Randomized, double-blind, dose-ranging study of pentosan polysulfate sodium for interstitial cystitis

To compare the current recommended dose of pentosan polysulfate sodium (PPS) with doses two to three times higher.

We evaluated three dosages (300, 600, and 900 mg) of PPS in a randomized, double-blind, double-dummy, parallel-group, multicenter, 32-week study. Adults (n = 380) with a diagnosis of interstitial cystitis (IC) as determined by a positive cystoscopic examination combined with bladder pain and urgency or a history of IC symptoms for at least 6 months were enrolled. Participants completed the Patient's Overall Rating of Symptom Index (PORIS) and the O'Leary-Sant Interstitial Cystitis Symptom Index (ICSI) at baseline (ICSI only) and during follow-up visits at 4, 8, 12, 16, 24, and 32 weeks.

Mean ICSI scores improved significantly during the 32 weeks for all dosages (baseline 11.2, 11.9, and 11.9 to endpoint 8.2, 8.1, 8.6 for 300, 600, and 900 mg, respectively; P <0.001) but the response to treatment was not dose dependent (no statistically significant difference in response among the three dosages). At baseline, 3.2%, 62.2%, and 34.6% reported mild, moderate, and severe symptoms, respectively, as assessed by the ICSI. At study end, 27.5%, 56.9%, and 15.7% reported mild, moderate, and severe symptoms, respectively. The PORIS scores improved within 4 weeks with 15.8% to 21.1% of all patients classified as responders (50% or greater improvement on PORIS). At 32 weeks, 49.6%, 49.6%, and 45.2% of all patients were responders at a dose of 300, 600, and 900 mg, respectively. Most adverse events were mild and resolved without intervention.

For all three dosages of PPS, a clinically significant but similar response was demonstrated. The duration of therapy appears to be more important than the dosage.