The stimulus properties of two common over-the-counter drug mixtures: dextromethorphan + ephedrine and dextromethorphan + diphenhydramine
Journal of Psychopharmacology January 1, 1998 D.V. Gauvin, S.A. Vanecek, T.J. Baird et al.
Rats were trained to distinguish two over-the-counter drug mixtures—dextromethorphan plus diphenhydramine and dextromethorphan plus ephedrine—from a placebo. The mixtures were not perceived as entirely new substances; instead, their individual components contributed to the rats' discrimination. Stimulant drugs like cocaine and amphetamine fully substituted for both mixtures, while pentobarbital did not. The findings suggest these common drug combinations have potential for abuse and caution against their use in children.