Disparate Serum Thioridazine Concentrations: Liquid Chromatography versus Radioreceptor Assay

2009 ◽  
Vol 50 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Markku Linnoila ◽  
Jack E. Rosenblatt ◽  
Dilip Jeste ◽  
Travis Skinner ◽  
William Z. Potter ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Radioreceptor Assay

Evidence for γ-aminobutyric acid as the inhibitor of γ-aminobutyric acid binding in the plasma of humans with liver disease and hepatic encephalopathy

1987 ◽  
Vol 73 (5) ◽  
pp. 531-534 ◽  
Author(s):  
L. J. Levy ◽  
J. Leek ◽  
M. S. Losowsky
Keyword(s):  
Liquid Chromatography ◽  
Liver Disease ◽  
Hepatic Encephalopathy ◽  
Inhibitory Activity ◽  
Radioreceptor Assay ◽  
Aminobutyric Acid ◽  
Gas Liquid Chromatography ◽  
Gaba Binding

1. Gas–liquid chromatography and a radioreceptor assay were used to measure plasma γ-aminobutyric acid (GABA) in patients with liver disease and hepatic encephalopathy. 2. There was a significant correlation between the results obtained by the two methods, and compared with controls plasma GABA was elevated. 3. These findings suggest that the increased GABA binding inhibitory activity of plasma of these patients is probably due to GABA itself.

A radioreceptor assay in which iodocyanopindolol is used to determine propranolol and its active metabolites in unextracted serum or plasma.

1986 ◽  
Vol 32 (1) ◽  
pp. 180-183 ◽  
Author(s):  
R P Elkins ◽  
J F Kelly ◽  
B J Rosenberg
Keyword(s):  
Liquid Chromatography ◽  
Beta Blockers ◽  
Isotonic Saline ◽  
Radioreceptor Assay ◽  
Membrane Receptors ◽  
Erythrocyte Membranes ◽  
Clinical Samples ◽  
Active Metabolites ◽  
Adrenergic Antagonist ◽  
Analytical Recovery

Abstract This rapid, sensitive, simple radioreceptor assay (RRA) for l-propranolol and its active metabolites in unextracted samples requires 5 microL of sample, a beta-adrenergic antagonist, 125-l-labeled (-)cyanopindolol (125ICYP), and turkey erythrocyte membrane receptors (Kd = 40 pmol/L). Equal volumes (100 microL) of diluted sample and 125ICYP are incubated with 500 microL of erythrocyte membranes for 30 min. Cold isotonic saline (2.5 mL) is added, and the mixture is centrifuged. The concentration of drug that inhibited receptor binding by 50% (IC50) was l-propranolol, 1.5 micrograms/L; d-propranolol, 243 micrograms/L; and 4-hydroxypropranolol, 8.8 micrograms/L. Analytical recovery of propranolol added to serum was 93 to 120%; results for 138 clinical samples tested by this method and by liquid chromatography correlated well (r = 0.96). Results correlated strongly (r = 0.98) for 23 clinical samples tested by RRA and analyzed for both propranolol and 4-hydroxypropranolol by liquid chromatography. The sensitivity of this RRA was 0.3 micrograms/L, and both intra- and interassay CVs were less than 12%. Modifications of this method could permit testing of other nonselective beta-blockers.

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