Tolerability and Efficacy of Duloxetine Compared to Amitriptyline in Women With Chronic Pelvic Pain Syndrome: Findings From a Clinical Trial

Objectives

Duloxetine has demonstrated efficacy in treating various types of chronic pain conditions. A double-blind clinical trial was conducted to assess the effectiveness and tolerability of duloxetine compared to amitriptyline in women suffering from chronic pelvic pain (CPP) syndrome.

Methods

Sixty-nine eligible women diagnosed with CPP syndrome were randomly assigned to receive either duloxetine or amitriptyline. Duloxetine was initiated at 30 mg/day and amitriptyline at 25 mg/day, with dosages increased to 60 mg/day for duloxetine and 50 mg/day for amitriptyline after the first week and maintained throughout weeks 2 to 8 of the treatment phase. The effectiveness of the treatment was assessed using the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) and its domain scores at weeks 4 and 8 after treatment. The safety and tolerability of the study medications were assessed using an antidepressant side effect checklist and spontaneous participant reports of adverse effects. All analyses were conducted on an Intention-to-Treat (ITT) analysis data set.

Results

Patients undergoing both medications experienced similar improvements in their total NIH-CPSI scores at weeks 4 and 8. The proportions of patients achieving a response, defined as at least a 6-point reduction in the total NIH-CPSI score at both weeks 4 and 8, were also comparable between the duloxetine and amitriptyline treatments. Further, at the end of the study period, a similar proportion of subjects reported marked or moderate overall symptom improvements with both treatments. However, in the analysis of NIH-CPSI domain scores, duloxetine-treated patients exhibited lower pain domain scores at both study endpoints, while amitriptyline-treated patients achieved better scores in the urinary symptoms domain. Regarding quality of life domain scores, no significant differences were observed between the groups. In terms of safety and tolerability, duloxetine demonstrated more favorable outcomes, with fewer patients experiencing adverse effects and a lower withdrawal rate due to adverse effects compared to amitriptyline.

Conclusions

These findings suggest that duloxetine is as effective as amitriptyline for managing CPP syndrome in women, with the added advantage of a more favorable safety profile.

Trial Registration

The trial was registered at the Iranian Registry of Clinical Trials (identifier code: IRCT20120215009014N457). Registration date: 2023-01-10