Bupropion is an antidepressant agent that is also effective as an aid to quit cigarette smoking. A single 150-mg tablet of sustained-release bupropion hydrochloride was administered to two groups of volunteers, cigarette smokers and nonsmokers, who were matched for race, gender, body frame, age, and weight. Pharmacokinetic parameters were calculated for bupropion, and three major metabolites (hydroxybupropion and the aminoalcohol isomers, threohydrobupropion and erythrohydrobupropion, expressed as a composite total). Mean (+/-SD) values of area under the concentration-time curve from time 0 extrapolated to infinity (AUC0-infinity), maximum concentration (Cmax), time to reach Cmax (tmax), and half-life (t1/2) of bupropion in smokers and nonsmokers, respectively, were 1,164 +/- 220 ng.hr/mL and 1,161 +/- 292 ng.hr/mL; 144 +/- 28 ng/mL and 143 +/- 39 ng/mL; 3.00 +/- 0.50 hours and 2.88 +/- 0.49 hours; and 19 +/- 5 hours and 18 +/- 3 hours. No clinically significant differences between smokers and nonsmokers or between male and female volunteers were observed for the pharmacokinetics of bupropion or its metabolites. The absence of pharmacokinetic differences indicates that dosage adjustments are not necessary when bupropion is prescribed to male and female cigarette smokers.