Overactive bladder syndrome: considerations in pharmacotherapy and new perspectives

Transdermal delivery of oxybutynin chloride proniosomal gels for the treatment of overactive bladder

CONTEXT

Overactive bladder (OAB) is a common problem and anticholinergic drugs are first-line therapy, but they have side effects.

OBJECTIVE

Development of oxybutynin chloride (OC) proniosomal gels and analyses of its efficacy for OAB treatment.

MATERIALS AND METHODS

Phase separation coacervation was used to prepare proniosomal gels using various non-ionic surfactants, lipids, soy lecithin and isopropyl alcohol. Gels were characterized with regard to entrapment efficiency (EE), vesicle size, surface morphology (using environmental scanning electron microscopy [E-SEM]), stability, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, in vitro skin permeation, in vivo animal studies and histopathology.

RESULTS AND DISCUSSION

EE was 87-92%, vesicle size was 0.38-5.0 μm, and morphology showed some loosened pores in proniosomes after hydration. ATR-FTIR spectroscopy showed no significant shifts in peaks corresponding to OC and excipients. Most formulations exhibited >50% permeation but the cholesterol-containing formulations P3 (Span 20:Span 60 [1:1]) and P4 [Tween 20:Tween 80 (1:1)] had the highest percent cumulative permeation. P3 and P4 also showed faster recovery of cholinergic effects on salivary glands than oral formulations. P3 and P4 had pronounced therapeutic effects in reduction of urinary frequency and demonstrated improvements in bladder morphology (highly regenerative surface of the transitional epithelium).

CONCLUSION

These results suggest that OC could be incorporated into proniosomal gels for transdermal delivery in the treatment of OAB.

Changes of neuregulin-1 (NRG-1) expression in a rat model of overactive bladder induced by partial urethral obstruction: is NRG-1 a new biomarker of overactive bladder?

Background

To determine whether neuregulin-1(NRG-1) is a potential new biomarker of overactive bladder (OAB) induced by partial urethral obstruction in a rat model of OAB and to evaluate the urothelium as a therapeutic target of OAB.

Methods

Female Sprague–Dawley rats were separated into three 20-animal groups: normal, OAB, and 5-hydroxymethyl tolterodine (5-HMT)-treated OAB. In the OAB and OAB + 5-HMT groups, the urethra of each animal was partially obstructed; the OAB + 5-HMT group received intravenous 5-HMT for 3 weeks. At the conclusion of the 5-HMT dosing, the rats in each group underwent cystometrography, and the bladders were histologically evaluated. The expression of brain derived-neurotrophic factor (BDNF) and NRG-1 were evaluated in the urothelium.

Results

Compared with the control group, the OAB group showed a markedly increased bladder weight and a significant decrease in the micturition interval and volume; rats in the OAB + 5-HMT group showed decreased bladder weights and an improved micturition interval and volume. BDNF and NRG-1 were expressed at significantly higher levels in the OAB group, and were significantly reduced in the OAB + 5-HMT group compared with the control group.

Conclusions

The study suggests that NRG-1 is a potential new biomarker of OAB; the urothelium might be a therapeutic target for OAB treatment.

A novel pathway underlying the inhibitory effects of melatonin on isolated rat urinary bladder contraction

