Study of Behavioral Modification Program and Mirabegron to Improve Urinary Urgency in Multiple Sclerosis

Inclusion Criteria: * Confirmed diagnosis of Multiple Sclerosis (MS) (no sub-type restrictions) * Age ≥18 * No change in disease modifying therapy in 60 days. * Patient willing and able to complete micturition diary * Urinary urgency (8 or more entries of bladder urgency score ≥2) in 72hr voiding diary recorded during screening period * Micturition frequency ≥ 8 / day or incontinence ≥ 2 episodes in 72 hour voiding diary recorded during screening period * At least 36 hours of voiding activity recorded in 72 hour voiding diary during screening period * Non-antimuscarinic medications that are likely to influence bladder function may not be initiated between screening and study completion. They may be continued with no dose changes during the study. * Discontinued use of antimuscarinics at least two weeks prior to screening * Able to give informed consent Exclusion Criteria: * Females who are breast-feeding, pregnant or have potential to become pregnant during the course of the study (fertile and unwilling/unable to use effective contraceptive measures) * Multiple Sclerosis exacerbation within 30 days of screening * Cognitive deficits that would interfere with the subject's ability to give informed consent or perform study testing * Screening blood pressure \> 165 systolic or 100 diastolic * History of allergy to Mirabegron * Screening post-void residual \> 200ml * Evidence of urinary tract infection at screening * Evidence of chronic inflammation such as interstitial cystitis, bladder stones, previous pelvic radiation therapy, or previous or current malignant disease of the pelvic organs * Intravesical botulinum toxin treatment within the previous six months of screening. * Presence of InterStim device * Use of indwelling catheter or self-catheterization * Concurrent use of thioridazine(Mellaril® or Mellaril-S®, flecainide (Tambocor®), propafenone (Rythmol®) or digoxin (Lanoxin®) * Concurrent use of antimuscarinics: oxybutynin (Ditropan®, Ditropan XL ®), tolterodine (Detrol®, Detrol LA®), fesoterodine extended-release (Toviaz®), solifenacin (Vesicare®), trospium (Sanctura®, Sanctura XR®), darifenacin extended release (Enablex®) * Screening estimated glomerular filtration rate (eGFR) \< 60, aspartate aminotransferase (AST) or alanine aminotransferase (ALT) \> 2x upper limit of normal * Any other serious and/or unstable medical condition