Adenosine

INDICATIONS AND USAGE: Intravenous adenosine injection, USP is indicated for the following: Conversion to sinus rhythm of paroxysmal supraventricular tachycardia (PSVT), including that associated with accessory bypass tracts (Wolff-Parkinson-White Syndrome). When clinically advisable, appropriate vagal maneuvers (e.g., Valsalva maneuver), should be attempted prior to adenosine injection, USP administration. It is important to be sure the adenosine injection, USP solution actually reaches the systemic circulation (see DOSAGE AND ADMINISTRATION ). Adenosine injection, USP does not convert atrial flutter, atrial fibrillation, or ventricular tachycardia to normal sinus rhythm. In the presence of atrial flutter or atrial fibrillation, a transient modest slowing of ventricular response may occur immediately following adenosine injection, USP administration.

DOSAGE AND ADMINISTRATION: For rapid bolus intravenous use only. Adenosine injection, USP should be given as a rapid bolus by the peripheral intravenous route. To be certain the solution reaches the systemic circulation, it should be administered either directly into a vein or, if given into an intravenous line, it should be given as close to the patient as possible and followed by a rapid saline flush. Adult Patients The dose recommendation is based on clinical studies with peripheral venous bolus dosing. Central venous (CVP or other) administration of adenosine injection, USP has not been systematically studied. The recommended intravenous doses for adults are as follows: Initial dose: 6 mg given as a rapid intravenous bolus (administered over a 1 to 2 second period). Repeat administration: If the first dose does not result in elimination of the supraventricular tachycardia within 1 to 2 minutes, 12 mg should be given as a rapid intravenous bolus. This 12 mg dose may be repeated a second time if required. Pediatric Patients The dosages used in neonates, infants, children and adolescents were equivalent to those administered to adults on a weight basis. Pediatric Patients with a Body Weight less than 50 kg: Initial dose: Give 0.05 mg/kg to 0.1 mg/kg as a rapid intravenous bolus given either centrally or peripherally. A saline flush should follow. Repeat administration: If conversion of paroxysmal supraventricular tachycardia does not occur within 1 to 2 minutes, additional bolus injections of adenosine can be administered at incrementally higher doses, increasing the amount given by 0.05 mg/kg to 0.1 mg/kg. Follow each bolus with a saline flush. This process should continue until sinus rhythm is established or a maximum single dose of 0.3 mg/kg is used. Pediatric Patients with a Body Weight greater than or equal to 50 kg: Administer the adult dose. Doses greater than 12 mg are not recommended for adult and pediatric patients. NOTE: Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration. Adult Patients The dose recommendation is based on clinical studies with peripheral venous bolus dosing. Central venous (CVP or other) administration of adenosine injection, USP has not been systematically studied. The recommended intravenous doses for adults are as follows: Initial dose: 6 mg given as a rapid intravenous bolus (administered over a 1 to 2 second period). Repeat administration: If the first dose does not result in elimination of the supraventricular tachycardia within 1 to 2 minutes, 12 mg should be given as a rapid intravenous bolus. This 12 mg dose may be repeated a second time if required. Pediatric Patients The dosages used in neonates, infants, children and adolescents were equivalent to those administered to adults on a weight basis. Pediatric Patients with a Body Weight less than 50 kg: Initial dose: Give 0.05 mg/kg to 0.1 mg/kg as a rapid intravenous bolus given either centrally or peripherally. A saline flush should follow. Repeat administration: If conversion of paroxysmal supraventricular tachycardia does not occur within 1 to 2 minutes, additional bolus injections of adenosine can be administered at incrementally higher doses, increasing the amount given by 0.05 mg/kg to 0.1 mg/kg. Follow each bolus with a saline flush. This process should continue until sinus rhythm is established or a maximum single dose of 0.3 mg/kg is used. Pediatric Patients with a Body Weight greater than or equal to 50 kg: Administer the adult dose. Doses greater than 12 mg are not recommended for adult and pediatric patients. NOTE: Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration.

