Ask the Doctor Part 2By Paul T. Twydell, DO
Low Dose Naltrexone For the Treatment of Myasthenia Gravis — Is it Right For Me?
Low dose naltrexone (LDN) has been a popular alternative, or "off-label" drug for the treatment of a variety of neurodegenerative and autoimmune diseases for over 25 years. It has thus been proposed by some as a complementary therapy for the treatment of myasthenia gravis (MG). Naltrexone, an opioid antagonist, is a synthetic drug with chemical similarities to oxymorphone, but with no opioid-like properties. It is indicated in the treatment of alcohol dependence, and block the effects of opioid medications. It can be administered in pill form, given intravenously, or subcutaneously by injection. LDN, a lower dose than used for opioid and alcohol addiction, is thought to exert its positive effects by blocking certain opioid receptors within the immune system that are not related to pain modulation. Blocking these receptors may have effects on natural killer cells, T-cells, cytokines, and interferons, all of which may play a role in the patient with autoimmune disease, or more specifically MG. Most of the work with LDN seems to date back to a Dr. Bernard Bihari, a physician who in the 1980's proposed its use in HIV and later other disorders of the immune system.
A PubMed (catalog of all published scientific literature) search using the terms "myasthenia gravis" and "low dose naltrexone" revealed no citations regarding using LDN in the treatment of MG.
There are not even any citations regarding experimental studies in animal models of MG. A Google search using the terms "low dose naltrexone" and "myasthenia gravis" turns up 238,000 results. A quick scan of the first couple of pages of results is notable for anecdotal reports about its successes in the treatment of MG, but these are mostly by people who are selling it.
One site reads, "No, I don't have studies to substantiate this information. Instead, I have over 40 years experience in pharmacy and over a decade helping people with their needs for compounded LDN." Another web site by a naturopathic doctor touts its use for the treatment of MG. but ends by noting "Dr. Weyrich has been trained in the use of Low Dose Naltrexone (LDN) and offers these protocols as a complement to other therapies; however at this time Dr. Weyrich has not treated any cases of Myasthenia Gravis using LDN."
Reactions reported with naltrexone include: "nausea, vomiting, injection site reactions (including induration, pruritus, nodules and swelling), muscle cramps, dizziness or syncope (passing out), somnolence or sedation, anorexia, decreased appetite or other appetite disorders." In addition, there is currently a black box warning for possible liver injury, and it is worth noting that naltrexone should not be used in patients with acute hepatitis or liver failure. These side effects and warnings, however, are based on normal dose (as opposed to low-dose) naltrexone. The cost is not very expensive compared to other treatments for MG. However, since there is no indication for the treatment of MG, insurance companies are unlikely to cover the cost.
In summary, there is no scientific evidence for the use of LDN in the treatment of MG, not even at the experimental level. More research is needed in order to see if there is a role for its use, preferably in the form of randomized, double blind masked, placebo controlled studies.