Krupitsky E.M., Blokhina E.A.
Current Opinion in Psychiatry: 2010, 23(3), p. 210–214.
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Researcher responsible for a major Russian trial of long-acting naltrexone for the treatment of heroin dependence reviews the effectiveness and safety of this form of the drug and of another long-acting form implanted under the skin.
Summary Naltrexone is a perfect opioid antagonist [a drug which blocks the effects of opiate-type drugs] to treat heroin dependence: 50mg (one tablet) blocks the subjective effects of heroin for 24–36 hours, it is easy to administer (one tablet per day or two tablets every other day), it is well tolerated (has a relatively small number of side effects), and tolerance does not develop to the opioid antagonism. However, there is one problem that makes naltrexone relatively low in effectiveness in heroin dependence management: heroin addicts do not like it and they do not take it on the regular daily basis that is required. Long-acting, sustained-release formulations of naltrexone (implantable and injectable) might help to improve compliance and, thus, increase the efficacy of abstinence-oriented treatment of heroin dependence with naltrexone.
There have been several implantable and injectable formulations of naltrexone developed within the last decade. Some of them are effective and relatively well tolerated medications for relapse prevention in heroin addicts.
This review concludes that in general, long-acting, sustained-release naltrexone formulations (implantable and injectable) seem to be well tolerated and more effective than oral naltrexone and placebo for preventing relapse to heroin dependence. However, studies comparing an injectable formulation with oral naltrexone are needed. Also, studies comparing the safety and efficacy of different naltrexone implant technologies as well as comparing implantable and injectable formulations seem to be important.
commentary This review was led by an author responsible for trials of oral and long-acting naltrexone in Russia. The article notes that he is a consultant to a pharmaceutical company which manufactures depot naltrexone. In the UK, neither implants nor depot injections of naltrexone have been licensed for medical use; they can still be and have been used, but patient and doctor have to accept the added responsibility of a product which has not yet been shown to meet the safety and efficacy requirements involved in licensing. These long-acting forms of naltrexone are a controversial technology. Readers are advised to refer to this Effectiveness Bank hot topic for more on the evidence and issues.
Last revised 27 July 2015. First uploaded 27 July 2015