WARNINGS AND PRECAUTIONS Cardiac Arrest, Ventricular Arrhythmias, and Myocardial Infarction. Fatal cardiac events have occurred. Avoid use in patients with symptoms or signs of acute myocardial ischemia. Appropriate resuscitative measures should be available ( 5.1 ) Sinoatrial (SA) and Atrioventricular (AV) Nodal Block. First-, second- or third-degree AV block, or sinus bradycardia can occur. Discontinue adenosine injection if patient develops persistent or symptomatic high-grade AV block ( 5.2 ) Bronchoconstriction. Can induce dyspnea, bronchoconstriction, and respiratory compromise, especially in patients with obstructive pulmonary disease. Discontinue adenosine injection if patient develops severe respiratory difficulties ( 5.3 ) Hypotension. Significant hypotension can occur. Discontinue adenosine injection if patient develops persistent or symptomatic hypotension ( 5.4 ) Cerebrovascular Accidents. Hemorrhagic and ischemic cerebrovascular accidents have occurred ( 5.5 ) Seizures. New onset or recurrence of convulsive seizures have occurred. Use of methylxanthines (e.g., caffeine, aminophylline and theophylline) is not recommended in patients who experience a seizures in association with adenosine injection ( 5.6 ) Hypersensitivity. Dyspnea, throat tightness, flushing, erythema, rash, and chest discomfort have occurred. Have personnel and resuscitative equipment immediately available ( 5.7 ) Atrial Fibrillation. Reported in patients with or without a history of atrial fibrillation ( 5.8 ) Hypertension. Clinically significant increases in systolic and diastolic pressure have been observed ( 5.9 ) 5.1 Cardiac Arrest, Ventricular Arrhythmias, and Myocardial Infarction Fatal and nonfatal cardiac arrest, sustained ventricular tachycardia (requiring resuscitation), and myocardial infarction have occurred following adenosine injection infusion. Avoid use in patients with symptoms or signs of acute myocardial ischemia, for example, unstable angina or cardiovascular instability; these patients may be at greater risk of serious cardiovascular reactions to adenosine injection. Appropriate resuscitative measures should be available [see Overdosage (10) ]. 5.2 Sinoatrial and Atrioventricular Nodal Block Adenosine injection exerts a direct depressant effect on the SA and AV nodes and may cause first-, second- or third-degree AV block, or sinus bradycardia. In clinical trials, approximately 6% of patients developed AV block following adenosine injection administration (first-degree heart block developed in 3%, second-degree in 3%, and third-degree in 0.8% of patients) [see Clinical Trials Experience (6.1) ]. Use adenosine injection with caution in patients with pre-existing first-degree AV block or bundle branch block. Do not use in patients with high-grade AV block or sinus node dysfunction (except in patients with a functioning artificial pacemaker). Discontinue adenosine injection in any patient who develops persistent or symptomatic high-grade AV block. 5.3 Bronchoconstriction Adenosine injection administration can cause dyspnea, bronchoconstriction, and respiratory compromise. Adenosine injection should be used with caution in patients with obstructive lung disease not associated with bronchoconstriction (e.g., emphysema, bronchitis). Do not use in patients with bronchoconstriction or bronchospasm (e.g., asthma). Discontinue adenosine injection in any patient who develops severe respiratory difficulties. Resuscitative measures should be available prior to adenosine injection administration [see Clinical Trials Experience (6.1) , Overdosage (10) , and Clinical Pharmacology (12.2) ]. 5.4 Hypotension Adenosine injection is a potent peripheral vasodilator and can induce significant hypotension. The risk of serious hypotension may be higher in patients with autonomic dysfunction, hypovolemia, stenotic valvular heart disease, pericarditis or pericardial effusions, or stenotic carotid artery disease with cerebrovascular insufficiency. Discontinue adenosine injection in any patient who develops persistent or symptomatic hypotension. 5.5 Cerebrovascular Accident Hemorrhagic and ischemic cerebrovascular accidents have occurred. Hemodynamic effects of adenosine injection including hypotension or hypertension can be associated with these adverse reactions. [see Warnings and Precautions (5.4) and ( 5.9 )]. 5.6 Seizures New-onset or recurrence of convulsive seizures has occurred following adenosine injection. Some seizures are prolonged and require emergent anticonvulsive management. Aminophylline may increase the risk of seizures associated with adenosine injection. Methylxanthine use is not recommended in patients who experience seizures in association with adenosine injection administration [see Overdosage (10) ]. 5.7 Hypersensitivity Dyspnea, throat tightness, flushing, erythema, rash, and chest discomfort have occurred. Symptomatic treatment may be required. Have personnel and appropriate treatment available. Resuscitative measures may be necessary if symptoms progress. [ see Clinical Trials Experience (6.1 )] . 5.8 Atrial Fibrillation Adenosine injection can cause atrial fibrillation in patients with or without a history of atrial fibrillation. Atrial fibrillation typically began 1.5 to 3 minutes after initiation of adenosine injection, lasted for 15 seconds to 6 hours, and spontaneously converted to normal sinus rhythm [see Post-Marketing Experience (6.2) ]. 5.9 Hypertension Adenosine injection can induce clinically significant increases in systolic and diastolic blood pressure. Most increases resolved spontaneously within several minutes, but in some cases, hypertension lasted for several hours [see Clinical Trials Experience (6.1) ].

