Gender specificity of tolterodine on micturition and the diurnal variation of urine production of the conscious rat

Gender specific pharmacokinetic and pharmacodynamic considerations for antimuscarinic drugs for overactive bladder treatment

Introduction: Overactive bladder (OAB) has a heterogeneous presentation that varies between individuals and by gender. Treatment with antimuscarinic medications is standard first line pharmacotherapy for most patients with OAB. However, gender specific differences in the pharmacokinetics and pharmacodynamics of antimuscarinic therapy are often overlooked and not discussed.Areas covered: This review will explore differences by gender between the presentation and treatment of OAB. We will discuss the differences between sexes in terms of lower urinary tract anatomy, muscarinic receptors, and hormone variation. The effect of antimuscarinics on males and females as well as adherence and persistence patterns will be reviewed in order to fully review all available literature on the gender specific pharmacokinetic and pharmacodynamic considerations for antimuscarinic use in the treatment of OAB.Expert opinion: Despite extensive research into various antimuscarinic formulations and therapeutic regimens for the treatment of OAB, identification of gender specific pharmacokinetic and pharmacodynamics considerations remains scant. As our knowledge and understanding of OAB, muscarinic receptors, and antimuscarinic medications evolve, we will hopefully be better able to understand and implement gender-specific and genomic-sprecific treatment regimens and considerations for improved clinical outcomes.

TRK-380, a novel selective human β3-adrenoceptor agonist, ameliorates formalin-induced pollakiuria in rats and carbachol-induced bladder contraction in dogs

OBJECTIVE

To investigate the effects of TRK-380, a selective β3-adrenoceptor (β3-AR) agonist, on voiding behavior in rats with pollakiuria and on carbachol (CCh)-induced bladder contraction in dogs.

METHODS

The voiding behavior of female Sprague Dawley rats was recorded continuously with a balance. Rats were intravesically pretreated with 2.5% formalin under isoflurane anesthesia. The next day, the effect of TRK-380 (7.5-30 mg/kg, orally) or tolterodine, an antimuscarinic drug (3.75-15 mg/kg, orally), on the voiding frequency was evaluated. In another experiment, male beagle dogs were anesthetized with pentobarbital, CCh (3 μg/kg, intravenously) was administered to them, and the effect of TRK-380 (0.1 or 0.3 μg/kg/minute, intravenously infusion) on CCh-induced bladder contraction was evaluated.

RESULTS

Rats treated with formalin showed a significant increase in the voiding frequency compared with the sham group, and the increase in it was significantly and dose-dependently suppressed by TRK-380 at doses of ≥15 mg/kg. In contrast, tolterodine did not lead to a significant change in the voiding frequency even at the highest dose. In dogs, CCh-induced bladder contraction was dose-dependently suppressed by TRK-380; the plasma concentration required for 30% suppression of the CCh-induced bladder contraction (30% relaxation) was 4.90 ng/mL.

CONCLUSION

This study indicated that TRK-380 ameliorated pollakiuria, which was resistant to an antimuscarinic drug, and that it also suppressed the bladder contraction induced by cholinergic stimulation in dogs, whose bladder relaxation is known to be predominantly mediated by β3-ARs, as in humans. These data strengthen the therapeutic potential of β3-AR for the treatment of overactive bladder.

Antidiuretic effect of antimuscarinic agents in rat model depends on C-fibre afferent nerves in the bladder

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Antichollnergic agents are anticipated to diminish storage symptoms, as well as nocturia. Nevertheless, the effect of this treatment on polyuria related to nocturia is not clear. By subgroup analysis of the data set from a phase III clinical trial of antimuscarinic agent for OAB patients in Japan, imidafenacin was found to improve nocturia with a reduction in nocturnal polyuria. This study adds the effects and underlying mechanism of antimuscarinic agents decreasing urine production through inhibition of C-fibre in the bladder of water-leaded rats.

OBJECTIVE

To evaluate the effects and underlying mechanisms of antimuscarinic agents used to decrease in urine production in water-loaded rats.

