TA-5538

TA-5538 is an investigational small molecule β3-adrenoceptor agonist that was developed by Tanabe Seiyaku (now Mitsubishi Tanabe Pharma) for the treatment of overactive bladder (OAB). The drug works by selectively activating β3-adrenergic receptors located on the detrusor muscle of the bladder, which promotes muscle relaxation and increases bladder storage capacity, thereby reducing symptoms of urinary urgency, frequency, and incontinence. TA-5538 reached Phase IIa clinical trials, including a randomized, double-blind, placebo-controlled study conducted in Sweden to evaluate its safety and efficacy over a 4-week period. Following the merger of Tanabe Seiyaku and Mitsubishi Pharma, the development of TA-5538 was discontinued, and it is no longer listed in the company's active pipeline.