CONTRAINDICATIONS Adenosine injection is contraindicated in patients with: Second- or third-degree AV block (except in patients with a functioning artificial pacemaker) [see Warnings and Precautions (5.2) ] Sinus node disease, such as sick sinus syndrome or symptomatic bradycardia (except in patients with a functioning artificial pacemaker) [see Warnings and Precautions (5.2) ] Known or suspected bronchoconstrictive or bronchospastic lung disease (e.g., asthma) [see Warnings and Precautions (5.3) ] Known hypersensitivity to adenosine injection [see Warnings and Precautions (5.7) ] Second- or third-degree AV block (except in patients with a functioning artificial pacemaker) ( 4 ) Sinus node disease, such as sick sinus syndrome or symptomatic bradycardia (except in patients with a functioning artificial pacemaker) ( 4 ) Known or suspected bronchoconstrictive or bronchospastic lung disease (e.g., asthma) ( 4 ) Known hypersensitivity to adenosine injection ( 4 )

DRUG INTERACTIONS Methylxanthines interfere with the activity of adenosine injection ( 7.1 , 10 ) Nucleoside transport inhibitors such as dipyridamole can increase the activity of adenosine injection ( 7.1 ) 7.1 Effects of Other Drugs on Adenosine Injection The vasoactive effects of adenosine are inhibited by adenosine receptor antagonists, (such as methylxanthines (e.g., caffeine, aminophylline, and theophylline). The safety and efficacy of adenosine injection in the presence of these agents has not been systematically evaluated [see Overdosage (10) ] . The vasoactive effects of adenosine injection are potentiated by nucleoside transport inhibitors such as dipyridamole. The safety and efficacy of adenosine in the presence of dipyridamole has not been systematically evaluated. Whenever possible, drugs that might inhibit or augment the effects of adenosine should be withheld for at least five half-lives prior to the use of adenosine injection. 7.2 Effects of Adenosine Injection on Other Drugs Adenosine injection has been given with other cardioactive drugs (such as beta adrenergic blocking agents, cardiac glycosides, and calcium channel blockers) without apparent adverse interactions, but its effectiveness with these agents has not been systematically evaluated. Because of the potential for additive or synergistic depressant effects on the SA and AV nodes, however, adenosine injection should be used with caution in the presence of these agents [see Warnings and Precautions (5.2) ] .

