UroToday - One commonly believed pathophysiologic hypothesis for BPS/IC is based on a disorder of the urine-tissue barrier. Disturbance of the balance between hyperosmolaric urine and the physiologic tissue compartment and penetration of toxic urinary compounds into the bladder wall is thought to be central in the induction of urgency, frequency and pain. Although reports about the demonstrability of glycosaminoglycan (GAG) deficiency in the IC bladder have been controversial, many urologists in Europe rely on GAG therapy as first-line treatment. Intravesical hyaluronan is derived from the acidic hyaluronic acid and is available in Europe for intravesical use.

Riedl and collegues from Austria report on an open label 6 year retrospective study of intravesical treatment with a solution of 50cc buffered saline containing 40mg of sodium hyaluronate in patients with a positive modified potassium test thought to indicate abnormal mucosal permeability. Only patients who could retain the solution for a minimum of 2 hours were included in the study. Instillations were weekly for a minimum of 10 weeks, and then continued until patients requested they be stopped.

A positive and durable impact was observed in 85% of 126 patients, with initial VAS scores dropping from 8.5 to 3.5. There was a 15% failure rate, 85% success rate, and 34.5% recurrence rate requiring reinitiation of therapy. 55% of patients were free of symptoms for up to 5 years. While one can question the study on the basis of patient selection, lack of control arm, placebo effect, regression to the mean, and the 2 hour minimum dwell time necessary to be included in the study, the results are nevertheless quite provocative. It is difficult to explain the failure of two large multicenter pivotal American trials using 40mg and 200mg concentrations to show any efficacy for intravesical hyaluronan. While these trials did not have a positive potassium test as an inclusion criteria, one would expect this group of potassium positive patients to have been equally divided between the placebo and active groups. Since the vast majority of patients are potassium positive, this would have been unlikely to account for failure of the trials to show efficacy. Unfortunately, these trial were not published, but hyaluronan remains unapproved in the United States. Riedl's study suggests that a multicenter, placebo controlled trial using a modified potassium test might be worth doing to once and for all demonstrate the value or lack of value of intravesical GAG therapy.

Int Urogynecol J Pelvic Floor Dysfunct. 2007 Dec 21
DOI 10.1007/s00192-007-0515-5

Reported by UroToday Contributing Editor Philip M. Hanno, MD

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