Nicotine metabolism glucuronidation

Quantitative aspects of the pattern of nicotine metabolism have been elucidated fairly well in people (Fig. 4). Approximately 90% of a systemic dose of nicotine can be accounted for as nicotine and metabolites in urine (Benowitz et al. 1994). Based on studies with simultaneous infusion of labeled nicotine and cotinine, it has been determined that 70-80% of nicotine is converted to cotinine (Benowitz and Jacob 1994). About 4-7% of nicotine is excreted as nicotine N -oxide and 3-5% as nicotine glucuronide (Benowitz et al. 1994 Byrd et al. 1992). Cotinine is excreted unchanged in urine to a small degree (10-15% of the nicotine and metabolites in urine). The remainder is converted to metabolites, primarily fra i -3 -hydroxycotinine (33 0%), cotinine glucuronide (12-17%), and trans-3 -hydroxycotinine glucuronide (7-9%). 

Benowitz ML, Jacob P 3rd, Fong I, Gupta S (1994) Nicotine metabolic profile in man comparison of cigarette smoking and transdermal nicotine. J Pharmacol Exp Ther 268 296-303 Benowitz NL, Perez-Stable EJ, Eong 1, Modin G, Herrera B, Jacob P 3rd (1999) Ethnic differences in N-glucuronidation of nicotine and cotinine. J Pharmacol Exp Ther 291 1196-1203 Benowitz NL, Griffin C, Tyndale R (2001) Deficient C-oxidation of nicotine continued. Chn Pharmacol Ther 70 567... 

In addition to oxidation of the pyrrolidine ring, nicotine is metabolized by two nonoxidative pathways, methylation of the pyridine nitrogen giving nicotine isomethonium ion (also called N-methylnicotinium ion) and glucuronidation. 

Nicotine phase 2 metabolites in human urine—structure of metabolically formed ra .s -3 -hydroxycotinine glucuronide. Med Sci Res 20 863, 1992. 

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