The nonobstructed patient population comprises several groups that are functionally distinct while symptomatically similar. Thus, treatment of nonobstructed cases based on symptoms may lead to inappropriate pharmacological therapy and unsuccessful clinical outcomes.
To evaluate the role of bladder afferent fibers in the hypogastric nerves (HGN) in modulation of the micturition reflex induced by chemical bladder irritation, voiding behavior, continuous cystometry, and spinal c-fos expression following intravesical acetic acid instillation were investigated in rats with or without HGN transection. Voiding behavior and continuous cystometry were examined in unanesthetized conscious rats. Following chemical bladder irritation, a significant increase in urinary frequency associated with a marked decrease in the voided volume per micturition, was noted in control rats with the intact HGN, but not in HGN-transected rats. Continuous infusion of acetic acid in control rats elicited irritative bladder responses characterized by a marked decrease in the intercontraction interval and a marked increase in maximal vesical pressure, both of which were absent in capsaicin-desensitized rats. HGN transection prevented the decrease in the intercontraction interval but not an increase in maximal vesical pressure following chemical bladder irritation. Compared with saline infusion, acetic acid infusion caused a significant increase in c-fos expression at L(1) and L(6) of the spinal cord, and HGN transection significantly reduced c-fos expression in the dorsal horn of the spinal cord at L(1) but not at L(6). These results suggest that capsaicin-sensitive bladder afferent fibers in the HGN, which travel through the rostral lumbar spinal cord, have a role in urinary frequency caused by chemical bladder irritation.
To evaluate the efficacy and safety of intravesical KRP-116D, 50% dimethyl sulfoxide solution compared with placebo, in interstitial cystitis/bladder pain syndrome patients. Methods: Japanese interstitial cystitis/bladder pain syndrome patients with an O'Leary-Sant Interstitial Cystitis Symptom Index score of ≥9, who exhibited the bladder-centric phenotype of interstitial cystitis/bladder pain syndrome diagnosed by cystoscopy and bladder-derived pain, were enrolled. Patients were allocated to receive either KRP-116D (n = 49) or placebo (n = 47). The study drug was intravesically administered every 2 weeks for 12 weeks. Results: For the primary endpoint, the change in the mean O'Leary-Sant Interstitial Cystitis Symptom Index score from baseline to week 12 was À5.2 in the KRP-116D group and À3.4 in the placebo group. The estimated difference between the KRP-116D and placebo groups was À1.8 (95% confidence interval À3.3, À0.3; P = 0.0188). Statistically significant improvements for KRP-116D were also observed in the secondary endpoints including O'Leary-Sant Interstitial Cystitis Problem Index score, micturition episodes/24 h, voided volume/micturition, maximum voided volume/micturition, numerical rating scale score for bladder pain, and global response assessment score. The adverse drug reactions were mild to moderate, and manageable. Conclusions: This first randomized, double-blind, placebo-controlled trial shows that KRP-116D improves symptoms, voiding parameters, and global response assessment, compared with placebo, and has a well-tolerated safety profile in interstitial cystitis/ bladder pain syndrome patients with the bladder-centric phenotype.
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