Investigation of Mirabegron-loaded Nanostructured Lipid Carriers for Improved Bioabsorption: Formulation, Statistical Optimization, and In-Vivo Evaluation.

Overactive bladder (OAB) is a usual medical syndrome that affects the bladder, and Mirabegron (MBG) is preferred medicine for its control. Currently, available marketed formulations (MYRBETRIQ® granules and MYRBETRIQ® ER tablets) suffer from low bioavailability (29-35%) hampering their therapeutic effectiveness and compromising patient compliance. By creating MBG nanostructured lipid carriers (MBG-NLCs) for improved systemic availability and drug release, specifically in oral administration of OAB treatment, this study aimed to address these issues. MBG-NLCs were fabricated using a hot-melt ultrasonication technique. MBG-GMS; MBG-oleic acid interaction was assessed by in silico molecular docking. QbD relied on the concentration of Span 80 (X1) and homogenizer speed (X2) as critical material attribute (CMA) and critical process parameter (CPP) respectively, while critical quality attributes (CQA) such as particle size (Y1) and cumulative drug release at 24 h (Y2) were estimated as dependent variables. 32 factorial design was utilized to investigate the interconnection in variables that are dependent and independents. Optimized MBG-NLCs with a particle size of 194.4 ± 2.25 nm were suitable for lymphatic uptake. A PDI score of 0.275 ± 0.02 and zeta potential of -36.2 ± 0.721 mV indicated a uniform monodisperse system with stable dispersion properties. MBG-NLCs exhibited entrapment efficiency of 77.3 ± 1.17% and a sustained release in SIF of 94.75 ± 1.60% for 24 h. MBG-NLCs exhibited the Higuchi model with diffusion as a release mechanism. A pharmacokinetic study in Wistar rats exhibited a 1.67-fold higher bioavailability as compared to MBG suspension. Hence, MBG-NLCs hold promise for treating OAB by improving MBG's oral bio absorption.

Enhanced browning of adipose tissue by mirabegron-microspheres.

Thermogenic brown adipose tissue (BAT) has emerged as an attractive target for combating obesity. However, pharmacological activation of energy expenditure by BAT and/or induction of browning of white adipose tissue (WAT) has been hampered by cardiovascular side effects. To address these concerns, we developed polylactide-co-glycolide acid (PLGA) microspheres loaded with mirabegron (MIR), a selective beta-3 adrenergic receptor (ADRB3) agonist, to achieve sustained local induction and activation of thermogenic adipocytes. MIR-loaded PLGA microspheres (MIR-MS) effectively activated brown adipocytes and enhanced the thermogenic program in white adipocytes. Moreover, treating isolated inguinal WAT (iWAT) with MIR-MS resulted in increased expression of browning markers and elevated lipolysis mainly via ADRB3. In mice, injection of MIR-MS over four weeks induced browning of iWAT at the injection site. Importantly, local MIR-MS injection successfully mitigated unwanted cardiovascular risks, including high systolic blood pressure (SBP) and heart rate, as compared to MIR-treated mice. Finally, injecting MIR-MS into human subcutaneous WAT led to a significant induction of lipolysis and an increase in the expression of thermogenic marker uncoupling protein 1 (UCP1). Taken together, our findings indicate that MIR-MS function as a local drug release system that induces browning of human and murine subcutaneous WAT while mitigating undesirable cardiovascular effects.

Physiologically based in vitro - in vivo correlation of modified release oral formulations with non-linear intestinal absorption: A case study using mirabegron.

