Effects of combined treatment with fesoterodine and mirabegron in a pelvic congestion rat model: Results from in vitro and in vivo functional studies.

OBJECTIVES: To examine the effect of combining a nonselective muscarinic receptor antagonist, 5-hydroxymethyl tolterodine (an active metabolite of fesoterodine), with a ß3 adrenoceptor agonist, mirabegron, in a rat model of pelvic congestion. METHODS: The rat pelvic congestion model used female Sprague-Dawley rats with their bilateral common iliac and uterine veins ligated. Expressions of M2 and M3 receptor subtypes in the urothelium and detrusor were detected by real-time polymerase chain reaction assays. The effects of both drugs were investigated on isolated bladder strips contracted by electrical field stimulation. in vivo single cystometry was used to assess the effects of 5-hydroxymethyl tolterodine and mirabegron independently or in combination on bladder capacity, micturition pressure, and threshold pressure. RESULTS: Pelvic congestion rats showed decreased bladder capacity compared with controls, but micturition pressure and threshold pressure were unchanged. Pelvic congestion model rats also demonstrated an approximately two-fold increase in expression of both M2 and M3 receptor subtypes in the urothelium. Additive relaxant effects of 5-hydroxymethyl tolterodine and mirabegron were observed in vitro in the electrical field stimulation-induced contractions of bladder strips from pelvic congestion rats. In vivo, bladder capacity was increased significantly by a combination of 5-hydroxymethyl tolterodine and mirabegron, with the combined effect exceeding the sum of the effects of monotherapies. Micturition pressure and threshold pressure did not significantly differ between groups. CONCLUSIONS: The combination of 5-hydroxymethyl tolterodine with mirabegron suggests the potential of synergistic effects in a rat pelvic congestion model.

Physiologically Based Pharmacokinetic Modeling Suggests Limited Drug-Drug Interaction for Fesoterodine When Coadministered With Mirabegron.

5-Hydroxymethyl tolterodine (5-HMT; the active fesoterodine metabolite) is metabolized via the cytochrome P450 (CYP) 2D6 and CYP3A pathways. Mirabegron is a moderate CYP2D6 inhibitor and weak CYP3A inhibitor. Potential drug-drug interactions (DDIs) following coadministration of these 2 overactive bladder treatments were estimated using physiologically based pharmacokinetic models, developed and verified by comparing predicted and observed pharmacokinetic profiles from clinical studies. Models predicted and verified mirabegron and desipramine (CYP2D6 substrate) and 5-HMT and ketoconazole (strong CYP3A inhibitor) DDIs. Mirabegron model-predicted mean steady-state AUC and Cmax were within 11% of clinical observations. The predicted versus observed geometric mean ratio (GMR) of AUCinf for CYP2D6 substrates desipramine and metoprolol coadministered with mirabegron 100 or 160 mg once daily were 3.47 versus 3.41 and 2.97 versus 3.29, respectively, indicating that the mirabegron model can be used to predict clinical CYP2D6 inhibition. 5-HMT fractional clearance by CYP3A and CYP2D6 was verified from clinical DDI studies with a potent CYP3A4 inhibitor (ketoconazole) and inducer (rifampicin) in CYP2D6 extensive and poor metabolizers and with a moderate CYP3A inhibitor (fluconazole) in healthy volunteers. 5-HMT AUCinf and Cmax GMRs for fesoterodine DDIs were all predicted within 1.26-fold of clinical observation, providing verification for the fesoterodine substrate model. The predicted changes in 5-HMT AUCinf and Cmax ratios for 8 mg fesoterodine when coadministered with 50 mg mirabegron were 1.22-fold and 1.17-fold, respectively, relative to 8 mg fesoterodine given alone. This modest increase in 5-HMT exposures by approximately 20% is considered clinically insignificant and would not require fesoterodine dose adjustment when coadministered with mirabegron within approved daily-dose ranges.

Detection of the Onset of the Epidemic Period of Respiratory Syncytial Virus Infection in Japan.

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection in young children worldwide. An annual epidemic of RSV infection generally begins around autumn, reaching a peak at the end of year in Japan, but in 2017 it started in early July and peaked in September. As the onset timing of RSV season varies, it is important to detect the beginning of an epidemic, to enable the implementation of preventive measures. However, there are currently no specified criteria or methods to determine the onset of RSV season in a timely manner. Therefore, we developed a model to detect the epidemic onset, based on data from the Infectious Diseases Weekly Report from 2012 to 2017. The 47 prefectures of Japan span 11 climate zones, which affect the timing of epidemic onset. Therefore, the onset of RSV season was assessed separately in each prefecture. Non-linear regression analysis was performed to generate a mathematical model of the annual epidemic cycle for each prefecture. A search index was used to determine the onset of RSV season, which was estimated using the number of RSV reports per week within an epidemic period (RSV-reports/w) and the number of reported cases included within an epidemic period relative to the total number of RSV reports (capture rate). A number of RSV-reports/w, which was used as a threshold (a number at onset line) to determine the condition of the onset of RSV season, was then estimated based on the search index. The mean number at the onset of RSV season for 47 prefectures was 29.7 reports/week (median 21.0, range 6.0-121.0 reports/ week). The model also showed that the onset of RSV season in 2017 was more than 1 month earlier than the previous year. In conclusion, the model detected epidemic cycles and their onset conditions in all prefectures, despite the 11 climate zones of Japan. The results are expected to contribute to infant medical care by allowing medical personnel to take preventive measures promptly at the beginning of the epidemic RSV season.

