The effects upon vigilance and reaction speed of the addition of ephedrine hydrochloride to chlorpheniramine maleate.

The addition of stimulant, ephedrine hydrochloride (15 mg), to the antihistamine, chlorpheniramine maleate (10 mg) is shown significantly to reduce the adverse drowsy effects of the latter upon various components of human performance. Auditory vigilance--a test of long-term attentiveness--is shown particularly to benefit from the addition of ephedrine. Whilst ephedrine does not aid simple reaction speed, it does reduce the pausing in serial-choice performance, indicative of a drowsy state, which otherwise occurs under chlorpheniramine alone.