A Study to Evaluate the Pharmacokinetics, Safety and Tolerability of Mirabegron OCAS (Oral Controlled Absorption System) in Pediatric Subjects With Neurogenic Detrusor Overactivity or Overactive Bladder

Inclusion Criteria: * Subject has a documented diagnosis of: * Neurogenic detrusor overactivity (NDO), or * Idiopathic overactive bladder (OAB) according to International Children's Continence Society (ICCS) criteria. * Subject's weight/height: * Subject should have a body weight of ≥ 20.0 kg (all cohorts). * For NDO: subject is not suffering from malnutrition and is not severely overweight, in the opinion of the Investigator. * For OAB: subject's weight and height are within the normal percentiles (3rd to 97th percentile) according to Centers for Disease Control and Prevention (CDC) growth charts. * Subject is able to swallow the study medication in accordance with the protocol. * Female subject must either: * Be of non-childbearing potential: * Clearly pre-menarchal or in the judgment of the Investigator is pre-menarchal * Documented surgically sterile. * Or, if of childbearing potential: Agree not to try to become pregnant during the study and for 28 days after the final study drug administration, * And have a negative urine pregnancy test pre-dose Day 1, * And, if heterosexually active agree to consistently use two forms of highly effective form of birth control starting at screening and throughout the study period and for 28 days after the final study drug administration. * Female subjects must agree not to breastfeed starting at screening and throughout the study period, and for 28 days after the last study drug administration. * Female subject…