Rubidium Rb-82 is a radioactive drug is indicated for Positron Emission Tomography (PET) imaging of the myocardium under rest or pharmacologic stress conditions to evaluate regional myocardial perfusion in adult patients with suspected or existing coronary artery disease. Rb-82 is analogous to potassium ion (K+) in its biochemical behavior and is rapidly extracted by the myocardium proportional to the blood flow. Rb+ participates in the sodium-potassium (Na+/K+) ion exchange pumps that are present in cell membranes. The intracellular uptake of Rb-82 requires maintenance of ionic gradient across cell membranes. Rb-82 radioactivity is increased in viable myocardium reflecting intracellular retention, while the tracer is cleared rapidly from necrotic or infarcted tissue. Rubidium Rb-82, a nonreactor produced tracer, is believed to have superior accuracy compared to Tc-99m and Tl-201 SPECT, with 5-20 times lower radiation dose. Specific drug-drug interactions have not been studied. Unintended radiation exposure has occurred in some patients who received rubidium Rb-82 chloride injections at clinical sites where generator eluate testing appeared insufficient.