A systematic literature review on the clinical efficacy of low dose naltrexone and its effect on putative pathophysiological mechanisms among patients diagnosed with fibromyalgia

The use of naltrexone in the treatment of chronic pain: a systematic review

This study aims to assess the efficacy of low-dose naltrexone (LDN) in treating chronic pain. We conducted a systematic review using the PICO strategy: (P) Patients with chronic pain, (I) Use of oral naltrexone, (C) Placebo or active drug and (O) Pain relief and quality of life. We included articles from PubMed, Scopus, Cochrane CENTRAL and EMBASE databases. Seven randomized clinical trials involving 406 patients were analyzed. The doses ranging from 2 to 4.5 mg once daily across all studies. Various chronic pain conditions were evaluated. The results suggest that low-dose naltrexone is not effective in managing chronic pain and improving the quality of life in patients with diverse chronic pain conditions. However, further research with larger sample sizes and standardized methodologies is necessary.

Long COVID management: a mini review of current recommendations and underutilized modalities

Long COVID is a condition that develops in a subset of patients after COVID-19 infection comprising of symptoms of varying severity encompassing multiple organ systems. Currently, long COVID is without consensus on a formal definition, identifiable biomarkers, and validated treatment. Long COVID is expected to be a long-term chronic condition for a subset of patients and is associated with suffering and incapacity. There is an urgent need for clear management guidelines for the primary care provider, who is essential in bridging the gap with more specialized care to improve quality of life and functionality in their patients living with long COVID. The purpose of this mini review is to provide primary care providers with the latest highlights from existing literature regarding the most common long COVID symptoms and current management recommendations. This review also highlights the underutilized interventions of stellate ganglion blocks and low-dose naltrexone, both with well-established safety profiles demonstrated to improve quality of life and functionality for patients suffering with some symptoms of long COVID, and encourages prompt referral to interventional pain management.

"Fibromyalgia - are there any new approaches?"

INTRODUCTION

Approaching patients with fibromyalgia (FM) is challenging due to the limited availability of scientifically proven effective therapies.

OBJECTIVE

Review the treatments in use for FM and present new knowledge that could benefit these patients. Non-pharmacological interventions are recommended as the first line of treatment: aerobic exercise, cognitive behavioral therapy and patient education, all aimed at improving pain and other symptoms. Additional approaches have been studied, such as, digital health interventions, combined treatments, noninvasive neuromodulation, and others. Concerning pharmacological therapy, the mechanism of action of the medications currently used is to promote pain modulation. Medications approved by Food and Drug Administration are duloxetine, milnacipran and pregabalin. Amitriptyline, cyclobenzaprine, gabapentin and naltrexone are considered for off-label use. Cannabinoids, vitamin D supplementation are still controversial and further research is needed.

CONCLUSION

The combination of therapies, whether old, recent or reformulated, are the most effective strategy for managing symptoms in patients with fibromyalgia.

KEY WORDS

fibromyalgia, treatment, nonpharmacological interventions, pharmacological treatment.

Naltrexone 6 mg once daily versus placebo in women with fibromyalgia: a randomised, double-blind, placebo-controlled trial

BACKGROUND

Low-dose naltrexone is used to treat fibromyalgia despite minimal evidence for its efficacy. This trial aimed to investigate whether 12-week treatment with 6 mg low-dose naltrexone was superior to placebo for reducing pain in women with fibromyalgia.

METHODS

We did a single-centre, randomised, double-blind, placebo-controlled trial in Denmark. We enrolled women aged 18-64 years who were diagnosed with fibromyalgia. Participants were randomly assigned 1:1 to receive low-dose naltrexone (6 mg) or an identical-appearing placebo, using a computerised algorithm with no stratifications applied. Participants, investigators, outcome assessors, and statistical analysts were all masked to treatment allocation. The primary outcome was change in pain intensity on an 11-point numeric rating scale from baseline to week 12, in the intention-to-treat population. Safety was assessed in participants in the intention-to-treat population who received at least one dose of their allocated intervention. This trial was registered with ClincalTrials.gov (NCT04270877) and EudraCT (2019-000702-30).

FINDINGS

We screened 158 participants for eligibility from Jan 6, 2021, to Dec 27, 2022, and 99 patients were randomly assigned to low-dose naltrexone (n=49) or placebo (n=50). The mean age was 50·6 years (SD 8·8), one (1%) of 99 participants was Arctic Asian and 98 (99%) were White. No participants were lost to follow-up. The mean change in pain intensity was -1·3 points (95% CI -1·7 to -0·8) in the low-dose naltrexone group and -0·9 (-1·4 to -0·5) in the placebo group, corresponding to a between-group difference of -0·34 (-0·95 to 0·27; p=0·27, Cohen's d 0·23). Discontinuations due to adverse events were four (8%) of 49 in the low-dose naltrexone group and three (6%) of 50 in the placebo group. 41 (84%) of 49 patients in the low-dose naltrexone group had an adverse event versus 43 (86%) of 50 in the placebo group. One serious adverse event occurred in the placebo group and no deaths occurred.

INTERPRETATION

This study did not show that treatment with low-dose naltrexone was superior to placebo in relieving pain. Our results indicate that low-dose naltrexone might improve memory problems associated with fibromyalgia, and we suggest that future trials investigate this further.

FUNDING

The Danish Rheumatism Association, Odense University Hospital, Danielsen's Foundation, and the Oak Foundation.

Opiate Antagonists for Chronic Pain: A Review on the Benefits of Low-Dose Naltrexone in Arthritis versus Non-Arthritic Diseases

Chronic pain conditions create major financial and emotional burdens that can be devastating for individuals and society. One primary source of pain is arthritis, a common inflammatory disease of the joints that causes persistent pain in affected people. The main objective of pharmacological treatments for either rheumatoid arthritis (RA) or osteoarthritis (OA) is to reduce pain. Non-steroidal anti-inflammatory drugs, opioids, and opioid antagonists have each been considered in the management of chronic pain in arthritis patients. Naltrexone is an oral-activated opioid antagonist with biphasic dose-dependent pharmacodynamic effects. The molecule acts as a competitive inhibitor of opioid receptors at high doses. However, naltrexone at low doses has been shown to have hormetic effects and provides relief for chronic pain conditions such as fibromyalgia, multiple sclerosis (MS), and inflammatory bowel disorders. Current knowledge of naltrexone suggests that low-dose treatments may be effective in the treatment of pain perception in chronic inflammatory conditions observed in patients with either RA or OA. In this review, we evaluated the therapeutic benefits of low-dose naltrexone (LDN) on arthritis-related pain conditions.