Comparison of procedures for measuring the quaternary N-glucuronides of amitriptyline and diphenhydramine in human urine with and without hydrolysis.
The activities of beta-glucuronidases from Helix pomatia, Escherichia coli and rat towards the N-glucuronides of amitriptyline and diphenhydramine were considerably lower than those towards standard substrates. The two N-glucuronides were analysed in urine samples by the following procedures: HPLC of the intact conjugate after solid-phase extraction on a cation exchanger cartridge or after direct injection of urine; HPLC of the aglycone after hydrolysis with beta-glucuronidase from H. pomatia or E. coli or after alkaline hydrolysis. Solid-phase extraction led to the highest recovery and precision, and sensitivity can be improved by extracting a larger volume of urine. On application to samples from patients under treatment with amitriptyline, the results of all procedures except alkaline hydrolysis were in good agreement. When diphenhydramine N-glucuronide was analysed in urine samples of volunteers, solid-phase extraction, hydrolysis by E. coli glucuronidase and alkaline hydrolysis resulted in similar values.
Fischer
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D
Department of Toxicology, University of Tübingen, Germany.
Breyer-Pfaff
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U
D000639:Amitriptyline / Q000652:urine*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004155:Diphenhydramine / Q000652:urine*; D004926:Escherichia coli / Q000201:enzymology; D005965:Glucuronates / Q000652:urine; D005966:Glucuronidase / Q000378:metabolism; D006372:Helix, Snails / Q000201:enzymology; D006801:Humans; D006868:Hydrolysis; D051381:Rats
D005965:Glucuronates; D000639:Amitriptyline; D004155:Diphenhydramine; D005966:Glucuronidase