DIFFERENTIAL EFFECTS OF TWO AMPHETAMINE-BARBITURATE MIXTURES IN MAN.

Abstract

Mixtures of amphetamine and a barbiturate continue to be fairly widely used in psychiatry, especially in the treatment of mild anxiety and depression (Lancet, 1962; British Medical Journal, 1962; Ornstein & Whitman, 1963), but relatively little is known about the effects of such mixtures from laboratory experiments on man. In a previous investigation (Legge & Steinberg, 1962) a mixture of 15 mg of amphetamine sulphate and 300 mg of cyclobarbitone and the two ingredients separately were studied in normal human subjects, and it was found that the mixture produced a different pattern of effects from the separate ingredients: it impaired the efficiency of the performance of three simple tasks less than did the barbiturate alone; it produced almost as big a rise in the pulse rate as did amphetamine alone; and it produced spontaneous reports suggesting elation from more subjects than did either drug separately, though there was no corresponding increase in reports of other feelings and sensations. The mixture used contained proportionally several times as much barbiturate as a widely used commercial preparation, Drinamyl (Smith, Kline & French), which contains dexamphetamine sulphate and amylobarbitone sodium in a ratio of 1: 6.5. In the experiments to be reported the earlier mixture was therefore compared with a mixture which contained the two drugs in approximately the same proportions as Drinamyl, except that for practical reasons amphetamine sulphate and cyclobarbitone were again the compounds used. Since the main clinical aim of using these drug mixtures appears to be to induce favourable changes in subjective reactions, especially in moods, a standardized and detailed method was adopted to elicit reports of the subjects' feelings. Otherwise the test methods were similar to those previously used.