Effects of β3 Agonists and Anticholinergic Drugs on Defecation in Patients With Overactive Bladder

In clinical practice, constipation is one of the most frequent adverse events caused by drugs for overactive bladder (OAB). The occurrence of constipation greatly deteriorates the patient's quality of life. The aim of the study was to evaluate and compare the effects of three commonly used β3 agonists and anticholinergic drugs on the defecation status in patients with OAB.

We retrospectively reviewed the defecation status in patients who received mirabegron, solifenacin, or fesoterodine for OAB. We evaluated changes in the (a) urological parameters using the OAB symptom score (OABSS) and (b) defecation status using the Bristol Stool Form Scale (BSFS) and constipation scoring system (CSS) following 12 weeks of drug administration.

We analyzed data from 165 patients (mirabegron=56, fesoterodine=52, and solifenacin=57). The solifenacin group showed a significant decrease in BSFS (from 3.2±1.0 at baseline to 2.3±12 post-treatment) and an increase in hardened stools (p<0.001). Elimination worsened as assessed by almost all items, and the total modified CSS scores worsened significantly from 4.8±2.6 points at baseline to 8.O±4.8 points after 12 weeks of solifenacin treatment (p<0.001). The mirabegron group showed no changes in any of the CSS items. In the fesoterodine group, the CSS scores for "completeness" and "assistance" increased significantly after treatment (p<0.001 and p=0.013, respectively).

All three drugs were effective for OAB. Mirabegron had almost no effect on constipation; fesoterodine, an anticholinergic drug, also had hardly any effect on defecation.