Establishing an in vitro - in vivo correlation (IVIVC) for oral modified release (MR) formulations would make it possible to substitute an in vitro dissolution test for human bioequivalence (BE) studies when changing the formulation or manufacturing methods. However, the number of IVIVC applications and approvals are reportedly low. One of the main reasons for failure to obtain IVIVCs using conventional methodologies may be the lack of consideration of the dissolution and absorption mechanisms of drugs in the physiological environment. In particular, it is difficult to obtain IVIVC using conventional methodologies for drugs with non-linear absorption processes. Therefore, the aim of the present study was to develop a physiologically based biopharmaceutics model (PBBM) that enables Level A IVIVCs for mirabegron MR formulations with non-linear absorption characteristics. Using human pharmacokinetic (PK) data for immediate-release formulations of mirabegron, the luminal drug concentration-dependent membrane permeation coefficient was calculated through curve fitting. The membrane permeation coefficient data were then applied to the human PK data of the MR formulations to estimate the in vivo dissolution rate by curve fitting. It was assumed that in vivo dissolution could be described using a zero-order rate equation. Furthermore, a Levy plot was generated using the estimated in vivo dissolution rate and the in vitro dissolution rate obtained from the literature. Finally, the dissolution rate of the MR formulations from the Levy plot was applied to the PBBM to predict the oral PK of the mirabegron MR formulations. This PB-IVIVC approach successfully generated linear Levy plots with slopes of almost 1.0 for MR formulations with different dose strengths and dissolution rates. The Cmax values of the MR formulations were accurately predicted using this approach, whereas the prediction errors for AUC exceeded the Level A IVIVC criteria. This can be attributed to the incomplete description of colonic absorption in the current PBBM.

Intestinal Absorption Site-Guided Development and Evaluation of Oral Disintegrating Controlled Release Tablets of Mirabegron.

The aim was to employ site-dependent absorption of mirabegron (MB) as a guide for fabrication of oral disintegrating controlled release tablet (ODCRT) which undergoes instantaneous release of loading fraction followed by delayed release of the rest of MB. The goal was to release MB in a manner consistent with the chronobiology of overactive bladder (OAB) syndrome. In situ rabbit intestinal permeability of MB was adopted to assess absorption sites. MB was subjected to dry co-grinding with citric acid to develop the fast-dissolving fraction in the mouth. Delayed release fraction was formulated by ethanol-assisted co-processing with increasing proportions of Eudragit polymer (S100) as pH responsive polymer. The developed dry mixtures underwent thermal (DSC) and physical (X-ray diffraction) characterization, in addition to in vitro release behavior. Optimized fast dissolving and delayed release formulations were mixed with tablet excipient before compression in ODCRT which was assessed for release profile using continuous pH variation. MB underwent preferential permeation through ileum and colon. Co-grinding with citric acid provided co-amorphous powder with fast dissolution. Co-amorphization of MB with Eudragit S100 (1:5) showed pH-dependent release to release most of the dose at pH 7.4. The developed ODCRT released 43.5% of MB in the buccal environment and retained MB at acidic pH to start release at pH 7.4. The study successfully fabricated ODCRT guided by site-dependent absorption. The ODCRT instantaneously released loading fraction to support the patient after administration with delayed fraction to sustain the effect.

Physiologically-Based Pharmacokinetic Models of CYP2D6 Substrate and Inhibitors Nebivolol, Cinacalcet and Mirabegron to Simulate Drug-Drug Interactions.

