Fatigue is commonly associated with multiple sclerosis and leads to significant disability and loss of quality of life. Several kind of interventions have been carried out, but definitive evidence on their relative efficacy and tolerability are not available. As quite recently it has been hypothesised a relationship between low carnitine levels in the blood and fatigue, and several studies showed that supplementation with carnitine produced improvement in fatigue symptoms. The Authors decided to perform a systematic review to assess the possible efficacy of carnitine in improving fatigue and to identify any adverse events in relapsing-remitting and secondary progressive MS patients. Most of the studies did not meet the inclusion criteria of methodological quality, but one with the enrollement of 36 patients for 12-month intervention with carnitine associated with amantadine, another drug commonly used to improve fatigue.
From this report, it is unclear if carnitine supplementation in MS patients improves fatigue, reduces the disability that results from fatigue or improves quality of life. It is also unclear if the use of carnitine for MS related fatigue is safe.
There is insufficient evidence that carnitine for the treatment of MS-related fatigue offers a therapeutic advantage over placebo or active comparators. Results of the ongoing trial are eagerly anticipated in order to provide clarity.
Fatigue is reported to occur in up to 92% of patients with multiple sclerosis (MS) and has been described as the most debilitating of all MS symptoms by 28% to 40% of MS patients.
To assess whether carnitine (enteral or intravenous) supplementation can improve the quality of life and reduce the symptoms of fatigue in patients with MS-related fatigue and to identify any adverse effects of carnitine when used for this purpose.
A literature search was performed using Cochrane MS Group Trials Register (09 September 2011), Cochrane Central Register of Controlled Trials (CENTRAL) "The Cochrane Library 2011, issue 3", MEDLINE (PubMed) (1966-09 September 2011), EMBASE (1974-09 September 2011), and www.clinicaltrials.gov for ongoing trials retrieval. Reference lists of review articles and primary studies were also screened. A hand search of the abstract book of recent relevant conference symposia was also conducted. Personal contact with MS experts and a manufacturer (Source Naturals, United States) of carnitine formulation was contacted to determine if they knew of other clinical trials. No language restrictions were applied.
Full reports of published and unpublished randomized controlled trials and quasi-randomized trials of any carnitine intervention in adults affected by multiple sclerosis with a clinical diagnosis of fatigue associated with multiple sclerosis were included.
Data from the eligible trials was extracted and coded using a standardized data extraction form and entered into RevMan 5. Discrepancies were to be resolved by discussion with a third reviewer, however this was not necessary.The quality items to be assessed were method of randomization, allocation concealment, blinding (participants, investigators, outcome assessors and data analysis), intention-to-treat analysis and completeness of follow up.
The search identified one ongoing randomized, placebo-controlled, cross-over trial (expected completion 2013) and one completed randomized, active-comparator, cross-over trial. In the completed study, adult patients with relapsing-remitting and secondary progressive MS were exposed to both acetyl L-carnitine 2 grams daily and amantadine 200 mg daily The effects of carnitine on fatigue are unclear. There was no difference between carnitine and amantadine for the number of patients withdrawing from the study due to an adverse event (relative risk ratio 0.20; 95% confidence interval 0.03 to 1.55) and no patients experienced a serious adverse event in either treatment group. Mortality and quality of life were not reported.