Naltrexone
From Drug Rehab Wiki
Naltrexone, or naltrexone hydrochloride (17-(cyclopropylmethyl)-4, 5α-epoxy-3, 14-dihydroxymorphinan-6-one hydrochloride), is an opioid antagonist used in the treatment of alcohol dependence and opioid dependence. Naltrexone is used primarily in the treatment of alcoholism to prevent cravings. In the treatment of opioid dependence naltrexone is used to block the euphoric effects of opioids. Both uses are considered to support abstinence in conjunction with other substance treatment modalities.
Naltrexone and Alcohol Cravings
Naltrexone is thought to reduce the intensity and frequency of cravings for alcohol. Reduction and control of alcohol cravings is believed to prevent relapse, or in individuals that do relapse, to reduce the severity of the relapse.
Naltrexone as Opioid Antagonist
Opioid antagonists are substances that bind to opioid receptors in the brain blocking the euphoric effects of opioids. Opioid antagonists block the effects of exogenous and endogenous opioids. Exogenous opioids are administered drugs such as heroin, morphine, codeine and methadone. Endogenous opioids are peptide hormones found in the brain such as endorphins that have analgesic effects. Naltrexone is considered an opioid antagonist that blocks the effects of administered exogenous opioids such as substances of abuse and dependence.
Naltrexone competes with opioids for receptor binding in the brain. The administration of naltrexone in opioid dependent individuals will precipitate severe withdrawal and block the effects of administered opioids for up to 24 hours in low and average doses or 72 hours at higher dosing.
History of Naltrexone
Naltrexone was originally developed by Endo laboratories in 1963 to be used in the treatment of narcotic overdosing. In 1969, DuPont acquired the rights to the formulation of naltrexone. In 1972, the U.S. Congress passed The Drug Abuse Office and Treatment Act which called for the development of non-addictive blocking and antagonist drugs for the treatment of heroin addiction. With governmental funds for research and development under this legislation, DuPont further developed naltrexone. In 1984, the FDA approved it as a treatment for heroin addiction. It was marketed at that time as Trexan. Research was done in the 1980s at the VA hospital in Philadelphia, and in the early 90s at Yale University, to determine the usefulness of naltrexone as a treatment for alcoholism. In 1995, DuPont changed the name of naltrexone to ReVia and marketed it as a treatment for alcoholism.
Beginning in 1997, companies other than DuPont were allowed to manufacture naltrexone. It has since been produced by Barr Laboratories, Bristol-Myers Squibb, Eon Labs, Amide Pharmaceutical and Mallinckrodt Pharmaceuticals.
Other names under which naltrexone has been marketed worldwide include:
• Celupan
• MorViva
• Naltrexona
• Naltrexonum
• Vivitrex
• Depade
Indications for Use
Treatment with naltrexone is indicated for individuals who have a diagnosis of alcohol dependence and/or opioid dependence, an interest in maintaining abstinence from these substances, some period of abstinence from alcohol, no acute medical conditions and who are not actively dependent upon opioids.
Contraindications for the Use of Naltrexone
Naltrexone should not be used by individuals who are actively using alcohol and/or opioids. A period of abstinence from these substances is required before beginning treatment. In order to prevent severe opioid withdrawal symptoms, individuals who are physiologically dependent upon opioids should be abstinent for 5-10 days prior to using naltrexone. Other contraindications for naltrexone treatment include:
• pregnancy
• opiate agonist use such as use of methadone and LAAM
• kidney disease
• acute hepatitis
• liver failure
Adverse Reactions to Naltrexone
Some of the adverse reactions to the use of naltrexone include overdose and liver damage.
Fatal opioid overdoses have occurred in individuals who attempt to compensate for the opioid blocking mechanism of naltrexone by taking higher doses of self-administered opioids.
Liver damage has occurred in individuals using naltrexone with a pre-existing liver condition and with higher doses of naltrexone.
Side-Effects of Naltrexone
Some individuals who take naltrexone will experience side-effects that are similar to mild opioid withdrawal symptoms. These may include:
• gastrointestinal distress
• abdominal cramping
• restlessness
• nausea
• runny nose
• achiness
Administration of Naltrexone
Naltrexone is typically taken orally as a tablet. It has also been developed as an implant and depot injection.
Naltrexone injections are depot medications that provide an extended release supply of naltrexone for up to 30 days. It is given as an intramuscular (IM) gluteal injection.
Naltrexone implants require a surgical incision through which an extended release ‘pellet’ of naltrexone is inserted typically in the abdomen or arm.
Course of Treatment
Treatment of alcohol and opioid dependencies with naltrexone are typically begun with a physical examination, medical history interview, mental health screening and lab tests. Where warranted, withdrawal and detoxification from alcohol or opioids are completed prior to beginning treatment.
Lab tests include liver functions tests, toxicology screens and a pregnancy test for women. The initial evaluation screens for contraindications such as pregnancy, recent opioid use, liver and kidney damage and mental health instability.
Naltrexone is typically administered in 50mg doses daily for the duration of treatment although some individuals may be maintained on lower or higher dosages.
Naltrexone treatment is considered an adjunctive treatment for substance disorders and is used along with other treatment modalities for substance dependence. These other modalities include psychosocial education, self-help recovery groups such as Alcoholics Anonymous and Narcotics Anonymous, individual, group and family counseling, cognitive behavioral therapy, nutrition, exercise and relaxation techniques. Naltrexone treatment can be obtained in inpatient or outpatient settings. Naltrexone is available only by prescription.
Lab tests to monitor liver and kidney functioning are typically done following the beginning of naltrexone treatment and at regular intervals during treatment.
The recommended course of treatment with Naltrexone is 3 months although the length of treatment is flexible and can be longer for some individuals.
Other Uses for Naltrexone
Naltrexone has been used in the treatment of conditions other than substance dependence. Some of the other conditions treated with naltrexone include:
• Fibromyalgia
• Multiple Sclerosis
• Chrohn’s Disease
• Rheumatoid Arthritis
• HIV
• Lupus