BACKGROUND AND OBJECTIVES: Index substrates and inhibitors to investigate the role of the polymorphic enzyme, cytochrome P450 (CYP) 2D6, in the metabolism of new compounds have been proposed by regulatory agencies. This work describes the development and verification of physiologically-based pharmacokinetic (PBPK) models for the CYP2D6-sensitive substrate, nebivolol and the index CYP2D6 inhibitors, mirabegron and cinacalcet. METHODS: PBPK models for nebivolol, mirabegron and cinacalcet were developed using in vitro and clinical data. The performance of the PBPK models was verified by comparing the simulated results against reported human systemic exposure and clinical drug-drug interactions (DDIs) studies. RESULTS: The exposure of nebivolol, cinacalcet and mirabegron predicted by the PBPK models was verified against pharmacokinetic data from 13, 3 and 9 clinical studies, respectively. For nebivolol, the predicted mean maximum plasma concentration (Cmax) and area under the plasma concentration-time (AUC) values in CYP2D6 extensive metaboliser subjects were within 0.9- to 1.49-fold of the observed values. In poor metaboliser CYP2D6 subjects, the predicted Cmax and AUC values were within 0.41- to 0.81-fold of observed values. For cinacalcet, the predicted Cmax and AUC values were within 0.97- to 1.32-fold of the observed data. For mirabegron, the predicted AUC values across all the studies investigated were within 0.71- to 1.88-fold of observed values. The PBPK model-predicted DDIs were in good agreement (within 2-fold) with observed DDIs in all verification studies (n = 8) assessed. The overall precision was 1.26 and 1.21 for Cmax and the AUC ratio, respectively. CONCLUSIONS: The developed PBPK models can be used to assess the DDI potential liability of new chemical entities that are substrates or inhibitors of CYP2D6.

Metabolite Profiling and Characterization of LW6, a Novel HIF-1α Inhibitor, as an Antitumor Drug Candidate in Mice.

A novel HIF (hypoxia-inducible factor)-1α inhibitor, the (aryloxyacetylamino)benzoic acid derivative LW6, is an anticancer agent that inhibits the accumulation of HIF-1α. The aim of this study was to characterize and determine the structures of the metabolites of LW6 in ICR mice. Metabolite identification was performed using a predictive multiple reaction monitoring-information dependent acquisition-enhanced product ion (pMRM-IDA-EPI) method in negative ion mode on a hybrid triple quadrupole-linear ion trap mass spectrometer (QTRAP). A total of 12 metabolites were characterized based on their MS/MS spectra, and the retention times were compared with those of the parent compound. The metabolites were divided into five structural classes based on biotransformation reactions: amide hydrolysis, ester hydrolysis, mono-oxidation, glucuronidation, and a combination of these reactions. From this study, 2-(4-((3r,5r,7r)-adamantan-1-yl)phenoxy)acetic acid (APA, M7), the metabolite produced via amide hydrolysis, was found to be a major circulating metabolite of LW6 in mice. The results of this study can be used to improve the pharmacokinetic profile by lowering the clearance and increasing the exposure relative to LW6.

Pharmacokinetic Characterization of LW6, a Novel Hypoxia-Inducible Factor-1α (HIF-1α) Inhibitor in Mice.

LW6, an (aryloxyacetylamino)benzoic acid derivative, was recently identified to be an inhibitor of hypoxia-inducible factor-1α (HIF-1α), which is an attractive target for cancer therapeutics. Although LW6 is known to act by inhibiting the accumulation of HIF-1α, pharmacokinetics needs to be evaluated to assess its potential as an anti-tumor agent. Here, we investigated the plasma pharmacokinetics and metabolism of LW6 in mice. LW6 exhibited a small volume of distribution (0.5 ± 0.1 L/kg), and a short terminal half-life (0.6 ± 0.1 h). Following intravenous or oral administration, LW6 was rapidly converted to its active metabolite, (4-adamantan-1-yl-phenoxy)acetic acid (APA). Although LW6 was rapidly absorbed, its oral bioavailability, estimated using AUClast values, was low (1.7 ± 1.8%). It was slowly degraded in mouse liver microsomes (t1/2 > 1 h) and serum (t1/2 > 6 h). About 54% or 44.8% of LW6 was available systemically as APA in the mouse after a single intravenous or oral administration, respectively. Thus, our results indicated the need to simultaneously consider the active metabolite as well as the parent compound for successful evaluation during lead optimization.

Possible Involvement of Muscarinic Receptor Blockade in Mirabegron Therapy for Patients with Overactive Bladder.

