CLINICAL PHARMACOLOGY SECTION

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Esmolol hydrochloride in sodium chloride injection is a beta1-selective (cardioselective) adrenergic receptor blocking agent with rapid onset, a very short duration of action, and no significant intrinsic sympathomimetic or membrane stabilizing activity at therapeutic dosages. Its elimination half- life after intravenous infusion is approximately 9 minutes. Esmolol hydrochloride in sodium chloride injection inhibits the beta1 receptors located chiefly in cardiac muscle, but this preferential effect is not absolute and at higher doses it begins to inhibit beta2 receptors located chiefly in the bronchial and vascular musculature.

12.2 Pharmacodynamics

Clinical pharmacology studies in normal volunteers have confirmed the beta blocking activity of Esmolol hydrochloride in sodium chloride injection, showing reduction in heart rate at rest and during exercise, and attenuation of isoproterenol-induced increases in heart rate. Blood levels of esmolol hydrochloride in sodium chloride injection have been shown to correlate with extent of beta blockade. After termination of infusion, substantial recovery from beta blockade is observed in 10 to 20 minutes. The acid metabolite of esmolol exihibits negligible pharmacological activity.

In human electrophysiology studies, esmolol hydrochloride in sodium chloride injection produced effects typical of a beta blocker; a decrease in the heart rate, increase in sinus cycle length, prolongation of the sinus node recovery time, prolongation of the AH interval during normal sinus rhythm and during atrial pacing, and an increase in antegrade Wenckebach cycle length.

In patients undergoing radionuclide angiography, esmolol hydrochloride in sodium chloride injection, at dosages of 200 mcg/kg/min, produced reductions in heart rate, systolic blood pressure, rate pressure product, left and right ventricular ejection fraction and cardiac index at rest, which were similar in magnitude to those produced by intravenous propranolol (4 mg). During exercise, esmolol hydrochloride in sodium chloride injection produced reductions in heart rate, rate pressure product and cardiac index which were also similar to those produced by propranolol, but esmolol hydrochloride in sodium chloride injection produced a significantly larger fall in systolic blood pressure. In patients undergoing cardiac catheterization, the maximum therapeutic dose of 300 mcg/kg/min of esmolol hydrochloride in sodium chloride injection produced similar effects and, in addition, there were small, clinically insignificant increases in the left ventricular end diastolic pressure and pulmonary capillary wedge pressure. At 30 minutes after the discontinuation of esmolol hydrochloride in sodium chloride injection infusion, all of the hemodynamic parameters had returned to pretreatment levels.

The relative cardioselectivity of esmolol hydrochloride in sodium chloride injection was demonstrated in 10 mildly asthmatic patients. Infusions of esmolol hydrochloride in sodium chloride injection 100, 200 and 300 mcg/kg/min produced no significant increases in specific airway resistance compared to placebo. At 300 mcg/kg/min, esmolol hydrochloride in sodium chloride injection produced slightly enhanced bronchomotor sensitivity to dry air stimulus. These effects were not clinically significant, and esmolol hydrochloride was well tolerated by all patients. Six of the patients also received intravenous propranolol, and at a dosage of 1 mg, two experienced significant, symptomatic bronchospasm requiring bronchodilator treatment. One other propranolol-treated patient also experienced dry air-induced bronchospasm. No adverse pulmonary effects were observed in patients with COPD who received therapeutic dosages of esmolol hydrochloride in sodium chloride injection for treatment of supraventricular tachycardia (51 patients) or in perioperative settings (32 patients).

12.3 Pharmacokinetics

Esmolol is rapidly metabolized by hydrolysis of the ester linkage, chiefly by the esterases in the cytosol of red blood cells and not by plasma cholinesterases or red cell membrane acetylcholinesterase. Total body clearance in man was found to be about 20 L/kg/hr, which is greater than cardiac output; thus the metabolism of esmolol is not limited by the rate of blood flow to metabolizing tissues such as the liver or affected by hepatic or renal blood flow. Esmolol has a rapid distribution half-life of about 2 minutes and an elimination half-life of about 9 minutes.

