title: Polymorphisms of CYP1A2 and CYP2A6 activity: phenotypes and the effect of age and sex in a Nigerian population.
abstract: BACKGROUND
  CYP1A2 and CYP2A6 are polymorphic enzymes that metabolise several compounds of clinical importance. This study investigated the prevalent phenotypes of these enzymes and the influence of age and sex on enzyme activity in a Nigerian population.
  
  
  METHODS
  Caffeine (110 mg) was administered to each of 129 healthy, unrelated subjects (85 males and 44 females) who were non-smokers. Urine voided within 7 h after caffeine administration was collected for a high performance liquid chromatographic assay of caffeine (137X), 1,7-dimethyluric acid (17U) and 1,7-dimethylxanthine (17X). CYP1A2 activity was measured as a ratio of (17U+17X) to 137X, while 17U/17X served as marker for CYP2A6. Transformed data were analysed and the influences of age and sex on activity were also determined.
  
  
  RESULTS
  Distribution of CYP1A2 activity in the population was bimodal with a mean±SD of 0.82±0.41, while that of CYP2A6 was trimodal with a mean±SD activity of 0.27±0.42 of the log-transformed urinary molar ratio of metabolites. The influences of age and sex on enzyme activity for both CYP1A2 and CYP2A6 were not significant (p>0.05).
  
  
  CONCLUSIONS
  The study established the prevalence of polymorphism in phenotypes of CYP1A2 and CYP2A6 activity in the Nigerian population, but no influence of age and sex on enzyme activity was observed in this population.
authors.forename: Ayorinde
authors.identifier: http://orcid.org/0000-0002-8295-7150
authors.initials: A
authors.lastname: Adehin
authors.forename: Oluseye O
authors.initials: OO
authors.lastname: Bolaji
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000465:Algorithms; D015415:Biomarkers / Q000652:urine; D001711:Biotransformation; D002110:Caffeine / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000652:urine; D003069:Coffee; D019388:Cytochrome P-450 CYP1A2 / Q000378:metabolism*; D065637:Cytochrome P-450 CYP2A6 / Q000378:metabolism*; D005260:Female; D057141:Food, Preserved; D006801:Humans; D008297:Male; D009549:Nigeria; D012727:Sex Characteristics; D013806:Theophylline / Q000652:urine; D014527:Uric Acid / Q000031:analogs & derivatives / Q000652:urine; D055815:Young Adult
chemical_list: D015415:Biomarkers; D003069:Coffee; D014527:Uric Acid; D002110:Caffeine; D013806:Theophylline; C504573:CYP1A2 protein, human; C585710:CYP2A6 protein, human; D019388:Cytochrome P-450 CYP1A2; D065637:Cytochrome P-450 CYP2A6; C021183:1,7-dimethylxanthine; C053084:1,7-dimethyluric acid