Naltrexone Treatments

What is Naltrexone?

Naltrexone is a drug that blocks the effects of heroin, methadone (Physeptone) and all other opiates, such as morphine, codeine, DF118 and Temgesic.

How does it work?

Naltrexone enters the brain and nervous system and attaches itself to small areas called receptor sites. For heroin to produce its effects, it must get to these same receptor sites, but Naltrexone stops heroin getting to them for up to three days after an oral dose. These receptors are part of the complex reward mechanisms that motivate us and lead to repetitive behaviour. If the reward is blocked, the craving and dependence behaviour reduces and new behaviours reassert themselves with time. It works well for opiate addiction and often, but less predictably, in alcohol dependence. Learn more about Naltrexone.

Naltrexone Formulations

Naltrexone comes in three different forms:


These are usually swallowed daily and it is best that consumption is supervised. If not taken for a couple of days, relapse to opiate use is possible. They do have a product licence.


A Naltrexone Implant is a specially formulated, sterilised preparation of the opiate-blocking drug, Naltrexone, that can be inserted under the skin during a 20-30 minute minor surgical procedure. Naltrexone Implants do not have product licences yet and are still regarded as experimental.

Depot Injections

This is a specially formulated, sterilised, liquid preparation of Naltrexone that can be injected into deep muscle. The Naltrexone is slowly released over approximately one month. The advantage is that no surgical procedure is needed and therefore no lump or scar is visible. The disadvantage is that it only lasts for approximately one month, so more commitment from the patient is required to have it repeated as necessary, without relapsing in between.


Currently, it does not have a product licence in the UK.

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