Effect of the CYP2D6 genotype on the pharmacokinetics of tropisetron in healthy Korean subjects.
OBJECTIVE
To evaluate the effect of the CYP2D6 genotype on the pharmacokinetics of tropisetron in healthy Korean subjects.


METHODS
A single 5-mg capsule of tropisetron was administered orally to 13 healthy subjects. Plasma concentrations were determined by validated HPLC procedures and data were analyzed by using noncompartmental linear PK methods. Four alleles, CYP2D6*1, CYP2D6*2 x2, CYP2D6*5, and CYP2D6*10, were identified by PCR.


RESULTS
Thirteen subjects, consisting of two homozygous carriers of the wild type allele ( *1/*1), four heterozygous carriers of poor metabolizer (PM)-associated allele (* 1/*10), six homozygous carriers of PM-associated alleles (four with *10/*10 and two with *5/*10), and one carrier of a duplicated allele *1/*2 x2. All tested pharmacokinetic parameters (AUC(inf), AUC(inf)(NL70), Cmax, Cmax(NL70), T(1/2), and Tec) were significantly different among four different genotypic groups. The mean AUCs of carriers with the heterozygous PM-associated allele and the homozygous PM-associated allele were 1.9- and 6.8-higher than those of carriers with the wild type allele, respectively. In contrast, the mean AUC of carriers with a duplicated allele was 0.5-fold lower than that of those carriers with the wild type allele.


CONCLUSIONS
The presence of CYP2D6*5, CYP2D6*10, and CYP2D6*2 x2 has an important impact on the pharmacokinetics of tropisetron, which may influence clinical response to tropisetron therapy.
Department of Pharmacology, College of Medicine, 28 Yongon-Dong, Chongno-Gu, 110-799, Seoul, South Korea.
Myo-Kyoung
MK
Kim
Joo-Youn
JY
Cho
Hyeong-Seok
HS
Lim
Kyoung-Seop
KS
Hong
Jae-Yong
JY
Chung
Kyun-Seop
KS
Bae
Dal-Seok
DS
Oh
Sang-Goo
SG
Shin
Sang-Hun
SH
Lee
Dong-Ho
DH
Lee
Bumchan
B
Min
In-Jin
IJ
Jang
D000328:Adult; D019540:Area Under Curve; D044466:Asian People / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics*; D005838:Genotype; D006207:Half-Life; D006579:Heterozygote; D006801:Humans; D007211:Indoles / Q000097:blood / Q000493:pharmacokinetics*; D007723:Korea; D008297:Male; D011110:Polymorphism, Genetic; D012702:Serotonin Antagonists / Q000097:blood / Q000493:pharmacokinetics*; D013997:Time Factors; D000077526:Tropisetron
D007211:Indoles; D012702:Serotonin Antagonists; D000077526:Tropisetron; D019389:Cytochrome P-450 CYP2D6