Pseudobulbar Affect is a condition characterized by frequent episodes of laughing and crying out of proportion. Other terms used to describe this condition include emotional lability, emotionalism, emotion incontinence, emotional discontrol, excessive emotionalism and pathological laughing and crying. AVP-923 is a new experimental drug that may assist in the reduction of uncontrolled episodes. This study will test the safety and efficacy of AVP-923 in the treatment of MS patients suffering from pseudobulbar affect.

Inclusion Criteria:

• 18 to 68 years of age
• Confirmed diagnosis of Multiple Sclerosis
• Clinical history of pseudobulbar affect

Exclusion Criteria:

• Sensitivity to quinidine or opiate drugs
• Recent diagnosed within 2 months with Multiple Sclerosis
• Patient on anti-depressants
• Patient with liver or kidney disease
• Patient with hypotension