Long-acting injectable versus oral naltrexone maintenance therapy with psychosocial intervention for heroin dependence: a quasi-experiment

Abstract

Objective: To conduct a quasi-experimental comparison of early clinical outcomes between injectable, sustained-release, depot naltrexone formulation versus oral naltrexone maintenance therapy in individuals with opiate dependence.

Method: Early retention in treatment and urine-confirmed opiate use in the first 8 weeks postdetoxification were compared between patients (diagnosed as opiate-dependent according to DSM-IV criteria) participating in 2 concurrently run randomized clinical trials of oral (n = 69; patients treated from September 1999 to May 2002) and long-acting injectable (n = 42; patients treated from November 2000 to June 2003) naltrexone maintenance therapy with psychosocial therapy.

Results: Long-acting injectable naltrexone produced significantly better outcome than oral naltrexone on days retained in treatment (F(1,106) = 6.49, P = .012) and for 1 measure of opiate use (F(1,106) = 5.26, P = .024); other measures were not significantly different, but differences were in the same direction. In subanalyses, there were interaction effects between baseline heroin use severity and type of treatment. In subanalyses, heroin users with more severe baseline use showed better retention with oral naltrexone maintenance therapy combined with intensive psychotherapy (behavioral naltrexone therapy) as compared to retention shown by severe heroin users treated with long-acting naltrexone injections combined with standard cognitive-behavioral therapy (χ²(1)= 9.31, P = .002); less severe heroin users evidenced better outcomes when treated with long-acting injectable naltrexone.

Conclusions: This quasi-experimental analysis provides tentative indications of superior outcomes for heroin-dependent patients treated with long-acting injectable naltrexone compared to oral naltrexone. The finding that heroin users with more severe baseline use achieved better outcomes with oral naltrexone is most probably attributable to the intensive nature of the psychosocial treatments provided and points to the opportunity for continued research in augmenting injectable naltrexone with psychosocial strategies to further improve outcome, especially in individuals with more severe use. The results should be considered exploratory given the quasi-experimental nature of the study.

Figure 1. Survival function over eight weeks in treatment demonstrating the interaction between treatment condition and baseline opioid severity for patients treated in High Dose Injection / CBT versus patients treated with Oral Maintenance and BNT

Figure displays survival functions for patients treated with 1) 384ng/ml injections of depot naltrexone plus twice weekly CBT or 2) oral naltrexone plus intensive behavioral treatment (BNT) as a function of baseline opioid dependence severity. Designations for high (10 bags/day) and low (3 bags/day) severity are plus or minus one standard deviation (3.6) from the mean (6.4), rounded to the nearest whole unit.