Notwithstanding these observations, there are case reports of significant methemoglobinemia in association with moderate overdoses of organic nitrates. None of the affected patients had been thought to be unusually susceptible. Methemoglobin levels are available from most clinical laboratories. The diagnosis should be suspected in patients who exhibit signs of impaired oxygen delivery despite adequate cardiac output and adequate arterial pO 2 . Classically, methemoglobinemic blood is described as chocolate brown, without color change on exposure to air. When methemoglobinemia is diagnosed, the treatment of choice is methylene blue, 1 to 2 mg/kg intravenously.

HOW SUPPLIED Nitroglycerin Transdermal System 0.1 mg/hr is a translucent rectangular patch with rounded corners (registered imprint ‘Nitroglycerin 0.1 mg/hr’ in white ink) affixed to a clear, peelable liner, and is supplied in a foil-lined pouch. NDC 0378-9102-93 Carton of 30 Systems Nitroglycerin Transdermal System 0.2 mg/hr is a translucent rectangular patch with rounded corners (registered imprint ‘Nitroglycerin 0.2 mg/hr’ in white ink) affixed to a clear, peelable liner, and is supplied in a foil-lined pouch. NDC 0378-9104-93 Carton of 30 Systems Nitroglycerin Transdermal System 0.4 mg/hr is a translucent rectangular patch with rounded corners (registered imprint ‘Nitroglycerin 0.4 mg/hr’ in white ink) affixed to a clear, peelable liner, and is supplied in a foil-lined pouch. NDC 0378-9112-93 Carton of 30 Systems Nitroglycerin Transdermal System 0.6 mg/hr is a translucent rectangular patch with rounded corners (registered imprint ‘Nitroglycerin 0.6 mg/hr’ in white ink) affixed to a clear, peelable liner, and is supplied in a foil-lined pouch. NDC 0378-9116-93 Carton of 30 Systems Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature.] Do not refrigerate. Do not store outside of the protective package. Apply immediately upon removal from the protective package. Mylan Pharmaceuticals Inc. Morgantown, WV 26505 U.S.A. REVISED NOVEMBER 2014 NTG:R14