Anxiolytic potential of a microgram dose of chlordiazepoxide in the open-field test

Diazepam, when administered in very low doses (100 micrograms/kg), can induce a specific inhibition of coarse and ambulation activities in the rat, suggesting a novel mechanism of action occurring in the microgram dose range. This study fails to reproduce the same effects with chlordiazepoxide. On the contrary, greater stimulant and anxiolytic effects were measured with the lowest dose tested (0.1 mg/kg). These results demonstrate that the familiar effects of benzodiazepines should not be extrapolated uncritically to lower dose ranges without empirical testing.