Vivitrol is a brand name of the drug naltrexone. Naltrexone is used to reduce drug and alcohol cravings in individuals who are dependent. It is taken orally as a pill or administered as an intramuscular injection once-a-month. Vivitrol is an opioid antagonist that blocks the effects of opioids, including those synthesized inside the body and those taken exogenously as a drug. Naltrexone is testable in the urine within the first four to six hours following administration and for up to 24 hours in the blood and saliva.
Vivitrol is closely studied as a treatment for alcoholism. When Vivitrol is administered as a treatment for alcoholism, doses are taken orally an hour before consuming alcohol. This method is known as the Sinclair method of treatment. When effective, patients will fail to feel the “buzz” that’s typically associated with consuming alcohol. By blocking the positive reinforcing effects of alcohol, the addictive compulsions to drink may be reduced in some patients. When used as a treatment for opioid use, patients merely abstain from opioids while receiving treatment in either a daily pill or monthly intramuscular injection. Over time, individuals may experience reduced cravings for the drug.
Naltrexone was first synthesized in 1963 and was patented by Endo Laboratories in 1967. Clinical trials for naltrexone as a treatment for opioid dependence began in 1973 as a collaborative effort between the National Institute on Drug Abuse (NIDA) and Dupont. Naltrexone was approved as an oral pill for the treatment of opioid dependence in 1984, and for alcohol dependence in 1995. It wasn’t until 2006 that an injectable form of naltrexone was released under the brand name Vivitrol. At that time, it was only approved for use as a treatment for alcohol dependence. Vivitrol was approved by the Federal Drug Administration for the treatment of opioid dependence in 2010.
Naltrexone is a medication that inhibits the enjoyment of narcotics and alcohol. It is not a drug that’s at risk of being abused. In fact, Naltrexone can be dangerous when taken to close to opioid use. Individuals should wait at least ten days since last using opioids before trying Vivitrol to avoid triggering severe complications.
Vivitrol blocks opioid receptors in the body. With no available opioid receptors to act on, the presence of heroin in the blood can have life-threatening effects.
The exact mechanism of action of naltrexone is not yet fully understood. Researchers believe that naltrexone modulates the dopaminergic mesolimbic pathway, a neuronal pathway in the brain that is thought to be closely involved in nearly all addictive behaviors. What has been confirmed is that Vivitrol effectively blocks opioid receptors, at least temporarily. The resulting effect is that when the patient takes a drink of alcohol, they don’t feel the intoxicating pleasurable effects generally associated with alcohol consumption.
Vivitrol is metabolized in the liver by the enzyme dihydrodiol dehydrogenase. There Vivitrol is metabolized by the liver into the metabolite 6Beta-naltrexol. Vivitrol has a plasma half-life of four hours. Its metabolite has a mean half-life of 13 hours.
The testable time ranges for Vivitrol vary depending on the method of administration and the patient’s metabolism. Several other health factors, including body mass, hydration level, age, and exercise habits can impact for how long naltrexone remains in the body.
The efficacy of naltrexone is largely dependent on whether or not the patient carries a specific variant of the opioid receptors gene: the G allele of OPRM1. Vivitrol is much more likely to work in patients who carry this gene. 25% of patients seeking treatment for addiction carry this gene variant. White patients with the G allele of OPRM1 have a five times greater rate of effectiveness when taking naltrexone. This gene variant is most common among people of Asian descent. Only 30% of Europeans and Indians carry the gene, while between 60% to 70% of people of Asian descent are carriers.
Naltrexone can be detected in the hair for up to 90 days, as with most drugs. It’s detectable in the urine for only four to six hours. Blood and saliva tests may read positive for Vivitrol for up to 24 hours following the time of the last dose.
Side effects of naltrexone may include nausea, difficulty sleeping, headaches, and anxiety. Metabolizing naltrexone can be taxing on the liver and is contraindicated for individuals with liver failure.
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