BERKELEY, CA (UroToday.com) - In an English study, 38 patients with interstitial cystitis were administered a modified potassium chloride sensitivity test (PST) and then treated with the intravesical glycosaminoglycan sodium hyaluronate (Cystostat®) weekly for 6 weeks. The PST test was positive in only 23 of 38 patients, thus making its reliability suspect for screening or diagnostic purposes. However, 17 patients with a positive PST showed improvement versus only 5 with a negative study. The 74% response rate with a positive test was statistically significantly higher than the 22% response rate of PST negative patients.

This is an interesting study, though the numbers are small. Twelve of 20 responders to sodium hyaluronate wished to continue with monthly instillations. The medication is not approved in the United States. Two large multicenter randomized, placebo controlled, pivotal trials of intravesical sodium hyaluronate have been conducted in the United States. A Bioniche study of Cystostat® failed to demonstrate superiority over placebo. A study of a preparation with five times the concentration of sodium hyaluronate by the Japanese company SKK in the United States also failed to demonstrate efficacy of intravesical hyaluronic acid. These were large studies, and one would have expected that PST positive and negative patients should have been equally distributed among the populations receiving placebo and active medication in these trials. In a large dose response trial of another glycosaminoglycan treatment, oral sodium pentosanpolysulfate (Elmiron®) where PST testing was done as a part of the study, no change in response to treatment was correlated with PST results.1

References

1. Nickel, J. C., Barkin, J., Forrest, J., Mosbaugh, P. G., Hernandez-Graulau, J., Kaufman, D. et al.: Randomized, double-blind, dose-ranging study of pentosan polysulfate sodium for interstitial cystitis. Urology, 65: 654, 2005.

BJU International 2005 November 96, 1063-1066