Summary
A radioreceptor assay (RRA) for the assay of beta-adrenoceptor antagonists in native human plasma is described. The hydrophilic antagonist3H-CGP 12177 was used as the radioligand. In contrast to the hydrophobic radioligand3H-dihydroalprenolol, which was investigated in parallel, the beta-adrenoceptor binding of3H-CGP 12177 by rat reticulocyte membranes was found not to be affected by inclusion of increasing proportions (0–66% of incubation volume) of human plasma in the assay. Thus, solvent extraction of drug and/or active metabolites was not necessary to avoid binding of the radioligand tracer to plasma added in the RRA. The assay of unprocessed samples was possible. Drug concentrations in plasma after oral administration of propranolol (240 mg) or carteolol (30 mg) to 6 healthy volunteers were measured by the RRA and in parallel by a chemical method. The results from both methods agreed when the plasma concentration kinetics of propranolol were investigated (elimination half-life: 3.9 h). In contrast, plasma concentrations of carteolol were consistently higher according to the RRA after oral administration of the drug. Identical concentrations, however, were found by the RRA and chemical method using plasma samples spiked with carteolol. Plasma concentrations of carteolol detected by the chemical method decline monoexponentially (elimination half-life: 5.4 h). A similar half-life of elimination for parent drug was found by the RRA (5.9 h), but an additional term describing the appearance of an active metabolite was necessary to account for the biphasic drug elimination (elimination half-life of metabolite: 17.3 h). The latter result is in agreement with the appearance of 8-hydroxy-carteolol as an active metabolite, which shows similar affinity for beta-adrenoceptors as the parent drug. The active metabolite, with a 3-fold longer elimination half-life than the parent drug, will prolong the duration of the clinical effects of orally administered carteolol. In conclusion, the RRA permits the determination of beta-adrenoceptor antagonistic activity in native human plasma at concentrations as low as 0.1-fold the IC50-value of the drug or an active metabolite.
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References
Barnett DB, Batta M, Davies B, Nahorski SR (1980) Evaluation of a radioreceptor assay for beta-adrenoceptor antagonists. Eur J Clin Pharmacol 17: 349–354
Bilezikian JP, Gammon DE, Rochester CL, Shand DG (1979) A radioreceptor assay for propranolol. Clin Pharmacol Ther 20: 173–180
Creese I, Snyder SH (1978) A simple and sensitive radioreceptor assay for antischizophrenic drugs. Nature 270: 180–182
Dorow RG, Seidler J, Schneider HH (1982) A radioreceptor assay to study the affinity of benzodiazepines and their receptor binding activity in human plasma including their active metabolites. Br J Clin Pharmacol 13: 561–565
Eichelbaum M, Mikus G, Vogelsang B (1984) Pharmacokinetics of (+)-, (−)- and (+/−)-verapamil after intravenous administration. Br J Clin Pharmacol 17: 453–458
Ensing K, Kluivingh F, Gerding TK, de Zeenw RA (1984) Development of a sensitive radioreceptor assay for oxyphenonium in plasma and urine. J Pharm Pharmacol 36: 235–239
Ensinger HA, Doevendans JE (1984) Plasma levels of opioid analgesics determined by radioreceptor assay. Arzneimittelforsch 34: 609–613
George CF, Fenyvesi T, Conolly ME, Dollery CT (1972) Pharmacokinetics of dextro-, laevo- and racemic propranolol in man. Eur J Clin Pharmacol 4: 74–76
Gould RJ, Murphy KMM, Snyder HH (1983) A simple and sensitive radioreceptor assay for calcium antagonist drugs. Life Sci 33: 2665–2672
