BACKGROUND: Pitolisant (BF2.649) is a nonimidazole histamine 3 receptor antagonist. In previous animal studies, it has been shown that pitolisant might be helpful in chronic seizure treatment of both partial and generalized epilepsies. The present study is a multicenter, national, pragmatic, noncomparative, open-label, exploratory phase II trial. It is the first reported study of the clinical effects of pitolisant in human epilepsy. OBJECTIVE: The goal of this trial was to explore the antiepileptic effect of 3 different doses of pitolisant (20, 30, and 40 mg once daily) in patients presenting partial seizure onset despite therapy with adequate dose of 1 to 3 appropriate antiepileptic drugs. METHODS: The study has been conducted in 6 study sites in France between 2005 and 2006. The primary end point was the proportion of responders having a seizure rate decrease by at least 50%. A larger clinical trial could be started according to the results. An interim analysis was planned in the protocol to decide if the study should be continued or not according to the efficacy and safety results. Descriptive statistics were used for the analysis. RESULTS: An initial goal of 40 patients included had been planned; 23 were finally included. Pitolisant was well tolerated and achieved a clinical response in one third of patients after 3 months of treatment. CONCLUSIONS: Despite encouraging data, there is no evidence for the efficacy of the drug for the regimen that was used, but no firm conclusions can be drawn because the number of included subject was small and the study was not placebo controlled.