Application of radioreceptor assays for systematic toxicological analysis--2. Theoretical considerations and evaluation

In this paper the applicability of radioreceptor assays for systematic toxicological analysis will be evaluated on a theoretical basis as well as on the basis of the outcomes of the analysis of a large number of urine samples collected after administration of a selected number of drugs to healthy volunteers and patients. Many drugs and other substances of toxicological relevance exert their action through an interaction with one or more receptor (sub)types. Whether the number of persons are using particular drugs intentionally or unintentionally, radioreceptor assays can be a useful tool for systematic toxicological analysis in that they can be applied to the identification of entire pharmacological classes of substances as well as pharmacologically active metabolites. In part 1 of this paper detailed procedures for radioreceptor assays for benzodiazepines, anticholinergics and antihistaminics have been described in detail in order to illustrate not only the potentials but also the limitations of assay conditions. Fifteen drugs were administered to patients and volunteers and urine samples were collected and determined with the three radioreceptor assays. The results of this study underline the theoretical applicability of receptor assays in systematic toxicological analysis though sample pretreatment procedures may contribute to an improvement in sensitivity and applicability to other biofluids.