Burden and Efficacy of Anticholinergic vs Mirabegron in Overactive Bladder - A Randomized Controlled Study

Starting soon · Phase 4

Conditions studied: Overactive Bladder (OAB)

In brief

Overactive bladder (OAB) is a common condition that causes a sudden, strong need to urinate, often with frequent daytime and night-time trips to the toilet, and sometimes leaking. It can have a substantial impact on everyday quality of life. Two of the most common medicines used to treat OAB work in different ways: one type (antimuscarinics, such as solifenacin) blocks a nerve signal in the bladder, while another type (beta-3 agonists, such as mirabegron) helps the bladder muscle relax. Many people with OAB are already taking other medicines - for example, for mood, sleep, or allergies - that, without being intended for the bladder, also block that same nerve signal. The combined effect of all these medicines is called the "anticholinergic burden." Researchers want to understand whether a person's existing anticholinergic burden changes how well each OAB treatment works. The idea is that if this nerve pathway is already heavily blocked by other medicines, an antimuscarinic might be less helpful, and a treatment that works in a different way (mirabegron) might be a better choice. In this study, adults with newly diagnosed OAB who have not yet been treated will be randomly assigned to take either solifenacin or mirabegron once a day. Before starting, each participant's anticholinergic burden will be measured using a validated tool called the Drug Burden Index (DBI) and ACB. Bladder symptoms will be assessed with a standard questionnaire (ICIQ-FLUTS) and a bladder diary at the start of treatment and again after 1 and 2 months. By comparing how participants respond depending on their baseline anticholinergic burden, the study aims to learn whether measuring this burden can help doctors choose the most effective first-line treatment for each patient.

Key facts

Study ID

NCT07711808

Run by

Universidade do Porto

People needed

208

Starts

2026-07-01

Expected to finish

2027-08-01

Last updated by the study team

2026-07-17

Who can join

Age: 18 and older. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• Adult patients with a clinical diagnosis of overactive bladder syndrome.
• Treatment-naïve for OAB pharmacotherapy (no prior antimuscarinic or mirabegron for OAB).
• Able to complete the ICIQ-OAB questionnaire and a frequency-volume chart.
• Written informed consent.

You may not qualify if…

• Neurogenic bladder.
• Previous treatment with anticholinergics or mirabegron for OAB.
• History of pelvic radiotherapy or bladder cancer.
• Post-void residual volume > 200 mL.
• Clinically significant stress urinary incontinence.
• Chronic pelvic pain syndrome.
• Congenital urinary tract malformations.
• Prior bladder surgery; history of mid-urethral sling or prostate surgery.
• Contraindication to solifenacin or mirabegron.
• End-stage renal disease on dialysis.

Full record on ClinicalTrials.gov

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