Effect of amitriptyline on symptoms in treatment naïve patients with interstitial cystitis/painful bladder syndrome

Purpose: Amitriptyline is frequently used to treat patients with interstitial cystitis/painful bladder syndrome. The evidence to support this practice is derived mainly from a small, single site clinical trial and case reports.

Materials and methods: We conducted a multicenter, randomized, double-blind, placebo controlled clinical trial of amitriptyline in subjects with interstitial cystitis/painful bladder syndrome who were naïve to therapy. Study participants in both treatment arms received a standardized education and behavioral modification program. The drug dose was increased during a 6-week period from 10 up to 75 mg once daily. The primary outcome was a patient reported global response assessment of symptom improvement evaluated after 12 weeks of treatment.

Results: A total of 271 subjects were randomized and 231 (85%) provided a global response assessment at 12 weeks of followup. Study participants were primarily women (83%) and white (74%), with a median age of 38 years. In an intent to treat analysis (271) the rate of response of subjects reporting moderate or marked improvement from baseline in the amitriptyline and placebo groups was 55% and 45%, respectively (p = 0.12). Of the subgroup of subjects (207) who achieved a drug dose of at least 50 mg, a significantly higher response rate was observed in the amitriptyline group (66%) compared to placebo (47%) (p = 0.01).

Conclusions: When all randomized subjects were considered, amitriptyline plus an education and behavioral modification program did not significantly improve symptoms in treatment naïve patients with interstitial cystitis/painful bladder syndrome. However, amitriptyline may be beneficial in persons who can achieve a daily dose of 50 mg or greater, although this subgroup comparison was not specified in advance.