Effect of Chlordiazepoxide Administered Early in Extinction on Subsequent Extinction of a Conditioned Emotional Response in Rats: Implications for Human Clinical Use

Two groups of albino rats ( n = 32), in which a conditioned emotional response (CER) to a tone had previously been established, were given two extinction trials: one group received chlordiazepoxide on the first extinction trial and the other group received saline. No drug was administered to either group on the second extinction trial. A standard extinction decrement was shown by the saline animals. The chlordiazepoxide animals not only failed to extinguish but showed a slight increment that was interpreted as being due to a “dissociation” of learning effect. These results suggest caution in the use of chlordiazepoxide in human clinical situations when the fear stimuli are delineated and the hope is for anxiety reduction that continues after withdrawal of the drug.