Findings from the one-year, open-label extension of the six-month pivotal study of extended-release naltrexone injection (Vivitrol®) in patients with opioid dependence disorder  have been presented at the 24th Annual U.S. Psychiatric and Mental Health Congress.

At the onset of the study, 114 patients from the original six-month trial continued into the open-label, 52-week extension study, of which 67 continued treatment with Vivitrol, while 47 patients on placebo crossed over to receive Vivitrol. The response profile based on the number of opioid-free urine screens was the primary efficacy endpoint of the six-month pivotal study. The extension study also measured opioid craving, improvements in quality of life measures, self-reported opioid use and incidence of physical opioid dependence, confirming the findings documented in the first phase of the study. All patients received psychosocial counseling.

The following findings were reported:

• Nearly 65% of patients completed the open-label study

• During the 18 months total observation period, improvements during the initial 6 month trial observed in patients treated on Vivitrol were maintained for the duration extension study.

• 49% patients who entered the one-year extension study (in combination with psychosocial treatment), after 6 months of Vivitrol in the initial study, were completely abstinent for the duration of the extension study, based on opioid-free urine screens.

• There was a low rate of clinical adverse events, an absence of severe adverse events and a low overall rate (2.6%) of injection site pain. The most common adverse events were toothache and influenza. All safety events observed during the open-label extension were consistent with those set out in the approved product labelling.

• No patients discontinued the open-label extension due to serious adverse events.

Vivitrol is the first and only once-monthly, extended-release injectable medication for the treatment of alcohol dependence and opioid dependence.