A medicament for treating cystitis and a method of treatment are provided. An agent to repair the damaged glycosaminoglycan (“GAG”) layers lining the urothelium, noted in cystitis, such as pentosan polysulfate, hyaluronic acid, chondroitin, etc., is provided in a liposomal carrier. Cystitis is treated by intravesically administering to a patient a therapeutically effective dose of the medicament.