Low dose naltrexone
Encyclopedia
Low Dose Naltrexone describes the "off-label
Off-label use
Off-label use is the practice of prescribing pharmaceuticals for an unapproved indication or in an unapproved age group, unapproved dose or unapproved form of administration...

" use of the medication naltrexone
Naltrexone
Naltrexone is an opioid receptor antagonist used primarily in the management of alcohol dependence and opioid dependence. It is marketed in generic form as its hydrochloride salt, naltrexone hydrochloride, and marketed under the trade names Revia and Depade...

, at low doses and for other diseases such as multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...

. Naltrexone
Naltrexone
Naltrexone is an opioid receptor antagonist used primarily in the management of alcohol dependence and opioid dependence. It is marketed in generic form as its hydrochloride salt, naltrexone hydrochloride, and marketed under the trade names Revia and Depade...

 is typically prescribed for opioid dependence or alcohol dependence
Alcohol dependence
Alcohol dependence, as described in the DSM-IV, is a psychiatric diagnosis describing an entity in which an individual uses alcohol despite significant areas of dysfunction, evidence of physical dependence, and/or related hardship.-Definition and diagnosis:According to the DSM-IV criteria for...

 as it is a strong opioid antogonist. Preliminary research suggests low dose naltrexone may be useful in preventing opioid tolerance and dependence when combined with an opioid, reduce the severity of opioid withdrawal, or improve fibromyalgia
Fibromyalgia
Fibromyalgia is a medical disorder characterized by chronic widespread pain and allodynia, a heightened and painful response to pressure. It is an example of a diagnosis of exclusion...

 symptoms, though much more research needs to be done before it can be recommended for clinical use.

There have also been pseudoscientific claims about its efficacy in treating a wide range of diseases such as cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

 and HIV
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

, which are not generally supported by scientific evidence. The treatment has been widely promoted through websites run by organizations advocating its use.

Background

Naltrexone is an opioid receptor antagonist, meaning it binds to opioid receptors in cells. These receptors bind endogenous
Endogenous
Endogenous substances are those that originate from within an organism, tissue, or cell. Endogenous retroviruses are caused by ancient infections of germ cells in humans, mammals and other vertebrates...

 pain relieving compounds such as endorphins as well as semi-synthetic opioids such as morphine
Morphine
Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...

 or heroin which are also used for pain relief, but can be abused, leading to opioid dependence. Government regulatory agencies such as the U.S. Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...

 have approved the use of naltrexone for chronic treatment of opioid dependence and for drug detoxification
Drug detoxification
Drug detoxification is a collective of interventions directed at controlling acute drug intoxication and drug withdrawal. It refers to a purging from the body of the substances to which a patient is addicted and acutely under the influence...

.

Information published by the US Department of Veteran Affairs has noted LDN is not covered by insurance and therefore all expenses for its use should be expected to be paid for out of pocket. This is not the case in other countries where it is available within the health services when a doctor prescribes it off label.

Scientific research

The studies that have been published on LDN have largely been pilot studies and are all preliminary in nature, which are useful for suggesting future directions in research, but not for justifying clinical use.

LDN use has been advocated for the treatment of multiple sclerosis, based on large amounts of anecdotal evidence
Anecdotal evidence
The expression anecdotal evidence refers to evidence from anecdotes. Because of the small sample, there is a larger chance that it may be true but unreliable due to cherry-picked or otherwise unrepresentative of typical cases....

 such as personal testimonials. The benefits in those with multiple sclerosis have not been evaluated in large studies, however, preliminary research shows it to be somewhat promising; a pilot study performed at the University of San Francisco
University of San Francisco
The University of San Francisco , is a private, Jesuit/Catholic university located in San Francisco, California. Founded in 1855, USF was established as the first university in San Francisco. It is the second oldest institution for higher learning in California and the tenth-oldest university of...

 reported a significant increase in "mental health quality of life indices," though the authors noted that the dropout rate in the study reduced its statistical power. Claims made by some personal testimonials suggesting LDN to be a "cure" or a "wonder drug" are not borne out by the preliminary research thus far, and as such, LDN should be considered an "unproven treatment" not to be used in place of more proven therapies, despite what some advocacy websites claim. A publication by the National Multiple Sclerosis Society
National Multiple Sclerosis Society
The National Multiple Sclerosis Society, a United States-based non-profit organization, and its network of chapters nationwide promote research, educate, advocate on issues relating to multiple sclerosis, and organize a wide range of programs, including support for the newly diagnosed and those...

 notes that further, more rigorous studies are needed before it can be confirmed that LDN has a positive effect on multiple sclerosis symptoms or is even safe for use. The UK National Health Service
National Health Service
The National Health Service is the shared name of three of the four publicly funded healthcare systems in the United Kingdom. They provide a comprehensive range of health services, the vast majority of which are free at the point of use to residents of the United Kingdom...

 has also found that there is not enough evidence to support LDN's effectiveness in the treatment of multiple sclerosis, and such use in the UK would be unlicensed.

