Amphetamine–Barbiturate Mixture: Effects on the Behaviour of Mice

Abstract

THE clinical impression that mixtures of amphetamine and barbiturates have psychoactive properties additional to those of the single constituents is supported by the results of experiments carried out with animals^1–3 and human subjects⁴. Experiments with female rats have shown that with several mixtures of amphetamine and amylobarbitone, including one containing 0.75 mg/kg of amphetamine sulphate and 15.0 mg/kg of amylobarbitone sodium, the locomotor activity into the arms of a Y-maze was increased much more than with the same, or other, doses of the drugs which were administered alone or in any other combination². Female rats which were given the mixture also learned to press a bar—in order to obtain water—more rapidly than others which received the single constituents³. This latter effect seemed to be less marked in male rats. There is a practical problem in using such a mixture for therapeutic or experimental purposes: the effect is only manifest over a relatively narrow range of doses and therefore the choice of an appropriate dose for individual patients or subjects is critical.