Long-Term Results of Amitriptyline Treatment for Interstitial Cystitis

Purpose: We have conducted a prospective open-label study to examine the safety and efficacy of the long-term administration of the tricyclic antidepressant amitriptyline in patients with interstitial cystitis (IC). Methods: Patients were stratified into 2 groups: an NIDDK group including patients fulfilling the NIDDK criteria for IC and a non-NIDDK group encompassing patients who presented the characteristic IC symptoms but met at least one of the NIDDK exclusion criteria. Amitriptyline was taken strictly at bedtime following an established self-titration protocol without a limitation of the maximum daily dosage. Patients reporting improvement in a global response assessment questionnaire were defined as treatment responders. Further efficacy measures included changes of pain and urgency, functional bladder capacity and frequency. Changes in the O'Leary-Sant IC index and rating of overall satisfaction with the therapeutic outcome are reported as well. Results: The mean follow-up of the study was 19.0 +/- 12.5 months. The response rate was 64% (60 patients). Overall mean dosage was 55 mg (range: 12.5-150 mg). Side effects occurred in 79 patients (84%) (dry mouth: 79%, weight gain: 59%). Patient overall satisfaction with the therapeutic result was either excellent or good in 43 patients (46%). The drop-out rate was 31% (29 patients) after a mean treatment period of 6 weeks at a mean dosage of 70 mg. Non-response to treatment was the primary reason for drop-out in all cases, side effects contributed to drop-out in 25 patients (86%). The various IC symptoms improved statistically significant compared with baseline. Conclusions: Long-term administration of amitriptyline is a feasible, safe and effective treatment for IC provided that the drug is used judiciously to minimise adverse effects. The therapeutic response to amitriptyline was uniformly observed in patients fulfilling the NIDDK criteria and in those patients with the pure clinical diagnosis of IC.