Researchers report that tenapanor — a small molecule inhibitor of the sodium/hydrogen exchanger isoform 3 — reduces serum phosphate levels in patients with hyperphosphataemia receiving haemodialysis. In this double-blind trial, 162 patients underwent washout of phosphate binders before being randomly assigned to receive either tenapanor or placebo for 4 weeks. Tenapanor treatment resulted in significant dose-dependent reductions in serum phosphate levels from baseline. The most common adverse event was diarrhoea.