Efficacy and safety of fesoterodine treatment for overactive bladder symptoms in elderly women with and without hypertension.

OBJECTIVE: To assess fesoterodine treatment in elderly women with overactive bladder with and without hypertension. METHODS: Data for 2527 elderly women with overactive bladder symptoms, including urgency urinary incontinence, were pooled from 10 double-blind, placebo-controlled fesoterodine studies. RESULTS: A total of 1523 elderly women (60.3%) had a history of hypertension, and 1004 women (39.7%) had no hypertension history. Overactive bladder symptoms, mean bodyweight and mean body mass index at baseline were significantly higher in women with overactive bladder and hypertension versus those without hypertension (P < 0.05). Statistically significant improvements in overactive bladder symptoms at week 12 were observed for fesoterodine treatment versus placebo in women with hypertension and those without (P < 0.05). The diary-dry rate (no urgency urinary incontinence episodes), the proportion with less than eight micturitions/24 h, overactive bladder symptom bother and health-related quality of life were also statistically significantly improved by fesoterodine treatment in both populations. Incidence of treatment-related adverse events with fesoterodine was similar in women with hypertension (39.3%) and without hypertension (44.6%). Dry mouth and constipation were the most common treatment-related adverse events with fesoterodine in women with hypertension (26.2% and 5.2%, respectively) and without hypertension (30.5% and 8.0%). CONCLUSIONS: A relationship among the severity of overactive bladder symptoms, hypertension and obesity in elderly women is suggested. Fesoterodine provides significantly greater improvements in overactive bladder symptoms and health-related quality of life versus placebo in women with or without hypertension. Hypertension does not appear to affect the efficacy and safety of fesoterodine in elderly women with overactive bladder symptoms, including urgency urinary incontinence.

Population pharmacokinetics of the 5-hydroxymethyl metabolite of tolterodine after administration of fesoterodine sustained release tablet in Western and East Asian populations.

This analysis was conducted to investigate factors that affect 5-hydroxymethyl tolterodine (5-HMT) pharmacokinetics after administration of fesoterodine sustained release tablets to Westerners and East Asians. Ten pharmacokinetic studies and three efficacy/safety studies in overactive bladder (OAB) patients were pooled for the population pharmacokinetic analysis. The plasma 5-HMT concentration data were described by a 1-compartment model with first order absorption and a lag time. Creatinine clearance (CLCR), hepatic impairment, CYP2D6 genotype, and concomitant medication with CYP3A inhibitor/inducer were identified as influential covariates. It was estimated that decreasing of CLCR from 80 to 15 mL/min resulted in a 39.5% reduction in 5-HMT apparent oral clearance (CL/F). Hepatic impairment, CYP2D6 poor metabolizer, and CYP3A inhibitor were estimated to reduce CL/F by about 60%, 40%, and 50%, respectively. CYP3A inducer resulted in about fourfold increase in CL/F. Although sex and Japanese ethnicity were selected as covariates on CL/F, each resulted in only about 10% decrease and increase of CL/F, respectively. Of the influential covariates of 5-HMT CL/F, CLCR, hepatic impairment, CYP2D6 genotype, and concomitant medication with CYP3A inhibitor/inducer were of significance, whereas sex and Japanese ethnicity covariates were considered not to have clinically significant impact on exposures of 5-HMT.

Efficacy of fesoterodine on nocturia and quality of sleep in Asian patients with overactive bladder.

OBJECTIVE: To investigate the efficacy of fesoterodine vs placebo on nocturia, sleep disturbance, and sleep-related quality of life (QoL) in patients with overactive bladder and nocturia. METHODS: This posthoc analysis used data from a 12-week, randomized, placebo-controlled trial of fesoterodine 4 and 8 mg per day in Asian adults reporting ≥8 micturitions and ≥1 urgency urinary incontinence episodes per 24 hours at baseline. Patients who reported ≥1 nocturnal micturition/24 h were included in this analysis. Efficacy variables included change from baseline to week 12/end of treatment in nocturnal micturitions/24 h, nocturnal voided volume/micturition, and hours of undisturbed sleep. Sleep-related QoL was assessed using King's Health Questionnaire Sleep/Energy domain. Treatment comparisons were made using analysis of covariance. RESULTS: Among 555 patients, reductions in nocturnal micturitions with fesoterodine 4 mg (-0.63) and 8 mg (-0.77) were numerically greater vs placebo (-0.56), but differences were not significant (P >.05). When patients with a nocturnal polyuria index >33% were excluded, the decrease in nocturnal micturitions was significantly greater with fesoterodine 8 mg vs placebo (-0.24; P = .031). Increases in nocturnal voided volume/micturition were significantly greater with fesoterodine 4 (38.07 mL; P = .013) and 8 mg (42.05 mL; P <.001) vs placebo (14.89 mL). Hours of undisturbed sleep was significantly longer with fesoterodine 4 mg vs placebo (80 vs 54 minutes; P = .032); improvement in King's Health Questionnaire Sleep/Energy scores was significantly greater with fesoterodine 4 (P = .034) and 8 mg (P = .019) vs placebo. CONCLUSION: These results suggest that fesoterodine may reduce nocturnal micturitions and improve sleep quality and QoL in overactive bladder patients with nocturia.