Study protocol for a randomised, double-blinded, placebo-controlled phase III trial examining the add-on efficacy, cost-utility and neurobiological effects of low-dose naltrexone (LDN) in patients with fibromyalgia (INNOVA study)

Efficacy and safety of low-dose naltrexone for the management of fibromyalgia: a systematic review and meta-analysis of randomized controlled trials with trial sequential analysis

Background

Fibromyalgia is characterized by the presence of chronic widespread pain that may impair patient's quality of life. Currently, the use of naltrexone as a therapeutic agent for fibromyalgia is not supported by enough evidence, especially from randomized controlled trials (RCTs). This study aims to analyze the efficacy and safety of low-dose naltrexone (LDN) for the management of fibromyalgia.

Methods

A comprehensive search was conducted on the Scopus, Medline, ClinicalTrials.gov, and Cochrane Library databases up until May 20th, 2024. This review incorporates RCTs that examine the comparison between LDN and placebo in fibromyalgia patients. We employed random-effect models to analyze the odds ratio and mean difference (MD) for presentation of the outcomes.

Results

A total of 4 RCTs with 222 fibromyalgia patients were incorporated. The results of our meta-analysis showed a significant reduction in pain scores (MD: -0.86, 95% confidence interval [CI]: -1.20, -0.51, P < 0.001, I2 = 33%) and higher increment in pressure pain threshold (MD: 0.17, 95% CI: 0.08, 0.25, P < 0.001, I2 = 0%) among fibromyalgia patients who received LDN than those who only received a placebo. The fibromyalgia impact questionnaire revised and pain catastrophizing scale did not differ significantly between the two groups. LDN was also associated with higher incidence of vivid dreams and nausea, but showed no significant difference with the placebo in terms of serious adverse events, headache, diarrhea, and dizziness.

Conclusions

This study suggests the efficacy of LDN in mitigating pain symptoms for fibromyalgia patients with a relatively good safety profile.

Pharmacotherapeutic advances in fibromyalgia: what's new on the horizon?

INTRODUCTION

This review delves into Fibromyalgia Syndrome (FMS), a chronic pain condition demanding thorough understanding for precise diagnosis and treatment. Yet, a definitive pharmacological solution for FMS remains elusive.

AREAS COVERED

In this article, we systematically analyze various pharmacotherapeutic prospects for FMS treatment, organized into sections based on the stage of drug development and approval. We begin with an overview of FDA-approved drugs, discussing their efficacy in FMS treatment. Next, we delve into other medications currently used for FMS but still undergoing further study, including opioids and muscle relaxants. Further, we evaluate the evidence behind medications that are currently under study, such as cannabinoids and naltrexone. Lastly, we explore new drugs that are in phase II trials. Our research involved a thorough search on PUBMED, Google Scholar, and clinicaltrials.gov. We also discuss the action mechanisms of these drugs and their potential use in specific patient groups.

EXPERT OPINION

A focus on symptom-driven, combination therapy is crucial in managing FMS. There is also a need for ongoing research into drugs that target neuroinflammation, immunomodulation, and the endocannabinoid system. Bridging the gap between benchside research and clinical application is challenging, but it holds potential for more targeted and effective treatment strategies.

Low-dose naltrexone for post-COVID fatigue syndrome: a study protocol for a double-blind, randomised trial in British Columbia

INTRODUCTION

A significant proportion of individuals suffering from post COVID-19 condition (PCC, also known as long COVID) can present with persistent, disabling fatigue similar to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and post-viral fatigue syndromes. There remains no clear pharmacological therapy for patients with this subtype of PCC, which can be referred to as post-COVID fatigue syndrome (PCFS). A low dose of the opioid antagonist naltrexone (ie, low-dose naltrexone (LDN)) has emerged as an off-label treatment for treating fatigue and other symptoms in PCC. However, only small, non-controlled studies have assessed LDN in PCC, so randomised trials are urgently required.