There has also been research on the use of LDN in treating Crohn's disease
Crohn's disease
Crohn's disease, also known as regional enteritis, is a type of inflammatory bowel disease that may affect any part of the gastrointestinal tract from mouth to anus, causing a wide variety of symptoms...

, fibromyalgia and autism
Autism
Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior. These signs all begin before a child is three years old. Autism affects information processing in the brain by altering how nerve cells and their...

, but this research is in the most preliminary of stages and does not currently justify clinical use. This preliminary research includes the finding of 30 percent reduction in fibromyalgia symptoms versus placebo in a small pilot study.

Low dose naltrexone can reverse or prevent the development of tolerance to opioids, and its use is being investigated in the combination drug Oxytrex
Oxytrex
Oxytrex is an investigational drug currently in clinical trials. It combines the well known opioid agonist oxycodone in the treatment of pain with an ultra-low dose of naltrexone, an opioid antagonist...

, which combines oxycodone
Oxycodone
Oxycodone is an opioid analgesic medication synthesized from opium-derived thebaine. It was developed in 1916 in Germany, as one of several new semi-synthetic opioids in an attempt to improve on the existing opioids: morphine, diacetylmorphine , and codeine.Oxycodone oral medications are generally...

 with low dose naltrexone. There is some evidence that very low doses of opioid antagonists such as naltrexone reduce the severity of opioid withdrawal.

Known mechanism of action

The mechanism of low dose naltrexone in reversing or preventing the development of tolerance of opioids involves its high-affinity binding to filamin A. The interaction of naltrexone with microglia
Microglia
Microglia are a type of glial cell that are the resident macrophages of the brain and spinal cord, and thus act as the first and main form of active immune defense in the central nervous system . Microglia constitute 20% of the total glial cell population within the brain...

 cells within the central nervous system is believed to be how the drug exerts its benefitial effects in individuals who suffer from fibromyalgia; this interaction on microglial cells results in a reduction of proinflammatory cytokines as well as neurotoxic superoxides.

Pseudoscientific claims

In addition to the known scientific uses for low dose naltrexone, there have been a number of pseudoscientific
Pseudoscience
Pseudoscience is a claim, belief, or practice which is presented as scientific, but which does not adhere to a valid scientific method, lacks supporting evidence or plausibility, cannot be reliably tested, or otherwise lacks scientific status...

 claims on various websites (such as "boosting" the immune system) about its use in a wide range of diseases such as cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

, HIV
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

 and lupus
Lupus
Lupus most commonly refers to the disease systemic lupus erythematosus.Lupus may also refer to:-Medicine:* Lupus erythematosus, a chronic autoimmune disease with several different forms...

, amongst others . These claims are not only unsupported by clinical research, but are also contradictory. They claim LDN is able to treat diseases of immune dysfunction (such as HIV) in addition to autoimmune diseases, where improving the immune system could make the autoimmune disease worse. Steven Novella
Steven Novella
Steven P. Novella is an American clinical neurologist, assistant professor and Director of General Neurology at Yale University School of Medicine...

, a noted skeptic
Scientific skepticism
Scientific skepticism is the practice of questioning the veracity of claims lacking empirical evidence or reproducibility, as part of a methodological norm pursuing "the extension of certified knowledge". For example, Robert K...

 and professor from Yale University School of Medicine, writes that claims of treating a wide range of diseases with different etiologies should be a red flag
Red flag (signal)
Red flag is a semi-official term to denote various attention and awareness indicators and signals, both explicit and implicit. It can be used in various contexts usually as a warning or when things seem too good to be true as well as unexpectedly good results.The earliest citation for "red flag" in...

to be skeptical about these claims, which are likely to be "bogus treatment with claims that are literally too good to be true."

Proposed mechanism of action

Basic science research has shown that opioid receptors may have other uses in the body than just for modulating pain, such as increasing the production of the body's natural endorphins and also regulating cell proliferation in certain cells such as T and B cells and tumour cells (refs available), and it is on these bases that supporters of LDN have chosen it as a treatment for selected diseases. Advocates have claimed that this increased endorphin production can help with pain, spasticity, fatigue, relapse rate and other symptoms. These claims, however, are not as of yet supported by clinical research.
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