John Meijer

Absorption, Metabolism and Excretion of [14C]Mirabegron (YM178), a Potent and Selective β3-Adrenoceptor Agonist, after Oral Administration to Healthy Male Volunteers

The mass balance and metabolite profiles of 2-(2-amino-1,3-thiazol-4-yl)-N-[4-(2-{[(2R)-2-hydroxy-2-phenylethyl]amino}ethyl)[U-14C]phenyl]acetamide ([14C]mirabegron, YM178), a β3-adrenoceptor agonist for the treatment of overactive bladder, were characterized in four young, healthy, fasted male subjects after a single oral dose of [14C]mirabegron (160 mg, 1.85 MBq) in a solution. [14C]Mirabegron was rapidly absorbed with a plasma tmax for mirabegron and total radioactivity of 1.0 and 2.3 h postdose, respectively. Unchanged mirabegron was the most abundant component of radioactivity, accounting for approximately 22% of circulating radioactivity in plasma. Mean recovery in urine and feces amounted to 55 and 34%, respectively. No radioactivity was detected in expired air. The main component of radioactivity in urine was unchanged mirabegron, which accounted for 45% of the excreted radioactivity. A total of 10 metabolites were found in urine. On the basis of the metabolites found in urine, major primary metabolic reactions of mirabegron were estimated to be amide hydrolysis (M5, M16, and M17), accounting for 48% of the identified metabolites in urine, followed by glucuronidation (M11, M12, M13, and M14) and N-dealkylation or oxidation of the secondary amine (M8, M9, and M15), accounting for 34 and 18% of the identified metabolites, respectively. In feces, the radioactivity was recovered almost entirely as the unchanged form. Eight of the metabolites characterized in urine were also observed in plasma. These findings indicate that mirabegron, administered as a solution, is rapidly absorbed after oral administration, circulates in plasma as the unchanged form and metabolites, and is recovered in urine and feces mainly as the unchanged form.

Development and validation of LC-MS/MS methods for the determination of mirabegron and its metabolites in human plasma and their application to a clinical pharmacokinetic study.

Mirabegron is being developed for the treatment of overactive bladder. To support the development of mirabegron, including pharmacokinetic studies, liquid chromatography/tandem mass spectrometry methods for mirabegron and eight metabolites (M5, M8, M11-M16) were developed and validated for heparinized human plasma containing sodium fluoride. Four separate bioanalytical methods were developed for the analysis of: (1) mirabegron; (2) M5 and M16; (3) M8; and (4) M11-M15. Either solid-phase extraction or liquid-liquid extraction was used to extract the analytes of interest from matrix constituents. For mirabegron, an Inertsil C₈-3 analytical column was used and detection was performed using a triple-quad mass spectrometer equipped with an atmospheric pressure chemical ionization interface. For the metabolite assays, chromatographic separation was performed through a Phenomenex Synergi Fusion-RP C₁₈ analytical column and detection was performed using a triple-quad mass spectrometer equipped with a Heated Electrospray Ionization interface. The validation results demonstrated that the developed liquid chromatography/tandem mass spectrometry methods were precise, accurate, and selective for the determination of mirabegron and its metabolites in human plasma. All methods were successfully applied in evaluating the pharmacokinetic parameters of mirabegron and metabolites in human plasma.

Evaluation of the Pharmacokinetic Interaction Between the β3-Adrenoceptor Agonist Mirabegron and the Muscarinic Receptor Antagonist Solifenacin In Healthy Subjects

Mirabegron, a selective β3‐adrenoceptor agonist, is approved for the treatment of overactive bladder (OAB). Solifenacin is a muscarinic receptor antagonist widely used in the treatment of OAB. This open‐label, 1‐sequence, 2‐arm study investigated whether any pharmacokinetic interaction exists between mirabegron and solifenacin. In arm 1, 21 healthy men and women received 10 mg solifenacin succinate alone and in combination with mirabegron 100 mg qd. In arm 2, 20 healthy men and women received 100 mg mirabegron alone and in combination with solifenacin succinate 10 mg qd. Plasma samples were collected and tolerability was assessed. Following coadministration of mirabegron and solifenacin in arm 1, solifenacin geometric mean ratios (90% confidence interval [CI]) for Cmax and AUCinf were 1.23 (1.15, 1.31) and 1.26 (1.17, 1.35), respectively, compared with solifenacin alone, with a 1.07‐fold increase in mean t1/2. In arm 2, mirabegron ratios (90% CI) for Cmax and AUCinf were 0.99 (0.78, 1.26) and 1.15 (1.01, 1.30), respectively, for the combination relative to mirabegron alone, with an increase in mean tmax of approximately 1 hour. Mirabegron or solifenacin alone or in combination was generally well tolerated.

An Exploratory Study in Healthy Male Subjects of the Mechanism of Mirabegron‐Induced Cardiovascular Effects

To explore the role of β1‐adrenoceptors (ARs) in the heart rate response to the selective β3‐adrenoceptor agonist mirabegron, 12 young male volunteers received single oral doses of the nonselective β1/2‐AR antagonist propranolol (160 mg), the selective β1‐AR antagonist bisoprolol (10 mg), or placebo on days 1 and 5 of each period in a 3‐period crossover study. On day 5, dosing was followed by a supratherapeutic dose of mirabegron (200 mg). Vital signs, impedance cardiography, and plasma renin activity were collected. Mirabegron increased heart rate and systolic blood pressure and reduced stroke volume, whereas cardiac output and diastolic blood pressure were unaffected. Mirabegron‐induced changes were attenuated by propranolol and bisoprolol. The data indicate that mirabegron has a positive chronotropic effect at supratherapeutic concentrations, which is at least partly mediated by stimulation of β1‐AR.

Determination of methionine-enkephalin and leucine-enkephalin by LC-MS in human plasma: Study of pre-analytical stability

The aim of this work was to assess the influence of preanalytical variables on the stability of two endogenous opioid peptides (Methionine-Enkephalin and Leucine-Enkephalin) in human plasma. For this purpose, first a sensitive LC-MS/MS analytical method was developed and validated for the simultaneous quantitative analysis of these two peptides. The methodology consisted of a simple protein precipitation step followed by UPLC separation and MRM quantitative analysis using a stable isotope labelled Methionine-Enkephalin as internal standard. The method with a limit of quantitation of 10 pg/mL showed good reproducibility with excellent accuracy and precision, and was linear up to 2000 pg/mL. An extensive evaluation of the pre-analytical stability of these peptides in human blood was carried out to ensure an adequate sample collection procedure to obtain reliable results in the analysis of clinical samples.

The application of control charts in regulated bioanalysis for monitoring long-term reproducibility

In regulated bioanalysis, the acceptance of results is batch-wise. When during clinical development derived pharmacokinetic or pharmacodynamic results from different studies will be combined or compared, it is recommendable to monitor the long-term reproducibility of bioanalytical assays. Long-term reproducibility can be evaluated by control charts generated from control samples included in each batch. We present a methodology for the implementation, construction and evaluation of control charts next to the regular batch acceptance of bioanalytical results. Decision rules can be set up for a statistical evaluation of the results. Violation of a decision rule may lead to a root-cause investigation and corrective actions to improve assay robustness. Three examples of control charts, for pharmacokinetic and pharmacodynamic analytes are presented.