METHODS AND ANALYSIS

A prospective, randomised, double-blind, parallel arm, placebo-controlled phase II trial will be performed to assess the efficacy of LDN for improving fatigue in PCFS. The trial will be decentralised and open to eligible individuals throughout the Canadian province of British Columbia (BC). Participants will be recruited through the province-wide Post-COVID-19 Interdisciplinary Clinical Care Network (PC-ICCN) and research volunteer platform (REACH BC). Eligible participants will be 19-69 years old, have had a confirmed or physician-suspected SARS-CoV-2 infection at least 3 months prior and meet clinical criteria for PCFS adapted from the Institute of Medicine ME/CFS criteria. Individuals who are taking opioid medications, have a history of ME/CFS prior to COVID-19 or history of significant liver disease will be excluded. Participants will be randomised to an LDN intervention arm (n=80) or placebo arm (n=80). Participants in each arm will be prescribed identical capsules starting at 1 mg daily and follow a prespecified schedule for up-titration to 4.5 mg daily or the maximum tolerated dose. The trial will be conducted over 16 weeks, with assessments at baseline, 6, 12 and 16 weeks. The primary outcome will be fatigue severity at 16 weeks evaluated by the Fatigue Severity Scale. Secondary outcomes will include pain Visual Analogue Scale score, overall symptom severity as measured by the Patient Phenotyping Questionnaire Short Form, 7-day step count and health-related quality of life measured by the EuroQol 5-Dimension questionnaire.

ETHICS AND DISSEMINATION

The trial has been authorised by Health Canada and approved by The University of British Columbia/Children's and Women's Health Centre of British Columbia Research Ethics Board. On completion, findings will be disseminated to patients, caregivers and clinicians through engagement activities within existing PCC and ME/CFS networks. Results will be published in academic journals and presented at conferences.

TRIAL REGISTRATION NUMBER

NCT05430152.

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.

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

Background

Low dose naltrexone (LDN) is used off-label by many individuals with fibromyalgia to help manage their pain. There is no current systematic literature review summarising the evidence to support this use of LDN. The objectives of this study were to evaluate if patients with fibromyalgia prescribed LDN have reduced pain scores and greater quality of life compared with those allocated to placebo in randomized controlled trials. Secondly to determine if changes in inflammatory markers and brain structure and function are observed among patients with fibromyalgia taking LDN.

Methods

Systematic literature searches were conducted in MEDLINE, Embase Classic + Embase, APA PsychInfo, and The Cochrane Library from inception to May 2022. Reference lists from the selected papers were cross-checked with database search results.

Results

Three studies met our inclusion criteria for the assessment of efficacy, and two studies on potential LDN mechanisms. Results indicated some evidence to suggest LDN reduces pain and increases quality of life. One study reported baseline erythrocyte sedimentation rate (ESR) predicted LDN response (≥30% reduction in fibromyalgia symptoms) and a second study showed plasma concentrations of inflammatory biomarkers were lower after LDN treatment. To our knowledge, there are no brain imaging studies reporting the effect of LDN in patients with fibromyalgia. All studies were based on small sample sizes, were restricted to women and the risk of bias was assessed to be high. There is also some evidence of publication bias.

Conclusion

The strength of evidence from randomized controlled trials to support the use of LDN among patients with fibromyalgia is low. Two small studies suggest ESR and cytokines may be involved in the mechanism by which LDN exerts its effects. Two trials (INNOVA and FINAL) are currently in progress, but further work is needed among men and different ethnic groups.

[Low-dose naltrexone (LDN): consumption trend in Brazilian capitals and the Federal District, 2014-2020]

The scope of this paper is an ecological study to determine the consumption of low-dose naltrexone (LDN) in the 26 Brazilian capitals and the Federal District and monitor the trend between the years 2014 to 2020. Data collection on the dispensation of manipulated naltrexone was done through the National Management System of Controlled Products, published in 2020, considering low-dose prescriptions of up to 5 mg. The calculation of the dispensation coefficients used the population estimates of the Brazilian Institute of Geography and Statistics. Descriptive statistical analysis and generalized Prais-Winsten regression analysis were used for the time series analysis. The trends observed were classified as increasing, stable, or decreasing, with a 95% confidence interval and 5% significance level. The results showed higher LDN consumption coefficients in the Mid-West, South and Southeast regions and lower coefficients in the North and Northeast. Increasing dispensation of LDN was observed in 55.6% of the capitals, being stationary in 44.4%, with no decreasing coefficients. Despite the limited evidence regarding LDN pharmacotherapy and its off-label prescription, the data show that prescription, dispensing, and consumption have been on the increase in Brazil, with emphasis on the central-south regions of the country.