Background: Even though bupropion is first-line pharmacological agent for smoking cessation, not all the smokers successfully quit smoking by bupropion. It means other factors like genetic predisposition could contribute to the therapeutic outcome.
Objectives: The aim of this study is to elucidate the question of whether the abstinence rates by bupropion trial would be different depending on the genotypes.
Methods: Six candidate genes, thought to be involved in the interaction of nicotine and bupropion (for example, the dopamine receptor type 2, dopamine transporter, norepinephrine transporter, serotonin transporter, catecholamine-O-methyltransferase), and the clinical outcomes of smoking behavior were investigated. The participants were 225 male smokers to whom 150 mg of bupropion SR was administered for 4 weeks. The abstinence rates of specific genotypes were also compared.
Main results: The results are as follows: (a) the frequencies of the A1/A2 genotype of the dopamine receptor type 2 TaqI A gene and SLC6A3-9 genotype of the dopamine transporter 1 gene were higher in the nonabstinence group than in the abstinence group (χ2=20.40, P<0.01 for A1/A2, χ2=7.76, P=0.01 for SLC6A3-9). The frequencies of the COMTH/COMTH and A/G genotypes of the norepinephrine transporter gene were higher in the abstinence group than in the nonabstinence group (χ2=8.12,P=0.02 for COMTH/COMTH, χ2=3.04, P<0.01 for A/G). (b) Participants having specific genotypes such as homozygotes (A1/A1 or A2/A2) of DRD2 TaqI A, COMTH/COMTH, AG of NET-8, and LL of 5-HTTLPR showed a higher abstinence rate than the other participants.
Conclusions: It can be concluded that genetic diversity might determine the effects of bupropion on smoking cessation.