To explore the safety and efficacy of IPX056 compared with baclofen tablets for alleviation of symptoms of spasticity associated with multiple sclerosis (MS).

IPX056 was compared with commercially available tablets as it was designed to provide a prolonged duration of absorption to reduce dose frequency and/or to provide prolonged duration of antispasticity effect.

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.