FDA denies approval of Tenapanor for controlling phosphorus levels in dialysis patients. The US Food and Drug Administration has asked for an additional clinical trial to demonstrate the benefits of Tenapanor before it approves the drug. Tenapanor has shown good prospects in trials to control serum phosphorus in adult individuals with chronic kidney disease (CKD) on dialysis. Tenapanor is an oral drug that inhibits the sodium-proton exchanger NHE3. The drug was submitted for approval to treat hyperphosphatemia in patients with CKD on dialysis. The data is supported by three phase-3 clinical trials involving more than 1000 patients. 

The FDA stated that approval of the drug application would require the drug manufacturer to carry out another “adequate and well-controlled trial” that shows this treatment can have a meaningful impact on the level of phosphorus in the blood or improve a health issue caused by hyperphosphatemia in dialysis patients with chronic kidney disease. 

CKD Patients receiving dialysis treatments are highly likely to be hyperphosphatemic. Current Therapies for Hyperphosphatemia are only moderately effective and challenging to implement. Current strategies for managing hyperphosphatemia can include more frequent hemodialysis therapies, dietary phosphate restriction, and phosphate binder therapy. Untreated hyperphosphatemia in patients can lead to dystrophic calcification, accelerated arteriosclerotic vascular disease, and fractures. 

In the previous study, 236 dialysis patients with hyperphosphatemia, despite treatment with a phosphate binder therapy, were given 4 weeks of treatment. The treatment included either the twice-daily oral Tenapanor or a placebo dose. The results showed that the drug treatment group significantly changed serum phosphorus concentration over placebo. 

Tenapanor previously received FDA approval in 2019 to treat irritable bowel syndrome (IBS) with constipation in adults.