The selective ß 3-adrenoceptor agonist mirabegron, an established alternative to antimuscarinic therapy for patients with overactive bladder, induces additional effects against receptors, transporters, and hepatic enzymes. The present study aimed to elucidate the effects of mirabegron on muscarinic receptors in the rat bladder using radioligand binding and functional assays. Mirabegron (0.1-100 µM) inhibited specific [N-methyl-3H]scopolamine methyl chloride binding in the bladder and other tissues of rats in a concentration-dependent manner. Binding affinity in the bladder was similar to that in the heart and significantly higher than those in the submaxillary gland and brain. Mirabegron induced the concentration-dependent relaxation of carbachol-induced contractions in the rat isolated bladder. Further analyses using a two-site model revealed that the relative quantities of high- and low-affinity components for mirabegron were 44.5% and 55.5%, respectively. Respective pEC50 values were 7.06 and 4.97. Based on the receptor binding affinity and pharmacokinetics of mirabegron, muscarinic receptor occupancy in the human bladder for 24 hours after the administration of a single oral dose of 50 mg mirabegron was 37%-76%. The present results demonstrate for the first time that mirabegron may relax the detrusor smooth muscle not only by ß 3-adrenoceptor activation but also muscarinic receptor blockade. SIGNIFICANCE STATEMENT: Mirabegron, the first selective ß 3-adrenoceptor agonist, represents an alternative to antimuscarinic agents for management of overactive bladder (OAB). The present study aimed to clarify whether mirabegron directly binds to muscarinic receptors and affects cholinergic agonist-induced contractions in rat urinary bladder and to predict muscarinic receptor occupancy in human bladder after oral administration of mirabegron. The results demonstrated that mirabegron therapy for patients with OAB may be due not only to ß 3-adrenoceptor activation but also muscarinic receptor blockade.

Probing phenylcarbamoylazinane-1,2,4-triazole amides derivatives as lipoxygenase inhibitors along with cytotoxic, ADME and molecular docking studies.

Hunting small molecules as anti-inflammatory agents/drugs is an expanding and successful approach to treat several inflammatory diseases such as cancer, asthma, arthritis, and psoriasis. Besides other methods, inflammatory diseases can be treated by lipoxygenase inhibitors, which have a profound influence on the development and progression of inflammation. In the present study, a series of new N-alkyl/aralky/aryl derivatives (7a-o) of 2-(4-phenyl-5-(1-phenylcarbamoyl)piperidine-4H-1,2,4-triazol-3-ylthio)acetamide was synthesized and screened for their inhibitory potential against the enzyme 15-lipoxygenase. The simple precursor ethyl piperidine-4-carboxylate (a) was successively converted into phenylcarbamoyl derivative (1), hydrazide (2), semicarbazide (3) and N-phenylated 5-(1-phenylcarbamoyl)piperidine-1,2,4-triazole (4), then in combination with electrophiles (6a-o) through further multistep synthesis, final products (7a-o) were generated. All the synthesized compounds were characterized by FTIR, 1H, 13C NMR spectroscopy, EIMS, and HREIMS spectrometry. Almost all the synthesized compounds showed excellent inhibitory potential against the tested enzyme. Compounds 7c, 7f, 7d, and 7g displayed potent inhibitory potential (IC50 9.25 ± 0.26 to 21.82 ± 0.35 µM), followed by the compounds 7n, 7h, 7e, 7a, 7b, 7l, and 7o with IC50 values in the range of 24.56 ± 0.45 to 46.91 ± 0.57 µM. Compounds 7c, 7f, 7d exhibited 71.5 to 83.5% cellular viability by MTT assay compared with standard curcumin (76.9%) when assayed at 0.125 mM concentration. In silico ADME studies supported the drug-likeness of most of the molecules. In vitro inhibition studies were substantiated by molecular docking wherein the phenyl group attached to the triazole ring was making a π-δ interaction with Leu607. This work reveals the possibility of a synthetic approach of compounds in relation to lipoxygenase inhibition as potential lead compounds in drug discovery.

