In this clinical study, heroin addicts were randomized into separate treatment groups of placebo, 40 mg/day MN-166 or 80 mg/day MN-166. Safety and tolerability and preliminary efficacy were major analyzed outcomes. Dose-related ibudilast efficacy was also observed in the study. For example, physical withdrawal symptoms were significantly reduced (p≤0.05) by MN-166 treatment as measured by the Subjective Opioid Withdrawal Scale (SOWS) and oxycodone-mediated analgesia (McGill pain questionnaire) was significantly enhanced (p≤0.05) by 80 mg/day ibudilast compared to placebo. Moreover, opioid-related pupil constriction was greater in the 80 mg/day ibudilast group compared to the placebo group (p≤0.05) suggesting lessened tolerance development. Ibudilast was safe and well-tolerated in the study with no serious adverse events, no discontinuations due to treatment and no impact on opioid respiratory changes compared to placebo."We are pleased with the outcome of this study and excited that it was selected for presentation at AAN," commented Dr. Yuichi Iwaki, President and CEO of MediciNova. "We look forward to the next milestone in this indication which will be completion of the ongoing Phase 2a clinical trial of MN-166 in subjects addicted to prescription opioids or heroin." About the Study The trial was led by Sandra Comer, Ph.D., Professor of Clinical Neurobiology, and additional drug addiction researchers, including Ziva Cooper, Ph.D., Assistant Professor of Clinical Neurobiology at Columbia. The 21-day, inpatient, double-blind, placebo-controlled study enrolled 30 non-treatment-seeking, heroin-dependent volunteers who were maintained on oral morphine for the first 14 days. In the first week, all subjects received placebo and on day 8, participants were randomized to continue placebo (P), low dose (L; 20 mg twice daily (40 mg/day)) ibudilast, or high dose (H; 40 mg twice daily (80 mg/day)) ibudilast. Data were analyzed from 10 subjects completing each treatment arm. In the third week, morphine was no longer administered so that withdrawal phenomena during detoxification could be monitored.