The following medications are approved by the FDA for use in opioid addiction treatment in conjunction with psychosocial therapy:
Methadone – Methadone, a synthetic opioid, is an agonist that mitigates opioid withdrawal symptoms and, at higher doses, blocks the effects of heroin and other drugs containing opiates. Maintenance of opioid addiction treatment with methadone is approved “in conjunction with appropriate social and medical services.” Used successfully for more than 40 years in the treatment of opioid dependence, methadone at therapeutic doses (generally 80-120 mg) has been shown to eliminate withdrawal symptoms produced by stopping use of heroin and prescription opiate medications because it acts on the same targets in the brain as those drugs. Methadone can be dispensed only at an outpatient Opioid Treatment Program (OTP) certified by SAMHSA and registered with the Drug Enforcement Administration (DEA), to a hospitalized patient in an emergency, or as a three-day bridge until a patient can be scheduled with an OTP. SAMHSA-certified OTP facilities provide daily doses.
Buprenorphine – Buprenorphine, approved by the FDA in 2002 to treat opioid dependence, is a partial opioid agonist that, when dosed appropriately, suppresses withdrawal symptoms. Although buprenorphine can produce opioid agonist effects and side effects, such as euphoria and respiratory depression, its maximal effects are generally milder than those of full agonists like heroin and methadone. Physicians are permitted to distribute buprenorphine at intensive outpatient treatment programs that are authorized to provide methadone if providers are trained in its use. Additionally, a special program has been established so that buprenorphine can be prescribed by physicians in office settings and dispensed by pharmacists.
In order to prescribe this medication, physicians must complete a training course and receive a waiver granted by the DEA. Buprenorphine was tested in clinical trials for addiction treatment in the United States both by itself and in combination with naloxone, a drug used to counter the effects of an overdose of opiates such as heroin or morphine. The buprenorphine/naloxone combination is sometimes referred to as Bup/Nx (marketed under the brand name Suboxone®). Formulations approved for drug abuse treatment are intended to be taken sublingually (placed under the tongue and allowed to dissolve). When taken this way, the naloxone has little effect. However, if a patient injects Bup/Nx, the naloxone (an antagonist) enters the bloodstream and will block the buprenorphine, causing the patient to enter opioid withdrawal. This combination formulation may deter abuse through injecting because abusers are motivated to avoid unpleasant withdrawal symptoms.
Naltrexone – Naltrexone is a non-addictive antagonist used in the treatment of alcohol and opioid dependence. The medication blocks opioid receptors so they cannot be activated. This “blockade” action, combined with naltrexone’s ability to bind to opioid receptors even in the presence of other opioids, helps keep abused drugs from exerting their effects when patients have taken or have been administered naltrexone. As an antagonist, naltrexone does not mimic the effects of opioids. Rather, it simply blocks opioid receptor sites so that other substances present in a patient’s system cannot bind to them. If a patient who has been administered naltrexone attempts to continue taking opioids, he or she will be unable to feel any of the opioid’s effects due to naltrexone’s blocking action. Naltrexone is administered in an injectable, long-acting formulation (marketed under the brand name Vivitrol®), which is designed for once-monthly dosing.
The FDA approved this medication for use in people with opioid use disorders to prevent relapse. Naltrexone should be used only in patients who have been detoxified from opioids and have been opioid free for 7–10 days. Naltrexone is non-narcotic and non-addictive; however, as with other medications that interact with the opioid receptors, there is a risk of overdose if a patient who is being treated with naltrexone misses a dose and takes an opioid, or if the patient takes large quantities of opioids in an attempt to “break the blockade.” Compliance measures that closely monitor patients during the treatment period may be beneficial.