title: The Karolinska cocktail for phenotyping of five human cytochrome P450 enzymes.
abstract: OBJECTIVE
  Our objectives were (1) to determine whether the drugs caffeine, losartan, omeprazole, debrisoquin (INN, debrisoquine), and quinine can be given simultaneously in low doses as a cocktail for the phenotyping of cytochrome P450 (CYP) 1A2, 2C9, 2C19, 2D6, and 3A4, respectively, and (2) to design an administration schedule to give as few sampling occasions as possible.
  
  
  METHODS
  Twenty-four subjects were given oral doses of 100 mg caffeine, 25 mg losartan, 20 mg omeprazole, 10 mg debrisoquin, and 250 mg quinine on separate days. After a washout period of at least 4 days, all drugs were given simultaneously except for quinine, which was given 8 hours after the other drugs. Blood and urine samples were collected to determine parent drug and metabolite concentrations for assessment of phenotyping indices. Any difference between both single and cocktail doses was tested on a log-normal distribution.
  
  
  RESULTS
  The phenotypic indices of CYP1A2 (paraxanthine/caffeine in 4-hour plasma), CYP2C9 (losartan/E-3174 [metabolite of losartan] in 0- to 8-hour urine), CYP2C19 (omeprazole/5-hydroxyomeprazole in 3-hour plasma), and CYP3A4 (quinine/3-hydroxyquinine in 16-hour plasma) were not significantly changed when probe drugs were administered alone compared with together, although a tendency toward higher concentrations of losartan was seen during simultaneous administration (95% confidence interval, 0.51-1.002; P =.051). The CYP2D6 phenotypic index (debrisoquin/4-hydroxydebrisoquin in 0- to 8-hour urine) was significantly changed when drugs were given together (95% confidence interval, 0.45-0.87; P =.007), indicating an inhibition of the debrisoquin metabolism. The within-subject coefficients of variation (8%-25%) were much lower than the between-subject coefficients of variation (34%-79%).
  
  
  CONCLUSIONS
  The administration of drugs together suggests an inhibition of debrisoquin metabolism caused by the concurrent drugs given. By separating debrisoquin from the other cocktail drugs, this method is likely to be used as a tool to phenotype the enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 with only 2 urinary collections and 2 blood-sampling occasions.
authors.affiliation: Division of Clinical Pharmacology, Department of Laboratory Medicine, Karolinska Institutet, Huddinge University Hospital, Stockholm, Sweden. magnus.christensen@labmed.ki.se
authors.forename: Magnus
authors.initials: M
authors.lastname: Christensen
authors.forename: Katarina
authors.initials: K
authors.lastname: Andersson
authors.forename: Per
authors.initials: P
authors.lastname: Dalén
authors.forename: Rajaa A
authors.initials: RA
authors.lastname: Mirghani
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Muirhead
authors.forename: Anna
authors.initials: A
authors.lastname: Nordmark
authors.forename: Gunnel
authors.initials: G
authors.lastname: Tybring
authors.forename: Anneli
authors.initials: A
authors.lastname: Wahlberg
authors.forename: Umit
authors.initials: U
authors.lastname: Yaşar
authors.forename: Leif
authors.initials: L
authors.lastname: Bertilsson
mesh_terms: D000328:Adult; D001711:Biotransformation; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D004338:Drug Combinations; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000235:genetics; D008297:Male; D008875:Middle Aged; D010599:Pharmacokinetics; D010641:Phenotype; D014018:Tissue Distribution
chemical_list: D004338:Drug Combinations; D007527:Isoenzymes; D003577:Cytochrome P-450 Enzyme System