Solifenacin-induced small bowel pseudo-obstruction

Safety and tolerability of solifenacin in children and adolescents with overactive bladder- a systematic review

BACKGROUND

Solifenacin is an anticholinergic that is used to treat overactive bladder syndrome (OAB) in children. It is important to ascertain the safety and tolerability of solifenacin in the paediatric population as solifenacin offers an alternative, is more bladder specific, and should have less anticholinergic side effects than other therapies.

OBJECTIVE

The aim of this study is to systematically evaluate the safety and tolerability of solifenacin in children and adolescents with OAB.

STUDY DESIGN

We included studies that reported the safety and tolerability of solifenacin in children and adolescents. All study types were included. Electronic searches were conducted in Ovid MEDLINE, Ovid Embase, TRIP, CINAHL and ICTRP on the 18th of January 2022. Risk of bias was assessed with the Cochrane Risk of Bias tool 2.0 (ROB-2) for randomised controlled trials (RCTs) and the Newcastle-Ottowa scale for cohort studies.

RESULTS

A total of twelve studies including two RCTs were included in this review. Results from the meta-analysis of RCTs showed the commonest side effects were constipation (RR 3.5, 95%CI 0.9-13.7) and dry mouth (RR 3.1 95%CI 0.2-53). In terms of tolerability, the effect estimate of ceasing solifenacin due to an adverse effect was 2.7 (95%CI 0.8-9.1). Within the cohort studies, out of the 779 patients 21.7% experienced side effects. The most common side effects were constipation (6.8%) and dry mouth/lips (6.0%) and 3.5% of patients ceased solifenacin due to adverse effects. Overall, the certainty of the evidence for side effects and tolerability were very low.

DISCUSSION

The reported incidence of side effects is low, and less than reported with oxybutynin use. However, the very low certainty of the evidence means the findings should be interpreted with caution. There is limited reporting of a prolonged QTc interval on ECG. Studies that described this only had an increase of QTc from baseline and not a clinically significant prolonged QTc that resulted in arrhythmias.

CONCLUSION

Solifenacin is an alternative anticholinergic for the treatment of OAB in children. However, given the paucity of good quality data on safety and tolerability it should be used cautiously in children with close monitoring for potential side effects.

Differential effects of selective and non-selective muscarinic antagonists on gastrointestinal transit and bowel function in healthy women

BACKGROUND

The gastrointestinal effects of antimuscarinic drugs used to treat overactive bladder may be related to the selectivity of these agents for M(3) -muscarinic receptor subtypes. We compared the effects of non-selective (fesoterodine) and M(3)-selective (solifenacin) antimuscarinics on gastrointestinal transit in healthy women.

METHODS

Gastric emptying (GE), small-intestinal transit (colonic filling at 6 h), colonic transit [geometric center at 24 h (GC24; primary endpoint) and 48 h (GC48)], and bowel habits were assessed by scintigraphy and bowel diaries before and after randomization to fesoterodine 8 mg, solifenacin 10 mg, or placebo (2 : 2 : 1) for 14 days. An interim analysis to finalize sample size was conducted.

KEY RESULTS

After 60 subjects [placebo (n = 12), fesoterodine (n = 25), solifenacin (n = 23)] completed the study, the study was terminated due to a prespecified criterion (sample size ≥ 452.5 needed to provide ≥ 80% power to demonstrate superiority of fesoterodine over solifenacin in GC24). Compared with baseline, (i) placebo delayed small-intestinal, but not colonic, transit, (ii) fesoterodine significantly increased GE t(1/2) vs placebo (17.0 min; P = 0.027), and (iii) fesoterodine and solifenacin delayed small-intestinal (-36.8% and -21.8%, respectively, P < 0.001 vs placebo) and colonic transit (GC24: -0.44 and -0.49, respectively, P < 0.05 vs placebo; GC48: -0.25 and -0.65, respectively, P > 0.05 vs placebo). Solifenacin increased stool hardness from baseline (P = 0.010 for difference vs fesoterodine); stool frequency was comparable.

CONCLUSIONS & INFERENCES

In healthy women, fesoterodine had greater effects on small-intestinal transit and solifenacin had greater effects on colonic transit; the latter finding may explain why solifenacin, but not fesoterodine, increased stool hardness.