Lexiscan(r) (regadenoson)

INDICATIONS & USAGE LEXISCAN® (regadenoson) injection is a pharmacologic stress agent indicated for radionuclide myocardial perfusion imaging (MPI) in patients unable to undergo adequate exercise stress.

DOSAGE AND ADMINISTRATION The recommended dose of LEXISCAN is 5 mL (0.4 mg regadenoson) administered as an intravenous injection within 10 seconds. • Patients should be instructed to avoid consumption of any products containing methylxanthines, including caffeinated coffee, tea or other caffeinated beverages, caffeine-containing drug products, aminophylline and theophylline for at least 12 hours before a scheduled radionuclide MPI [see Drug Interactions ( 7- 7.1) and Clinical Pharmacology ( 12- 12.2)]. • Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Do not administer LEXISCAN if it contains particulate matter or is discolored. • Administer LEXISCAN as an intravenous injection within 10 seconds into a peripheral vein using a 22 gauge or larger catheter or needle. • Administer a 5 mL saline flush immediately after the injection of LEXISCAN. • Administer the radionuclide myocardial perfusion imaging agent 10–20 seconds after the saline flush. The radionuclide may be injected directly into the same catheter as LEXISCAN.

WARNINGS AND PRECAUTIONS 5.1 Myocardial Ischemia Fatal and nonfatal myocardial infarction (MI), ventricular arrhythmias, and cardiac arrest have occurred following LEXISCAN injection. 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 LEXISCAN. Cardiac resuscitation equipment and trained staff should be available before administering LEXISCAN. Adhere to the recommended duration of injection [see Dosage and Administration ( 2 )]. As noted in an animal study, longer injection times may increase the duration and magnitude of increase in coronary blood flow [see Clinical Pharmacology ( 12- 12.2)]. If serious reactions to LEXISCAN occur, consider the use of aminophylline, an adenosine antagonist, to shorten the duration of increased coronary blood flow induced by LEXISCAN [see Overdosage ( 10 )]. 5.2 Sinoatrial and Atrioventricular Nodal Block Adenosine receptor agonists, including LEXISCAN, can depress the SA and AV nodes and may cause first-, second- or third-degree AV block, or sinus bradycardia requiring intervention. In clinical trials first-degree AV block (PR prolongation > 220 msec) developed in 3% of patients within 2 hours of LEXISCAN administration; transient second-degree AV block with one dropped beat was observed in one patient receiving LEXISCAN. In post-marketing experience, third-degree heart block and asystole within minutes of LEXISCAN administration have occurred [see Adverse Reactions ( 6- 6.2)]. 5.3 Atrial Fibrillation/Atrial Flutter New-onset or recurrent atrial fibrillation with rapid ventricular response and atrial flutter have been reported following LEXISCAN injection [see Adverse Reactions ( 6- 6.2)]. 5.4 Hypersensitivity, Including Anaphylaxis Anaphylaxis, angioedema, cardiac or respiratory arrest, respiratory distress, decreased oxygen saturation, hypotension, throat tightness, urticaria and rashes have occurred. In clinical trials, hypersensitivity reactions were reported in fewer than 1 percent of patients [see Adverse Reactions (6.1)]. Have personnel and resuscitative equipment immediately available. 5.5 Hypotension Adenosine receptor agonists, including LEXISCAN, induce arterial vasodilation and hypotension. In clinical trials, decreased systolic blood pressure (> 35 mm Hg) was observed in 7% of patients and decreased diastolic blood pressure (> 25 mm Hg) was observed in 4% of patients within 45 minutes of LEXISCAN administration. The risk of serious hypotension may be higher in patients with autonomic dysfunction, hypovolemia, left main coronary artery stenosis, stenotic valvular heart disease, pericarditis or pericardial effusions, or stenotic carotid artery disease with cerebrovascular insufficiency. In post-marketing experience, syncope, transient ischemic attacks and seizures have been observed [see Adverse Reactions ( 6- 6.2)]. 5.6 Hypertension Administration of adenosine receptor agonists, including LEXISCAN, may result in clinically significant increases in blood pressure in some patients. Among patients who experienced an increase in blood pressure in clinical trials, the increase was observed within minutes of LEXISCAN administration. Most increases resolved within 10 to 15 minutes, but in some cases, increases were observed at 45 minutes following administration [see Clinical Pharmacology ( 12- 12.2)]. In post-marketing experience, cases of potentially clinically significant hypertension have been reported, particularly with underlying hypertension and when low-level exercise was included in the MPI [see Adverse Reactions ( 6- 6.2)]. 5.7 Bronchoconstriction Adenosine receptor agonists, including LEXISCAN, may cause dyspnea, bronchoconstriction, and respiratory compromise. Appropriate bronchodilator therapy and resuscitative measures should be available prior to and following LEXISCAN administration [see Adverse Reactions ( 6- 6.1), Clinical Pharmacology ( 12- 12.2), Overdosage ( 10 ) and Patient Counseling Information ( 17 )]. 5.8 Seizure LEXISCAN may lower the seizure threshold; obtain a seizure history. New-onset or recurrence of convulsive seizures has occurred following LEXISCAN injection. Some seizures are prolonged and require emergent anticonvulsive management. Aminophylline may increase the risk of seizures associated with LEXISCAN injection. Methylxanthine use is not recommended in patients who experience a seizure in association with LEXISCAN administration. 5.9 Cerebrovascular Accident (Stroke) Hemorrhagic and ischemic cerebrovascular accidents have occurred. Hemodynamic effects of LEXISCAN including hypotension or hypertension may be associated with these adverse reactions [see Warnings and Precautions ( 5- 5.5) and ( 5- 5.6)].

