Low Dose Naltrexone for Treatment of Pain in Patients With Fibromyalgia - Effect Via a Central Mechanism?

Rigshospitalet, Denmark58 enrolled

Overview

This study evaluates the effect and mechanism of low dose naltrexone for treatment of pain in patients with fibromyalgia. It s a randomised, double-blinded, placebo-controlled, cross-over study. The study takes place at The Multidisciplinary Pain Center in Grindsted.

Fibromyalgia syndrome is a prevalent musculoskeletal disorder characterized by pain, profound fatigue, sleep disorder, mood disturbance etc. The prevalence is estimated to be 2-8%. Treatment of pain in patients with fibromyalgia is often based on opioids. However, opioids may lead to tolerance, addiction and hyperalgesia and alternative treatments are therefore warranted. Low dose naltrexone (3-5mg) (LDN) has shown promising results in the treatment of pain in patients with fibromyalgia, but there is a need for further research. At the typical dose of naltrexone, 50 mg, it is an opioid antagonist. However LDN demonstrates analgesic and anti-inflammatory effects, possibly involving an antagonism of microglia in the CNS. The investigators hypothesize, that LDN has a better pain relieving effect than placebo in in patients with fibromyalgia (FM). The investigators also hypothesize that LDN has a better effect upon experimentally induced pain in FM-patients, compared to placebo. A tentative mechanism is a central facilitation of the endogenous pain inbitory system.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

QUADRUPLE

Enrollment

Conditions

Fibromyalgia

Interventions

Low dose naltrexoneDRUG

Active comparator

PlaceboDRUG

Placebo comparator

Eligibility

Sex: ALLMin age: 18 YearsMax age: 65 Years

Medical Language ↔ Plain English

Patients diagnosed with fibromyalgia based on the criteria of American College of Rheumatology. Inclusion Criteria: * Widespread pain in patients with fibromyalgia (based on the above criteria) * Enrolled as a patient in one of the multidisciplinary pain clinics involved in the project * Inflammatory rheumatic disease (peripheral inflammation, including arthritis), must be excluded * Women must be treated with a contraceptive measure, if not menopausal Exclusion Criteria: * Cancer * Treatment with opioids (other analgesic treatments in stabile dose 14 days prior to study start are allowed) * Change in stabile treatment (p.n. paracetamol is allowed, but must be registered) * Pregnant/breastfeeding * Does not speak/understand Danish * Allergy to the ingredient * Severe liver impairment * Severe kidney impairment * Acute hepatitis

Locations (1)

Multidisciplinary Pain Centre

Grindsted, Denmark

Outcomes

Primary Outcomes

Change in pain scores (during rest, during household activity, during personal daily hygienic procedures)

The patient indicates using a questionnaire-based numerical rating scale (0 = no pain; 100 = worst imaginable pain) mean values of pain at rest, pain during household activity and pain during personal hygienic procedures in the preceding 24 hrs. The cumulated pain scores are used in the statistical analyses.

Time frame: Baseline: Day -2 to day 1 (baseline before treatment 1); Treatment 1: Day 19 to 21 ; Washout: Day 33 to 35 (baseline before treatment 2); Treatment 2: Day 54 to 56

Secondary Outcomes

Fibromyalgia Impact Questionnaire Revised (FIQR)

The FIQR is a fibromyalgia-specific questionnaire containing three domains: function domain, impact domain and symptom domain. The total score of FIQR is calculated by: * the function domain sum is divided by 3 (upper limit 30) * the impact domain sum is unchanged (upper limit 20) * the symptom domain sum is divided by 2 (upper limit 50) The three resulting processed domain scores are summed to obtain the total score of the FIQR (range 0-100)

Time frame: Before baseline: Day -3; Treatment 1: Baseline (Day 1) + Day 14 + 21 ; Washout: Before baseline day -3; Treatment 2: Baseline (Day 35) + Day 49 + 56

Daily Sleep Interference Scale (DSIS)

Pain-related sleep interference is evaluated with the DSIS (0 =pain does not interfere with sleep, 10 = pain completely interferes with sleep\]).

Time frame: Diary (Treatment 1: baseline (Day 1) to Day 21; Treatment 2: baseline (Day 35) to Day 56)

Pressure algometry (1 sq.cm probe)

Pressure algometry in pre-specified points: 1. right occipital region at insertion of m. subocipitalis 2. right m. trapezius at the midpoint of the upper border 3. right paraspinal region, 3 cm lateral of the midline at level of mid-scapula 4. right second costochondral junction 5. right lateral epicondyle 6. right knee region, at the medial "fat pad" proximal of the meniscus margin In addition at following control sites: 1. right lower arm, at the dorsal lower third 2. right fingernail of first digit 3. right third metatarsal bone at midpoint Cut-off point is 400 kPa, rate 10-30 kPa/s

Data from ClinicalTrials.gov

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