Amantadine for fatigue in multiple sclerosis

Background Fatigue is one of the most common and disabling symptoms of people with Multiple Sclerosis (MS). The effective management of fatigue has an important impact on the patient's functioning, abilities, and quality of life. Although a number of strategies have been devised for reducing fatigue, treatment recommendations are based on a limited amount of scientific evidence. Many textbooks report amantadine as a first-choice drug for MS-related fatigue because of published randomised controlled trials (RCTs) showing some benefit. Objectives To determine the effectiveness and safety of amantadine in treating fatigue in people with MS. Search strategy We searched The Cochrane MS Group Trials Register (July 2006), The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1, 2006), MEDLINE (January 1966 to July 2006), EMBASE (January 1974 to July 2006), bibliographies of relevant articles and handsearched relevant journals. We also contacted drug companies and researchers in the field. Selection criteria Randomised, placebo or other drugs-controlled, double-blind trials of amantadine in MS people with fatigue. Data collection and analysis Three reviewers selected studies for inclusion in the review and they extracted the data reported in the original articles. We requested missing and unclear data by correspondence with the trial's principal investigator. A meta-analysis was not performed due to the inadequacy of available data and heterogeneity of outcome measures. Main results Out of 13 pertinent publications, 5 trials met the criteria for inclusion in this review: one study was a parallel arms study, and 4 were crossover trials. The number of randomised participants ranged between 10 and 115, and a total of 272 MS patients were studied. Overall the quality of the studies considered was poor and all trials were open to bias. All studies reported small and inconsistent improvements in fatigue, whereas the clinical relevance of these findings and the impact on patient's functioning and health related quality of life remained undetermined. The number of participants reporting side effects during amantadine therapy ranged from 10% to 57%. Authors' conclusions The efficacy of amantadine in reducing fatigue in people with MS is poorly documented, as well as its tolerability. It is advisable to: (1) improve knowledge on the underlying mechanisms of MS-related fatigue; (2) achieve an agreement on accurate, reliable and responsive outcome measures of fatigue; (3) perform good quality RCTs.