Radioreceptor assay for benzodiazepines in biological fluids using a new dry and stable receptor preparation.

A method for determination of benzodiazepines in human blood, plasma, saliva and urine has been developed. The method is based upon the competition between 3H-flunitrazepam and biologically active benzodiazepines in biological fluids for brain specific receptors, prepared in a stable, dry form and easy to handle. The pharmacological specificity for benzodiazepines of the dry stable receptor preparation is closely similar to that of fresh membrane-bound rat brain receptors. The method is specific for biologically active benzodiazepines; it is relatively rapid, sensitive and reproducible, and can be performed at room temperature.