A prospective, randomized, placebo controlled, double-blind study of amitriptyline for the treatment of interstitial cystitis.

PURPOSE

We conducted a prospective study to examine the safety and efficacy of the tricyclic antidepressant amitriptyline in patients with interstitial cystitis (IC).

MATERIALS AND METHODS

The study comprised 44 women and 6 men who all met the symptom criteria of the National Institute of Diabetes, Digestive and Kidney Diseases for IC. The patients were randomly assigned to amitriptyline or placebo. Patients were prospectively treated for 4 months with a self-titration protocol that allowed them to escalate drug dosage in 25 mg increments in 1 week-intervals (maximum dosage 100 mg). The change from baseline in the O'Leary-Sant IC symptom and problem index was the primary outcome parameter. Changes in functional bladder capacity and frequency (48-hour voiding log), and intensity of pain and urgency (visual analog scales) were chosen as secondary outcome parameters.

RESULTS

Two patients (1 on amitriptyline, 1 on placebo) dropped out of the study due to side effects. Thus, the data of 48 patients (24 patients in each group) were available for evaluation. Mean symptom score decreased from 26.9 to 18.5 in the amitriptyline group compared with 27.6 to 24.1 in the placebo group (p = 0.005). Pain and urgency intensity improved statistically significantly in the amitriptyline group compared with the placebo group (p <0.001). The frequency and functional bladder capacity improved to a much greater degree in the amitriptyline group but the differences were not statistically significant (p = 0.063, p = 0.083). Anticholinergic side effects were reported by all except 2 patients in the amitriptyline group (92%) and by 5 patients in the placebo group (21%). Mouth dryness was the most frequent side effect reported in the amitriptyline group (79%).

CONCLUSIONS

Amitriptyline therapy for 4 months is safe and effective for treating IC. A statistically significant change in the symptom score and statistically significant improvement of pain and urgency intensity compared with placebo were observed. Anticholinergic side effects constitute the major drawback of amitriptyline treatment for IC.