Effects of intravenously and orally administered solifenacin succinate (YM905) on carbachol-induced intravesical pressure elevation and salivary secretion in mice

Suppression of Inflammatory and Fibrotic Signals by Cinnamon (Cinnamomum cassia) and Cinnamaldehyde in Cyclophosphamide-Induced Overactive Bladder in Mice

Cinnamon (Cinnamomum cassia) is a well-known traditional Chinese medicine used to treat nocturia by tonifying and warming the kidney. Our recent clinical study found that overactive bladder (OAB) patients treated with cinnamon powder (CNP) patches exhibited significantly ameliorated OAB symptoms without significant side effects, but the mechanism of action is unclear. To explore the beneficial effects and action mechanisms of CNP and its major active component cinnamaldehyde (CNA) in an OAB-related murine model, cyclophosphamide- (CYP-) induced OAB injury was performed on male ICR mice in the presence or absence of CNP and CNA, as well as solifenacin, a clinical drug for OAB as a reference. Twenty-four-hour micturition patterns (frequency of urination and volume of urine per time), as well as histopathological examination, immunohistochemistry (IHC), and Western blotting of the bladder, were analyzed for mechanism elucidation. Administration of CYP (300 mg/kg, i.p.) induced typical OAB pathophysiological changes, including increased frequency of urination and reduced volume of urine. CYP-induced mice displayed strong edema of the bladder and hemorrhagic cystitis, accompanied by loss of normal corrugated folds and decreased muscarinic receptors (M2/M3) in the urothelium, and disordered/broken structures of the lamina propria and detrusor. These changes were correlated with increased leukocyte (CD11b) infiltration colocalized with inflammatory (pp65 NFκB, macrophage migration inhibitory factor (MIF)/Toll-like receptor 4 (TLR4)) and fibrotic (stem cell factor (SCF)/c-Kit, α-smooth muscle actin (α-SMA)/β-catenin) signals. Treatment with CNP (600 mg/kg, p.o.) and CNA (10–50 mg/kg, p.o.), but not solifenacin (50 mg/kg), 30 min after CYP induction significantly ameliorated CYP-induced dysfunction in micturition patterns and pathophysiological changes. CNP and CNA further suppressed MIF/TLR4-associated inflammatory and SCF/c-Kit-related fibrotic signaling pathways. Our findings indicate that suppression of inflammatory and fibrotic signals contributes to the crucial mechanism in the improvement of CYP-induced OAB by CNP and CNA.

Pharmacological characterization of DA-8010, a novel muscarinic receptor antagonist selective for urinary bladder over salivary gland

Several antimuscarinics have been commonly used for overactive bladder patients, but dry mouth as a major anticholinergic side effect remains a shortcoming to limit long-term use. The aim of this study was to elucidate the pharmacological properties of DA-8010, a novel muscarinic receptor antagonist selective for urinary bladder over salivary gland. DA-8010 exhibited a high binding affinity for human muscarinic M₃ receptor with pK_i of 8.81 ± 0.05 and great potencies for human M₃ receptor and rat bladder preparation. The potency of DA-8010 for bladder smooth muscle cells was 3.6-fold higher than that for salivary gland cells isolated from mice. Intravenous administration of DA-8010 dose-dependently inhibited rhythmic urinary bladder contractions induced by distension in rats, indicating the most potent activity (ID₃₀ = 0.08 mg/kg) among the antimuscarinics tested. Taken together with the inhibitory effects of DA-8010 and other antimuscarinics on carbachol-induced salivary secretion in rats, the in vivo functional selectivity of DA-8010 for urinary bladder over salivary gland was 3.1-fold, 3.2-fold and 5.2-fold greater than those observed for solifenacin, oxybutynin and darifenacin, respectively. Furthermore, oral administration of DA-8010 in mice resulted in more selective and persistent binding for muscarinic receptors in the bladder rather than in the submaxillary gland, in comparison with other antimuscarinics. These findings suggest that DA-8010 is a potent muscarinic M₃ receptor antagonist to be highly selective for bladder over salivary gland, which might be a promising agent with greater efficacy and less dry mouth in the treatment of overactive bladder.

