Affymax Inc. and its partner Takeda Pharmaceutical Co. said Tuesday they have asked regulators to approve a drug designed to treat anemia in patients with chronic kidney disease.

The companies asked the Food and Drug Administration to clear the way for marketing of their drug candidate peginesatide. It is intended to treat anemia in patients who have chronic kidney failure and are on dialysis. Affymax and Takeda previously called the drug candidate Hematide. Takeda, a Japanese drugmaker, has marketing rights outside the U.S.

FDA reviews typically take 10 months.

Affymax, of Palo Alto, California, and Takeda have also studied peginesatide in chronic kidney disease patients who are on dialysis. However the drug appeared less effective for those patients, and the side effects were more severe.

The companies still face the threat of a lawsuit from health care giant Johnson & Johnson, whose drug Procrit is used to treat anemia in patients who are on dialysis for kidney disease or who are being treated for cancer. In October, an arbitrator ruled that Johnson & Johnson was the sole owner of a group of patents on those drugs.

Affymax said it doesn't think the patent is valid and doesn't apply to Procrit or peginesatide, but the ruling could allow Johnson & Johnson to sue Affymax for patent infringement.

Affymax said it plans to ask a federal court to overturn the arbitrator's decision. The decision applied to a patent and related applications in the U.S., Europe, Japan, Canada and Australia.