Association of CYP2B6 genetic polymorphisms with bupropion and hydroxybupropion exposure: A systematic review and...

Bupropion is metabolized to its active metabolite, hydroxybupropion (HB), by the genetically polymorphic cytochrome P450 2B6 (CYP2B6) enzyme. Despite its significant role in bupropion metabolism, the magnitude of the impact of CYP2B6 genotype on the exposure of bupropion has not been quantified.

A systematic review and meta-analysis was conducted to quantify the association of bupropion and HB exposure with CYP2B6 variant alleles and genotype-defined metabolizer phenotypes.

MEDLINE, EMBASE, Web of Science, Scifinder, PsycINFO, and CENTRAL were screened to identify studies that met the following inclusion criteria (search updated on February 2021): (1) area under the plasma drug concentration-time curve (AUC) of bupropion and/or HB in relation to CYP2B6 genotypes was studied, and (2) study participants were genotyped for common CYP2B6 variant alleles including at least CYP2B6*6. The Newcastle Ottawa Scale was used to assess risk of bias in each included study. The ratio of means (RoM) between CYP2B6 genotype or genotype-defined phenotype groups for bupropion exposure was calculated for each study and combined in a meta-analysis.

Eleven studies met the inclusion criteria for this systematic review, and 10 (including N = 413 participants) were included in the meta-analysis. All 10 studies involved healthy adult volunteers, where other medications were not allowed. The AUCs of HB and the active moiety (bupropion + HB) were significantly reduced in CYP2B6*6 carriers compared with the non-carriers (HB: RoM 0.77, 95% CI 0.71-0.83; active moiety: RoM 0.81, 95% CI 0.75-0.88). Both CYP2B6 poor and intermediate metabolizers had significantly decreased exposures to HB and the active moiety than normal metabolizers.

The CYP2B6*6 allele and genotype-determined CYP2B6 poor and intermediate metabolizer phenotypes are associated with significantly lower exposures to HB and the total active moiety. The findings of this study suggest opportunities to further study precision dosing strategies for bupropion therapy based on CYP2B6 genotype.