Intravesical treatment of bladder pain syndrome/interstitial cystitis: from the conventional regimens to the novel botulinum toxin injections

Introduction: Bladder pain syndrome (BPS) includes interstitial cystitis (IC) and is often used as a synonym of it (i.e., BPS/IC). It is associated with lower urinary tract symptoms as well as with negative cognitive, behavioral, sexual and/or emotional consequences. Unfortunately, none of the numerous existing oral and intravesical treatments have been effective for all of the BPS subtypes and therefore relevant research is ongoing. Areas covered: In this review, the authors analyze the existing literature for the intravesical treatment of BPS/IC with focus on the novel administration of botulinum toxin (BTX). Several intravesical drugs have been studied in the past, including lidocaine, heparin, pentosan polysulfate sodium, dimethyl sulfoxide, chondroitin sulfate, hyaluronic acid as well as investigational drugs such as GM-0111. Recently, intravesical submucosal injections of BTX have been studied in patients with BPS/IC. Expert opinion: Most of the recent studies use BTX-A with no serious adverse effects and with satisfactory results in patients who do not respond to oral or standard intravesical therapy. Nevertheless, there is no consensus regarding the best dosage scheme of BTX, the injection sites and the treatment intervals. BTX intravesical administration in patients with BPS/IC is a safe and efficient treatment option; yet the level of evidence of the initial studies is not high. There is still the need for large randomized controlled studies so that a consensus can be reached for the ideal BTX dosage, injection sites and intervals between treatments.