A panel of advisers to the U.S. health regulator on Wednesday recommended the approval of Ardelyx Inc's drug for chronic kidney disease patients on dialysis, more than a year after it was initially rejected.

The Food and Drug Administration's advisory panel voted 9-4 in favor of the drug, tenapanor, to be administered as a single therapy for treating high phosphate levels in the blood of patients on dialysis.

The advisers also voted 10-2 in favor of the drug's use alongside existing treatment. One member abstained from voting.

Tenapanor is an oral drug that reduces the level of phosphate in the body by targeting the pathway that absorbs it.

Currently, phosphate binders are the only approved therapy for hyperphosphatemia, a condition resulting in abnormally high levels of phosphorus in the blood, which is a sign of kidney damage.

Around 37 million people, or one in seven people, in the United States have chronic kidney disease, as per a government report last year.

"I do think (the drug) should be made available for those patients that are otherwise being untreated. It is probably better than nothing," said a panel member C. Noel Bairey Merz from Cedars-Sinai Medical Center in Los Angeles.

The advisers' vote followed the release of briefing documents on Monday, in which FDA's staff reviewers cited similar concerns about unclear benefits of the drug that the agency had mentioned in the complete response letter issued July last year.

The FDA had called the advisers' meeting due to Ardelyx's appeal against the drug's initial rejection.

Ardelyx Chief Executive Officer Mike Raab was optimistic about the FDA deciding on similar lines as the panel's vote.

FDA, which usually follows the recommendations of its expert panel, is expected to make its final decision on the drug within 30 days of the conclusion of the panel meeting.