Nitroglycerin

1 INDICATIONS AND USAGE Nitroglycerin ointment, 0.4% is indicated for the treatment of moderate to severe pain associated with chronic anal fissure. Nitroglycerin ointment, 0.4% is a nitrate vasodilator indicated for the treatment of moderate to severe pain associated with chronic anal fissure ( 1 ).

DOSAGE AND ADMINISTRATION As noted above ( CLINICAL PHARMACOLOGY ), controlled trials have demonstrated that nitroglycerin ointment can effectively reduce exercise-related angina for up to 7 hours after a single application. Doses used in clinical trials have ranged from 1/2 inch (1.3 cm; 7.5 mg) to 2 inches (5.1 cm; 30 mg), typically applied to 36 square inches (232 square centimeters) of truncal skin. It is reasonable to believe that the rate and extent of nitroglycerin absorption from ointment may vary with the site and square measure of the skin over which a given dose of ointment is spread, but these relationships have not been adequately studied. Controlled trials with other formulations of nitroglycerin have demonstrated that if plasma levels are maintained continuously, all anti-anginal efficacy is lost within 24 hours. This tolerance cannot be overcome by increasing the dose of nitroglycerin. As a result, any regimen of nitroglycerin ointment administration should include a daily nitrate-free interval. The minimum necessary length of such an interval has not been defined, but studies with other nitroglycerin formulations have shown that 10 to 12 hours is sufficient. Thus, one appropriate dosing schedule for nitroglycerin ointment would begin with two daily 1/2- inch (7.5 mg) doses, one applied on rising in the morning and one applied six hours later. The dose could be doubled, and even doubled again, in patients tolerating this dose but failing to respond to it. The pouch is intended as a unit dose package only and is equivalent to approximately 1 inch as squeezed from the tube. Use entire contents of pouch to obtain full dose and discard immediately after use. Each tube of ointment and each box of pouchs is supplied with a pad of ruled, impermeable, paper applicators. These applicators allow ointment to be absorbed through a much smaller area of skin than that used in any of the reported clinical trials, and the significance of this difference is not known. To apply the ointment using one of the applicators, place the applicator on a flat surface, printed side down. Squeeze the necessary amount of ointment from the tube onto the applicator, place the applicator (ointment side down) on the desired area of the skin, and tape the applicator into place.

3 DOSAGE FORMS & STRENGTHS Nitroglycerin Ointment, USP 0.4% w/w (4 mg /1 g) in 30 g tubes. Ointment 0.4% w/w (4 mg nitroglycerin/1 g ointment).

4 CONTRAINDICATIONS Use of PDE5 inhibitors (e.g. sildenafil, vardenafil and tadalafil) as these are shown to potentiate the hypotensive effects of organic nitrates. ( 4.1 ). Severe anemia ( 4.2 ) Increased intracranial pressure ( 4.3 ) Known hypersensitivity to nitroglycerin, other nitrates and nitrites, or any components of the ointment. ( 4.4 ) 4.1 PDE5 Inhibitor Use Administration of nitroglycerin ointment, 0.4% is contraindicated in patients who are using a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), such as sildenafil, vardenafil, and tadalafil, as these are shown to potentiate the hypotensive effects of organic nitrates [see 7.1 DRUG INTERACTIONS ]. 4.2 Severe Anemia Nitroglycerin ointment, 0.4% is contraindicated in patients with severe anemia. 4.3 Increased Intracranial Pressure Nitroglycerin ointment, 0.4% is contraindicated in patients with increased intracranial pressure. 4.4 Hypersensitivity Nitroglycerin ointment, 0.4% is contraindicated in patients who have shown hypersensitivity to it or to other nitrates or nitrites. Skin reactions consistent with hypersensitivity have been observed with organic nitrates.