CONTRAINDICATIONS Do not administer LEXISCAN to patients with: • Second- or third-degree AV block, or • sinus node dysfunction unless these patients have a functioning artificial pacemaker [see Warnings and Precautions ( 5- 5.2)].

DRUG INTERACTIONS No formal pharmacokinetic drug interaction studies have been conducted with LEXISCAN. 7.1 Effects of Other Drugs on LEXISCAN • Methylxanthines (e.g., caffeine, aminophylline and theophylline) are non-specific adenosine receptor antagonists that interfere with the vasodilation activity of LEXISCAN [see Clinical Pharmacology ( 12- 12.2) and Patient Counseling Information ( 17 )]. Patients should avoid consumption of any products containing methylxanthines as well as any drugs containing theophylline or aminophylline for at least 12 hours before LEXISCAN administration. Aminophylline may be used to attenuate severe or persistent adverse reactions to LEXISCAN [see Overdosage ( 10 )]. • In clinical studies, LEXISCAN was administered to patients taking other cardioactive drugs (i.e., β-blockers, calcium channel blockers, ACE inhibitors, nitrates, cardiac glycosides, and angiotensin receptor blockers) without reported adverse reactions or apparent effects on efficacy. • Dipyridamole may change the effects of LEXISCAN. When possible, withhold dipyridamole for at least two days prior to LEXISCAN administration. 7.2 Effect of LEXISCAN on Other Drugs Regadenoson does not inhibit the metabolism of substrates for CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, or CYP3A4 in human liver microsomes, indicating that it is unlikely to alter the pharmacokinetics of drugs metabolized by these cytochrome P450 enzymes.

ADVERSE REACTIONS The following adverse reactions are discussed in more detail in other sections of the labeling. • Myocardial Ischemia [see Warnings and Precautions ( 5- 5.1)] • Sinoatrial and Atrioventricular Nodal Block [see Warnings and Precautions ( 5- 5.2)] • Atrial Fibrillation/Atrial Flutter [see Warnings and Precautions ( 5- 5.3)] • Hypersensitivity, Including Anaphylaxis [see Warnings and Precautions ( 5- 5.4)] • Hypotension [see Warnings and Precautions ( 5- 5.5)] • Hypertension [see Warnings and Precautions ( 5- 5.6)] • Bronchoconstriction [see Warnings and Precautions ( 5- 5.7)] • Seizure [see Warnings and Precautions ( 5- 5.8)] • Cerebrovascular Accident (Stroke) [see Warnings and Precautions ( 5- 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. During clinical development, 1,651 patients were exposed to LEXISCAN, with most receiving 0.4 mg as a rapid (≤ 10 seconds) intravenous injection. Most of these patients received LEXISCAN in two clinical studies that enrolled patients who had no history of bronchospastic lung disease as well as no history of a cardiac conduction block of greater than first-degree AV block, except for patients with functioning artificial pacemakers. In these studies (Studies 1 and 2), 2,015 patients underwent myocardial perfusion imaging after administration of LEXISCAN (N = 1,337) or ADENOSCAN (N = 678). The population was 26–93 years of age (median 66 years), 70% male and primarily Caucasian (76% Caucasian, 7% African American, 9% Hispanic, 5% Asian). Table 1 shows the most frequently reported adverse reactions. Overall, any adverse reaction occurred at similar rates between the study groups (80% for the LEXISCAN group and 83% for the ADENOSCAN group). Aminophylline was used to treat the reactions in 3% of patients in the LEXISCAN group and 2% of patients in the ADENOSCAN group. Most adverse reactions began soon after dosing, and generally resolved within approximately 15 minutes, except for headache which resolved in most patients within 30 minutes. Table 1 Adverse Reactions in Studies 1 and 2 Pooled (Frequency ≥ 5%) ECG Abnormalities The frequency of rhythm or conduction abnormalities following LEXISCAN or ADENOSCAN is shown in Table 2 [see Warnings and Precautions ( 5- 5.2)]. Table 2 Rhythm or Conduction Abnormalities* in Studies 1 and 2 * 12-lead ECGs were recorded before and for up to 2 hours after dosing. † includes rhythm abnormalities (PACs, PVCs, atrial fibrillation/flutter, wandering atrial pacemaker, supraventricular or ventricular arrhythmia) or conduction abnormalities, including AV block. Respiratory Abnormalities