ADVERSE REACTIONS Most common adverse reactions (incidence greater than or equal to 10%) are: flushing; chest discomfort; shortness of breath; headache; throat, neck or jaw discomfort; gastrointestinal discomfort; and dizziness ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Northstar Rx LLC at 1-800-206-7821 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. The following adverse reactions are discussed in more detail in other sections of the prescribing information: Fatal Cardiac Arrest, Ventricular Arrhythmias, and Myocardial Infarction [see Warnings and Precautions (5.1) ] Sinoatrial and Atrioventricular Nodal Block [see Warnings and Precautions (5.2) ] Bronchoconstriction [see Warnings and Precautions (5.3) ] Hypotension [see Warnings and Precautions (5.4) ] Cerebrovascular Accident [see Warnings and Precautions (5.5) ] Seizures [see Warnings and Precautions (5.6) ] Hypersensitivity [see Warnings and Precautions (5.7) ] Atrial fibrillation [see Warnings and Precautions (5.8) ] Hypertension [see Warnings and Precautions (5.9) ] 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 practice. The following adverse reactions, with an incidence of at least 1%, were reported with adenosine injection among 1,421 patients in clinical trials. 11% of the adverse reactions occurred several hours after adenosine injection administration. 8% of the adverse reactions began with adenosine injection infusion and persisted for up to 24 hours. The most common (incidence greater than or equal to 10%) adverse reactions to adenosine injection are flushing, chest discomfort, shortness of breath, headache, throat, neck or jaw discomfort, gastrointestinal discomfort, and dizziness (Table 2). Table 2 Adverse Reactions in Clinical Trials (Frequency Greater Than or Equal To 1%) Adverse Reactions Adenosine N= 1,421 Flushing 44% Chest discomfort 40% Dyspnea 28% Headache 18% Throat, neck or jaw discomfort 15% Gastrointestinal discomfort 13% Lightheadedness/dizziness 12% Upper extremity discomfort 4% ST segment depression 3% First-degree AV block 3% Second-degree AV block 3% Paresthesia 2% Hypotension 2% Nervousness 2% Arrhythmias 1% Adverse reactions to adenosine injection of any severity reported in less than 1% of patients include: Body as a Whole: back discomfort, lower extremity discomfort, weakness Cardiovascular System: myocardial infarction, ventricular arrhythmia, third-degree AV block, bradycardia, palpitation, sinus exit block, sinus pause, T-wave changes, hypertension (systolic blood pressure greater than 200 mm Hg) Respiratory System: cough Central nervous System: drowsiness, emotional instability, tremors Genital/Urinary System: Vaginal pressure, urgency Special Senses: blurred vision, dry mouth, ear discomfort, metallic taste, nasal congestion, scotomas, tongue discomfort 6.2 Post-Marketing Experience The following adverse reactions have been reported from marketing experience with adenosine injection. Because these reactions are reported voluntarily from a population of uncertain size, are associated with concomitant diseases and multiple drug therapies and surgical procedures, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Cardiac Disorders: cardiac arrest, atrial fibrillation, cardiac failure, myocardial infarction, tachycardia, ventricular arrhythmia Gastrointestinal Disorders: nausea and vomiting General Disorders and Administration Site Conditions: chest pain, injection site reaction, infusion site pain Immune System Disorders: hypersensitivity Nervous System Disorders: cerebrovascular accident including intracranial hemorrhage, seizure activity including tonic-clonic (grand mal) seizures, loss of consciousness Respiratory, Thoracic and Mediastinal Disorders: bronchospasm, respiratory arrest, throat tightness

CLINICAL PHARMACOLOGY: Mechanism of Action Adenosine injection, USP slows conduction time through the A-V node, can interrupt the reentry pathways through the A-V node, and can restore normal sinus rhythm in patients with paroxysmal supraventricular tachycardia (PSVT), including PSVT associated with Wolff-Parkinson-White Syndrome. Adenosine injection, USP is antagonized competitively by methylxanthines such as caffeine and theophylline, and potentiated by blockers of nucleoside transport such as dipyridamole. Adenosine injection, USP is not blocked by atropine. Hemodynamics The intravenous bolus dose of 6 mg or 12 mg adenosine injection, USP usually has no systemic hemodynamic effects. When larger doses are given by infusion, adenosine decreases blood pressure by decreasing peripheral resistance. Pharmacokinetics Intravenously administered adenosine is rapidly cleared from the circulation via cellular uptake, primarily by erythrocytes and vascular endothelial cells. This process involves a specific transmembrane nucleoside carrier system that is reversible, nonconcentrative, and bidirectionally