The objective of this study is to determine the effect of multiple doses of mirabegron on the pharmacokinetics of an oral contraceptive.

Inclusion Criteria:

• Subjects above 35 years inclusive are re-evaluated for the risks of using of a COC
• Body Mass Index between 18.5 and 30.0 kg/m2, inclusive
• On oral contraceptive with 30ʯg ethinyl estradiol (EE) plus either 125ʯg or 150ʯg levonorgestrel (LNG) for at least three months prior to date of randomization and well tolerated
• During the study the subject is willing to use 1 of the 3 following contraceptive methods: diaphragm with spermicide, intrauterine device or partner is using condoms in combination with a spermicidal cream

Exclusion Criteria:

Subjects will be excluded from participation if any of the following apply:

• Known or suspected hypersensitivity to YM178 or any components of the formulation used
• Pregnant or breast feeding within 6 months before screening assessment
• Any of the liver function tests (i.e. ALT, AST and Alkaline phosphatase) above the upper limit of normal
• Any clinically significant history of asthma, eczema, any other allergic condition or previous severe hypersensitivity to any drug (excluding non-active Hay-fever)
• Any clinically significant history of any other disease or disorder - gastrointestinal, cardiovascular, respiratory, renal, hepatic, neurological, dermatological, psychiatric or metabolic as judged by the medical investigator
• Any clinically significant abnormality following the investigator's review of the pre-study physical examination, ECG and clinical laboratory tests
• Abnormal pulse and/or blood pressure measurements at the pre-study visit as follows: Pulse <40 or >90 bpm; mean systolic blood pressure >140 mmHg; mean diastolic blood pressure >90 mmHg (blood pressure measurements taken in triplicate after subject has been resting in supine position for 5 min; pulse will be measured automatically)
• A marked baseline prolongation of QT/QTc interval after repeated measurements of >450 ms, a history of unexplained syncope, cardiac arrest, unexplained cardiac arrhythmias or torsades de pointes, structural heart disease, or a family history of Long QT Syndrome (LQTS)
• Use of any prescribed or OTC (over-the-counter) drugs (including vitamins, natural and herbal remedies, e.g. St. John's wort) in the 2 weeks prior to admission to the Clinical Unit, except for occasional use of paracetamol (up to 3 g/day)
• Regular use of any inducer of liver metabolism (e.g. barbiturates, rifampin) in the 3 months prior to admission to the Clinical Unit
• Any use of drugs of abuse within 3 months prior to admission to the Clinical Unit
• History of drinking more than 14 units of alcohol per week (1 unit = 270 cc of beer or 40 cc of spirits or 1 glass of wine) within 3 months prior to admission to the Clinical Unit
• Positive test for drugs of abuse or positive alcohol test on the day of admission into the clinical unit
• History of smoking more than 10 cigarettes (or equivalent amount of tobacco) per day within 3 months prior to admission to the Clinical Unit
• Participation in any clinical study within 3 months or participation in more than 3 clinical studies within 12 months, prior to the expected date of enrolment into the study
• Donation of blood or blood products within 3 months prior to admission to the Clinical Unit
• Positive serology test for HBsAg, anti HAV (IgM), anti-HCV or anti-HIV 1+2
• Subjects who, in the opinion of the investigator, are not likely to complete the trial for any reason
• Unwillingness to use additional barrier contraceptive methods for the course of the study and for one month after the end of study visit
• Any clinical condition, which, in the opinion of the investigator would not allow safe completion of the study