In a randomized, placebo-controlled trial of 999 patients with asthma (n = 532) or stable chronic obstructive pulmonary disease (n = 467), the overall incidence of pre-specified respiratory adverse reactions was greater in the LEXISCAN group compared to the placebo group (p < 0.001). Most respiratory adverse reactions resolved without therapy; a few patients received aminophylline or a short-acting bronchodilator. No differences were observed between treatment arms in the reduction of >15% from baseline at two-hours in FEV1 (Table 3). Table 3 Respiratory Adverse Effects* * All patients continued the use of their respiratory medications as prescribed prior to administration of LEXISCAN. † Patients may have reported more than one type of adverse reaction. Adverse reactions were collected up to 24 hours following drug administration. Pre-specified respiratory adverse reactions included dyspnea, wheezing, obstructive airway disorder, dyspnea exertional, and tachypnea. ‡ Change from baseline at 2 hours. Renal Impairment In a randomized, placebo-controlled trial of 504 patients (LEXISCAN n=334 and placebo n=170) with a diagnosis or risk factors for coronary artery disease and NKFK/DOQI Stage III or IV renal impairment (defined as GFR 15-59 mL/min/1.73 m2), no serious adverse events were reported through the 24-hour follow-up period. Inadequate Exercise Stress In an open-label, multi-center trial evaluating LEXISCAN administration following inadequate exercise stress, 1,147 patients were randomized into one of two groups. Each group underwent two LEXISCAN stress myocardial perfusion imaging (MPI) procedures. Group 1 received LEXISCAN 3 minutes following inadequate exercise in the first LEXISCAN stress (MPI 1). Group 2 rested 1 hour after inadequate exercise to allow hemodynamics to return to baseline prior to receiving LEXISCAN (MPI 1). Both groups returned for a second stress MPI 1-14 days later and received LEXISCAN without exercise (MPI 2). The most common adverse reactions are similar in type and incidence to those in Table 1 above for both Groups. The timing of the administration of LEXISCAN following inadequate exercise did not alter the common adverse reaction profile. Table 4 shows a comparison of cardiac events of interest for the two groups [see Warnings and Precautions ( 5- 5.1)]. The cardiac events were numerically higher in Group 1. Table 4 Cardiac Events of Interest in Inadequate Exercise Stress Study * A clinically significant cardiac event was defined as any of the following events found on the Holter ECG/12-lead ECG within one hour after regadenoson administration: ventricular arrhythmias (sustained ventricular tachycardia, ventricular fibrillation, Torsade de Pointes, ventricular flutter); ST-T depression (≥ 2 mm); ST-T elevation (≥ 1 mm); AV block (2:1 AV block, AV Mobitz I, AV Mobitz II, complete heart block); sinus arrest > 3 seconds in duration Or • a Treatment Emergent Adverse Event (TEAE) per the MedDRA SMQ (narrow Scope) for myocardial infarction Or • a TEAE preferred term (PT) of angina unstable within 24 hours of regadenoson administration. 6.2 Post-Marketing Experience The following adverse reactions have been reported from worldwide marketing experience with regadenoson. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Cardiovascular Myocardial infarction, cardiac arrest, ventricular arrhythmias, supraventricular tachyarrhythmias including atrial fibrillation with rapid ventricular response (new-onset or recurrent), atrial flutter, heart block (including third-degree block), asystole, marked hypertension, symptomatic hypotension in association with transient ischemic attack, acute coronary syndrome (ACS), seizures and syncope [see Warnings and Precautions ( 5- 5.1), ( 5- 5.2), ( 5- 5.3), ( 5- 5.5), ( 5- 5.6) and ( 5- 5.8)] have been reported. Some events required intervention with fluids and/or aminophylline [see Overdosage ( 10 )]. QTc prolongation shortly after LEXISCAN administration has been reported. Central Nervous System Tremor, seizure, transient ischemic attack, and cerebrovascular accident including intracranial hemorrhage [see Warnings and Precautions ( 5- 5.8) and ( 5- 5.9)]. Gastrointestinal Abdominal pain, occasionally severe, has been reported a few minutes after LEXISCAN