A Study With IPX056 in Subjects With Spasticity Associated With Multiple Sclerosis

Inclusion Criteria: * Male or female at least 18 years old. * Agrees to use a medically acceptable method of contraception throughout the study * Diagnosed with MS as defined by Poser or McDonald Criteria. * Receiving commercial baclofen tablets at a stable total daily dose ranging from 15 mg to 80 mg in a TID dosing regimen for at least 4 weeks prior to the Screening Visit that has resulted in improved spasticity. * Willing to wash out and remain off other antispasticity medications during the study. Exclusion Criteria: * If female, the subject is pregnant, planning to become pregnant, or breastfeeding. * History of allergy or severe intolerance to baclofen. * Did not respond to previous baclofen treatment in any formulation. * Has experienced an exacerbation of MS within 1 month. * Urinary tract infection (UTI) within 2 weeks or two symptomatic UTIs within 6 months prior to the study. * Subjects with clinically significant impairment of renal function * History of active seizure disorder or epilepsy, or currently taking an anticonvulsant for treatment or control of seizure. * Other conditions causing spasticity (e.g., stroke, cerebral palsy, traumatic brain injury) or rigidity (e.g. Parkinson's Disease). * Treated with Botulinum Toxin Type A or B within the previous 4 months, or with phenol or therapeutic alcohol nerve block within 12 months or planned use of these drugs during this study. * Has clinically significant limitation of passive range of motion of lower extremities. * Has had major surgery within 6 months prior to Screening Visit that may affect spasticity assessments such as abdominal surgery, back surgery, lower leg and knee surgeries.