Using an appropriate loading dose, steady-state blood levels of esmolol hydrochloride in sodium chloride injection for dosages from 50 to 300 mcg/kg/min are obtained within five minutes. Steady-state is reached in about 30 minutes without the loading dose. Steady-state blood levels of esmolol increase linearly over this dosage range and elimination kinetics are dose- independent over this range. Steady-state blood levels are maintained during infusion but decrease rapidly after termination of the infusion. Because of its short half-life, blood levels of esmolol can be rapidly altered by increasing or decreasing the infusion rate and rapidly eliminated by discontinuing the infusion.

Consistent with the high rate of blood-based metabolism of esmolol, less than 2% of the drug is excreted unchanged in the urine. Within 24 hours of the end of infusion, the acid metabolite of esmolol in urine accounts for approximately 73 to 88% of the dosage.

Metabolism of esmolol results in the formation of the corresponding free acid and methanol. The acid metabolite has been shown in animals to have negligible activity, and in normal volunteers its blood levels do not correspond to the level of beta blockade. The acid metabolite has an elimination half-life of about 3.7 hours and is excreted in the urine with a clearance approximately equivalent to the glomerular filtration rate.

After a 4 hours maintenance infusion of 150 mcg/kg, the plasma concentrations of esmolol are similar in subjects with normal renal function and in patients with ESRD on dialysis. The half-life of the acid metabolite of esmolol hydrochloride in sodium chloride injection, which is primarily excreted unchanged by the kidney, is increased about 12-fold to 48 hours in patients with ESRD. The peak concentrations of the acid metabolite are doubled in ESRD.

Methanol blood levels, monitored in subjects receiving esmolol hydrochloride in sodium chloride injection for up to 6 hours at 300 mcg/kg/min and 24 hours at 150 mcg/kg/min, approximated endogenous levels and were less than 2% of levels usually associated with methanol toxicity.

Esmolol hydrochloride in sodium chloride injection has been shown to be 55% bound to human plasma protein, while the acid metabolite is only 10% bound.

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CONTRAINDICATIONS SECTION

Highlight: •

Severe sinus bradycardia (4) 

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Heart block greater than first degree (4) 

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Sick sinus syndrome (4) 

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Decompensated heart failure (4) 

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Cardiogenic shock (4) 

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Coadministration of IV cardiodepressant calcium-channel antagonists (e.g. verapamil) in close proximity to esmolol hydrochloride in sodium chloride injection (4, 7) 

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Pulmonary hypertension (4) 

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Known hypersensitivity to esmolol (4) 

4 CONTRAINDICATIONS

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Esmolol hydrochloride in sodium chloride injection is contraindicated in patients with: 

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Severe sinus bradycardia: May precipitate or worsen bradycardia resulting in cardiogenic shock and cardiac arrest [see Warnings and Precautions (5.2)]. 

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Heart block greater than first degree: Second- or third-degree atrioventricular block may precipitate or worsen bradycardia resulting in cardiogenic shock and cardiac arrest [see Warnings and Precautions (5.2)]. 

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Sick sinus syndrome: May precipitate or worsen bradycardia resulting in cardiogenic shock and cardiac arrest [see Warnings and Precautions (5.2)]. 

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Decompensated heart failure: May worsen heart failure. 

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Cardiogenic shock: May precipitate further cardiovascular collapse and cause cardiac arrest. 

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IV administration of cardiodepressant calcium-channel antagonists (e.g.,verapamil) and esmolol hydrochloride in sodium chloride injection in close proximity (i.e., while cardiac effects from the other are still present); fatal cardiac arrests have occurred in patients receiving esmolol hydrochloride in sodium chloride injection and intravenous verapamil. 

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Pulmonary hypertension: May precipitate cardiorespiratory compromise. 

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Hypersensitivity reactions, including anaphylaxis, to esmolol or any of the inactive ingredients of the product (cross-sensitivity between beta blockers is possible). 

