A limited number of studies suggested tobacco smoking increases the metabolism of caffeine, an effect possibly mediated by caffeine.
"Caffeine metabolism is increased by smoking, an effect mediated by an acceleration in its demethylation (it also increases xanthine oxidase activity) (Parsons and Neims, 1978). Smoking cessation returns caffeine clearance rates to nonsmoking values (Murphy et al., 1988)."
"Caffeine metabolism is increased by smoking, an effect mediated by an acceleration in its demethylation (it also increases xanthine oxidase activity) (Parsons and Neims, 1978). Smoking cessation returns caffeine clearance rates to nonsmoking values (Murphy et al., 1988)."
https://www.ncbi.nlm.nih.gov/books/NBK223808/#:~:text=Caffei....