What are the major limitations and concerns with opioid antagonists used to treat opioid dependence?
The treatment for opioid dependence is done using two types of medication. The first type of medication is known as opioid agonists. These include Methadone, LAAM and Buprenorphine. The analgesic and other pleasurable effects that are felt by people when they consume drugs like morphine and heroin is due to the opioids binding to the mu opiate receptors on the surface of brain cells. During treatment of addiction, patients have to endure painful withdrawal symptoms. The opioid agonists help by binding to the same cells and producing similar effects. This makes it easier for addicts to stop using the drugs.
The second type of medication used in the treatment of opioid addiction is the use of opioid antagonists like Naltrexone. This works by binding to the mu opiate receptors very tightly. It does not allow heroin and morphine to bind to the receptors and even displaces them and blocks their effects. The use of Naltrexone can lead to the same painful withdrawal symptoms that stopping the use of drugs has on addicts and which makes it very difficult for them to quit. It has been seen that most of those solely using opioid antagonists cannot complete the de-addiction treatment and return to using drugs.
The advantage of the use of Naltrexone over opioid agonists is that it has no narcotic effect or withdrawal symptom. It is also not possible to abuse this medication with addicts substituting this for the heroin or morphine.