Visualization of the distribution of nanoparticle-formulated AZD2811 in mouse tumor model using matrix-assisted laser desorption ionization mass spectrometry imaging.

Penetration of nanoparticles into viable tumor regions is essential for an effective response. Mass spectrometry imaging (MSI) is a novel method for evaluating the intratumoral pharmacokinetics (PK) of a drug in terms of spatial distribution. The application of MSI for analysis of nanomedicine PK remains in its infancy. In this study, we evaluated the applicability of MALDI-MSI for nanoparticle-formulated drug visualization in tumors and biopsies, with an aim toward future application in clinical nanomedicine research. We established an analytic method for the free drug (AZD2811) and then applied it to visualize nanoparticle-formulated AZD2811. MSI analysis demonstrated heterogeneous intratumoral drug distribution in three xenograft tumors. The intensity of MSI signals correlated well with total drug concentration in tumors, indicating that drug distribution can be monitored quantitatively. Analysis of tumor biopsies indicated that MSI is applicable for analyzing the distribution of nanoparticle-formulated drugs in tumor biopsies, suggesting clinical applicability.

Potential of Mirabegron and its Extended-release Formulations for the Treatment of Overactive Bladder Syndrome.

BACKGROUND: Overactive bladder syndrome is a broadly occurring urological disorder with a distressing impact on the quality of life. The commonly used antimuscarinic drugs show poor patient compliance because of unsatisfactory potency, tolerability and high occurrence of adverse effects such as dry mouth, blurred vision, constipation, dizziness etc. Mirabegron is the first approved ß3-adrenoreceptor agonist, used as mono or in combination therapies for overactive bladder syndrome. OBJECTIVE: The present review provides an insight into the mechanism, pharmacokinetics, toxicokinetics, clinical trials and the development of various conventional and modified-release dosage forms of mirabegron for the treatment of overactive bladder syndrome. RESULTS: The clinical trials of phase II and phase III of mirabegron demonstrated symptomatic relief from the overactive bladder without disturbing the micturition cycle. To date, mirabegron showed promising results for safety, tolerability and efficacy in patients with overactive bladder syndrome. The modified-release tablet dosage form of mirabegron appear to be a proficient and suitable replacement for antimuscarinics and revealed the tremendous potential to overcome the adverse effects of conventional antimuscarinic drugs like Oxybutyline chloride ER, Detrol LA, VESIcare, etc. Conclusion: Mirabegron shows a distinct mode of action, i.e., targeting ß3-adrenoreceptors and improving bladder storage without altering void contractions. The limited side effects, high safety, efficacy and tolerability of mirabegron present an adequate substitute to antimuscarinics. However, long-term analysis and clinical studies are prerequisites for assessing the safety, tolerability and efficacy profile of mirabegron.

The pharmacokinetics, safety, and tolerability of mirabegron in children and adolescents with neurogenic detrusor overactivity or idiopathic overactive bladder and development of a population pharmacokinetic model-based pediatric dose estimation.