Hunt P, Husson JM, Raynaud JP (1979) A radioreceptor assay for benzodiazepines. J Pharm Pharmacol 31: 448–451
Innis RB, Bylund BD, Snyder SH (1978) A simple, sensitive and specific radioreceptor assay for beta-adrenergic antagonist drugs. Life Sci 23: 2031–2038
Ishizaki T, Ohnishi A, Sasaki T, Chiba K, Suganuma T, Kushida K (1983) Concentration-effect and time-effect relationship of carteolol. Eur J Clin Pharmacol 25: 749–757
Janis RA, Krol GJ, Noe AJ, Pan M (1983) Radioreceptor and high performance liquid chromatographic assay for the calcium channel antagonist nitrendepine in serum. J Clin Pharmacol 23: 266–273
Kaiser G, Wiemer G, Kremer G, Dietz J, Palm D (1978) Identification and quantification of beta-adrenoceptor sites in red blood cells from rats. Naunyn-Schmiedeberg's Arch Pharmacol 305: 41–50
Lee HR, Roeske WR, Yamamura HI (1983) The measurement of free nitrendipine in human serum by an equilibrium dialysis — radioreceptor assay. Life Sci 33: 1821–1829
Lemmer B, Batke K (1983) Stereospecific and circadian-phase-dependent kinetic behaviour of d-, l- and dl-propranolol in plasma, heart and brain of light-dark synchronized rats. J Cardiovasc Pharmacol 4: 635–644
Mori H, Kido M, Murakami N, Morita S, Kohri H, Nakagawa K (1977) Metabolic fate of carteolol hydrochloride, 5-(3-tertbutylamino-2-hydroxypropoxy)-3,4-dihydrocarbostyril hydrochloride, OPC-1085, a new beta-blocker. V. Identification of metabolism in rat, dog and human. J Pharmaceut Soc Japan 97: 350
Palm D, Wellstein A (1983) Relationship between plasma half-life, receptor binding parameters and duration of clinical effects of beta-adrenoceptor blocking drugs. Naunyn-Schmiedeberg's Arch Pharmacol 324 [Suppl]: R 79
Rahn KH (1983) Racemates or specific isomers: clinical practice. In: Ariëns EJ, Soudijn W, Timmermans PBMWM (eds) Stereochemistry and biological activity of drugs. Blackwell, Oxford, pp 181–185
Rochester CL, Gammon DE, Shane E, Bilezikian JP (1980) A radioreceptor assay for propranolol and 4-hydroxypropranolol. Clin Pharmacol Ther 28: 32–39
Schäfer M, Geissler ME, Mutschler E (1977) Fluorimetrische Bestimmung von Propranolol und seinem Metaboliten N-Desisopropylpropranolol im Plasma und Urin durch direkte Auswertung von Dünnschichtchromatogrammen. J Chromatogr 143: 607–613
Staehelin M, Simons P, Jaeggi K, Wigger N (1983) CGP 12177. A hydrophilic beta-adrenergic receptor radioligand reveals high affinity binding of agonists to intact cells. J Biol Chem 258: 3496–3502
Stoll RW, Cavanaugh JH, Mac Leod CM (1981) Betablocking effect of single oral doses of carteolol. Clin Pharmacol Ther 30: 605–610
Vermeulen NPE, Breimer DD (1983) Stereoselectivity in drug and xenobiotic metabolism. In: Ariëns EJ, Soudijn W, Timmermans PBMWM (eds) Stereochemistry and biological activity of drugs. Blackwell, Oxford, pp 33–53
Wellstein A, Palm D (1984) Correlation between pharmacological response, kinetics of plasma concentration and in vitro receptor affinities exemplified with beta-adrenoceptor blocking drugs. Meth Find Exp Clin Pharm 6: 1–4 (in press)
Wiemer G, Wellstein A, Palm D, v. Hattingberg HM, Brockmeier D (1982) Properties of agonist binding at the beta-adrenoceptor of the rat reticulocyte. Naunyn-Schmiedeberg's Arch Plarmacol 321: 11–19
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Wellstein, A., Palm, D., Wiemer, G. et al. Simple and reliable radioreceptor assay for beta-adrenoceptor antagonists and active metabolites in native human plasma. Eur J Clin Pharmacol 27, 545–553 (1984). https://doi.org/10.1007/BF00556890
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DOI: https://doi.org/10.1007/BF00556890