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A review of the clinical use of low dose naltrexone appeared today by Younger, et al. from Stanford (see e-Pub below).

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Naltrexone is one of the most important medications I have prescribed, alone or in combination with other medications for intractable chronic pain and/or treatment resistant Major Depressive Disorder or Bipolar Disorder. It has been most extensively used anecdotally and off label since 1985 for treatment of Multiple Sclerosis.

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Naltrexone acts on two receptors in the central nervous system: (1) the opioid receptor and (2) the TLR4 receptor on glia.

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(1) The opioid receptor is blocked by naltrexone. Naltrexone cannot be given to someone who uses opioid analgesics because it would cause a severe or unpleasant opioid withdrawal reaction. But in low dose, it can do better than opioids for relief of intractable pain. I would like to see it tried for pain, alone or in combination, before any opioid is started. And if on opioids, taper slowly off opioid in order to see how superior low dose naltrexone is. See case reports elsewhere on this site.

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Low dose naltrexone is quite different than its use in high dose where it is FDA approved for addiction to alcohol and opiates. Naltrexone reduces craving. However, in high dose, it blocks the endorphins, the opiates that your brain produces, thus causing pain and depression.

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(2) The TLR4 receptor was discovered by Bruce Beutler, MD, working at Scripps Research Institute. He won the Nobel Prize in 2011 for that profound work. The TLR4 receptor is found on the microglial cell in the central nervous system. The microglia far outnumber nerve cells in the brain and spinal cord. I discussed a small portion of the vast science of the importance of glia, your innate immune system and inflammatory cytokines, here. This research on glia, the innate immune system, is new, largely in the last 10 to 15 years.

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One of the mechanisms by which opioids create pain is that opioids trigger glia to release pro-inflammatory cytokines, i.e. opioids create a neuroinflammatory response in a manner similar to endotoxin from bacteria. Opioids upset the balance of pro- and anti-inflammatory cytokines to create more pain. Naltrexone does the opposite by its action on the glial TLR4 receptor reducing pro-inflammatory cytokines and relieving pain.

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Inflammation kills! Glia and/or the inflammation produced by glia are involved in many pathological processes: Alzheimer’s, Parkinsons, ALS, MS, chronic pain, depression, autoimmune disease, cancer, atherosclerosis. The TLR4 receptor is necessary for death or destruction of oligodendrocytes and myelin, as occurs in multiple sclerosis. Does that mean low dose naltrexone may play a role in modulating these conditions?

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See reviews by distinguished Professor Linda Watkins, PhD, and Mark Hutchinson, PhD, on glia, neuroinflammation and the neuroimmunopharmacology of opioids. Besides glia, Watkins and Hutchinson have recently discovered Toll-like expression of neuronal receptors in pain states.

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For access to articles on glia, cytokines and the TLR4 receptor, see the RSD Syndrome Association library of key publications. And donate to them. They have supported key research in pain when NIH gave less than half of 1% to pain research in 2006, now far less since the deadly the recession of 2008 and the ever threatened fight over funding the national debt.

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Being interested in glia, and treating so many patients with Major Depressive Disorder who had failed other treatments, I did a review of depression and glia and found the same increase in pro-inflammatory cytokines in depression that are found in chronic pain. Since low dose naltrexone is anti-inflammatory, i.e. it modulates or resets the balance of pro-inflammatory and anti-inflammatory cytokines that are produced by glia, I felt it important to try in Major Depressive Disorder. Besides, I had seen its profound effect on so many different forms of intractable pain for many years. Use of LDN has never been associated with toxicity and rarely any side effects.

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My patient had severe suicidal ideation with Major Depressive Disorder for more than three months, unchanged after treatment at a psychiatric center where she had stayed almost four weeks. She began with 4.5 mg in the office and 25 minutes later, on the drive home, her appetite returned! She walked in the house and her dad was astonished – she no longer walked like she was 105 years old! She had the energy to do her laundry and cook for the family for the first time in more than three months.

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Another person for whom I prescribe naltrexone for Major Depression, wrote to me saying Massachusetts General, a Harvard Hospital, was starting clinical trials of low dose naltrexone for Major Depressive Disorder. Other new clinical trials of low dose naltrexone can be found here.

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Jared Younger, PhD, from Stanford first published on the use of naltrexone in fibromyalgia – see my discussion here.

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Today in PubMed, ahead of print, Dr. Younger et al. publish a review of low dose naltrexone, a glial modulator.

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The use of low-dose naltrexone (LDN) as a novel

anti-inflammatory treatment for chronic pain

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