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# FDA Complete Response Letter for Ardelyx’ Tenapanor NDA
- URL: https://www.fdaweb.com/fda-complete-response-letter-for-ardelyx-tenapanor-nda/
- Published: 2021-08-05T12:00:00.000Z
- Updated: 2026-09-14T17:09:26.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5149877

FDA has sent a complete response letter to Ardelyx for its NDA for tenapanor for the control of serum phosphorous in adult patients with chronic kidney disease on dialysis. The company [says](https://ir.ardelyx.com/news-releases/news-release-details/ardelyx-receives-complete-response-letter-us-fda-new-drug?ref=fdaweb.com) FDA found that the submitted data provide substantial evidence that tenapanor is effective in reducing serum phosphorous in the target patients but the magnitude of the treatment effect is small and of unclear clinical significance.

FDA also reportedly said that for the NDA to be approved, Ardelyx would have to conduct an additional adequate and well-controlled trial demonstrating a clinically relevant treatment effect on serum phosphorous or an effect on the clinical outcome thought to be caused by hyperphosphatemia in chronic kidney disease patients on dialysis.

The company says it will seek a meeting with FDA to discuss options for obtaining approval.