Another heroin treatment that is less common in Australia is use of the blocking agent (or ‘antagonist’) naltrexone. In high enough doses, naltrexone blocks the sites in the brain activated by heroin, so that any heroin taken will have no effect. However, most people who start taking the medication will discontinue its use. 

Naltrexone brings on a severe withdrawal reaction. Because of this, people planning to enter naltrexone treatment are often required to go through withdrawal before entering treatment. The treatment appears to be best suited to highly motivated people with good social support. 

Naltrexone can also be administered via an implant. However, as naltrexone implants are not registered for use in Australia treatment can only be authorised under the Therapeutic Goods Administration Special Access Scheme

For more information, see Heroin.