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DRUG INTERACTIONS SECTION

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Digitalis glycosides: Risk of bradycardia (7) 

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Anticholinesterases: Prolongs neuromuscular blockade (7) 

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Antihypertensive agents: Risk of rebound hypertension (7) 

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Sympathomimetic drugs: Dose adjustment needed (7) 

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Vasoconstrictive and positive inotropic effect substances: Avoid concomitant use (7) 

7 DRUG INTERACTIONS

Concomitant use of esmolol hydrochloride in sodium chloride injection with other drugs that can lower blood pressure, reduce myocardial contractility, or interfere with sinus node function or electrical impulse propagation in the myocardium can exaggerate esmolol hydrochloride in sodium chloride injection’s effects on blood pressure, contractility, and impulse propagation. Severe interactions with such drugs can result in, for example, severe hypotension, cardiac failure, severe bradycardia, sinus pause, sinoatrial block, atrioventricular block, and/or cardiac arrest. In addition, with some drugs, beta blockade may precipitate increased withdrawal effects. (See clonidine, guanfacine, and moxonidine below.) Esmolol hydrochloride in sodium chloride injection should therefore be used only after careful individual assessment of the risks and expected benefits in patients receiving drugs that can cause these types of pharmacodynamic interactions, including but not limited to:

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Digitalis glycosides: Concomitant administration of digoxin and esmolol hydrochloride in sodium chloride injection leads to an approximate 10% to 20% increase of digoxin blood levels at some time points. Digoxin does not affect esmolol hydrochloride in sodium chloride injection pharmacokinetics. Both digoxin and beta blockers slow atrioventricular conduction and decrease heart rate. Concomitant use increases the risk of bradycardia. 

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Anticholinesterases: Esmolol hydrochloride in sodium chloride injection prolonged the duration of succinylcholine-induced neuromuscular blockade and moderately prolonged clinical duration and recovery index of mivacurium. 

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Antihypertensive agents clonidine, guanfacine, or moxonidine: Beta blockers also increase the risk of clondidine-, guanfacine-, or moxonidine-withdrawal rebound hypertension. If, during concomitant use of a beta blocker, antihypertensive therapy needs to be interrupted or discontinued, discontinue the beta blocker first, and the discontinuation should be gradual. 

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Calcium channel antagonists: In patients with depressed myocardial infarction, use of esmolol hydrochloride in sodium chloride injection with cardiodepressant calcium channel antagonists (e.g., verapamil) can lead to fatal cardiac arrests. 

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Sympathomimetic drugs: Sympathomimetic drugs having beta-adrenergic agonist activity will counteract effects of esmolol hydrochloride in sodium chloride injection. 

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Vasoconstrictive and positive inotropic agents: Because of the risk of reducing cardiac contractility in presence of high systemic vascular resistance, do not use esmolol hydrochloride in sodium chloride injection to control tachycardia in patients receiving drugs that are vasoconstrictive and have positive inotropic effects, such as epinephrine, norepinephrine, and dopamine. 

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USE IN SPECIFIC POPULATIONS SECTION

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Pregnancy Category C. Esmolol hydrochloride has been shown to produce increased fetal resorptions with minimal maternal toxicity in rabbits when given in doses approximately 8 times the maximum human maintenance dose (300 mcg/kg/min). There are no adequate and well-controlled studies in pregnant women. Esmolol hydrochloride in sodium chloride injection should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Teratogenicity studies in rats at intravenous dosages of esmolol hydrochloride) up to 3000 mcg/kg/min (10 times the maximum human maintenance dosage) for 30 minutes daily produced no evidence of maternal toxicity, embryotoxicity or teratogenicity, while a dosage of 10,000 mcg/kg/min produced maternal toxicity and lethality. In rabbits, intravenous dosages up to 1000 mcg/kg/min for 30 minutes daily produced no evidence of maternal toxicity, embryotoxicity or teratogenicity, while 2500 mcg/kg/min produced minimal maternal toxicity and increased fetal resorptions.

8.2 Labor and Delivery

Although there are no adequate and well-controlled studies in pregnant women, use of esmolol in the last trimester of pregnancy or during labor or delivery has been reported to cause fetal bradycardia, which continued after termination of drug infusion. Esmolol hydrochloride in sodium chloride injection should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

8.3 Nursing Mothers

It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from esmolol hydrochloride in sodium chloride injection, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

8.4 Pediatric Use

The safety and effectiveness of esmolol hydrochloride in sodium chloride injection in pediatric patients have not been established.