6 ADVERSE REACTIONS Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The most common adverse reaction of nitroglycerin ointment applied to the anal canal is headache. Headache may be recurrent following each dose. Headaches are typically of short duration and can be treated with an analgesic, e.g. acetaminophen, and are reversible upon discontinuation of treatment. In Study REC-C-001, a double-blind, placebo-controlled trial in patients with a painful chronic anal fissure, the most frequent ( > 2%) adverse reactions reported were as follows (Table 1) Table 1: Incidence of Adverse Reactions ( > 2%) in Study REC-C-001 Nitroglycerin Ointment N = 123 Placebo N = 124 System Organ Class Preferred term Patients n (%) Events n Patients n (%) Events n Nervous system disorders Headache 79 (64) 938 51 (41) 225 Dizziness 6 (5) 26 0 0 Hypotension Transient episodes of light-headedness, occasionally related to blood pressure changes, also may occur. Hypotension (including orthostatic hypotension) occurs infrequently, but in some patients may be severe enough to warrant discontinuation of therapy. Allergic Reactions Flushing, allergic reactions, and application site reactions (including drug rash and exfoliative dermatitis) have been reported rarely. Methemoglobinemia In rare cases, therapeutic doses of organic nitrates have caused methemoglobinemia [see OVERDOSAGE (10) ]. Most common adverse reactions are headache and dizziness. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Encube Ethicals Private Limited, at 1-833-285-4151 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

7 DRUG INTERACTIONS PDE5 inhibitors: potentiation of hypotensive effects of organic nitrates; concomitant use is contraindicated. ( 4.1 , 7.1 ) Antihypertensives: possible additive hypotensive effects. ( 7.2 ) Aspirin: increased nitroglycerin levels. ( 7.3 ) Tissue-type Plasminogen Activator (t-PA): decreased thrombolytic effect. ( 7.4 ) Heparin: anticoagulant effect of heparin may be reduced. Monitor APTT. ( 7.5 ) Ergotamine: increased bioavailability of ergotamine. ( 7.6 ) Alcohol: Additive vasodilatory effects to nitroglycerin. Consumption of alcohol should be avoided. ( 7.7 ) 7.1 PDE5 Inhibitors Phosphodiesterase type 5 (PDE5) inhibitors such as sildenafil, vardenafil, and tadalafil have been shown to potentiate the hypotensive effects of organic nitrates. The time course of the interaction appears to be related to the half-life of the PDE5 inhibitor, however, the dose dependence of this interaction has not been studied. Use of nitroglycerin ointment, 0.4% within a few days of PDE5 inhibitors is contraindicated. 7.2 Antihypertensives Patients receiving antihypertensive drugs, beta-adrenergic blockers, and other nitrates should be observed for possible additive hypotensive effects when using nitroglycerin ointment, 0.4%. Marked orthostatic hypotension has been reported when calcium channel blockers and organic nitrates were used concomitantly. Beta-blockers blunt the reflex tachycardia produced by nitroglycerin without preventing its hypotensive effects. If beta-blockers are used with nitroglycerin ointment, 0.4% in patients with angina pectoris, additional hypotensive effects may occur. 7.3 Aspirin Coadministration of aspirin (at doses between 500 mg and 1000 mg) and nitroglycerin has been reported to result in increased nitroglycerin maximum concentrations by as much as 67% and AUC by 73% when administered as a single dose. The pharmacological effects of nitroglycerin ointment, 0.4% may be enhanced by concomitant administration of aspirin. 7.4 Tissue-type Plasminogen Activator (t-PA) Intravenous administration of nitroglycerin decreases the thrombolytic effect of tissue-type plasminogen activator (t-PA). Plasma levels of t-PA are reduced when coadministered with nitroglycerin. Therefore, caution should be observed in patients receiving nitroglycerin ointment, 0.4% during t-PA therapy. 7.5 Heparin Although an interaction has been reported between intravenous heparin and intravenous nitroglycerin (resulting in a decrease in the anticoagulant effect of heparin), the data are not consistent. If patients are to receive intravenous heparin and nitroglycerin ointment, 0.4% concurrently, the anticoagulation status of the patient must be checked. 7.6 Ergotamine Oral administration of nitroglycerin markedly decreases the first-pass metabolism of dihydroergotamine and consequently increases its oral bioavailability. Ergotamine is known to precipitate angina pectoris. Therefore the possibility of ergotism in patients receiving nitroglycerin ointment, 0.4% should be considered. 7.7 Alcohol The vasodilating effects of nitroglycerin have been shown to be additive to the effects observed with alcohol.

