Differentiation of alcohol and barbital physical dependence.

In order to elucidate the fundamental differences between alcohol and barbital physical dependence, comparative studies were made on the effect of various drugs on the withdrawal signs developed in alcohol and barbital dependent mice. Ethanol, barbital and diazepam, drugs of alcohol-barbiturate type dependence liability, and ethosuximide, an anticonvulsant, suppressed both withdrawal signs in a dose dependent manner. The effects of these drugs were different from each other only quantitatively and no special difference was observed between the effects on alcohol and barbital withdrawal signs. On the other hand, the effects of phenytoin, an anticonvulsant, and pentylenetetrazol, a convulsant, were only evident in alcohol dependent animals. Phenytoin elicited body tremor and markedly exacerbated the alcohol withdrawal signs, but slightly suppressed the barbital withdrawal signs. Dose-response curves for the convulsive effect of pentylenetetrazol obtained at the peak of the withdrawal signs shifted greatly to the left in alcohol withdrawn animals but less in barbital withdrawn animals. These discrepancies between the effects on alcohol and barbital withdrawal signs may suggest a difference in the underlying mechanisms for the production of alcohol and barbital physical dependence.