ATB-429 is a mesalazine derivative capable of releasing H2S, demonstrating significant analgesic and anti-inflammatory effects in an irritable bowel syndrome (IBS) model. By releasing hydrogen sulfide (H2S), ATB-429 modulates hypersensitivity induced by colorectal distension in healthy and post-colitis rats. It alleviates abdominal withdrawal responses and inhibits spinal c-Fos mRNA expression, indicating its potential to relieve pain associated with gastrointestinal inflammation. Furthermore, ATB-429 downregulates mRNA expression of colonic cyclooxygenase-2 (COX-2) and IL-1β, an effect not observed with mesalazine alone. The mechanism involves ATP-sensitive K+ (KATP) channels, evidenced by the reversal of ATB-429's effects with glibenclamide. These findings suggest that ATB-429 may offer therapeutic benefits for treating inflammatory pain-related bowel conditions.