Pharmacokinetic optimisation of sustained-release bupropion for smoking cessation.

Sustained-release bupropion (bupropion SR) is a unique, non-nicotine smoking cessation aid that is hypothesised to act upon neurological pathways involved in nicotine dependence. Pharmacokinetic and metabolism studies reveal that bupropion SR is metabolised by multiple pathways with no single pathway predominating. When one pathway is inhibited, others are available to compensate. Therefore, only a few clinically relevant drug-drug interactions involving bupropion SR have been observed, although the potential for interactions exists, as with any extensively metabolised drug. Population pharmacokinetic/pharmacodynamic analyses of data from patients receiving daily oral doses of 100mg, 150mg, or 300mg reveal that the anti-smoking efficacy of bupropion SR is directly related to dose. The incidences of dry mouth and insomnia were directly related to bupropion plasma concentrations while the incidence of anxiety was inversely proportional to bupropion plasma concentrations. To maximise efficacy (with an acceptable safety profile), the optimal daily dose for the majority of patients is 300mg.