Gabapentin: a novel drug as add-on therapy in cases of refractory overactive bladder in children

Personalised 3D-Printed Mucoadhesive Gastroretentive Hydrophilic Matrices for Managing Overactive Bladder (OAB)

Overactive bladder (OAB) is a symptomatic complex condition characterised by frequent urinary urgency, nocturia, and urinary incontinence with or without urgency. Gabapentin is an effective treatment for OAB, but its narrow absorption window is a concern, as it is preferentially absorbed from the upper small intestine, resulting in poor bioavailability. We aimed to develop an extended release, intragastric floating system to overcome this drawback. For this purpose, plasticiser-free filaments of PEO (polyethylene oxide) and the drug (gabapentin) were developed using hot melt extrusion. The filaments were extruded successfully with 98% drug loading, possessed good mechanical properties, and successfully produced printed tablets using fused deposition modelling (FDM). Tablets were printed with varying shell numbers and infill density to investigate their floating capacity. Among the seven matrix tablet formulations, F2 (2 shells, 0% infill) showed the highest floating time, i.e., more than 10 h. The drug release rates fell as the infill density and shell number increased. However, F2 was the best performing formulation in terms of floating and release and was chosen for in vivo (pharmacokinetic) studies. The pharmacokinetic findings exhibit improved gabapentin absorption compared to the control (oral solution). Overall, it can be concluded that 3D printing technology is an easy-to-use approach which demonstrated its benefits in developing medicines based on a mucoadhesive gastroretentive strategy, improving the absorption of gabapentin with potential for the improved management of OAB.

Does gabapentin impact response to anticholinergics for overactive bladder?

INTRODUCTION AND HYPOTHESIS

It is unknown whether gabapentin modulates the therapeutic effect of anticholinergics (AC) in patients with overactive bladder. We hypothesized that pre-existing gabapentin use would improve response rates in these patients.

METHODS

Female patients treated with AC between 2010-2018 were identified. Data were collected on gabapentin use, indication, dose and duration of use as well as demographic and clinical characteristics. Patients were stratified by those that only took AC and those that took both AC and gabapentin ("combination therapy"). Response was determined through chart review. Descriptive statistics were expressed as medians and interquartile ranges (IQR). Pairwise analysis was performed using Wilcoxon rank-sum. Multivariable logistic regression was used to identify independent variables predicting response. A subgroup analysis was performed in patients with chronic pain disorders.

RESULTS

Seven hundred fifty-six subjects met all criteria; 16.5% (n = 125) were on combination therapy. Those taking gabapentin were more likely to have chronic (49.6% vs. 22.5%, p < 0.001) or neuropathic pain (25.6% vs. 9.4%, p < 0.001) and to use narcotics (41.6% vs. 15.5%, p < 0.001). Patients taking combination therapy were not more likely to improve compared to patients taking AC alone (41.6% vs. 47.7%, p = 0.211), which persisted after adjusting for confounders (aOR = 1.02, 95% CI: 0.63-1.65). In the 182 patients with chronic pain, those receiving combination therapy were more likely to respond than those taking AC alone (35.2% vs. 21.9%, p = 0.0015), although this did not persist after adjusting for confounders (aOR = 1.15, 95% CI: 0.70-1.90).

CONCLUSIONS

Pre-existing gabapentin use does not seem to influence response to AC in patients with overactive bladder.

Effects of Preoperative Gabapentin on Clinical Outcomes After Outpatient Midurethral Sling Placement

OBJECTIVES

This study aimed to evaluate transient urinary retention in women undergoing outpatient midurethral sling placement who received preoperative gabapentin (treated) versus those who did not (untreated). Secondary outcomes included unexpected admission rates, analgesic usage, time to discharge, and pain.

METHODS

This was a retrospective cohort study including women who underwent outpatient midurethral sling placement from 2015 to 2019. Exclusion criteria included suprapubic catheter placement, planned overnight admission, abnormal preoperative postvoid residual volume, and prolonged postoperative catheterization. Logistic regression was performed to evaluate gabapentin usage and urinary retention after adjusting for patient characteristics.