8 USE IN SPECIFIC POPULATIONS 8.1 Pregnancy Risk Summary There are no data on the use of nitroglycerin ointment intra-anally during pregnancy to determine a drug-associated risk of major birth defects, miscarriage or other adverse maternal or fetal outcomes. In animal reproduction studies, no malformations were observed in offspring of pregnant rats and rabbits administered nitroglycerin by topical or dietary route during the period of organogenesis ( see Data ). The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Animal Data Animal reproduction studies in rats and rabbits were conducted with topically applied nitroglycerin ointment at doses up to 80 mg/kg/day and 240 mg/kg/day, respectively. No toxic effects on dams or fetuses were seen at any dose tested. An animal reproduction study was conducted in rats with nitroglycerin administered in the diet at levels up to 1% content (approximately 430 mg/kg/day) on days 6 to 15 of gestation. In offspring of the high-dose group, an increased but not statistically significant incidence of diaphragmatic hernias was noted together with decreased hyoid bone ossification. The latter finding probably reflects delayed development, thus indicating no clear evidence of a potential teratogenic effect of nitroglycerin. 8.2 Lactation Risk Summary There are no data on the presence of nitroglycerin in either human or animal milk following topical administration, or the effects of nitroglycerin on milk production. A publication describing 40 lactating patients who used nitroglycerin ointment to treat chronic anal fissures for varied durations did not report signs of adverse effects in their breastfed infants, however, the dosing regimens were not described. The developmental and health benefits of breastfeeding should be considered along with the clinical need for nitroglycerin ointment and any potential adverse effects on the breastfed infant from nitroglycerin ointment or from the underlying maternal condition. 8.4 Pediatric Use The safety and effectiveness of nitroglycerin ointment in pediatric patients under 18 years of age have not been established. 8.5 Geriatric Use Clinical studies of nitroglycerin ointment did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Clinical data from the published literature indicate that the elderly demonstrate increased sensitivity to nitrates, which may be therapeutic but also manifest by more frequent or severe hypotension and related dizziness or fainting. Increased sensitivity may reflect the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

12.1 Mechanism of Action 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 leads to dephosphorylation of myosin light chains, which regulates the contractile state in smooth muscle and results in vasodilatation.

11 DESCRIPTION Nitroglycerin ointment, USP 0.4% is intended for intra-anal use. Nitroglycerin is 1,2,3,-propanetriol trinitrate, an organic nitrate vasodilator whose structural formula is as follows: and whose molecular weight is 227.09. Nitroglycerin ointment, USP 0.4% contains 0.4% nitroglycerin w/w (4 mg nitroglycerin/1 g ointment), propylene glycol, lanolin, sorbitan sesquioleate, paraffin wax, and white petrolatum. Nitroglycerin ointment, USP 0.4% is available in tubes with a one-inch dosing line on the carton allowing the measurement of approximately 375 mg of nitroglycerin ointment, USP 0.4% (1.5 mg nitroglycerin) for application. structure

OVERDOSAGE: Hemodynamic Effects: The ill effects of nitroglycerin overdose are generally the results of nitroglycerin's capacity to induce vasodilation, 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 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 the 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, 1-2 mg/kg intravenously.

HOW SUPPLIED Nitroglycerin ointment USP, 2%, is a pale yellow ointment. (Package includes a supply of ruled applicators for convenient application.) NDC 21922-054-47 Carton for 48 x 1 gram pouch pack NDC 21922-054-59 1 gram Pouch Pack NDC 21922-054-05 30 gram Aluminum tubes. Close tightly, immediately after each use. Store at 20°C to 25°C (68°F to 77°F), excursions permitted 15°C to 30°C (59°F to 86°F). [See USP Controlled Room Temperature]. To report SUSPECTED ADVERSE REACTIONS, contact Encube Ethical Private Limited at 1-833-285-4151, or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. Manufactured by: Encube Ethicals Pvt. Ltd. Plot No. C-1, Madkaim Industrial Estate, Madkaim, Post: Mardol, Ponda, Goa - 403 404, India. Distributed by: Encube Ethicals, Inc. 200 Meredith Drive, Suite 202, Durham, NC 27713 USA Revised: 05/2025