1. Radioimmunoassay for doxepin and desmethyldoxepin.
- Author
-
Virtanen R, Salonen JS, Scheinin M, Iisalo E, and Mattila V
- Subjects
- Antibody Specificity, Chromatography, High Pressure Liquid, Humans, Mental Disorders blood, Radioimmunoassay methods, Time Factors, Doxepin analogs & derivatives, Doxepin blood
- Abstract
A simple and sensitive radioimmunoassay (RIA) for the determination of doxepin and desmethyldoxepin in plasma or serum has been developed using a previously reported antiserum to the tricyclic anti-depressants. Before assay, doxepin is separated from desmethyldoxepin with selective extraction at different pH values enabling each to be measured specifically. 3H-imipramine is used as tracer. By using the extraction procedure doxepin and desmethyldoxepin concentrations can be measured down to 9 nmol/1 from a 0.1 ml sample. If necessary, sensitivity can be doubled by taking a 0.2 ml sample to extraction. Recoveries of doxepin and desmethyldoxepin were quantitative when the drugs were added at different concentrations to normal, pooled human plasma and the inter- and intra-assay coefficients of variation did not exceed 9%. The concentrations obtained from patient samples by the present RIA correlated well with those by high-pressure liquid chromatography. The RIA was also shown to be useful in pharmacokinetic single dose studies with doxepin.
- Published
- 1980
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