title: Pharmacogenetic relevance of the CYP2C9*3 allele in a tenoxicam bioequivalence study performed on Spaniards.
abstract: We performed a study to quantify CYP2C9 and CYP2C8 alleles influence on the variability observed in tenoxicam pharmacokinetic (PK) and implication in a bioequivalence study design performed on Spaniards. Eighteen healthy volunteers were included in an open, randomized, crossover, phase I bioequivalence study. Significant increases were found in CYP2C9*3 alleles vs. *1 and *2 in AUC(0-infinity) (median (min-max)): 256 (230-516) vs. 150 (100-268) and 169 (124-197) microg h/mL (p<0.01) and half-life time (t1/2) 102 (79-36) vs. 56 (45-94) and 64 (60-80)h (p<0.01). Non-significant differences were observed in C(max) 1.9 (1.8-2.9) vs. 2.4 (1.7-3.4), 2.5 (1.6-2.9) microg/mL or in according to CYP2C8 alleles presence. CYP2C9*3 allele is associated to a longer elimination time of tenoxicam. PK parameters calculated in bioequivalence studies (AUC(0-infinity), t1/2) may be influenced by the presence of CYP2C9*3 allele resulting in a high variability. Thus, bioequivalence studies of tenoxicam formulations should be designed considering genotype profile.
authors.affiliation: Division of Pharmacology and Therapeutics, Instituto de Bioingeniería, Miguel Hernández University, Campus de San Juan, San Juan de Alicante, Alicante, Spain.
authors.forename: A M
authors.initials: AM
authors.lastname: Peiró
authors.forename: J
authors.initials: J
authors.lastname: Novalbos
authors.forename: P
authors.initials: P
authors.lastname: Zapater
authors.forename: R
authors.initials: R
authors.lastname: Moreu
authors.forename: R
authors.initials: R
authors.lastname: López-Rodríguez
authors.forename: V
authors.initials: V
authors.lastname: Rodríguez
authors.forename: F
authors.initials: F
authors.lastname: Abad-Santos
authors.forename: J F
authors.initials: JF
authors.lastname: Horga
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D018592:Cross-Over Studies; D065729:Cytochrome P-450 CYP2C9; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D010597:Pharmacogenetics; D010894:Piroxicam / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D013030:Spain; D013810:Therapeutic Equivalency
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D010894:Piroxicam; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C032801:tenoxicam