RT Journal Article
SR Electronic
T1 Formation of the Quaternary Ammonium-Linked Glucuronide of Nicotine in Human Liver Microsomes: Identification and Stereoselectivity in the Kinetics
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1525
OP 1528
VO 29
IS 12
A1 Ghosheh, Omar
A1 Vashishtha, Sarvesh C.
A1 Hawes, Edward M.
YR 2001
UL http://dmd.aspetjournals.org/content/29/12/1525.abstract
AB The formation of the N1-glucuronide metabolite of each nicotine enantiomer was studied in pooled human liver microsomes (n = 6). The metabolite formed from natural S(−)-nicotine was identified by comparison of the high-pressure liquid chromatography (HPLC) retention time and positive ion electrospray ionization-mass spectral characteristics with a synthetic reference standard. A radiometric HPLC method was used to quantify the metabolite. The specificity of the assay method was demonstrated by experiments in which β-glucuronidase treatment of incubated assay samples resulted in elimination of the peak due to theN1-glucuronide metabolite. The glucuronides ofS(−)- and R(+)-nicotine were formed by one-enzyme kinetics, with Km values of 0.11 and 0.23 mM and Vmax values of 132 and 70 pmol/min/mg of protein, respectively. There is marked stereoselectivity in the apparent intrinsic clearance values (Vmax/Km) in that the value for S(−)-nicotine is 4 times greater than for the R(+)-isomer (1.2 versus 0.31 μl/min/mg of protein). The American Society for Pharmacology and Experimental Therapeutics