The aim of the present study was to elucidate the direct effects of melatonin on bladder activity and to determine the mechanisms responsible for the detrusor activity of melatonin in the isolated rat bladder. We evaluated the effects of melatonin on the contractions induced by phenylephrine (PE), acetylcholine (ACh), bethanechol (BCh), KCl, and electrical field stimulation (EFS) in 20 detrusor smooth muscle samples from Sprague-Dawley rats. To determine the mechanisms underlying the inhibitory responses to melatonin, melatonin-pretreated muscle strips were exposed to a calcium channel antagonist (verapamil), three potassium channel blockers [tetraethyl ammonium (TEA), 4-aminopyridine (4-AP), and glibenclamide], a direct voltage-dependent calcium channel opener (Bay K 8644), and a specific calcium/calmodulin-dependent kinase II (CaMKII) inhibitor (KN-93). Melatonin pretreatment (10^-8~10^-6 M) decreased the contractile responses induced by PE (10^-9~10^-4 M) and Ach (10^-9~10^-4 M) in a dose-dependent manner. Melatonin (10^-7 M) also blocked contraction induced by high KCl ([KCl]_ECF; 35 mM, 70 mM, 105 mM, and 140 mM) and EFS. Melatonin (10^-7 M) potentiated the relaxation response of the strips by verapamil, but other potassium channel blockers did not change melatonin activity. Melatonin pretreatment significantly decreased contractile responses induced by Bay K 8644 (10^-11~10^-7 M). KN-93 enhanced melatonin-induced relaxation. The present results suggest that melatonin can inhibit bladder smooth muscle contraction through a voltage-dependent, calcium-antagonistic mechanism and through the inhibition of the calmodulin/CaMKII system.

Triple therapy in refractory detrusor overactivity: a preliminary study

PURPOSE

To evaluate in a prospective study the impact of the "three-drug therapy" (antimuscarinic, alpha-blocker and tricyclic antidepressants) on the treatment of refractory detrusor overactivity (DO).

METHODS

Data from 27 consented patients with refractory DO were available for study. They were asked to complete a daily urinary chart and underwent urodynamic evaluation (UD) before and 60 days after treatment. Response to treatment was considered the presence of one or less involuntary detrusor contractions (IDC) on post-treatment UD. Statistical analysis was performed with Fisher and Mann-Whitney tests, besides Spearman's correlation. P values <0.05 were considered significant.

RESULTS

The mean follow-up was 15 months. The comparison of the daily urinary chart before and after treatment showed significant increase on bladder capacity and decreases on urgency, urge-incontinence and frequency. Objective data from UD showed that the mean maximum bladder capacity (MBC) ranged from 200 to 300 mL (P < 0.001) with treatment. The same trend was observed with the other UD variables. When compared to baseline, the questionnaire OAB-v8 showed significant improvement (P < 0.01). Main side effects comprised dry mouth and constipation (40%), with average scores of 5.16 and 3.08, respectively (visual scale from 0 to 10).

CONCLUSIONS

Triple therapy may be an effective, easily employed and well-tolerated option to refractory DO treatment. More studies are necessary to achieve more consistent data on the matter.

Correlation Between the Overactive Bladder Questionnaire (OAB-q) and Urodynamic Data of Parkinson Disease Patients Affected by Neurogenic Detrusor Overactivity During Antimuscarinic Treatment

INTRODUCTION

Parkinson disease (PD) patients present urinary symptoms during the course of the disease, very often suggestive of overactive bladder and sustained by neurogenic detrusor overactivity. These symptoms cause a severe lowering of quality of life determining social withdrawal and they need to be early diagnosed to restore social interaction and prevent urinary tract complications. Today overactive bladder diagnosis is easier, thanks to the availability of new investigative tools, particularly voiding questionnaires. The aim of the present study was to evaluate the reliability of the Overactive Bladder screener (OAB screener/OAB-questionnaire), a new voiding questionnaire specifically developed for the overactive bladder diagnosis in PD subjects suffering from overactive bladder symptoms. Clinical data obtained by the questionnaire were compared with urodynamic outcomes, at basal conditions and after antimuscarinic treatment, to better explorate the questionnaire reliability.

MATERIALS AND METHODS

Forty PD patients have been enrolled in the protocol, and submitted to the OAB screener, voiding diary and urodynamic investigation before and after antimuscarinic treatment. OAB-score and urodynamic parameters were statistically analyzed and compared.

RESULTS

The OAB-q well correlated with voiding diary and urodynamic data of Parkinson subjects either at baseline or after the antimuscarinic treatment. The study suggests that this clinical tool might be used for neurogenic overactive bladder diagnosis and that it seems to be a useful outcome measure for treatments of neurogenic OAB.