What is the chemistry?
Naltrexone is an opiate antagonist, meaning it binds to the brain’s opiate receptors to “close the door” on opioid drugs and their effects. It is closely related to naloxone, the drug used by emergency and first-aid providers to “cut off” an opioid overdose in progress.
Often prescribed to people in opioid-addiction-recovery programs, naltrexone can react dangerously with opioids and should be used only by people whose physical systems are completely clean from such drugs. Common naltrexone brand names in the United States include ReVia (taken as daily pills) and Vivitrol (given by monthly injection).
What is the history of the drug?
Naltrexone was first synthesized in 1963 by Endo Laboratories (acquired by Du Pont in 1969). FDA approval for opioid-addiction treatment came in 1984. The first brand name was Trexan.
It is not listed as a “scheduled” drug under U.S. law, meaning doctors have complete discretion in prescribing it.
What are the side effects?
The more common side effects of naltrexone include stomach cramps, trouble sleeping, headaches, joint pain, and fatigue. Some people develop chills, constipation, runny nose, dizzy spells, diarrhea, or sore throat.
Occasionally, there are cases of mental confusion, hallucinations, depression, chest pain, difficulty urinating, tinnitus, swelling of face or legs, or unexplained weight gain. If you experience any of these symptoms, talk to your doctor.
How was it intended to be used?
As an opiate antagonist, naltrexone has proved helpful to many people recovering from opioid addiction—it kills cravings for a fresh dose by keeping the brain’s opiate-accustomed sections from reactivating the “time for more” signal.
Surprisingly, naltrexone is also used for treating dependence on alcohol, a drug not classified with the opioids. However, alcohol is a depressant drug, as are opioids, and shares opioids’ ability to stimulate the release of pleasure-generating endorphin chemicals—which are closely tied to the opioid receptors blocked by naltrexone.
How is it used illicitly?
To date, there have been virtually no illicit-use issues tied to naltrexone. The drug is considered non-addictive and has no known abuse and diversion potential.
There is, however, a not-used-as-directed risk if naltrexone is taken by someone who has recently taken opioid drugs of any kind: the patient’s physical system may react badly to the combination, triggering opiate withdrawal symptoms; or the patient may respond to not getting the accustomed high by taking more opiate, risking an overdose. Consuming alcohol while taking it is not known to carry similar dangers.
What are the signs of illicit use?
Illicit use is very unlikely to be a problem with naltrexone. However, to minimize any possible risk, it is important to take the medication strictly according to prescription—including abstaining from all opiate use—and to report any side effects to your doctor.
Also, naltrexone should not be expected to solve all addiction-related problems by itself. If you are prescribed the drug as part of a treatment plan, make sure to stick to the rest of the treatment plan, including therapy, support groups, and finding nondrug methods of pain management.