Mirabegron versus Solifenacin in Children with Overactive Bladder: Prospective Randomized Single-Blind Controlled Trial

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.

Mirabegron in the Management of Overactive Bladder Syndrome

Overactive bladder (OAB) negatively affects work productivity and quality of life in sufferers. Its overall impact is likely to increase as a result of increasing prevalence in an ageing population. The pathophysiology of OAB is not completely understood but the β3-adrenoceptor, which is highly expressed in the urinary bladder, is thought to be important for mediating human detrusor relaxation during the storage phase. Clinical trial results have demonstrated that mirabegron, a selective β3-adrenoceptor agonist offers substantial clinical efficacy and good adherence rates over 12 months. Furthermore, due to its different mechanism of action, it is likely to offer a favourable tolerability profile when compared with antimuscarinic agents, resulting in improved persistence over long-term treatment. Finally, from a health economic perspective, despite its higher drug acquisition cost, mirabegron has been found to be cost-effective, owing to the greater increase in quality-adjusted-life-years gained, when compared to antimuscarinic medications. The PubMed database was searched for English language articles published between 1 January 2005 to 31 January 2022, on the subject of mirabegron. Search terms included "mirabegron", "overactive bladder", "β3-adrenoceptor agonist", "urinary incontinence". This review summarises the evidence for mirabegron as a treatment option for the management of OAB.

Comprehensive overview of the available pharmacotherapy for the treatment of non-neurogenic overactive bladder in children

INTRODUCTION

Overactive bladder (OAB) is a chronic condition highly prevalent in children and causing bothersome symptoms. It is often associated with deterioration of quality of life and can be devastating for patients and their families. Prompt initiation of conservative measures should be the backbone of treatment. When conservative management fails, pharmacological options must be considered.

AREAS COVERED

Although antimuscarinics are considered the mainstay of pharmacological treatment for OAB, only two agents are currently approved for the pediatric population. Oxybutynin and propiverine are discussed in this review, as well as other non-approved antimuscarinic agents and β3-agonists with related literature to substantiate their use in children. Dual therapy along with medication adherence and persistence is also discussed.

EXPERT OPINION

The treatment of OAB in children is demanding and one must rely on a structured, stepwise approach to achieve success. Discussing conservative measures and prescribing medication is not enough. Clinicians should actively involve children and their families in the treatment, set realistic expectations, and closely monitor side effects and medication adherence to ensure maximal efficacy.

The Effectiveness in Activating M-Type K+ Current Produced by Solifenacin ([(3R)-1-azabicyclo[2.2.2]octan-3-yl] (1S)-1-phenyl-3,4-dihydro-1H-isoquinoline-2-carboxylate): Independent of Its Antimuscarinic Action

Solifenacin (Vesicare^®, SOL), known to be a member of isoquinolines, is a muscarinic antagonist that has anticholinergic effect, and it has been beneficial in treating urinary incontinence and neurogenic detrusor overactivity. However, the information regarding the effects of SOL on membrane ionic currents is largely uncertain, despite its clinically wide use in patients with those disorders. In this study, the whole-cell current recordings revealed that upon membrane depolarization in pituitary GH₃ cells, the exposure to SOL concentration-dependently increased the amplitude of M-type K⁺ current (I_K(M)) with effective EC₅₀ value of 0.34 μM. The activation time constant of I_K(M) was concurrently shortened in the SOL presence, hence yielding the K_D value of 0.55 μM based on minimal reaction scheme. As cells were exposed to SOL, the steady-state activation curve of I_K(M) was shifted along the voltage axis to the left with no change in the gating charge of the current. Upon an isosceles-triangular ramp pulse, the hysteretic area of I_K(M) was increased by adding SOL. As cells were continually exposed to SOL, further application of acetylcholine (1 μM) failed to modify SOL-stimulated I_K(M); however, subsequent addition of thyrotropin releasing hormone (TRH, 1 μM) was able to counteract SOL-induced increase in I_K(M) amplitude. In cell-attached single-channel current recordings, bath addition of SOL led to an increase in the activity of M-type K⁺ (K_M) channels with no change in the single channel conductance; the mean open time of the channel became lengthened. In whole-cell current-clamp recordings, the SOL application reduced the firing of action potentials (APs) in GH₃ cells; however, either subsequent addition of TRH or linopirdine was able to reverse SOL-mediated decrease in AP firing. In hippocampal mHippoE-14 neurons, the I_K(M) was also stimulated by adding SOL. Altogether, findings from this study disclosed for the first time the effectiveness of SOL in interacting with K_M channels and hence in stimulating I_K(M) in electrically excitable cells, and this noticeable action appears to be independent of its antagonistic activity on the canonical binding to muscarinic receptors expressed in GH₃ or mHippoE-14 cells.