administration, in association with nausea, vomiting, or myalgias; administration of aminophylline, an adenosine antagonist, appeared to lessen the pain. Diarrhea and fecal incontinence have also been reported following LEXISCAN administration. Hypersensitivity Anaphylaxis, angioedema, cardiac or respiratory arrest, respiratory distress, decreased oxygen saturation, hypotension, throat tightness, urticaria, rashes have occurred and have required treatment including resuscitation [see Warnings and Precautions ( 5- 5.4)]. Musculoskeletal Musculoskeletal pain has occurred, typically 10-20 minutes after LEXISCAN administration; the pain was occasionally severe, localized in the arms and lo

CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Regadenoson is a low affinity agonist (Ki ≈ 1.3 µM) for the A2A adenosine receptor, with at least 10-fold lower affinity for the A1 adenosine receptor (Ki > 16.5 µM), and weak, if any, affinity for the A2B and A3 adenosine receptors. Activation of the A2A adenosine receptor by regadenoson produces coronary vasodilation and increases coronary blood flow (CBF). 12.2 Pharmacodynamics Coronary Blood Flow LEXISCAN causes a rapid increase in CBF which is sustained for a short duration. In patients undergoing coronary catheterization, pulsed-wave Doppler ultrasonography was used to measure the average peak velocity (APV) of coronary blood flow before and up to 30 minutes after administration of regadenoson (0.4 mg, intravenously). Mean APV increased to greater than twice baseline by 30 seconds and decreased to less than twice the baseline level within 10 minutes [see Clinical Pharmacology (12.3)]. Myocardial uptake of the radiopharmaceutical is proportional to CBF. Because LEXISCAN increases blood flow in normal coronary arteries with little or no increase in stenotic arteries, LEXISCAN causes relatively less uptake of the radiopharmaceutical in vascular territories supplied by stenotic arteries. MPI intensity after LEXISCAN administration is therefore greater in areas perfused by normal relative to stenosed arteries. Effect of duration of injection A study in dogs compared the effects of intravenous injection of 2.5 μg/kg regadenoson (in 10 mL) over 10 seconds and 30 seconds on CBF. The duration of a two-fold increase in CBF was 97±14 seconds (n=6) and 221±20 seconds (n=4), respectively, for the 10 second and 30 second injections. The peak effects (i.e., maximal increase) on CBF after the 10 second and 30 second injections were 217±15% and 297±33% above baseline, respectively. The times to peak effect on CBF were 17±2 seconds and 27±6 seconds, respectively. Effect of Aminophylline Aminophylline (100 mg, administered by slow intravenous injection over 60 seconds) injected 1 minute after 0.4 mg LEXISCAN in patients undergoing cardiac catheterization, was shown to shorten the duration of the coronary blood flow response to LEXISCAN as measured by pulsed-wave Doppler ultrasonography [see Overdosage ( 10 )]. Effect of Caffeine Ingestion of caffeine decreases the ability to detect reversible ischemic defects. In a placebo-controlled, parallel group clinical study, patients with known or suspected myocardial ischemia received a baseline rest/stress MPI followed by a second stress MPI. Patients received caffeine or placebo 90 minutes before the second LEXISCAN stress MPI. Following caffeine administration (200 or 400 mg), the mean number of reversible defects identified was reduced by approximately 60%. This decrease was statistically significant [see Drug Interactions ( 7- 7.1) and Patient Counseling Information ( 17 )]. Hemodynamic Effects In clinical studies, the majority of patients had an increase in heart rate and a decrease in blood pressure within 45 minutes after administration of LEXISCAN. Maximum hemodynamic changes after LEXISCAN and ADENOSCAN in Studies 1 and 2 are summarized in Table 5. Table 5 Hemodynamic Effects in Studies 1 and 2 Hemodynamic Effects Following Inadequate Exercise In a clinical study, LEXISCAN was administered for MPI following inadequate exercise stress. More patients with LEXISCAN administration three minutes following inadequate exercise stress had an increase in heart rate and a decrease in systolic blood pressure compared with LEXISCAN administered at rest. The