Overview
11 DESCRIPTION Regadenoson is an A2A adenosine receptor agonist that is a coronary vasodilator [see Clinical Pharmacology ( 12- 12.1)]. Regadenoson is chemically described as adenosine, 2-[4-[(methylamino)carbonyl]-1H-pyrazol-1-yl]-, monohydrate. Its structural formula is: The molecular formula for regadenoson is C15H18N8O5 • H2O and its molecular weight is 408.37.
Mechanism of Action
12 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).
Indications
- 1 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.
Common Doses
- 5 mL
- 0.4 mg
Dosage
2 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)].
Contraindications
- 4 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)].
Side Effects
- 6 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.
Interactions
- 7 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.