[Injectable extended-release naltrexone for opioid dependence: an open label study of long-term safety and efficacy]

To evaluate efficacy and safety of injectable extended-release naltrexone (XR-NTX, Vivitrol), an opioid receptor antagonist, in the treatment of opioid dependence, we carried out a 1-year open-label extension study.

The study followed the initial 6-month randomized, double-blind, PBO-controlled investigation of XR-NTX, used in dose 380 mg, as a treatment for opioid dependence. The study was conducted at 13 clinical sites in Russia. The main measurements were monthly urine samples (efficacy) and adverse events (safety).

The open-label extension included 114 patients (67 continued on XR-NTX and 47 switched from placebo). Overall, 62.3% (95% CI: 52.7%, 71.2%) of patients completed the extension. Urine testing revealed that 50.9% (41.5%, 60.4%) were abstinent from opioids at all assessments during the 1-year open-label phase. Adverse events were reported by 21.1% of patients. Elevations in liver function tests occurred in 16.7% of patients. No severe adverse events were reported. The data obtained demonstrate the long-term safety and efficacy of XR-NTX in opioid dependent patients.