changes were not associated with any clinically significant adverse reactions. Maximum hemodynamic changes are presented in Table 6. Table 6 Hemodynamic Effects in Inadequate Exercise Stress Study Respiratory Effects The A2B and A3 adenosine receptors have been implicated in the pathophysiology of bronchoconstriction in susceptible individuals (i.e., asthmatics). In in vitro studies, regadenoson has not been shown to have appreciable binding affinity for the A2B and A3 adenosine receptors. In a randomized, placebo-controlled clinical trial of 999 patients with a diagnosis, or risk factors for, coronary artery disease and concurrent asthma or COPD, the incidence of respiratory adverse reactions (dyspnea, wheezing) was greater with LEXISCAN compared to placebo. Moderate (2.5%) or severe (< 1%) respiratory reactions were observed more frequently in the LEXISCAN group compared to placebo [see Adverse Reactions ( 6- 6.1)]. 12.3 Pharmacokinetics In healthy subjects, the regadenoson plasma concentration-time profile is multi-exponential in nature and best characterized by 3-compartment model. The maximal plasma concentration of regadenoson is achieved within 1 to 4 minutes after injection of LEXISCAN and parallels the onset of the pharmacodynamic response. The half-life of this initial phase is approximately 2 to 4 minutes. An intermediate phase follows, with a half-life on average of 30 minutes coinciding with loss of the pharmacodynamic effect. The terminal phase consists of a decline in plasma concentration with a half-life of approximately 2 hours [see Clinical Pharmacology ( 12- 12.2)]. Within the dose range of 0.3–20 µg/kg in healthy subjects, clearance, terminal half-life or volume of distribution do not appear dependent upon the dose. A population pharmacokinetic analysis including data from subjects and patients demonstrated that regadenoson clearance decreases in parallel with a reduction in creatinine clearance and clearance increases with increased body weight. Age, gender, and race have minimal effects on the pharmacokinetics of regadenoson. Specific Populations Renally Impaired Patients: The disposition of regadenoson was studied in 18 patients with various degrees of renal function and in 6 healthy subjects. With increasing renal impairment, from mild (CLcr 50 to < 80 mL/min) to moderate (CLcr 30 to < 50 mL/min) to severe renal impairment (CLcr < 30 mL/min), the fraction of regadenoson excreted unchanged in urine and the renal clearance decreased, resulting in increased elimination half-lives and AUC values compared to healthy subjects (CLcr ≥ 80 mL/min). However, the maximum observed plasma concentrations as well as volumes of distribution estimates were similar across the groups. The plasma concentration-time profiles were not significantly altered in the early stages after dosing when most pharmacologic effects are observed. No dose adjustment is needed in patients with renal impairment. Patients with End Stage Renal Disease: The pharmacokinetics of regadenoson in patients on dialysis has not been assessed; however, in an in vitro study regadenoson was found to be dialyzable. Hepatically Impaired Patients: The influence of hepatic impairment on the pharmacokinetics of regadenoson has not been evaluated. Because greater than 55% of the dose is excreted in the urine as unchanged drug and factors that decrease clearance do not affect the plasma concentration in the early stages after dosing when clinically meaningful pharmacologic effects are observed, no dose adjustment is needed in patients with hepatic impairment. Geriatric Patients: Based on a population pharmacokinetic analysis, age has a minor influence on the pharmacokinetics of regadenoson. No dose adjustment is needed in elderly patients. Metabolism The metabolism of regadenoson is unknown in humans. Incubation with rat, dog, and human liver microsomes as well as human hepatocytes produced no detectable metabolites of regadenoson. Excretion In healthy volunteers, 57% of the regadenoson dose is excreted unchanged in the urine (range 19-77%), with an average plasma renal clearance around 450 mL/min, i.e., in excess of the glomerular filtration rate. This indicates that renal tubular secretion plays a role in regadenoson elimination. CLINICAL P 1 CLINICAL P 2