Is bupropion a cytochrome P450 (CYP) 2D6 inhibitor?
Dr. Preskorn: Yes. At 300 mg/day bupropion will cause a similar degree of inhibition of CYP2D6 as fluoxetine or paroxetine, and hence a similar degree of increase in concentration of co-prescribed CYP2D6 substrates. That information is in the package insert which gives the results of a study in which participants were treated with bupropion 300 mg/day and then a challenge dose of desipramine as a CYP2D6 probe. The blood levels of desipramine went up five-fold comparable to what is seen when desipramine is co-prescribed with fluoxetine or paroxetine 20 mg/day.
