Retention in naltrexone implant treatment for opioid dependence

Naltrexone's usefulness in the treatment of opioid dependence stems from its ability to block the action of heroin and other opioids. However, many patients are ambivalent towards naltrexone and often drop out of treatment with orally administered naltrexone. Sustained release naltrexone seems promising in reducing opioid use, but the extent to which patients remain in treatment beyond the first dosage of naltrexone is not clear.

Patients (n=61) receving treatment with sustained release naltrexone implants were offered a second naltrexone implant after 6 months. Patients who remained in treatment were compared to those who did not, on drug use, mental health, and social problems before and during naltrexone implant treatment. Information was obtained on other treatments sought by patients who discontinued naltrexone. Blood samples were used to verify naltrexone release, and hair samples to confirm opioid intake.

Of the patients who received the first naltrexone implant, 51% (n=31) remained in naltrexone implant treatment. Among those who discontinued treatment, 21% expressed a wish to reimplant but failed to attend for reimplantation and 28% declined reimplantation: 6 non-retained patients initiated maintenance or residential treatment. Remaining in naltrexone treatment was related to pre-study length of employment, illicit drug use, and concern for family problems. Higher levels of substance misuse and criminal activity during naltrexone treatment were negatively related to subsequent retention.

Rates of retention among opioid-dependent patients receiving naltrexone implant treatment are encouraging and support this as a feasible long-term treatment option.