The dual serotonin and noradrenaline reuptake inhibitor duloxetine for the treatment of interstitial cystitis: results of an observational study

PURPOSE: We report an observational study to evaluate the efficacy and tolerability of duloxetine for interstitial cystitis. MATERIALS AND METHODS: A total of 48 women were prospectively treated for 2 months following an uptitration protocol to the target dose of 2 x 40 mg duloxetine per day. Patients received the target dose for 5 weeks. The efficacy of duloxetine treatment was assessed at week 8. The primary end point was a change in the overall well-being evaluated by a patient reported global response assessment. Secondary end points were changes in pain and urgency (visual analog scales), frequency and functional bladder capacity (48-hour voiding log), and changes in overall symptom severity (O'Leary-Sant index). RESULTS: There were 5 patients (10.4%) who were identified as responders and 17 patients (35.4%) who dropped out of the study exclusively due to side effects, with nausea present in all dropouts. No severe adverse events were reported. All 5 responders reported onset of symptom improvement but not until they had reached the target dose. Regarding secondary outcome parameters, duloxetine treatment did not result in statistically significant improvement of symptoms. Maximum urinary flow rate and residual volume were influenced more prominently in patients at the target dose, however, the changes did not appear to be clinically meaningful. CONCLUSIONS: Treatment of interstitial cystitis with duloxetine did not result in significant improvement of symptoms. The drug administration was safe but the tolerability of the drug was poor mainly due to nausea occurring with the starting dose of 20 mg per day. Based on the preliminary data of this observational trial we currently cannot recommend duloxetine as a therapeutic approach for interstitial cystitis.