Measurement of beta-adrenoceptor antagonists in biological fluids using a radioreceptor assay

A new assay for plasma levels of beta-adrenoceptor antagonists is described. The assay depends upon the ability of the drug to compete with a labelled beta-adrenoceptor antagonist (-)-[3H]dihydroalprenolol for beta-adrenoceptor binding sites on lung membranes. The assay is simple to perform, very sensitive and does not require prior extraction of plasma. The assay can also detect bioactive metabolites of these agents and is clearly not limited to a single beta-adrenoceptor antagonist.