The prescribing information recommends minimizing the use of alcohol, since in rare cases bupropion reduces alcohol tolerance.Caution should be observed when combining bupropion with a monoamine oxidase inhibitor (MAOI), as it may result in hypertensive crisis. Pharmacology
Pharmacodynamics
The mechanism of action of bupropion in the treatment of depression and for other indications is unclear. However, it is thought to be related to the fact that bupropion is a norepinephrine–dopamine reuptake inhibitor (NDRI) and antagonist of several nicotinic acetylcholine receptors. It is uncertain whether bupropion is a norepinephrine–dopamine releasing agent. Pharmacological actions of bupropion, to a substantial degree, are due to its active metabolites hydroxybupropion, threo-hydrobupropion, and erythro-hydrobupropion that are present in the blood plasma at comparable or much higher levels. In fact, bupropion could accurately be conceptualized as a prodrug of these metabolites. Overall action of these metabolites, and particularly one enantiomer S,S-hydroxybupropion, is also characterized by inhibition of norepinephrine and dopamine reuptake and nicotinic antagonism (see the chart on the right). Bupropion has no meaningful direct activity at a variety of receptors, including α- and β-adrenergic, dopamine, serotonin, histamine, and muscarinic acetylcholine receptors.The occupancy of dopamine transporter (DAT) by bupropion (300 mg/day) and its metabolites in the human brain as measured by several positron emission tomography (PET) studies is approximately 20%, with a mean occupancy range of about 14 to 26%. For comparison, the NDRI methylphenidate at therapeutic doses is thought to occupy greater than 50% of DAT sites.
With time, however, this effect becomes negligible.The bupropion treatment course lasts for seven to twelve weeks, with the patient halting the use of tobacco about ten days into the course. After the course, the effectiveness of bupropion for maintaining abstinence from smoking declines over time, from 37% of tobacco abstinence at 3 months to 20% at one year. It is unclear whether extending bupropion treatment helps to prevent relapse of smoking.Overall, six months after the therapy, bupropion increases the likelihood of quitting smoking by approximately 1.6 fold as compared to placebo. In this respect, bupropion is as effective as nicotine replacement therapy but inferior to varenicline. Combining bupropion and nicotine replacement therapy does not improve the quitting rate.In children and adolescents, the use of bupropion for smoking cessation does not appear to offer any significant benefits. The evidence for its use to aid smoking cessation in pregnant women is insufficient. Attention deficit hyperactivity disorder
The treatment of attention deficit hyperactivity disorder (ADHD) is not an approved indication of bupropion, and it is not mentioned in the current (2019) guideline on the ADHD treatment from the American Academy of Pediatrics. Systematic reviews of bupropion for the treatment of ADHD in both adults and children note that bupropion may be effective for ADHD but warn that this conclusion has to be interpreted with caution, because clinical trials were of low quality due to small sizes and risk of bias.