INTRODUCTION: Mirabegron, a selective ß3-adrenoreceptor agonist, is a well-established alternative to antimuscarinics in adults with overactive bladder (OAB) symptoms and is under development for use in pediatric patients. Understanding drug pharmacokinetics (PK) in pediatric patients is needed to determine appropriate dosing. Conducting these studies is ethically complex, particularly as regulatory guidance requires that PK is assessed in pediatric patients with a therapeutic need for the drug. It is also vital to evaluate the safety/tolerability and palatability/acceptability of pediatric formulations. PURPOSE: The purpose of the study was to characterize the PK of mirabegron in pediatric patients with neurogenic detrusor overactivity or idiopathic OAB, to provide a basis for a weight-based dosing algorithm, and to evaluate the safety, tolerability, and palatability/acceptability of the formulations. MATERIALS AND METHODS: A preliminary population PK model constructed from adult data with allometric scaling was used to predict single weight-adjusted mirabegron doses. This was developed to achieve exposures in pediatric patients in two phase 1 studies that were consistent with steady state in adults following once-daily 25 mg ('low dose') and 50 mg ('high dose') dosing. In study 1, adolescents (12-<18 years) and children (5-<12 years) received a single tablet under fed or fasted conditions. In study 2, children (3-<12 years) received a single oral suspension dose under fed conditions. The PK data were used to assess the predictive value of the preliminary PK model and to update it to analyze mirabegron PK in pediatric patients. The safety/tolerability and palatability/acceptability of the formulations were evaluated. RESULTS: Forty-three patients comprised six study cohorts: adolescents, low-dose tablets, fed (n = 7); children, low-dose tablets, fed (n = 7); adolescents, high-dose tablets, fed (n = 8); children, high-dose tablets, fed (n = 6); children, high-dose tablets, fasted (n = 6); and children, high-dose oral suspension, fed (n = 9). The population PK model-based doses for tablets and oral suspension achieved exposures that were typically consistent with steady state in adults. The final population PK model was used to describe the PK for mirabegron in pediatric patients (Table). Both formulations were well tolerated, and there were no reports of bad taste or swallowing difficulties for the tablets, although some found the oral suspension unpleasant. CONCLUSIONS: The single, weight-adjusted pediatric mirabegron doses were successfully predicted by population PK modeling to achieve drug exposures comparable with steady state in adults. The finalized PK model used to characterize the pediatric PK of mirabegron will be utilized to develop a weight-based dosing algorithm. The single mirabegron doses were well tolerated.

Mixed micelles loaded with the 5-benzylidenethiazolidine-2,4-dione derivative SKLB023 for efficient treatment of non-alcoholic steatohepatitis.

Background: SKLB023, a novel 5-benzylidenethiazolidine-2,4-dione based-derivative, specifically inhibits inducible nitric oxide synthase and shows promise for treating non-alcoholic steatohepatitis (NASH). However, its poor water solubility and low bioavailability limits its clinical use. Here the drug was loaded into phosphatidylcholine-bile salt-mixed micelles (PBMM/SKLB023) to overcome these limitations. Methods: PBMM/SKLB023 was developed using a simple co-precipitation method, and formulation parameters were optimized. The pharmacokinetics of PBMM/SKLB023 were investigated in Wistar rats, and therapeutic efficacy was assessed in a mouse model of NASH induced by a diet deficient in methionine- and choline. Results: PBMM/SKLB023 particles were 11.36±2.08 nm based on dynamic light scattering, and loading the drug into micelles improved its water solubility 300-fold. PBMM/SKLB023 inhibited proliferation and activation of HSC-T6 cells more strongly than free SKLB023. PBMM/SKLB023 showed longer mean retention time and higher bioavailability than the free drug after intravenous injection in Wistar rats. In the mouse model of NASH, PBMM/SKLB023 alleviated hepatic lipid accumulation, inflammation, and fibrosis to a significantly greater extent than free SKLB023. Conclusion: PBMM/SKLB023 shows therapeutic potential for treating NASH and liver fibrosis.

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.

Application of a physiologically based pharmacokinetic model for the prediction of mirabegron plasma concentrations in a population with severe renal impairment.

