An experimental treatment for anemia in kidney dialysis patients is as effective as leading drugs on the market now, the U.S. Food and Drug Administration reported Monday. However, some safety concerns remain for the new injectable drug by Affymax, Inc. known as peginesatide.

Drug reviewers found the new drug works as well as Amgen's Epogen and Aranesp, and Johnson & Johnson's Procrit. But, the late-stage trials involving over 2,500 patients showed a higher rate of heart attack and stroke in patients with renal failure but not yet on dialysis.

Although the drugmaker seeks to use the drug in dialysis patients only, the safety discrepancy between those on dialysis and those not yet on dialysis has raised some concerns. A final decision on the new drug is expected by April 2012.

People with anemia do not have enough oxygen-carrying red blood cells. Symptoms of anemia include feeling cold, fatigued, irritable and dizzy.