Tolerability and Pharmacokinetics of Delayed-Release Dimethyl Fumarate Administered With and Without Aspirin in Healthy Volunteers

Background: Delayed-release dimethyl fumarate (DR-DMF) has cytoprotective and antiinflammatory properties and has recently been approved in the United States as an oral treatment for relapsing forms of multiple sclerosis. The most common adverse events associated with DR-DMF are flushing and gastrointestinal (GI) events, the incidences of which diminish over time. Objective: The purpose of this study was to evaluate the tolerability and pharmacokinetic (PK) profile of DR-DMF with or without concomitant acetylsalicylic acid (aspirin), a cyclooxygenase inhibitor. Methods: Healthy volunteers (N = 56) were randomized to receive different dosing regimens of DR-DMF or matching placebo with or without pretreatment with 325 mg aspirin for 4 days. Plasma levels of the active metabolite monomethyl fumarate were assessed on days 1 and 4. Flushing and GI events were assessed using patient-reported scales. Potential flushing mediators were explored. Results: DR-DMF showed a safety, tolerability, and PK profile consistent with previous clinical experience, with no evidence of accumulation. Pretreatment with aspirin had no effect on the primary PK parameters, AUC(0-10h), or C-max. Flushing severity, assessed by 2 subject-reported rating scales, was generally mild and was rated highest at the start of treatment. Pretreatment with aspirin reduced flushing incidence and intensity without affecting GI events or the PK profile of DR-DMF. In some DR-DMF treated individuals, plasma concentrations of a prostaglandin D-2 (PGD(2)) metabolite were increased. Conclusions: In healthy volunteers, DR-DMF was well tolerated over 4 days of dosing, with a PK profile consistent with that previously reported and no evidence of accumulation. Aspirin pretreatment reduced the incidence and intensity of flushing without affecting GI events or the DR-DMF PK profile. Elevated levels of PGD(2) in some DR-DMF treated individuals suggest that flushing may be, at least in part, prostaglandin mediated. ClinicalTrials.gov identifier: ID: NCT01281111. (C) 2013 The Authors. Published by Elsevier, Inc. All rights reserved.