STX-101

STX-101 is a small molecule 5-HT3 receptor partial agonist being developed by Serotonix for the treatment of severe refractory irritable bowel syndrome with diarrhea (IBS-D). Unlike full 5-HT3 receptor antagonists, which are associated with risks of severe constipation and ischemic colitis, STX-101 is designed as a partial agonist to provide a more balanced modulation of gastrointestinal motility and visceral hypersensitivity. The drug has completed Phase 1 clinical trials in Australia and China (including NCT04296799 and NCT05029518), demonstrating a clean safety profile and predictable pharmacokinetics. It is currently positioned as Phase 2 ready for the treatment of patients who do not respond adequately to existing IBS-D therapies.