SUBJECTS AND METHODS

Urine production was measured using a cystostomy catheter in female Sprague-Dawley rats every 2 h. The effect of the antimuscarinic agents atropine, tolterodine and imidafenacin on urine production was investigated under water-loaded conditions, which were induced by i.p. injection of 15 mL saline. Blood samples were collected to determine the levels of antidiuretic hormone (ADH), aldosterone (ALD), atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) before, and 2 and 8 h after, antimuscarinic agent administration. To induce desensitization of C-fibre afferent nerves, resiniferatoxin (RTX)was injected s.c. or intravesically 2 days before experiments.

RESULTS

Urine production increased and reached its maximum 2 h after 15 mL saline injection. Imidafenacin and tolterodine decreased urine production in water-loaded rats, but ADH, ALD, ANP and BNP levels were not different between imidafenacin-treated and vehicle-treated rats. The inhibitory effect on urine production was not found in RTX-treated rats. Atropine did not reduce urine production.

CONCLUSION

These results suggest that antimuscarinic agents decrease urine volume through C-fibres in the bladder; thus, antimuscarinics with inhibitory effects on C-fibres could be beneficial for nocturia with nocturnal polyuria.

Sex differences in the physiology and pharmacology of the lower urinary tract

Sexual dimorphism is not only noticed in the prevalence of many diseases, but also in multiple physiological functions in the body. This review has summarized findings from published literature on the sex differences of the pathophysiology and pharmacology of the lower urinary tract (LUT) of humans and animals. Sex differences have been found in several key areas of the LUT, such as overactive bladder, expression and function of neurotransmitter receptors in the bladder and urethra, and micturition patterns in humans and animals. It is anticipated that this review will not only evoke renewed interest for further research on the mechanism of sex differences in the pathophysiology of the LUT (especially for overactive bladder), but might also open up the possibilities for gender-based drug development by pharmaceutical industries in order to find separate cures for men and women with diseases of the LUT.

Water intake and bladder cancer risk in Los Angeles County

The overall evidence of an association between fluid intake and bladder cancer is not entirely consistent. We examined the fluid intake-bladder cancer relationship in the Los Angeles bladder cancer case-control study. A total of 1,586 cases and their age-, sex-, and race-matched neighborhood controls were interviewed in-person from 1987 to 1999. Information on total fluid intake was derived from the consumption of specific fluids including water, coffee, tea, alcohol, milk, juice, hot chocolate and soda. Total fluid intake was not associated with bladder cancer. Daily water intake was associated with a slight decrease in bladder cancer risk, with the protection more pronounced among women (p for trend = 0.039) than among men (p for trend = 0.62). Compared to drinking <1 glass of water per day, drinking > or =6 glasses/day was associated with 0.91 (95% confidence interval, 0.67-1.22) times the risk of bladder cancer among all subjects, 0.94 (0.67-1.32) times the risk among men, and 0.69 (0.36-1.33) times the risk among women. The water intake-bladder cancer association also seemed to be modified by daytime urination frequency with significant inverse association among subjects who urinated > or =6 times/day (p for trend = 0.015), but not among those who urinated less frequently. Similarly, the protection from water intake was confined to women who did not experience nocturia and to men who did. Results from our study suggest that water intake may be associated with a slight reduction in bladder cancer risk.

Number of Daytime Micturitions and Volume Voided per Micturition in the Evaluation of Efficacy of Drugs for Overactive Bladder: Findings from Randomized Clinical Trials

OBJECTIVE

To analyze the relationship between mean volume voided per micturition and number of daytime micturitions.

METHODS

We reviewed data from randomized clinical trials on the medical treatment of overactive bladder published in the international literature between 1997 and 2004. Fourteen studies including data on these two parameters were identified.

