The U. S. Food and Drug Administration said on Wednesday that it would review the safety of popularly used anemia drugs sold by Amgen and Johnson & Johnson after another clinical trial results show that high doses of one of the drugs may cause strokes.

The New England Journal of Medicine contained a commentary by agency officials that the results of the new trial as well as old ones increase major issues about the usage of the drugs to treat the anemia caused by chronic kidney disease.

An outside advisory committee would be convened to re-evaluate the use of the drugs in patients with kidney disease and to consider new ways to control doses of the products.

A large biotechnology company, Amgen, was originally built on the sales of its anemia drugs, Epogen and Aranesp. The drugs raise the body’s level of red blood cells which transfer to the body’s tissues.

Despite the success of these drugs, the sales were reducing since 2007, when studies renewed concerns that the drugs might cause heart attacks and strokes and also deteriorate the condition of patients with cancer. The drugs are also used to treat the anemia caused by chemotherapy.