Differential amnestic properties of short- and long-acting benzodiazepines.

It has been demonstrated previously that orally administered lorazepam can cause anterograde amnesia in young adults. In this study, the effects of 7.5 and 15 mg clorazepate and 1 and 2 mg lorazepam on recall were compared in 74 healthy adults. Word list presentation tests were administered to subjects at selected intervals to measure immediate and delayed recall. Statistically significant memory impairment was found with 2 mg lorazepam during both immediate and delayed recall testing. Clorazepate produced no statistically significant amnestic effects. The data suggest that benzodiazepines differ in their potential for causing memory impairment.

Limited in vivo bioassays on some benzodiazepines: lack of experimental initiating or promoting effect of the benzodiazepine tranquillizers diazepam, clorazepate, oxazepam and lorazepam.

Four benzodiazepine tranquillizers were tested for their ability to initiate or promote the development of preneoplastic and neoplastic rat liver lesions. In comparison with the liver carcinogen, N-2-fluorenylacetamide, the benzodiazepines exhibited no initiating activity during a 14-week period of daily administration by gavage. To study the promoting activity, N-2-fluorenylacetamide was used to initiate altered foci and neoplastic nodules in rat liver during 8 weeks and then the benzodiazepines were administered by daily gavage for a period of 12 weeks. The liver tumor promoter phenobarbital had a substantial enhancing effect upon the persistence of nodules but none of the benzodiazepines showed a similar effect. Thus, in the process model systems used, to detect initiating or promoting potential effect, the benzodiazepine tranquillizers failed to exhibit either an initiating or a promoting action.