Sedative effects of PK 9084 and PK 8165, alone and in combination with chlordiazepoxide.

1 The sedative effects in rats of two phenylquinolines, PK 9084 and PK 8165 (5-50 mg/kg), were examined in a holeboard: both when given alone and when given in conjunction with chlordiazepoxide (5 mg/kg). 2 Both phenylquinolines produced significant dose-related decreases in locomotor activity and rearing, with an ED50 about twice that for chlordiazepoxide. 3 When the phenylquinolines were combined with chlordiazepoxide the degree of sedation was equal to that seen with either drug given alone, whichever produced the greater sedation; the sedative effects of the two drugs were never additive. 4 PK 9084 (10 and 50 mg kg) significantly reduced rectal temperature, as did chlordiazepoxide (5 mg/kg), but there was no addition nor interaction of their effects. 5 Both phenylquinolines also reduced exploratory head-dipping, as did chlordiazepoxide, but in combination they antagonized each other's effects. 6 The classification of the phenylquinolines as non-sedative anxiolytics, acting as agonists at the benzodiazepine receptors needs revision.