Naltrexone May Hold Benefits for Fibromyalgia

This article originally appeared on Clinical Pain Advisor.

PALM SPRINGS, Calif. — Clinicians treating patients with fibromyalgia may want to consider low-dose naltrexone (LDN) as a treatment option, even if the appropriate dosage is still undetermined.

Presenting at the 32nd Annual Meeting of the American Academy of Pain Medicine (AAPM), Sean Mackey, MD, PhD, professor of anesthesiology at Stanford University, reviewed why he believes prescribing LDN can be an effective way to treat patients with fibromyalgia.

Typically prescribed for opioid or alcohol dependence, LDN, a typical dose being 4.5mg/day, can be used to help patients with HIV/AIDS, autoimmune diseases, and central system disorders. Clinicians can also prescribe it to reduce symptom severity in patients with fibromyalgia.

Using low doses of naltrexone will block microglia receptors without blocking opioid receptions on neurons.¹ Patients undergoing treatment with LDN have reported improvements to their symptoms.² Specifically, mechanical and heat pain thresholds are improved by the drug. The greatest reduction of symptoms in response to LDN occur in individuals with high sedimentation rates. 

Even though side effects of LDN are rare and often described as minor and transient, they do include insomnia and vivid dreams. "I get patients who report to us that they get technicolor dreams," he said. "Generally it's not nightmares."

Other benefits of using LDN: it's cheap, well-tolerated, and it is generic and of little interest to drug companies, he noted.

The appropriate dosage of LDN for patients with fibromyalgia is still unknown. "We have no idea whether it's 4.5, or 6, or 3, and we need to have additional studies," he said. There is also a lack of long-term safety data. 

"I think it's a great option for you because it's been so incredibly safe and easy to use," he said. "In my experience, I either find people get dramatic results or they get nothing."

Source:

1. Younger J, Mackey S. Fibromyalgia symptoms are reduced by low-dose naltrexone: a pilot study. Arthritis & Rheumatology. 2009;10(4):663-72. doi:10.1111/j.1526-4637.2009.00613.
2. Younger J, McCue R, Noor N, Mackey S. Low-dose naltrexone for the treatment of fibromyalgia: findings of a small, randomized, double-blind, placebo-controlled, counterbalanced, crossover trial assessing daily pain levels. 2013;65(2):529-38. doi:10.1002/art.37734.