Evaluation of a radioreceptor assay for beta-adrenoceptor antagonists in plasma.
A radioreceptor assay (RRA) recently developed in this laboratory for beta-adrenoceptor antagonists in plasma was evaluated in normal volunteers and compared with a radioimmunoassay (RIA) for propranolol. The RRA depends upon the ability of beta-adrenoceptor antagonists to complete with a radiolabelled ligand for beta-adrenoceptor binding sites on lung membranes. Unlike other assays, it measures biologically active drugs including active metabolites of the parent compound. In volunteers given a single oral dose of (+/-)-propranolol, considerable differences between the two assay methods were demonstrated. In other experiments this difference was shown to relate to the RIA's sensitivity to the inactive (+)-isomer of propranolol and possibly to inactive metabolites. The facility of the RRA in measuring plasma levels of several other non-selective beta-adrenoceptor antagonists was also demonstrated. By employing (-)-propranolol as the standard in the RRA, all of these drugs can be directly compared with a single and relatively simple assay technique.
D000318:Adrenergic beta-Agonists / Q000097:blood*; D000328:Adult; D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D004082:Dihydroalprenolol / Q000378:metabolism; D005069:Evaluation Studies as Topic; D006801:Humans; D066298:In Vitro Techniques; D008168:Lung / Q000378:metabolism; D008297:Male; D008566:Membranes / Q000378:metabolism; D011433:Propranolol / Q000097:blood; D011863:Radioimmunoassay; D011869:Radioligand Assay; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism
D000318:Adrenergic beta-Agonists; D011943:Receptors, Adrenergic, beta; D004082:Dihydroalprenolol; D011433:Propranolol