Drug Interactions between Benadryl and dimethyl fumarate

GENERALLY AVOID: Use of anticholinergic agents with alcohol may result in sufficient impairment of attention so as to render driving and operating machinery more hazardous. In addition, the potential for abuse may be increased with the combination. The mechanism of interaction is not established but may involve additive depressant effects on the central nervous system. No effect of oral propantheline or atropine on blood alcohol levels was observed in healthy volunteers when administered before ingestion of a standard ethanol load. However, one study found impairment of attention in subjects given atropine 0.5 mg or glycopyrrolate 1 mg in combination with alcohol.

MANAGEMENT: Alcohol should generally be avoided during therapy with anticholinergic agents. Patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them.

Food does not significantly affect the oral bioavailability of dimethyl fumarate. Administration of dimethyl fumarate with a high-fat, high-calorie meal did not affect the systemic exposure (AUC) to its active metabolite, monomethyl fumarate (MMF), but decreased its peak plasma concentration (Cmax) by 40% and prolonged the time to reach peak concentration (Tmax) from 2.0 hours to 5.5 hours. In the study, the incidence of flushing was reduced by approximately 25% in the fed state. Dimethyl fumarate may be taken with or without food; however, taking it with food may help reduce flushing.