The trial is being carried out at Columbia University and the New York State Psychiatric Institute, and led by Dr. Sandra Comer, Professor of Neurobiology and principal investigator.
The interim analysis was carried out after the first seven patients had completed the trial, which required a six-week stay on the inpatient unit.
During the trial, MN-166 (ibudilast) showed a number of beneficial effects on the subjective, analgesic, and reinforcing effects of oxycodone.
The company said that MN-166 significantly reduced the craving for heroin, cocaine, and tobacco.
Comer said: "We are excited to report these interim findings, and look forward to completion of the study and moving on to the next clinical trial of ibudilast."
MediciNova president and chief executive officer Yuichi Iwaki said the company is happy with the results of the interim analysis.
"We believe the craving data is particularly important, as it establishes that ibudilast has potential to be used as a long-term therapy to prevent relapses in recovering opioid-dependent patients," Iwaki said.
"This data is complementary to the data from our previous study in heroin abusers, in which ibudilast demonstrated a reduction in withdrawal symptoms. The data also confirms the positive effects of ibudilast on analgesia which we have seen in a previous study."