We previously verified a physiologically based pharmacokinetic (PBPK) model for mirabegron in healthy subjects using the Simcyp Simulator by incorporating data on the inhibitory effect on cytochrome P450 (CYP) 2D6 and a multi-elimination pathway mediated by CYP3A4, uridine 5'-diphosphate-glucuronosyltransferase (UGT) 2B7 and butyrylcholinesterase (BChE). The aim of this study was to use this PBPK model to assess the magnitude of drug-drug interactions (DDIs) in an elderly population with severe renal impairment (sRI), which has not been evaluated in clinical trials. We first determined the system parameters, and meta-analyses of literature data suggested that the abundance of UGT2B7 and the BChE activity in an elderly population with sRI was almost equivalent to and 20% lower than that in healthy young subjects, respectively. Other parameters, such as the CYP3A4 abundance, for an sRI population were used according to those built into the Simcyp Simulator. Second, we confirmed that the PBPK model reproduced the plasma concentration-time profile for mirabegron in an sRI population (simulated area under the plasma concentration-time curve (AUC) was within 1.5-times that of the observed value). Finally, we applied the PBPK model to simulate DDIs in an sRI population. The PBPK model predicted that the AUC for mirabegron with itraconazole (a CYP3A4 inhibitor) was 4.12-times that in healthy elderly subjects administered mirabegron alone, and predicted that the proportional change in AUC for desipramine (a CYP2D6 substrate) with mirabegron was greater than that in healthy subjects. In conclusion, the PBPK model was verified for the purpose of DDI assessment in an elderly population with sRI.

Determination of Mirabegron in rat plasma by UPLC-MS/MS after oral and intravenous administration.

Mirabegron is a kind of ß3 adrenergic receptor agonist which is an effective drug for the treatment of overactive bladder. In this research, a UPLC-MS/MS method is developed and validated for the study of mirabegron pharmacokinetic in rats. A protein precipitation method is applied for sample preparation with acetonitrile. m/z 397.3→379.6, m/z 326.4→121.0 for mirabegron, tolterodine (IS), respectively in the positive ion mode was performed for quantitation. The method is reliable and reproducible in our study (intra-day precision≤11.06%, inter-day precision≤11.43%) with concentration curves linear from 5 to 2500 ng/mL(R2>0.999). Stability studies demonstrated that mirabegron was stable under a variety of storage conditions. This method was successfully applied for determining mirabegron in rats after oral and intravenous administration.

Determination of Mirabegron in rat plasma by UPLC-MS/MS after oral and intravenous administration

SUMMARY Mirabegron is a kind of β3 adrenergic receptor agonist which is an effective drug for the treatment of overactive bladder. In this research, a UPLC-MS/MS method is developed and validated for the study of mirabegron pharmacokinetic in rats. A protein precipitation method is applied for sample preparation with acetonitrile. m/z 397.3→379.6, m/z 326.4→121.0 for mirabegron, tolterodine (IS), respectively in the positive ion mode was performed for quantitation. The method is reliable and reproducible in our study (intra-day precision≤11.06%, inter-day precision≤11.43%) with concentration curves linear from 5 to 2500 ng/mL(R2>0.999). Stability studies demonstrated that mirabegron was stable under a variety of storage conditions. This method was successfully applied for determining mirabegron in rats after oral and intravenous administration.

RESUMO Mirabegron é um tipo de agonista do receptor adrenérgico beta 3 que demonstra eficácia no tratamento de bexiga hiperativa. Nesta pesquisa, o método UPLC-MS/MS é desenvolvido e validado para o estudo da farmacocinética mirabegron em ratos. Um método de precipitação de proteínas é aplicado para a preparação de amostras com acetonitrilo. 397.3 → 379.6 M / Z, M / Z 326.4 → 121.0 para mirabegron, tolterodina (IS), respectivamente, para o íon positivo foi realizado para quantificação. O método é fiável e reprodutível em nosso estudo (precisão intradia ≤ 11,06%; precisão entredia ≤ 11.43%), com curvas de concentração linear de 5 a 2 ng/ml (R2 > 0,999). Estudos de estabilidade demonstraram que mirabegron permanece estável sob uma variedade de condições de armazenamento. Este método foi aplicado com sucesso para a determinação de mirabegron em ratos após administração oral e intravenosa.

Mirabegron: A Novel and Promising Medical Expulsive Treatment for Ureteral Stones?

