This study collected preliminary information on the efficacy of extended-release naltrexone, a long-acting, injectable form of naltrexone, in reducing drinking, and attempts to drive after drinking, among repeat driving-while-impaired offenders with an ignition interlock device installed in their vehicles.
Methods: Volunteers received three monthly injections of extended-release naltrexone and provided information regarding their drinking behavior. Datalogger information on failures to start their vehicles because of detectable breath alcohol were monitored during, and for 4 months following, the last injection.
Results: Ten subjects were enrolled; of them, eight received all three injections. Subjects reported a decrease in their drinking behavior while on medication. All subjects reported a decrease in average drinks per day while on treatment, compared with pre-treatment levels, and this effect persisted after treatment concluded (p<0.01 for both comparisons).
On average, subjects decreased drinking by about 2.3 drinks per day during the 3-month extended-release naltrexone treatment period compared to baseline levels, and sustained this reduction (2.1 fewer drinks compared to baseline) after therapy for an additional 2 months. Interlock results showed a 1.29% decrease that was not statistically significant in failures to start from the pre-treatment period to the in-treatment period.
Conclusion: This preliminary study demonstrated the feasibility of enrolling and retaining repeat driving-while-impaired offenders in a clinical trial of extended-release naltrexone and using results of ignition interlock testing as an external measure of attempts to drive after drinking.