To Compare Blood and Urine Concentrations of Mirabegron (YM178) in Healthy Poor or Extensive Metabolizers for CYP2D6 and to Assess the Effect of Mirabegron on the Metabolism of Metoprolol

Inclusion Criteria: For Part I: * Subject genotyped and phenotyped for CYP2D6 * Body weight between 60 and 100 kg and Body Mass Index less than or equal to 30 kg/m2 For Part II: * Subject genotyped and phenotyped as extensive metaboliser for CYP2D6 * Body weight between 60 and 100 kg and Body Mass Index less than or equal to 30 kg/m2 Exclusion Criteria: * Known or suspected hypersensitivity to β-adrenergic receptor agonists or constituents of the formulations used * Any clinically significant history of asthma, eczema, any other allergic condition or previous severe hypersensitivity to any drug * Any clinically significant history of upper gastrointestinal symptoms (such as nausea, vomiting, abdominal discomfort or upset, or heartburn) in the 4 weeks prior to admission to the Research Unit * Any clinically significant history of any other disease or disorder - gastrointestinal, cardiovascular, respiratory, renal, hepatic, neurological, dermatological, psychiatric or metabolic * Any clinically significant abnormality following the investigator's review of the pre-study physical examination, ECG and clinical laboratory tests * QTc intervals of \>430 msec * Abnormal pulse rate measurement (\<40 or \>90 bpm) taken by manual counting at the pre-study visit after subject has been resting in supine position for 5 min * Abnormal blood pressure measurements taken at the pre-study visit after subject has been resting in supine position for 5 min as follows: systolic blood pressure \<95 or \>160 mmHg; diastolic blood pressure \<40 or \>95 mmHg * Positive orthostatic test at screening i.e. any symptoms of dizziness, light-headedness etc. and/or a fall of ≥ 20 mmHg in systolic blood pressure after 2 min standing (preceded by 5 min. supine rest) and/or an increase in pulse rate of ≥ 20 bpm * Regular use of any prescribed or OTC drugs except paracetamol up to 3 g/day, in the 4 weeks prior to admission to the Research Unit OR any use of such drugs in the 2 weeks prior to admission to the Research Unit