• painful bladder disease;
  • cimetidine;
  • interstitial cystitis

Objective To evaluate the efficacy of oral cimetidine as a treatment for painful bladder disease (PBD, variously described as a ‘symptom complex’ of suprapubic pain, frequency, dysuria and nocturia in the absence of overt urine infection) by assessing symptom relief and histological changes in the bladder wall tissue components, compared with placebo.

Patients and methods The study comprised 36 patients with PBD enrolled into a double-blind clinical study with two treatment arms, i.e. oral cimetidine or placebo, for a 3-month trial. Patients were asked to complete a symptom questionnaire (maximum score 35), and underwent cystoscopy and bladder biopsy before treatment allocation. On completing treatment the patients were re-evaluated by the questionnaire and biopsy. The symptom scores and bladder mucosal histology were compared before and after treatment, and the results analysed statistically to assess the efficacy of cimetidine.

Results Of the 36 patients recruited, 34 (94%) completed the study. Those receiving cimetidine had a significant improvement in symptoms, with median symptom scores decreasing from 19 to 11 (P < 0.001). Suprapubic pain and nocturia decreased markedly (P = 0.009 and 0.006, respectively). However, histologically the bladder mucosa showed no qualitative change in the glycosaminoglycan layer or basement membrane, or in muscle collagen deposition, in either group. The T cell infiltrate was marginally decreased in the cimetidine group (median 203 before and 193 after) and increased in the placebo group (median 243 and 250, P > 0.3 and > 0.2, respectively). Angiogenesis remained relatively unchanged. The incidence of mast cells and B cells was sporadic in both groups.

Conclusions Oral cimetidine is very effective in relieving symptoms in patients with PBD but there is no apparent histological change in the bladder mucosa after treatment; the mechanism of symptom relief remains to be elucidated.