Drugs online research references
Br J Pharmacol. 1983 Aug;79(4):965-71.
Beta-adrenoceptor heterogeneity in guinea-pig airways: comparison of functional and receptor labelling studies.
Carswell H, Nahorski SR.
The distribution of beta-adrenoceptor subtypes in guinea-pig airways has been studied by radioligand binding assays and analysis of mechanical responses. Binding studies with the ligands [3H]-dihydroalprenolol and [125I]-cyanopindolol, revealed that beta-adrenoceptors were unevenly distributed throughout the airways with the highest density located in the parenchyma and the lowest density in the trachea. The relative proportion of beta 1:beta 2-adrenoceptor binding sites was assessed by computer-assisted analysis of the inhibition curves generated by selective agents. It was virtually identical in each region and in the order of 15:85%. beta-Adrenoceptor agonists caused concentration-dependent relaxations of both tracheal spirals and parenchymal lung strips. This response appeared to be mediated by both beta 1- and beta 2-adrenoceptors in tracheal spirals as the pA2 value for the beta 1-selective antagonist, atenolol, varied depending upon which agonist was used, and, in the presence of the beta 2-adrenoceptor antagonist ICI 118,551, noradrenaline and isoprenaline produced biphasic concentration-effect curves. In parenchymal lung strips only the one subtype was involved as antagonist pA2 values were not dependent on the agonist used and the properties were consistent with those expected for a beta 2-adrenoceptor.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6317123&dopt=Abstract
J Chromatogr. 1991 Jul 17;568(1):239-45.
Reversed-phase high-performance liquid chromatographic analysis of atenolol enantiomers in plasma after chiral derivatization with (+)-1-(9-fluorenyl)ethyl chloroformate.
Rosseel MT, Vermeulen AM, Belpaire FM.
Heymans Institute of Pharmacology, University of Ghent Medical School, Belgium.
A sensitive high-performance liquid chromatographic method for the determination of the enantiomers of atenolol in rat plasma has been developed. Racemic atenolol and practolol (internal standard) were extracted from alkalinized plasma (pH 12) into dichloromethane containing 3% (v/v) heptafluoro-1-butanol, and the organic layer was evaporated. The samples were derivatized with (+)-1-(9-fluorenyl)ethyl chloroformate at pH 8.5 for 30 min. After removal of excess reagent, the diastereomers were extracted into dichloromethane. The diastereomers were separated on a Microspher C18 column (3 microns) with a mobile phase of acetonitrile-sodium acetate buffer (0.01 M, pH 7) (50:50, v/v) at a flow-rate of 0.8 ml/min. Fluorescence detection (lambda ex = 227 nm, lambda em = 310 nm) was used. When 100 microliters of plasma were used, the quantitation limit was 10 ng/ml for the atenolol enantiomers. The assay was applied to measure concentrations of atenolol enantiomers in plasma after intravenous administration of racemic atenolol to rats.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1770102&dopt=Abstract
Pharm Res. 1991 Sep;8(9):1195-8.
Stereospecific high-performance liquid chromatographic assay of sotalol in plasma.
Carr RA, Foster RT, Bhanji NH.
Faculty of Pharmacy & Pharmaceutical Sciences, University of Alberta, Edmonton, Canada.
A convenient high-performance liquid chromatographic (HPLC) assay was developed for determination of sotalol (STL) enantiomers in plasma. Following addition of the internal standard (IS; racemic atenolol), enantiomers of STL and IS were extracted using ethyl acetate. After evaporation of the organic layer, samples were derivatized with a solution of S-(+)-1-(1-naphthyl)ethyl isocyanate (NEIC). The resulting diastereomers were chromatographed with normal-phase HPLC with chloroform:hexane:methanol [65:33:2 (v/v)] as the mobile phase at a flow rate of 2 ml/min. The fluorescence detection wavelength was set at 220 nm for excitation with no emission filter. The suitability of the assay for pharmacokinetic studies was determined by measuring STL enantiomers in the plasma of a healthy subject after administration of a single 160-mg oral, racemic dose of STL.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1788167&dopt=Abstract
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