8.5 Geriatric Use

Clinical studies of esmolol hydrochloride in sodium chloride injection did not include sufficient numbers of subjects aged 65 and over to determine whether they responded differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should usually start at the low end of the dosing range, reflecting greater frequency of decreased renal or cardiac function and of concomitant disease or other drug therapy.

8.6 Hepatic Impairment

No special precautions are necessary in patients with hepatic impairment because esmolol hydrochloride in sodium chloride injection is metabolized by red-blood cell esterases [seeClinical Pharmacology (12.3)].

8.7 Renal Impairment

No dosage adjustment is required for esmolol in patients with renal impairment receiving a maintenance infusion of esmolol 150 mcg/kg for 4 hours. There is no information on the tolerability of maintenance infusions of esmolol using rates in excess of 150 mcg/kg or maintained longer than 4 hours [seeClinical Pharmacology (12.3)].

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ADVERSE REACTIONS SECTION

Highlight: Most common adverse reactions (incidence> 10%) are symptomatic hypotension (hyperhidrosis, dizziness) and asymptomatic hypotension (6)

To report SUSPECTED ADVERSE REACTIONS, contact Mylan Pharmaceuticals Inc. at 1-877-446-3679 (1-877-4-INFO-RX) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6 ADVERSE REACTIONS

6.1 Clinical Trials Experience

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 clinical practice.

The following adverse reaction rates are based on use of esmolol hydrochloride in sodium chloride injection in clinical trials involving 369 patients with supraventricular tachycardia and over 600 intraoperative and postoperative patients enrolled in clinical trials. Most adverse effects observed in controlled clinical trial settings have been mild and transient. The most important and common adverse effect has been hypotension [see Warnings and Precautions (5.3)]. Deaths have been reported in post-marketing experience occurring during complex clinical states where esmolol hydrochloride in sodium chloride injection was presumably being used simply to control ventricular rate [seeWarnings and Precautions (5.5)].

Table 2 Clinical Trial Adverse Reactions (Frequency ≥3%)

Clinical Trial Adverse Reactions (Frequency <3%)

Psychiatric Disorders

Confusional state and agitation (~2%)

Anxiety, depression and abnormal thinking (<1%)

Nervous System Disorders

Headache (~ 2%)

Paresthesia, syncope, speech disorder, and lightheadedness (<1%)

Convulsions (<1%), with one death

Vascular Disorders

Peripheral ischemia (~1%)

Pallor and flushing (<1%)

Gastrointestinal Disorders

Vomiting (~1%)

Dyspepsia, constipation, dry mouth, and abdominal discomfort have (<1%)

Renal and Urinary Disorders

Urinary retention (<1%)

6.2 Post-Marketing Experience

In addition to the adverse reactions reported in clinical trials, the following adverse reactions have been reported in the post-marketing experience. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to estimate reliably their frequency or to establish a causal relationship to drug exposure.

Cardiac Disorders

Cardiac arrest, Coronary arteriospasm

Skin and Subcutaneous Tissue Disorders

Angioedema, Urticaria, Psoriasis

CLINICAL STUDIES SECTION

14 CLINICAL STUDIES

Supraventricular Tachycardia

esmolol hydrochloride in sodium chloride injection were found to be more effective than placebo and about as effective as propranolol, 3 to 6 mg given by bolus injections, in the treatment of supraventricular tachycardia, principally atrial fibrillation and atrial flutter. The majority of these patients developed their arrhythmias postoperatively. About 60 to 70% of the patients treated with esmolol hydrochloride in sodium chloride injection developed either a 20% reduction in heart rate, a decrease in heart rate to less than 100 bpm, or, rarely, conversion to normal sinus rhythm and about 95% of these patients did so at a dosage of 200 mcg/kg/min or less. The average effective dosage of esmolol hydrochloride in sodium chloride injection was approximately 100 mcg/kg/min in the two studies. Other multicenter baseline- controlled studies gave similar results. In the comparison with propranolol, about 50% of patients in both the esmolol hydrochloride in sodium chloride injection and propranolol groups were on concomitant digoxin. Response rates were slightly higher with both beta blockers in the digoxin-treated patients.