RESULTS

Six studies compared tolterodine with placebo, two tolterodine and oxybutynin with placebo, two tolterodine with oxybutynin, two solifenacin and tolterodine with placebo, one oxybutynin CR with oxybutynin IR, and one different doses of solifenacin. The correlation between the percent change in the mean voided volume and in the number of daytime micturitions was assessed using the Spearman rank correlation coefficient (r), with r=-0.67 for all the studies. For groups of patients treated with each drug, we found r=-0.09 for oxybutynin, r=-0.59 for tolterodine, r=-0.85 for solifenacin, and r=-0.34 for placebo.

CONCLUSION

The results of this analysis suggest that in the evaluation of the efficacy of a drug for overactive bladder, the mean volume voided per micturition may be a useful measure of efficacy.

Suitability of 5/6 nephrectomy (5/6NX) for the induction of interstitial renal fibrosis in rats--influence of sex, strain, and surgical procedure

Chronic renal failure (CRF) is a serious clinical problem and currently there are no adequate therapeutic strategies for treatment. Many possible treatment strategies have been tested in rats with CRF induced by subtotal nephrectomy. However, reports in the literature concerning the consequences of this procedure on rat kidney function are contradictory. For instance, such an intervention in male Sprague-Dawley rats apparently initiates the development of interstitial renal fibrosis, while in our similar studies on female Wistar rats (HW) there was minimal renal fibrosis. Therefore, we carried out experiments in adult rats to investigate the long-term consequences of 5/6 nephrectomy (5/6NX) in relation to (1) sex, (2) strain, and (3) two methods of surgical ablation. Ten weeks after 5/6NX, body weight gain, systolic blood pressure, creatinine clearance, and urinary protein were measured, along with renal hydroxyproline concentration determinations to assess the deposition of extracellular matrix. Also, light microscopic investigations were done to characterize renal damage. The functional parameters clearly indicated the development of CRF, while morphologic investigations showed only moderate fibrotic areas containing atrophic tubules and lymphocytic infiltrates. However, 45-60% of glomeruli were sclerotic. In summary, 5/6NX, using either method of partial nephrectomy, induces signs of moderate glomerulonephritis preferentially in female HW rats. Thus 5/6NX in female HW rats can be recommended as a suitable model in the induction of renal fibrosis.

A randomized, double-blind, parallel-group comparison of controlled- and immediate-release oxybutynin chloride in urge urinary incontinence

OBJECTIVE

The aim of this study was to evaluate the efficacy and safety of a new PO controlled-release (CR) QD oxybutynin tablet relative to PO immediate-release (IR) TID oxybutynin in patients with urge urinary incontinence (UI).

METHODS

In this multicenter, double-blind trial, patients with UI (> or = 7 episode/wk) and frequency (> or = 8 micturitions/d) were randomized to CR or IR oxybutynin for 6 weeks. Patients initiated treatment at 15 mg/d and the dose was adjusted (in 5-mg/d increments) over 2 weeks according to tolerability. Efficacy (UI episodes, voids, absorbent pads used, urgency, and volume voided per micturition) was assessed during the final 2 weeks of treatment. Tolerability was assessed by evaluating adverse events and treatment withdrawals.

RESULTS

Of the 125 patients randomized, 94 (75%) were evaluable for efficacy; tolerability was assessed in all patients. In the CR group, 48 patients (91%) were women and 5 (9%) were men; the mean (SD) age was 58.0 (12.4) years (range, 26-78 years). In the IR group, 37 patients (90%) were women and 4 (10%) were men; the mean (SD) age was 60.6 (14.8) years (range, 26-83 years). Both CR and IR oxybutynin significantly reduced the mean number of total UI episodes per week (both P < 0.001 vs baseline). Both treatments produced equivalent reductions in mean voiding frequency and urinary urgency (all P < 0.001 vs. baseline). Significantly more patients rated CR oxybutynin tolerable on the initial dose of 15 mg/d (P = 0.020) and completed the study at a dose of > or = 15 mg/d (P = 0.018). Dry mouth was the most common adverse event, reported by 68% and 72% of patients in the CR and IR oxybutynin groups, respectively.

CONCLUSIONS

Among the patients with urge UI included in this study, CR oxybutynin was as effective as IR oxybutynin for improving primary symptoms, with the additional benefit of QD administration.