Effect of 24 cytochrome P450 2D6 variants found in the Chinese population on the N-demethylation of amitriptyline in vitro.
BACKGROUND
Amitriptyline (AT), one of the tricyclic antidepressants, is still widely used for the treatment of the depression and control of anxiety states and panic disorders in the developing countries.


OBJECTIVE
This study evaluates the catalytic activities of CYP2D6*1, CYP2D6*2, CYP2D6*10 and 22 novel alleles in Han Chinese population and their effects on the N-demethylation of AT in vitro.


METHODS
CYP2D6*1 and 24 CYP2D6 allelic variants were highly expressed in insect cells, and all variants were characterized using AT as a substrate. Reactions were performed at 37 °C with 10-1000 μM substrate for 30 min. We established a HPLC method to quantify the levels of nortriptyline (NT). The kinetic parameters Km, Vmaxand intrinsic clearance (Vmax/Km) of NT were calculated.


RESULTS
Among the 24 CYP2D6 variants, all variants exhibited decreased intrinsic clearance values compared with wild-type CYP2D6.1. Kinetic parameters of two CYP2D6 variants (CYP2D6*92, *96) could not be determined because of absent enzyme activities.


CONCLUSIONS
The comprehensive in vitro assessment of CYP2D6 variants provides significant insight into allele-specific activity towards AT in vivo.
a School of Pharmacy , Wenzhou Medical University , Wenzhou , Zhejiang , P.R. China.
Qinghua
Q
Weng
a School of Pharmacy , Wenzhou Medical University , Wenzhou , Zhejiang , P.R. China.
Bingqing
B
Liang
a School of Pharmacy , Wenzhou Medical University , Wenzhou , Zhejiang , P.R. China.
Yali
Y
Zhou
a School of Pharmacy , Wenzhou Medical University , Wenzhou , Zhejiang , P.R. China.
Xiangyu
X
Li
a School of Pharmacy , Wenzhou Medical University , Wenzhou , Zhejiang , P.R. China.
Hao
H
Wang
a School of Pharmacy , Wenzhou Medical University , Wenzhou , Zhejiang , P.R. China.
Yunyun
Y
Zhan
b The Key Laboratory of Geriatrics , Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health , Beijing , P.R. China.
Dapeng
D
Dai
b The Key Laboratory of Geriatrics , Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health , Beijing , P.R. China.
JianPing
J
Cai
a School of Pharmacy , Wenzhou Medical University , Wenzhou , Zhejiang , P.R. China.
Guoxin
G
Hu
D000483:Alleles; D000639:Amitriptyline / Q000378:metabolism*; D000929:Antidepressive Agents, Tricyclic / Q000378:metabolism*; D044466:Asian People; D002681:China / Q000208:ethnology; D002851:Chromatography, High Pressure Liquid; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics* / Q000502:physiology; D003640:Dealkylation; D014644:Genetic Variation; D006801:Humans
D000929:Antidepressive Agents, Tricyclic; D000639:Amitriptyline; D019389:Cytochrome P-450 CYP2D6
Drug metabolism; nortriptyline; tricyclic antidepressants