Medical expulsive therapy (MET) is used especially in distal ureteral stones to reduce colics and decrease the number of endourological surgical interventions. A broad spectrum of agents can be used for the relaxation and the dilatation of the ureter, reducing the intraureteric pressure. Alfa-blockers, calcium channel blockers, phosphodiesterase (PDE) inhibitors, and spasmolytics have been shown as effective in clinical trials on urolithiasis. It is a fact that the urothelium itself, the interstitial cells and the ureteric smooth muscle, have B-beta-2 and beta-3 adrenoreceptors. Stimulation of these receptors results in relaxation of the ureter. A recent beta-3 agonist, mirabegron, is commonly used for overactive bladder nowadays. The mechanism of action is adrenergic agonism that affects with the storage phase of the bladder, without interfering the voiding phase, which is regulated by parasympathetic pathways, commonly muscarinic. Agonism of the beta-3 receptors in the ureter has been shown to decrease the intraluminal pressure. By this mechanism, mirabegron can be thought as an alternative MET agent. Acting through different pathways, and having low adverse effect profile, can be thought as the most striking advantages of mirabegron as a MET. In vitro and in vivo trials should be conducted to support this hypothesis.

Physiologically-based pharmacokinetic modeling for mirabegron: a multi-elimination pathway mediated by cytochrome P450 3A4, uridine 5'-diphosphate-glucuronosyltransferase 2B7, and butyrylcholinesterase.

This was the first study to construct a physiologically-based pharmacokinetic (PBPK) model for mirabegron which incorporates the overall elimination pathways of metabolism by cytochrome P450 (CYP) 3A4, uridine 5'-diphosphate-glucuronosyltransferase (UGT) 2B7, and butyrylcholinesterase (BChE) and renal excretion. The objective was to assess the risk of drug-drug interactions (DDIs) by estimating the contribution of each elimination pathway and simulating the magnitude of the DDIs with UGT2B7 inhibitors. A PBPK model for mirabegron was constructed to reproduce the plasma concentration-time curves from a phase 1 study and the magnitude of the DDI with ketoconazole taking into account the overall elimination pathways. The PBPK model was subsequently verified using data from other DDI studies. The constructed PBPK model estimated the contribution for each elimination pathway: 44% and 29% for CYP3A4 and UGT2B7 in the liver, 1.6% for UGT2B7 in the kidney, 3.2% for BChE in plasma, and 22% for renal excretion. Co-administration of probenecid (an UGT2B7 inhibitor) or fluconazole (an UGT2B7 and CYP3A4 inhibitor) was predicted to increase area under the curve for mirabegron to 115% or 174%, respectively. In conclusion, PBPK modeling and simulation revealed a low DDI risk for mirabegron following co-administration with BChE or UGT2B7 inhibitors.

The BET Bromodomain Inhibitor OTX015 Synergizes with Targeted Agents in Multiple Myeloma.

Treatment failure remains a main challenge in the management of high-risk multiple myeloma (MM) even with the expanding repertoire of new drugs. Combinatorial therapy is considered an encouraging strategy that can overcome the compensatory mechanisms and undesirable off-target effects that limit the benefits of many prospective agents. Preliminary results of a current phase I trial have indicated that the new BET bromodomain inhibitor OTX015 has favorable activity and tolerability. However, OTX015 is not efficacious enough as a monotherapy. Here, we provide evidence that synergistic drug combinations with OTX015 were generally more specific to particular cellular contexts than single agent activities. In addition, pairing OTX015 with three classes of drugs dramatically enhanced the antitumor activity in mouse models of disseminated human myeloma. Our studies further underscored that the BET inhibitor OTX015 sensitized MM cells by interrupting several pathways and genes critical for MM cell proliferation and drug response, which provided the rationale for multiple myeloma therapy with OTX015 combined with conventional chemotherapeutic drugs. Thus, the context specificity of synergistic combinations not only provide profound insights into therapeutically relevant selectivity but also improve control of complex biological systems.