Women metabolize nicotine faster than men do — especially women who are taking oral contraceptives — according to a new report. The researchers say this could affect women’s smoking behavior, as well as their response to nicotine-based quitting aids.
Dr. Neal L. Benowitz from University of California, San Francisco, and colleagues, compared nicotine metabolism in 88 men and 206 women, and compared the 53 women who used oral contraceptives with the 153 who did not. For the investigation, the subjects received an infusion of nicotine that was “labeled” so it could be traced as it passed through the body, which was followed by frequent blood sampling. The findings are reported in the journal Clinical Pharmacology and Therapeutics
The rate of nicotine passage through the body was significantly higher for women (18.8 mL/min/kg) than for men (15.6 mL/min/kg), the investigators found. The rate was also higher in women who were using oral contraceptives (22.5 mL/min/kg), compared with those who were not (17.6 mL/min/kg.)
By the same token, nicotine persisted in the body longer in men (132 minutes) than in women not taking oral contraceptives (118 minutes) and in women who were taking oral birth control (96 minutes), the researchers note.
There seems to be a spectrum of nicotine metabolism time that varies by level of female sex hormones, with metabolism times progressing from slower in men, to intermediate in women not on oral contraceptives, to faster in women taking oral contraceptives, Benowitz and colleagues observed.
“Further research is needed to examine the question of whether oral contraceptive use influences either smoking behavior or intake of tobacco smoke from cigarettes (or both) among women,” the team points out.
Because some studies have shown that the “success rates with nicotine replacement therapies are lower in women than men,” the researchers suggest that future studies should try to identify the optimal dose of nicotine these products should contain for women users.