RESULTS

Three hundred two women met the inclusion criteria, with 19.5% experiencing urinary retention after midurethral sling placement. Women older than 65 years were more likely to have urinary retention than those aged 18-65 years (29.8% vs 17.6%, P = 0.054). Of treated participants, 26% had urinary retention versus 18% of untreated participants (P = 0.162). Adjusting for age, parity, pain, operative time, blood loss, sling type, analgesic, scopolamine patch, or hemostatic agent use, treated participants had 72% higher odds of urinary retention (adjusted odds ratio, 1.72; 95% confidence interval, 0.88-3.38; P = 0.113). There was no difference in unexpected admission, analgesic usage, time to discharge, or pain between groups.

CONCLUSIONS

One of 5 women had urinary retention after outpatient midurethral sling placement. Although no statistically significant difference was found in urinary retention between groups, the odds of urinary retention in the treated group were increased. Because there was no difference in pain, analgesic usage, or time to discharge between groups, investigation regarding gabapentin use for outpatient urogynecologic surgery is needed.

Gabapentin add-on therapy for patients with spinal cord injury associated neurogenic overactive detrusors that are unresponsive to combined anticholinergic and beta-3 adrenergic therapy

Introduction

Spinal cord injury is a major cause of lifelong morbidity and functional micturition problems. Some patients are refractory to the available therapeutics, even when used in combination. In this paper we report our results of using gabapentin as an add-on treatment in refractory overactive detrusor cases secondary to spinal cord injury.

Material and methods

A total of 27 patients who had a spinal cord injury between the levels of the second thoracic and fourth lumbar vertebrae and had an overactive detrusor in urodynamic studies were included in this retrospective study. The patients were selected due to the fact that they also had not responded to a combination of an anticholinergic and mirabegron and had neuropathic pain. Gabapentin treatment was added to the previous therapy. Demographics, previous treatments, chronic conditions, urodynamic findings, clinical and urodynamic responses are reported in this paper.

Results

We observed a response to treatment in the urodynamic studies of 11 patients (40.17%), in terms of decreased detrusor contractions, maximal detrusor pressure, and the number of incontinence episodes. Sixteen patients did not respond to the gabapentin add-on therapy and were referred for Botulinum toxin injections to the bladder.

Conclusions

Gabapentin add-on therapy can be considered as a third or further option, before Botulinum toxin injection, for patients with neurogenic overactive detrusor who did not respond to the combination of anticholinergics and mirabegron. The approved usage of gabapentin for neurogenic pain justifies its usage in this area. In our selected patient group, who had not responded to the combination therapy, we observed a clinical benefit in one-third of the patients.

The effects of pregabalin, solifenacin and their combination therapy on ureteral double-J stent-related symptoms: A randomized controlled clinical trial

Background:

Many medical therapies have been tested to deal with urinary stent-related symptoms (USRS). Several preventive and pharmaceutical methods have been already used for better compatibility of stents. However, the existing evidence for pharmacological treatment is still controversial. This study aims to evaluate the effects of pregabalin, solifenacin, and combination therapy on ureteral double-J stent-related symptoms following ureteroscopy and transureteral lithotripsy (TUL).

Materials and methods:

In a randomized controlled clinical trial, from November 2017 to March 2019, 256 patients who underwent ureteroscopy were enrolled. Patients were randomly divided into four groups including: group A received pregabalin 75mg BID (twice daily), group B received solifenacin 5mg orally once daily, group C received combination of pregabalin and solifenacin and the group D (control) given no drugs.

Results:

One hundred and fifty-one (58.9%) males and 101 (41.1%) females were enrolled in this study with a mean age of 43.47±7 (p=0.32, p=0.67). USSQ domains score such as urinary symptoms, pain, general condition, work performance, sexual matters and additional problems were significantly differenced during second and fourth week of follow-up among study groups (p <0.0001).

In Tukey's multiple comparison test, urinary symptoms (p=0.735), pain (p=0.954) and sexual matters (p=0.080) in second week and work performance in forth week in group B was not significantly better than group D. Only group C in all indexes of USSQ showed significantly beneficial effects over group D (p <0.0001).

