Background: 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.
Objectives: 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.
Search strategy: A literature search was performed using Cochrane MS Group Trials Register (21 May 2009), Cochrane Central Register of Controlled Trials (CENTRAL) "The Cochrane Library 2009, issue 2, MEDLINE (PubMed) (1966-21 May 2009), EMBASE (1974-21 May 2009). 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.
Selection criteria: Full reports of published and unpublished randomized controlled trials and quasi-randomized trials of any carnitine intervention in adults with a clinical diagnosis of fatigue associated with multiple sclerosis were included.
Data collection and analysis: 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.
Main results: The search identified one randomized cross-over trial. In this study patients were exposed to both acetyl L-carnitine (ALCAR(tm)) 2 grams daily and amantadine 200 mg daily in adult patients with relapsing-remitting and secondary progressive MS. The effects of carnitine on fatigue are not clear based on the one included crossover RCT. 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. Mortality, serious adverse events, total adverse events, and quality of life were not reported.
Authors' conclusions: There is insufficient evidence that carnitine for the treatment of MS-related fatigue offers a therapeutic advantage over placebo or active comparators.