Application of a pharmacokinetic/pharmacogenetic approach to assess the nicotine metabolic profile of smokers in the real-life setting.
The nicotine metabolite ratio, i.e., the ratio 3-hydroxycotinine/cotinine, is used to assess the nicotine metabolic status and has been proven to predict the response to smoking cessation treatments in randomized clinical trials. In the current study, a pharmacokinetic-pharmacogenetic integrated approach is described, based on the development of a liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for nicotine metabolite ratio assay in plasma and a real-time PCR analysis for fast genotyping of CYP2A6. The pharmacokinetic-pharmacogenetic approach was validated in 66 subjects with different smoking status. The LC/MS/MS assay was rapid and sensitive enough to detect plasma cotinine levels also in second-hand exposed abstainers. In the cohort of patients of the present study the following results were obtained: (i) the frequencies of CYP2A6 genetic variants were comparable with those from clinical trials carried out in Caucasian populations; (ii) all the subjects carrying the CYP2A6 deficient allele also had a slow metabolizer phenotype; (iii) slow metabolizers had mean nicotine metabolite ratio approximately 50% of that of the normal/fast metabolizers; (iv) women had higher nicotine metabolite ratio than men; and (v) salivary nicotine metabolite ratio measures were comparable to plasma levels. Overall, the findings of the current study demonstrate that the simultaneous assessment of nicotine metabolite ratio and CYP2A6 genotype from human blood samples is feasible and accurate and could be used in a smoking cessation program to optimize treatments and identify those smokers who inherit metabolically deficient CYP2A6 alleles.
Department of Pharmacy, University of Pisa, Pisa, Italy. Electronic address: stefano.fogli@farm.unipi.it.
Stefano
S
Fogli
Department of Pathology, University of Pisa, Pisa, Italy.
Alessandro
A
Saba
Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
Marzia
M
Del Re
Cardio-Thoracic and Vascular Department, University Hospital of Pisa, Pisa, Italy.
Francesco
F
Pistelli
Cardio-Thoracic and Vascular Department, University Hospital of Pisa, Pisa, Italy.
Ferruccio
F
Aquilini
Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
Riccardo
R
Zucchi
Department of Pathology, University of Pisa, Pisa, Italy; Cardio-Thoracic and Vascular Department, University Hospital of Pisa, Pisa, Italy.
Antonio
A
Palla
Department of Pharmacy, University of Pisa, Pisa, Italy.
Maria Cristina
MC
Breschi
Department of Pathology, University of Pisa, Pisa, Italy; Cardio-Thoracic and Vascular Department, University Hospital of Pisa, Pisa, Italy.
Laura
L
Carrozzi
Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
Romano
R
Danesi
D002853:Chromatography, Liquid; D003367:Cotinine / Q000031:analogs & derivatives / Q000032:analysis / Q000097:blood; D065637:Cytochrome P-450 CYP2A6 / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D009538:Nicotine / Q000097:blood / Q000493:pharmacokinetics*; D016133:Polymerase Chain Reaction; D012463:Saliva / Q000378:metabolism; D012727:Sex Characteristics; D012907:Smoking / Q000097:blood / Q000235:genetics*; D053719:Tandem Mass Spectrometry
C001381:hydroxycotinine; D009538:Nicotine; C585710:CYP2A6 protein, human; D065637:Cytochrome P-450 CYP2A6; D003367:Cotinine
CYP2A6; Genotyping; Mass spectrometry; Nicotine metabolite ratio; Smoking cessation