symmetrical. Intracellular adenosine is rapidly metabolized either via phosphorylation to adenosine monophosphate by adenosine kinase, or via deamination to inosine by adenosine deaminase in the cytosol. Since adenosine kinase has a lower K m and V max than adenosine deaminase, deamination plays a significant role only when cytosolic adenosine saturates the phosphorylation pathway. Inosine formed by deamination of adenosine can leave the cell intact or can be degraded to hypoxanthine, xanthine, and ultimately uric acid. Adenosine monophosphate formed by phosphorylation of adenosine is incorporated into the high-energy phosphate pool. While extracellular adenosine is primarily cleared by cellular uptake with a half-life of less than 10 seconds in whole blood, excessive amounts may be deaminated by an ecto-form of adenosine deaminase. As adenosine injection, USP requires no hepatic or renal function for its activation or inactivation, hepatic and renal failure would not be expected to alter its effectiveness or tolerability. Clinical Trial Results In controlled studies in the United States, bolus doses of 3 mg, 6 mg, 9 mg, and 12 mg were studied. A cumulative 60% of patients with paroxysmal supraventricular tachycardia had converted to normal sinus rhythm within one minute after an intravenous bolus dose of 6 mg adenosine injection, USP (some converted on 3 mg and failures were given 6 mg), and a cumulative 92% converted after a bolus dose of 12 mg. Seven to sixteen percent of patients converted after 1 to 4 placebo bolus injections. Similar responses were seen in a variety of patient subsets, including those using or not using digoxin, those with Wolff-Parkinson-White Syndrome, males, females, blacks, Caucasians, and Hispanics. Adenosine is not effective in converting rhythms other than PSVT, such as atrial flutter, atrial fibrillation, or ventricular tachycardia, to normal sinus rhythm. Mechanism of Action Adenosine injection, USP slows conduction time through the A-V node, can interrupt the reentry pathways through the A-V node, and can restore normal sinus rhythm in patients with paroxysmal supraventricular tachycardia (PSVT), including PSVT associated with Wolff-Parkinson-White Syndrome. Adenosine injection, USP is antagonized competitively by methylxanthines such as caffeine and theophylline, and potentiated by blockers of nucleoside transport such as dipyridamole. Adenosine injection, USP is not blocked by atropine. Hemodynamics The intravenous bolus dose of 6 mg or 12 mg adenosine injection, USP usually has no systemic hemodynamic effects. When larger doses are given by infusion, adenosine decreases blood pressure by decreasing peripheral resistance. Pharmacokinetics Intravenously administered adenosine is rapidly cleared from the circulation via cellular uptake, primarily by erythrocytes and vascular endothelial cells. This process involves a specific transmembrane nucleoside carrier system that is reversible, nonconcentrative, and bidirectionally symmetrical. Intracellular adenosine is rapidly metabolized either via phosphorylation to adenosine monophosphate by adenosine kinase, or via deamination to inosine by adenosine deaminase in the cytosol. Since adenosine kinase has a lower K m and V max than adenosine deaminase, deamination plays a significant role only when cytosolic adenosine saturates the phosphorylation pathway. Inosine formed by deamination of adenosine can leave the cell intact or can be degraded to hypoxanthine, xanthine, and ultimately uric acid. Adenosine monophosphate formed by phosphorylation of adenosine is incorporated into the high-energy phosphate pool. While extracellular adenosine is primarily cleared by cellular uptake with a half-life of less than 10 seconds in whole blood, excessive amounts may be deaminated by an ecto-form of adenosine deaminase. As adenosine injection, USP requires no hepatic or renal function for its activation or inactivation, hepatic and renal failure would not be expected to alter its effectiveness or tolerability. Clinical Trial Results In controlled studies in the United States, bolus doses of 3 mg, 6 mg, 9 mg, and 12 mg were studied. A cumulative 60% of patients with paroxysmal supraventricular tachycardia had converted to normal sinus rhythm within one minute after an intravenous bolus dose of 6 mg adenosine injection, USP (some converted on 3 mg and failures were given 6 mg), and a cumulative 92% converted after a bolus dose of 12 mg. Seven to sixteen percent of patients converted after 1 to 4 placebo bolus injections. Similar responses were seen in a variety of patient subsets, including those using or not using digoxin, those with Wolff-Parkinson-White Syndrome, males, females, blacks, Caucasians, and Hispanics. Adenosine is not effective in converting rhythms other than PSVT, such as atrial flutter, atrial fibrillation, or ventricular tachycardia, to normal sinus rhythm.