Improving clinical outcomes in treating heroin dependence: randomized, controlled trial of oral or implant naltrexone.

CONTEXT: Oral naltrexone hydrochloride effectively antagonizes heroin, but its utility is limited by patient noncompliance. Sustained-release preparations may overcome this limitation.

OBJECTIVE

To compare the safety and efficacy of a single-treatment sustained-release naltrexone implant with daily oral naltrexone treatment.

DESIGN

Seventy heroin-dependent volunteers entered a randomized, double-blind, double-placebo controlled trial with a 6-month follow-up period.

PATIENTS: Eligibility criteria were DSM-IV opioid (heroin) dependence; age 18 years or older; willingness to be randomized; residing in the Perth, Western Australia, metropolitan area; and completion of preclinical screening and written consent. A total of 129 eligible participants were identified, and 70 (54%) provided informed consent and were randomized as per the study design.

INTERVENTION: Participants received oral naltrexone, 50 mg/d, for 6 months (plus placebo implants) or a single dose of 2.3 g of naltrexone implant (plus placebo tablets).

MAIN OUTCOME MEASURES: (1) Maintaining therapeutic naltrexone levels above 2 ng/mL; (2) return to regular heroin use (>or=4 d/wk); (3) other heroin use and abstinence; (4) use of illicit nonopioid drugs; (5) number of opiate overdoses requiring hospitalization; (6) treatment-related unexpected and expected adverse events; and (7) blood naltrexone levels (ie, pharmacokinetic profile) for recipients of active naltrexone implants.

RESULTS

More participants in the oral vs the implant group had blood naltrexone levels below 2 ng/mL in months 1 (P < .001) and 2 (P = .01); in addition, more oral group participants had returned to regular heroin use by 6 months (P = .003) and at an earlier stage (median [SE], 115 [12.0] days vs 158 [9.4] days). There were 10 trial-related, unexpected adverse events. One serious adverse event, a wound hematoma, was associated with surgical implantation. Naltrexone blood levels in implant recipients were maintained above 1 and 2 ng/mL for 101 (95% confidence interval, 83-119) and 56 (39-73) days, respectively, among men and 124 (88-175) and 43 (16-79) days among women.

CONCLUSIONS

The naltrexone implant effectively reduced relapse to regular heroin use compared with oral naltrexone and was not associated with major adverse events. Clinical Trial Registration anzctr.org.au Identifier: ACTRN12606000308594.