Impact of pharmacokinetics and pharmacogenetics on the efficacy of pranlukast in Japanese asthmatics.
OBJECTIVE
Wide inter-individual variability in therapeutic effects limits the efficacy of leukotriene (LT) receptor antagonists in the treatment of asthma. We have reported that genetic variability in the expression of LTC(4) synthase is associated with responsiveness to pranlukast in Japanese asthmatic patients. However, the effects of pharmacokinetic variability are less well known. This was an analysis of the pharmacokinetics of pranlukast in a population of adult asthmatics, and its effect on clinical responses. Other factors that may be related to the therapeutic effects of pranlukast, including LTC(4) synthase gene polymorphisms, were also investigated.


METHODS
The population pharmacokinetics of pranlukast was analysed in a one-compartment model, using data collected in 50 Japanese adults with moderate to severe asthma, who were treated with pranlukast, 225 mg bd for 4 days. In 32 of these patients, in whom the clinical response to pranlukast (increase in FEV(1) after 4 weeks of treatment) was measured in a previous study, a combined pharmacokinetic and pharmacogenetic analysis was performed.


RESULTS
Using the population pharmacokinetic model, the estimated the mean oral clearance (CL/F) of pranlukast was 16.4 L/h, and the inter-individual variability was 30.1%. Univariate and multivariate analyses showed that LTC(4) synthase polymorphisms, but not the CL/F of the drug, predicted an improvement in pulmonary function with pranlukast treatment (P < 0.05).


CONCLUSIONS
There was marked inter-individual variability in the pharmacokinetics of pranlukast among adult asthmatics, but this had little impact on the clinical effectiveness of the drug.
Asano
Koichiro
K
Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan. ko-asano@qa2.so-net.ne.jp
Nakade
Susumu
S
Shiomi
Tetsuya
T
Nakajima
Takeshi
T
Suzuki
Yusuke
Y
Fukunaga
Koichi
K
Oguma
Tsuyoshi
T
Sayama
Koichi
K
Fujita
Hirofumi
H
Tanigawara
Yusuke
Y
Ishizaka
Akitoshi
A
D000483:Alleles; D018927:Anti-Asthmatic Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D044466:Asian People / Q000235:genetics; D001249:Asthma / Q000188:drug therapy* / Q000208:ethnology / Q000235:genetics*; D002867:Chromones / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010597:Pharmacogenetics; D011110:Polymorphism, Genetic / Q000235:genetics; D012189:Retrospective Studies; D016896:Treatment Outcome
D018927:Anti-Asthmatic Agents; D002867:Chromones; D005982:Glutathione Transferase; C041116:leukotriene-C4 synthase; C047681:pranlukast