Open study with (-)-OSU6162 in multiple sclerosis-related fatigue

Objectives: The main objective of this study was to investigate the tolerability and safety of the monoaminergic stabilizer (-)-OSU6162 in patients with multiple sclerosis (MS). In addition, a potential therapeutic effect of (-)-OSU6162 with focus on MS-related fatigue was estimated by means of various self-assessment rating scales as well as a clinical investigator-rated scale.

Materials and methods: In this open-label, single-arm study, 30 MS patients received treatment with the monoaminergic stabilizer (-)-OSU6162 during 12 weeks. The dose of (-)-OSU6162 was 15 mg twice daily during the first 4-week period, up to 30 mg twice daily during the second 4-week period and up to 45 mg twice daily during the third 4-week period, with follow-up visits after 16 and 20 weeks. MS-related fatigue was rated by the clinical investigator or by self-assessments, using mainly established rating scales. Twenty-five patients completed the study.

Results: (-)-OSU6162 was well tolerated by all patients, and no serious adverse events were observed. Therapeutically, improvements were observed with respect to fatigue and mood, as judged by ratings on the Mental Fatigue Scale (MFS), Short Form-36 (SF-36) scale and Beck Depression Inventory (BDI). Furthermore, the large majority of patients were rated as globally improved in the medical observers' rating scale Clinical Global Impression of Change (CGI-C).

Conclusions: In view of its good tolerability, (-)-OSU6162 may offer a new treatment option for alleviating mental fatigue, as well as depression, in MS. Larger, randomized double-blind controlled trials are warranted to confirm the present preliminary observations.