Clinical pharmacokinetics and pharmacodynamics of solifenacin

The succinate salt of solifenacin, a tertiary amine with anticholinergic properties, is used for symptomatic treatment of overactive bladder. Solifenacin peak plasma concentrations of 24.0 and 40.6 ng/mL are reached 3-8 hours after long-term oral administration of a 5 or 10 mg solifenacin dose, respectively. Studies in healthy adults have shown that the drug has high absolute bioavailability of about 90%, which does not decrease with concomitant food intake. Solifenacin has an apparent volume of distribution of 600 L, is 93-96% plasma protein bound, and probably crosses the blood-brain barrier. Solifenacin is eliminated mainly through hepatic metabolism via cytochrome P450 (CYP) 3A4, with about only 7% (3-13%) of the dose being excreted unchanged in the urine. Solifenacin metabolites are unlikely to contribute to clinical solifenacin effects. In healthy adults, total clearance of solifenacin amounts to 7-14 L/h. The terminal elimination half-life ranges from 33 to 85 hours, permitting once-daily administration. Urinary excretion plays a minor role in the elimination of solifenacin, resulting in renal clearance of 0.67-1.51 L/h. Solifenacin does not influence the activity of CYP1A1/2, 2C9, 2D6 and 3A4, and shows a weak inhibitory potential for CYP2C19 and P-glycoprotein in vitro; however, clinical drug-drug interactions with CYP2C19 and P-glycoprotein substrates are very unlikely. Exposure to solifenacin is increased about 1.2-fold in elderly subjects and about 2-fold in subjects with moderate hepatic and severe renal impairment, as well as by coadministration of the potent CYP3A4 inhibitor ketoconazole 200 mg/day. The full therapeutic effects of solifenacin occur after 2-4 weeks of treatment and are maintained upon long-term therapy. Although solifenacin pharmacokinetics display linearity at doses of 5-40 mg, no obvious dose dependency was observed in efficacy and tolerability studies. The efficacy of solifenacin (5 or 10 mg/day) is at least equal to that of extended-release (ER) tolterodine (4 mg/day) in reducing the mean number of micturitions per 24 hours and urgency episodes, and in increasing the volume voided per micturition. Solifenacin (5 mg/day) appears to be superior to ER tolterodine (4 mg/day) in reducing incontinence episodes (mean -1.30 vs -0.90, p = 0.018) and is superior to propiverine (20 mg/day) at the dose of 10 mg/day in reducing urgency (-2.30 vs -2.78, p = 0.012) and nocturia episodes. Based on withdrawal rates due to adverse effects during the 52-week treatment period, solifenacin appears to have better tolerability than immediate-release (IR) oxybutynin 10-15 mg/day and IR tolterodine 4 mg/day. With regard to the pharmacokinetics of solifenacin, and for safety reasons, doses exceeding 5 mg/day are not recommended for patients with moderate hepatic impairment (Child-Pugh score 7-9), patients with severe renal impairment (creatinine clearance <30 mL/min) and subjects undergoing concomitant therapy with CYP3A4 inhibitors.

Solifenacin: pharmacology and clinical efficacy

While antimuscarinic drug therapy has been proven to be effective in the management of patients with symptoms of overactive bladder syndrome, compliance and persistence with medication is often affected by the bothersome antimuscarinic adverse effects of dry mouth, constipation, somnolence and blurred vision. The development of bladder-selective M3-specific antagonists, such as solifenacin, has introduced the possibility of increasing efficacy while minimizing adverse effects. This article will review the preclinical and clinical data surrounding the development of solifenacin as well as providing an overview of the extensive body of evidence supporting its use in the management of patients with overactive bladder syndrome.