Immediate effects on human performance of a 1,5-genzodiazepine (clobazam) compared with the 1,4-benzodiazepines, chlordiazepoxide hydrochloride and diazepam.

1 The immediate effects on human performance of the 1,5-benzodiazepine, clobazam (20 mg), and the 1,4-benzodiazepines, chlordiazepoxide hydrochloride (20 mg) and diazepam (10 mg), were studied by adaptive tracking and measurement of reaction time. Each drug was ingested at 09.00 h and performance was measured at 09 h 30 min (0.5 h), 11 h 30 min (2.5 h), 14 h 30 min (5.5 h) and 18 h 30 min (9.5 h after ingestion). 2 With diazepam decrements in performance on adaptive tracking were observed at 0.5 h and 2.5 h and performance was enhanced at 9.5 h after ingestion. With clobazam performance at individual times did not differ significantly from control, but there was evidence of an improvement in performance during the day. There was no evidence of impaired performance on adaptive tracking after chlordiazepoxide hydrochloride. 3 Reaction time was slowed at 0.5 h and 2.5 h after diazepam and chlordiazepoxide hydrochloride. A decrease in reaction time was observed at 9.5 h after diazepam. No changes in reaction time were observed after clobazam. 4 The subjects as a group differentiated correctly between performance decrements on adaptive tracking after diazepam and the absence of performance decrements after clobazam and chlordiazepoxide hydrochloride. The persistence of the decrement in performance after diazepam was accurately assessed. 5 It is evident that the nature and persistence of impaired performance and the ability to appreciate impaired performance vary considerably between the benzodiazepines, and that the choice of a benzodiazepine should include careful consideration of performance sequelae.