Background: Modafinil is a unique wake-promoting agent that is chemically distinct from traditional stimulants. Results of a placebo-controlled study showed it to improve fatigue in multiple sclerosis (MS) at a dose of 200 mg daily, but not at a dose of 400 mg daily.

Objective: To establish the efficacy, safety and appropriate dose of modafinil in the treatment of fatigue and sleepiness in patients with multiple sclerosis.

Method: A total of 50 patients diagnosed with MS (mean age 40.4 +/- 10.3 years, 30 females/20 males; MS type: 36 relapsing remitting, 1 primary progressive, 13 secondary progressive; mean disability level 3.8 +/- 1.5 on the Kurtzke EDSS) and complaining of chronic fatigue were enrolled in a prospective 3-month, two-center, open-label study. Efficacy was evaluated with the Fatigue Severity Scale (FSS, score range 0-42), the Epworth Sleepiness Scale (ESS, score range 0-24) and by subjective patient appraisal of change of fatigue, quality of life and overall satisfaction with treatment. Adverse effects (AEs) were recorded throughout the study. Treatment was started with a single daily dose of 100 mg in all patients. In non-responders the dose was increased by 100 mg increments up to a maximum daily dose of 400 mg.

Results: Three patients discontinued modafinil because of AEs (nervousness, dizziness). Two patients (4 %) were treated with 50 mg, 25 (50 %) with 100 mg, 21 (42 %) with 200 mg and 2 (4 %) with 300 mg daily. No patient required 400 mg daily. Mean FSS scores were 30.3 +/- 8.5 at baseline and 25.4 +/- 3.7 at 3 months (p < 0.0001). Mean ESS scores were 9.7 +/- 3.9 at baseline and 4.9 +/- 2.9 at 3 months (p < 0.0001). Self-appraisal of change of fatigue showed clear improvement in 41 patients (87.2 %), some improvement in 4 (8.5 %) and no change in 2 (4.3 %). Overall clinical condition was clearly improved in 43 patients (91.5 %), somewhat improved in 1 patient (2.1 %), and unchanged in 3 patients (6.4 %). No patient reported worsening of overall clinical condition.

Conclusions: Treatment with modafinil significantly improves fatigue and sleepiness and is well tolerated by patients with MS. Unlike the higher dose regimen required in narcolepsy, a low-dose regimen of modafinil is effective in MS.