A radioreceptor assay for β-adrenergic blocking drugs described here is based on the ability of the blood content of drugs to compete with the binding of 3H-dihydroalprenolol (3H-DHA) to β-adrenergic receptors in calf cerebellar membranes. Plasma protein greatly inhibits the binding of 3H-DHA to β-receptors by binding the 3H-DHA so it is unavailable to the β-receptors. As little as 0.01 ml of human plasma in a final volume of 1 ml reduces binding 25-45%. Assays conducted on plasma dialysates can be performed without such inhibition. The radioreceptor assay is simple to perform as 100 samples can be processed in a morning. It is sensitive, detecting low nanomolar concentrations of plasma propranolol, and it is specific. No drugs clinically employed other than β-blocking agents compete for β-receptor binding. The assay detects all pharmacologically active metabolites of β-blocking drugs as well as the parent drug.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)