Conclusion:

Combination therapy of pregabalin and solifenacin has a significant effect on stent-related symptoms and is preferred over monotherapy of the respected medications.

Gabapentin reduces painful bladder hypersensitivity in rats with lipopolysaccharide-induced chronic cystitis

Although interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic condition causing bladder pain and urinary symptoms, effective treatments have not been established. The aim of this study was to adapt a chronic cystitis model in rats using lipopolysaccharide (LPS), which reflects IC/BPS pathology, and characterize the model's histological and behavioral effects. Furthermore, we investigated the effect of an α2 δ subunit ligand, gabapentin (GBP), on bladder hypersensitivity of rats with chronic cystitis. Cystitis models were created by repeated intravesical injections of LPS. In the histological examination, the LPS-injected group had greater inflammatory response, fibrosis, and abnormally thick re-epithelialization. In the LPS-injected group, LPS prompted hyperalgesia in both the lower abdomen and hind paw regions after day 1 of the first injection compared with the saline-injected controls, without any recovery for 21 days at least. During cystometry, the LPS-injected group showed bladder hyperactivity at all times. Systemic administration of GBP reduced cystitis-related pain due to chronic inflammation and reduced the increased frequency of voiding in the LPS-injected group. These results suggest that repeated intravesical injections of LPS induce long-lasting bladder inflammation, pain, and overactivity in rats, while GBP is effective in the management of those symptoms in this chronic cystitis model. The current study identifies a relatively simple method to develop an animal model for chronic cystitis and provides evidence that GBP may be an effective treatment option for patients with IC/BPS.

Investigations of urethral sphincter activity in mice with bladder hyperalgesia before and after drug administration of gabapentin

PURPOSE

This study investigated the effect of gabapentin on lower urinary tract dysfunction focusing on urethral activities and cystitis-induced hyperalgesia in a mouse model of painful bladder syndrome/interstitial cystitis (PBS/IC). The electromyography (EMG) of external urethral sphincter (EUS) was difficult to obtain, but contained useful information to examine the drug effect in mice.

METHODS

Female C57BL/6J mice were intraperitoneally (ip) administration with either saline or 200 mg/kg of cyclophosphamide (CYP) 48 h before experimental evaluation. Cystitis mice were treated with administration of gabapentin (25 or 50 mg/kg, ip). Cystometry and EUS EMG were obtained and analyzed during continuous bladder infusion. The visceral pain-related visceromotor reflex (VMR) was recorded in response to isotonic bladder distension.

RESULTS

Cystitis mice showed shorter inter-contraction intervals and increased occurrence of non-voiding contractions during bladder infusion, with increased VMR during isotonic bladder distension, indicating cystitis-induced bladder hyperalgesia. Gabapentin (50 mg/kg) suppressed effects of CYP on cystometry, but not on EUS EMG activity, during bladder infusion. The effect on urodynamic recordings lasted 4 h. VMR was significantly reduced by gabapentin.

CONCLUSIONS

The present study showed that CYP-induced cystitis in mice is a model of visceral hyperalgesia affecting detrusor contractions, not urethral activations. The technique of using EUS EMG to evaluate the drug effects on urethral activities is novel and useful for future investigations. Gabapentin can be as a potential treatment for detrusor overactivity and PBS/IC.

Role of gabapentin and anticholinergics in management of neurogenic bladder after repair of spina bifida - a randomized controlled study

BACKGROUND

Anticholinergics are well established in the management of neurogenic bladders. However, some patients do have sub-optimal response or severe side effects. This study is designed to assess and compare efficacy of gabapentin with oxybutynin in neurogenic bladders after surgery for spina bifida.

METHODS

Patients were randomized into three groups after urodynamic studies and started on oxybutynin, gabapentin, and combination of both, respectively. Thorough clinical and urodynamic reassessment was done at 6months and one year after starting treatment.

