Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) is a chronic condition characterized by pelvic pain and urinary dysfunction, significantly impacting quality of life. The management of IC/BPS remains challenging, necessitating the evaluation of different therapeutic approaches. This study compares the efficacy of intravesical hyaluronic acid (HA) instillations and oral amitriptyline in improving bladder compliance and alleviating symptoms.

This prospective, comparative study included adult women (>18 years) diagnosed with IC/BPS based on bladder diaries, cystoscopy, bladder biopsies, and urodynamic assessments. Exclusion criteria comprised neurological disorders, pelvic surgeries, antidepressant use, and urological conditions such as bladder lithiasis or recurrent urinary tract infections. Participants were allocated to two groups: Group A received intravesical HA instillations weekly for 6 weeks, followed by monthly sessions for 6 months, while Group B received 50 mg/day of amitriptyline for 6 months. Bladder compliance, capacity, and symptoms were assessed at baseline and after 6 months using the O’Leary/Sant questionnaire.

A total of 24 participants (mean age: 38.5 years) were enrolled, with 12 in each group. Baseline assessments showed no significant intergroup differences in bladder capacity, compliance, or urinary frequency. At baseline, Group A exhibited a mean maximum voided volume (MVV) of 120 mL, compliance of 17.5, and urinary frequency of 11, whereas Group B had an MVV of 110 mL, compliance of 16.5, and frequency of 13. After 6 months, Group A demonstrated significant improvements in MVV (210 mL, p=0.04) and compliance (24.5, p=0.03), along with a reduction in frequency (8, p=0.09). In contrast, Group B showed minimal changes in MVV (125 mL, p=0.743), compliance (16, p=0.912), and frequency (14, p=0.845). Both groups exhibited modest symptom score improvements, though only Group B achieved a significant reduction in pain (p=0.03).

The findings suggest that intravesical HA instillations significantly enhance bladder compliance and capacity in IC/BPS patients, whereas amitriptyline primarily provides symptomatic relief, particularly in pain reduction. The observed improvement in compliance in the HA group may be attributable to its role in restoring the glycosaminoglycan (GAG) layer, which maintains urothelial integrity and prevents irritant infiltration. HA's anti-inflammatory properties may further contribute to reduced bladder wall stiffness and improved compliance. In contrast, the absence of significant compliance improvements in the amitriptyline group suggests that its primary mechanism involves neuromodulation rather than direct effects on bladder structure.
These results align with prior research indicating that HA instillations may exert disease-modifying effects by addressing bladder dysfunction rather than merely alleviating symptoms. However, the observed pain relief in the amitriptyline group highlights its potential utility in symptom management. This underscores the possibility of a multimodal approach incorporating HA for bladder function improvement and amitriptyline for pain modulation.

Intravesical HA instillations appear superior to amitriptyline in improving bladder compliance and capacity in women with IC/BPS. These findings suggest that HA should be considered a primary therapeutic option for patients with compromised bladder function, while amitriptyline may be more suitable for cases where pain management is the primary concern. Further research with larger cohorts and extended follow-up periods is warranted to validate these findings and refine treatment strategies for IC/BPS management.

Sun Y, Fang Z, Ding Q, et al. Effect of amitriptyline in treatment interstitial cystitis or bladder pain syndrome according to two criteria: does ESSIC criteria change the response rate? Neurourol Urodyn. 2014 Mar;33(3):341-4. doi: 10.1002/nau.22407.
Barua JM, Arance I, Angulo JC, et al. A systematic review and meta-analysis on the efficacy of intravesical therapy for bladder pain syndrome/interstitial cystitis. Int Urogynecol J. 2016 Aug;27(8):1137-47. doi: 10.1007/s00192-015-2890-7
Hanno PM, Erickson D, Moldwin R, Faraday MM; American Urological Association. Diagnosis and treatment of interstitial cystitis/bladder pain syndrome: AUA guideline amendment. J Urol. 2015 May;193(5):1545-53. doi: 10.1016/j.juro.2015.01.086