N-Methylnornicotinium ion, a new in vivo metabolite of R-(+)-nicotine.

N-Methylnornicotinium ion has been identified as a metabolite in the urine of male Hartley guinea pigs that had been chronically dosed ip with R-(+)-nicotine. Under similar conditions, S-(-)-nicotine is not biotransformed into this metabolite. The metabolite was isolated and purified by preparative high performance cation-exchange liquid chromatography. The structural identity of the metabolite was determined by UV spectrophotometric analysis and sodium borohydride reduction followed by GLC-mass spectrometric analysis, and Fourier transform 1H NMR spectrometric analysis. The formation of this metabolic product from nicotine represents a unique example of N-demethylation and N-methylation reactions both occurring within the same molecule.