Mirabegron as adjuvant treatment for patients with interstitial cystitis/bladder pain syndrome

Pathophysiology, assessment, and treatment of overactive bladder symptoms in patients with interstitial cystitis/bladder pain syndrome

INTRODUCTION

Interstitial cystitis/bladder pain syndrome (IC/BPS) is prevalent, difficult to treat, and has close symptom overlap with overactive bladder (OAB). A review of the pathophysiology, assessment, and treatment of IC/BPS patients with overlapping OAB symptoms has not been summarized recently in the published literature.

METHODS

A review of the published literature on the overlap of IC/BPS and OAB was conducted using MeSH terminology (1992-2022).

RESULTS

The pathophysiology of IC/BPS is not fully understood. Animal research has found the bladder trigone and base are richly populated by afferent fibers, including many small unmyelinated C-fibers that may be upregulated in IC/BPS. Successful therapies with multimodal effects on OAB symptoms in patients with IC/BPS are likely to exert beneficial effects on both pain and lower urinary tract symptoms. Potentially efficacious therapies for the treatment of OAB in IC/BPS include pelvic floor physical therapy, oral pharmacotherapy (antimuscarinics and beta-3 agonists), sacral neuromodulation, percutaneous tibial nerve stimulation, and botulinum toxin A (BTA). Antimuscarinics and beta-3 agonists have yielded partial efficacy in IC/BPS, although may help differentiate symptoms of OAB from those associated with IC/BPS. The transvaginal trigone treatment (T3) intradetrusor injection approach allows for delivery of therapeutics to the bladder without the need for a cystoscope and appears to be feasible.

CONCLUSIONS

Further research is needed to understand the pathophysiology of IC/BPS and symptom overlap with OAB, which in turn should enable the development of more personalized therapeutics.

Managing Interstitial Cystitis/Bladder Pain Syndrome in Older Adults

In this review, the current literature regarding pharmacotherapy treatment strategies available for the management of interstitial cystitis/bladder pain syndrome in older adults is addressed. The focus is on those treatments described by the American Urologic Association guidelines, organized according to clinical phenotype. Symptoms at presentation can vary with age, with older adults being more likely to experience nocturia, urinary incontinence, and Hunner's lesions than their younger counterparts. As such, treatment of interstitial cystitis/bladder pain syndrome should follow an individualized multimodal plan based on the patient's unique phenotype(s), starting with the most conservative options and escalating as needed. The side-effect profile and medication interactions should be reviewed, especially when treating older adults, requesting the aid of pharmacists or the primary care physician as needed to safely provide treatment.

Medications used to treat bladder disorders may alter effects of neuromodulation

AIMS

Neuromodulation (nerve stimulation) can produce analgesia. One form, bilateral pudendal nerve stimulation (bPNS), suppresses responses to urinary bladder distension (UBD) in hypersensitive rats. Drugs can modify this effect (eg, benzodiazepines, but not opioids, suppress bPNS effects). Prior to a clinical trial of bPNS effects on bladder pain, we felt it was prudent to survey the effects of medications commonly used in patients with bladder disorders.

METHODS

Bladder hypersensitivity was produced by neonatal bladder inflammation in rat pups coupled with a second inflammatory insult as an adult. Antimuscarinic (oxybutynin), β₃ -adrenoceptor agonist (mirabegron, CL316243), α₁ -adrenoceptor antagonist (tamsulosin), antidepressant (amitriptyline), muscle relaxing (baclofen), and sedative (propofol) agents were administered and effects of bPNS on responses to UBD assessed. bPNS consisted of bilateral biphasic electrical stimulation of the mixed motor/sensory component of the pudendal nerves. Visceromotor responses (VMRs; abdominal muscle contractile responses) were used as nociceptive endpoints.

RESULTS

Many of these drugs directly inhibited the VMRs to UBD, but only mirabegron, at the doses employed, significantly reduced inhibitory effects of bPNS. In the presence of the other drugs, bPNS continued to produce statistically significant inhibition of VMRs to UBD.

CONCLUSIONS

This study suggests that concurrent therapy with drugs used to treat bladder disorders could affect assessment of the effects of bPNS on bladder hypersensitivity. This study gives guidance to clinical trials using bPNS for the treatment of painful bladder syndromes and suggests potential clinical use of some of these medications in the treatment of these same disorders.