PT - JOURNAL ARTICLE AU - K C Cundy AU - C S Godin AU - P A Crooks TI - Evidence of stereospecificity in the in vivo methylation of [14C](+/-)-nicotine in the guinea pig. DP - 1984 Nov 01 TA - Drug Metabolism and Disposition PG - 755--759 VI - 12 IP - 6 4099 - http://dmd.aspetjournals.org/content/12/6/755.short 4100 - http://dmd.aspetjournals.org/content/12/6/755.full SO - Drug Metab Dispos1984 Nov 01; 12 AB - In vivo metabolism of [14C]nicotine to N-methylnicotinium ion in the guinea pig appears to be a stereospecific biotransformation, involving only the R-(+)-isomer. The detection and quantitation of urinary radiolabeled nicotine metabolites after ip injection of either [N-14CH3](+/-)-nicotine or [2'-14C](+/-)-nicotine, was carried out on an HPLC cation-exchange analytical system. Utilizing the recently discovered phenomenon of differential enantiomeric association, the stereo-chemistry of the methylation pathway was determined. Significant differences in the tissue distribution of 14C label from the [N-14CH3]-vs. [2'-14C]nicotine-treated animals were observed 24 hr after nicotine administration. An unidentified metabolite with high affinity on cation-exchange chromatography, was detected as a metabolite of [2'-14C](+/-)-nicotine, but was not observed as a metabolite of [N-14CH3](+/-)-nicotine.