COMMENT: At first, montelukast was believed to be an inhibitor of multiple CYPs because of invitro evidence. In 2005, had it been shown that it was a selective invitro CYP2C8 inhibitor (PMID 15608135). However, the study below shows unequivocally that it is not a CYP2C8 inhibitor in vivo.
ABSTRACT:
Br J Clin Pharmacol. 2007 Mar;63(3):339-45. Epub 2006 Sep 19
Effect of multiple doses of montelukast on the pharmacokinetics of rosiglitazone, a CYP2C8 substrate, in humans.Kim KA, Park PW, Kim KR, Park JY.
AIMS
To investigate the effect of multiple dosing with montelukast, a selective leukotriene-receptor antagonist, on the pharmacokinetics of rosiglitazone, a CYP2C8 substrate, in humans.
METHODS
A two- period, randomized crossover study was conducted in 10 healthy subjects. After administration of oral doses of placebo or 10 mg montelukast daily for 6 days, 4 mg rosiglitazone was administered and plasma samples were obtained for 24 h and analyzed for rosiglitazone and N-desmethylrosiglitazone using high-performance liquid chromatography with fluorescence detection.
RESULTS
During the montelukast phase, the total area under the time-concentration curve(AUC) and peak plasma concentration of rosiglitazone were 102% (90% CI 98, 107%) and 98% (90% CI 92, 103%) of the corresponding values during the placebo phase, respectively. Multiple dosing with montelukast did not affect the oral clearance of rosiglitazone significantly (90% CI 94, 105%; P = 0.50). The AUC ratio and plasma concentration ratios of N-desmethylrosiglitazone : rosiglitazone were not changed by multiple dosing with montelukast (90% CI 90, 103%; P = 0.14).
CONCLUSIONS
Multiple doses of montelukast do not inhibit CYP2C8-mediated rosiglitazone metabolism in vivo despite in vitro findings indicating that montelukast is a selective CYP2C8 inhibitor. PMID: 16981900
Filed under: Cytochrome P450, Personalized Medicine Tagged: | CYP2C8, Cytochrome P450, rosiglitazone
