Biomaterial Database

The metabolism of tramadol by human liver microsomes. 1992

W D Paar, and P Frankus, and H J Dengler

Zentrum für Innere Medizin-Allgemeine Innere Medizin, Universität Bonn.

The metabolism of tramadol was investigated in vitro using microsomal fractions of human liver. The parent compound and its main metabolites were determined by a newly developed high performance liquid chromatography assay. O-demethylation of tramadol was found to be stereoselective. The Vmax of the O-demethylation of (-)-tramadol was 210 pmol.mg-1.min-1, whereas (+)-tramadol was O-demethylated with a Vmax of 125 pmol.mg-1.min-1. The Km for both enantiomers was determined to be 210 microM. O-demethylation was inhibited competitively by quinidine (ki = 15 nM) and propafenone (ki = 34 nM). N-demethylation was also stereoselective, preferentially metabolizing the (+)-enantiomer. Whereas O-demethylation displayed monophasic Michaelis-Menten kinetics, N-demethylation was best described by a two-site model. Competitive inhibition of the O-demethylation both by quinidine and propafenone suggests that O-demethylation is carried out by P-450IID6.

UI	MeSH Term	Description	Entries
D008745	Methylation	Addition of methyl groups. In histo-chemistry methylation is used to esterify carboxyl groups and remove sulfate groups by treating tissue sections with hot methanol in the presence of hydrochloric acid. (From Stedman, 25th ed)	Methylations
D008862	Microsomes, Liver	Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.	Liver Microsomes,Liver Microsome,Microsome, Liver
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D014147	Tramadol	A narcotic analgesic proposed for severe pain. It may be habituating.	Adolonta,Amadol,Biodalgic,Biokanol,Contramal,Jutadol,K-315,MTW-Tramadol,Nobligan,Prontofort,Ranitidin 1A Pharma,Takadol,Theradol,Tiral,Topalgic,Tradol,Tradol-Puren,Tradonal,Tralgiol,Trama 1A Pharma,Trama AbZ,Trama KD,Trama-Dorsch,Tramabeta,Tramadin,Tramadoc,Tramadol 1A,Tramadol AL,Tramadol Asta Medica,Tramadol Basics,Tramadol Bayvit,Tramadol Bexal,Tramadol Cinfa,Tramadol Edigen,Tramadol Heumann,Tramadol Hydrochloride,Tramadol Kern,Tramadol Lichtenstein,Tramadol Lindo,Tramadol Mabo,Tramadol Normon,Tramadol PB,Tramadol Ratiopharm,Tramadol Stada,Tramadol acis,Tramadol-Dolgit,Tramadol-Hameln,Tramadol-ratiopharm,Tramadolor,Tramadura,Tramagetic,Tramagit,Tramake,Tramal,Tramex,Tramundin,Trasedal,Ultram,Xymel 50,Zamudol,Zumalgic,Zydol,Zytram,K 315,K315,MTW Tramadol,MTWTramadol,Tradol Puren,TradolPuren,Trama Dorsch,TramaDorsch,Tramadol Dolgit,Tramadol Hameln,TramadolDolgit,TramadolHameln,Tramadolratiopharm
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In