The US Food and Drug Administration (FDA) has approved CV Therapeutics' and Astellas Pharma US's Lexiscan (regadenoson) injection, an A2A adenosine receptor agonist, for use as a pharmacologic stress agent in radionuclide myocardial perfusion imaging (MPI) -- a test that detects and characterises coronary artery disease -- in patients unable to undergo adequate exercise stress.

Lexiscan is the first A2A adenosine receptor agonist shown to be safe and effective as a pharmacologic stress agent in MPI studies. Lexiscan is delivered as a rapid bolus (approximately 10 seconds) with no dose adjustment required for body weight. The A2A adenosine receptor is the adenosine receptor subtype responsible for coronary vasodilation.

MPI tests, commonly called cardiac stress tests, identify areas of poor blood flow in the heart to help detect and characterize coronary artery disease, the most common type of heart disease. Many patients exercise on a treadmill to generate the increase in coronary blood flow necessary to perform an MPI study. However, almost half of the patients undergoing the 7.5 to 9.3 million cardiac stress tests each year are unable to exercise adequately because of medical conditions. For these patients, a pharmacologic stress agent that temporarily increases blood flow through the coronary arteries is used to mimic the increase in coronary blood flow caused by exercise.

"Lexiscan represents the second novel chemical entity in cardiovascular medicine that CV Therapeutics has received approval for in just over two years," said, Louis G. Lange, chairman and chief executive officer, CV Therapeutics. "We are very excited to have Astellas -- the clear market leader in pharmacologic stress for MPI -- commercializing Lexiscan."

In two identically designed phase III clinical trials, Lexiscan met primary endpoints for scan agreement rates by showing with 95 percent confidence that MPI studies conducted with Lexiscan were similar to MPI studies conducted with Adenoscan(R) (adenosine injection).

Lexiscan was generally well-tolerated in both phase III studies. The most common adverse events reported in patients who received Lexiscan were shortness of breath, headache, flushing, chest discomfort, dizziness and nausea.

"We are extremely pleased that the FDA has approved Lexiscan, an exciting new option for diagnosing coronary artery disease in patients who cannot undergo an exercise stress test," said Yoshihiko Hatanaka, president and chief executive officer, Astellas Pharma US, Inc. "We are preparing to launch Lexiscan soon after this approval in order to provide clinicians with this important new option for patients who need pharmacologic stress agents for MPI studies."

Lexiscan is an A2A adenosine receptor agonist approved for use as a pharmacologic stress agent in radionuclide MPI studies in patients unable to undergo adequate exercise stress. Lexiscan was designed to produce coronary vasodilation and increase coronary blood flow by activation of the A2A adenosine receptor. Lexiscan is administered as a rapid bolus (approximately 10 seconds) with no dose adjustment required for body weight. Lexiscan should not be administered to patients with second- or third-degree AV block or sinus node dysfunction who do not have a functioning artificial pacemaker. Adenosine receptor agonists, including Lexiscan, induce arterial vasodilation and hypotension. The risk of serious hypotension may be higher in patients with cardiac or cerebrovascular insufficiency.