Study of DA-9801 to Treat Diabetic Neuropathy

This is a double-blind, randomized, parallel group, dose ranging, placebo-controlled study where eligible subjects (age 18 to 75 years) will have an average pain score ≥ 4 on an 11-point Likert numerical rating scale (NRS) for at least four days each week prior to randomization as assessed by daily pain diaries. Eligible subjects will be randomized to a 1:1:1:1 ratio to receive 300mg, 600mg, 900mg of DA-9801, or placebo three times a day for 12 weeks. During and at the end of the 12-week treatment period subjects will be evaluated for safety and efficacy parameters. A follow-up visit for safety will occur two weeks after the last treatment visit (TV). The Screening Phase (2 weeks) is designed to determine whether subjects are eligible to proceed to the Treatment Phase of the study and consists of a series of screening assessments designed to determine eligibility. Eligible subjects will undergo a two-week washout period for medications and therapies administered for pain management. At or up to 21 days before the Screening Visit, written informed consent from (ICF) the subject will be obtained by the Investigator or a suitably qualified designee before the performance of any protocol specific procedure. At the Screening Visit, the subject will be issued a daily diary in order to record daily pain level during the screening phase. The Treatment Phase (TV0 to TV12) begins with a series of assessments designed to confirm the subjects' continued eligibility. The site will collect the daily diary and the subject's pain score will be determined. Only subjects whose average pain score is ≥ 4 for at least four days each week will be randomized to any of the four treatment groups. DA-9801 administration schedule is three times per day, starting from TV0 to TV12. During this study phase subjects will be evaluated on a weekly basis. Efficacy evaluations each week will include the subject's global impression of improvement and CGI of pain. Safety evaluations during the Treatment Phase will consist of adverse event assessments at each visit. The Follow-up Visit (two weeks after last TV) The Follow-up Visit is designed to assess safety and will occur 14 days after the last TV. If the subject is withdrawn from the study prior to TV12, the subject should be exited from the study AFTER completing the specified assessments for that visit.