Naltrexone implants : a therapeutic advance both behavioural as well as pharmacological

ENGLISH :
The pioneers of naltrexone (NTX) treatment the early 1970s realized that an implant or depot injection of NTX would largely eliminate the poor compliance that undermined its potential effectiveness. Animal studies of implantable formulations appeared in the mid-1970s and human studies soon showed that effective plasma NTX levels could be maintained for several weeks using standard implant formulations. Yet only in the past few years have implants and depot injections become available for clinical use. This paper reviews their development, their rationale and the increasing number of papers describing their effectiveness for relapse-prevention in a surprisingly wide range of indications, including addicted physicians, pregnant addicts and troubled adolescents taking frequent opiate overdoses. It is clear that typical plasma levels of NTX from implants can completely block opiate effects from as much as 500 mg of pharmaceutical heroin and effective blockade can be maintained for well over six months. Even shorteracting "first generation" implants appear to reduce considerably the high rates of early relapse that are common after opiate detoxification. Depot NTX also has potential in alcoholism treatment. However, the obviously pharmacological nature of NTX implants should not obscure the fact that they also facilitate and reinforce important psychological processes that may be crucial to the long-term success of addiction treatment. The development of long-acting blocking agents for other drugs of abuse means that the emerging principles of treatment with NTX implants may soon be applied to problems involving benzodiazepines, stimulants and cannabis. We suggest the term "Antagonist-Assisted Abstinence" for this approach but stress that maintenance treatments continue to have an important place. (Review' s abstract)