Safety and Efficacy of AVP-923 in the Treatment of Central Neuropathic Pain in Multiple Sclerosis

The objectives of the study are to evaluate the safety, tolerability, and efficacy of 3 doses
of AVP-923 (dextromethorphan [DM]/quinidine [Q])capsules containing either 45 mg DM and 10 mg
Q (AVP-923-45) or 30 mg DM 10 mg Q (AVP-923-30) or 20 mg DM and 10 mg Q (AVP-923-20) compared
to placebo, for the treatment of central neuropathic pain in a population of patients with
multiple sclerosis (MS) over a 12-week period. The MS patients population enrolled includes
patients with relapsing-remitting multiple sclerosis (RRMS) and patients with secondary
progressive multiple sclerosis (SPMS).

Main Inclusion Criteria:

Multiple Sclerosis (RRMS or SPMS), Clinical history and symptoms of central neuropathic
pain (dysesthetic pain)for at least 3 months prior to screening, PRS baseline score = or >
4, No MS relapse within previous 30 days.

Main Exclusion Criteria:

Personal history of complete heart block, QTc prolongation, or torsades de pointes, family
history of congenital QT interval prolongation syndrome, Myasthenia Gravis, BDI score > 19