In all studies significant decreases of blood pressure occurred in 20 to 50% of patients, identified either as adverse reaction reports by investigators, or by observation of systolic pressure less than 90 mmHg or diastolic pressure less than 50 mmHg. The hypotension was symptomatic (mainly hyperhidrosis or dizziness) in about 12% of patients, and therapy was discontinued in about 11% of patients, about half of whom were symptomatic. Hypotension was more common with esmolol hydrochloride in sodium chloride injection (53%) than with propranolol (17%). The hypotension was rapidly reversible with decreased infusion rate or after discontinuation of therapy with esmolol hydrochloride in sodium chloride injection. For both esmolol hydrochloride in sodium chloride injection and propranolol, hypotension was reported less frequently in patients receiving concomitant digoxin.

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OVERDOSAGE SECTION

10 OVERDOSAGE

10.1 Signs and Symptoms of Overdose

Overdoses of esmolol hydrochloride in sodium chloride injection can cause cardiac and central nervous system effects. These effects may precipitate severe signs, symptoms, sequelae, and complications (for example, severe cardiac and respiratory failure, including shock and coma), and may be fatal. Continuous monitoring of the patient is required.

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Cardiac effects include bradycardia, atrioventricular block (1st -, 2nd -, 3rd degree), junctional rhythms, intraventricular conduction delays, decreased cardiac contractility, hypotension, cardiac failure (including cardiogenic shock), cardiac arrest/asystole, and pulseless electrical activity. 

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Central nervous system effects include respiratory depression, seizures, sleep and mood disturbances, fatigue, lethargy, and coma. 

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In addition, bronchospasm, mesenteric ischemia, peripheral cyanosis, hyperkalemia, and hypoglycemia (especially in children) may occur. 

10.2 Treatment Recommendations

Because of its approximately 9-minute elimination half-life, the first step in the management of toxicity should be to discontinue the esmolol hydrochloride in sodium chloride injection infusion. Then, based on the observed clinical effects, consider the following general measures.

Bradycardia:

Consider intravenous administration of atropine or another anticholinergic drug or cardiac pacing.

Cardiac Failure

Consider intravenous administration of a diuretic or digitalis glycoside. In shock resulting from inadequate cardiac contractility, consider intravenous administration of dopamine, dobutamine, isoproterenol, or inamrinone. Glucagon has been reported to be useful.

Symptomatic hypotension

Consider intravenous administration of fluids or vasopressor agents such as dopamine or norepinephrine.

Bronchospasm

Consider intravenous administration of a beta2 stimulating agent or a theophylline derivative.

10.3 Dilution Errors

Massive accidental overdoses of esmolol hydrochloride in sodium chloride injection have resulted from dilution errors. Use of Esmolol Hydrochloride in Sodium Chloride Injection [10 mg/mL] [250 mL] and Esmolol Hydrochloride in Sodium Chloride Injection [20 mg/mL] [100 mL] may reduce the potential for dilution errors. Some of these overdoses have been fatal while others resulted in permanent disability. Bolus doses in the range of 625 mg to 2.5 g (12.5 to 50 mg/kg) have been fatal. Patients have recovered completely from overdoses as high as 1.75 g given over one minute or doses of 7.5 g given over one hour for cardiovascular surgery. The patients who survived appear to be those whose circulation could be supported until the effects of esmolol hydrochloride in sodium chloride injection resolved.

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NONCLINICAL TOXICOLOGY SECTION

13 NONCLINICAL TOXICOLOGY

Because of its short term usage no carcinogenicity, mutagenicity, or reproductive performance studies have been conducted with esmolol.

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INFORMATION FOR PATIENTS SECTION

17 PATIENT COUNSELING INFORMATION

Physicians should inform patients of the risks associated with esmolol hydrochloride in sodium chloride injection:

The most common adverse reactions are symptomatic hypotension (hyperhidrosis, dizziness) and asymptomatic hypotension.

Manufactured for:

Mylan Institutional LLC

Rockford, IL 61103 U.S.A.

Manufactured by:

Mylan Laboratories Limited

Bangalore, India

DECEMBER 2017

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