Pentosan polysulfate sodium (PPS) is a low molecular weight, semi-synthetic heparin-like polysaccharide. Its primary action in interstitial cystitis involves replenishing the glycosaminoglycan (GAG) layer of the urothelium, which acts as a protective barrier against urinary irritants. PPS also exhibits mild anticoagulant, anti-inflammatory, and fibrinolytic activity. It inhibits mast cell degranulation and may prevent the infiltration of inflammatory cells into the bladder wall, thereby reducing pain, urgency, and discomfort.