RESULTS

Forty-four patients (3-19years) were studied. Improvement was noted in symptoms as well as urodynamic parameters in all groups. Maximal improvement of symptom score was with combination of drugs at 1year. In urodynamic studies, compliance, pressures, and capacity showed improvement, which was significant between the groups at both six months and 1year for bladder pressures and volume. Improvement in compliance though marked was not statistically significant. Best response was seen in group receiving both drugs. Gabapentin was better tolerated than oxybutynin.

CONCLUSION

Gabapentin is a good alternative to oxybutynin for management of neurogenic bladder, both as monotherapy and as an add-on therapy. It has potential application in patients with inadequate response to anticholinergics.

LEVEL OF EVIDENCE

prospective competitive treatment study - level II.

Pioneering drugs for overactive bladder and detrusor overactivity: Ongoing research and future directions

The ongoing research on pioneering drug candidates for the overactive bladder (OAB) aimed to overcome the limitations of currently licensed pharmacotherapies, such as antimuscarinics, β3-adrenergic agents, and botulinum neurotoxin, has been reviewed performing a systematic literature review and web search. The review covers the exploratory agents alternative to available medications for OAB and that may ultimately prove to be therapeutically useful in the future management of OAB patients based on preclinical and early clinical data. It emerges that many alternative pharmacological strategies have been discovered or are under investigation in disease-oriented studies. Several potential therapeutics are known for years but still find obstacles to pass the clinical stages of development, while other completely novel compounds, targeting new pharmacological targets, have been recently discovered and show potential to translate into clinical therapeutic agents for idiopathic and neurogenic OAB syndrome. The global scenario of investigational drugs for OAB gives promise for the development of innovative therapeutics that may ultimately prove effective as first, combined or second-line treatments within a realistic timescale of ten years.

Management of refractory OAB in the non-neurogenic patient

Overactive bladder (OAB) is one of the most common bothersome urological diseases. It also has a negative economic impact. Pathophysiology entails changes in neurogenic and myogenic factors, as well as urinary biomarkers such as nerve growth factor (NGF) and prostaglandins (PGs). With symptoms from OAB-Dry to OAB-Wet, the urodynamic pattern of OAB bladder is often characterized by idiopathic detrusor overactivity with lower threshold of sensation, diminished compliance and capacity. Treatment ranges from a combination of behavioral modifications (BM)/ pelvic floor muscle training (PFMT) to combinations of antimuscarinics, Botox injection, nerve stimulation and augmentation cystoplasty. Herein, a contemporary review on the different aspects of management of refractory OAB in patients without neuropathic disorders is presented.

Innovative pharmacotherapies for women with overactive bladder: where are we now and what is in the pipeline?

INTRODUCTION AND HYPOTHESIS

The impressive prevalence of overactive bladder (OAB) and the relevant limitations of current treatments urge the need for novel therapeutic approaches.

METHODS

A systematic literature and web search was performed to identify investigational drugs that entered the early and late phases of clinical development for women with OAB symptoms.

RESULTS

Approved pharmacological therapies for OAB (antimuscarinics, beta-3 agonists, and botulinum toxin) are evolving with the development of alternative administration methods, combination strategies, and novel compounds, expected to improve effectiveness, bladder selectivity, and dose flexibility. A wealth of investigational compounds, developed with both public and companies' indoor nonclinical disease-oriented studies, entered the early and late stages of clinical development in the last decade. Most non-anticholinergic compounds in ongoing clinical trials target central and peripheral neurotransmitter receptors involved in neurological modulation of micturition, nonadrenergic-noncholinergic mechanisms, cyclic nucleotide metabolism, different subtypes of ion channels or peripheral receptors of prostaglandins, vanilloids, vitamin D3, and opioids. Fascinating advances are ongoing also in the field of genetic therapy.

CONCLUSIONS

New pharmaceutical formulations and drug combinations are expected to be available in the next decade in order to overcome the limitations of current drugs for OAB. Although proof-of-concept, patient-oriented studies yielded disappointing results for several tentative drugs, a lot of clinical research is ongoing that is expected to provide clinicians with novel therapeutic agents in the near future.