Effect of deglucuronidation on the results of the Basel phenotyping cocktail

Abstract

We investigated the effect of deglucuronidation on the plasma concentration of the constituents of the Basel phenotyping cocktail and on the interpretation of the phenotyping results under basal conditions and after cytochrome P450 (CYP) induction with metamizole. The cocktail containing caffeine (CYP1A2), efavirenz (CYP2B6), flurbiprofen (CYP2C9), omeprazole (CYP2C19), metoprolol (CYP2D6) and midazolam (CYP3A4) was administered to 12 healthy subjects before (basal) and after treatment with metamizole for 1 week. In the basal state, deglucuronidation caused an increase in the plasma concentrations and area under the curve (AUC) of metoprolol, 8′‐hydroxyefavirenz, 4′‐hydroxyflurbiprofen and 1′‐hydroxymidazolam. This effect could be visualized in Bland–Altman plots, where the values for 8′‐hydroxyefavirenz, 4′‐hydroxyflurbiprofen and 1′‐hydroxymidazolam were mostly above the +20% threshold. As a result, the metabolic ratio (MR), calculated as AUCparent drug/AUCmetabolite, decreased with deglucuronidation for CYP2B6, CYP2C9 and CYP3A4 and increased for CYP2D6. Treatment with metamizole, a constitutive androstane receptor‐dependent inducer of CYP2B6, CYP2C9, CYP2C19 and CYP3A4, accentuated the effect of deglucuronidation on AUC and MR. The correlation of MRs calculated as the plasma concentration ratio parent drug/metabolite with the MR calculated as the AUC ratio showed that 1 sample obtained between 2 and 6 hours after cocktail ingestion and analysed with and without deglucuronidation is sufficient to obtain reliable phenotyping results. Importantly, CYP2C9 and 3A4 induction would have been missed without deglucuronidation of the plasma samples. In conclusion, deglucuronidation of the plasma samples improves the stability of the phenotyping results of the Basel phenotyping cocktail and is necessary to reliably detect CYP induction.

Liver Cirrhosis Affects the Pharmacokinetics of the Six Substrates of the Basel Phenotyping Cocktail Differently

“…For midazolam, we deglucuronidated the plasma samples before quantification because 1′-hydroxymidazolam is rapidly and almost completely glucuronidated [ 33 ] and the MR 0–24h provides more reliable results when the total (glucuronidated and non-glucuronidated) 1′-hydroxymidazolam is used for the calculation [ 31 ]. Similar to omeprazole and metoprolol, the elimination rate of midazolam decreased with increasing severity of liver cirrhosis, resulting in a higher exposure and lower Cl/F (drop by 84% in patients with Child C cirrhosis compared with control subjects).…”

“…The substrates of the Basel phenotyping cocktail were quantified in plasma via high-performance liquid chromatography tandem mass spectrometry as described previously [ 30 ]. The plasma concentrations of caffeine, efavirenz, flurbiprofen, omeprazole, and metoprolol and their metabolites were determined without prior deglucuronidation, whereas for midazolam and 1′-OH-midazolam, the samples were first treated with β-glucuronidase (from Helix pomatia , ≥ 100,000 units/mL; Sigma-Aldrich, Buchs, Switzerland) [ 31 ]. Analyte extraction was performed by the addition of 150 µL of methanol to 50 µL of plasma.…”

Evaluation of CYP1A2 activity: Relationship between the endogenous urinary 6‐hydroxymelatonin to melatonin ratio and paraxanthine to caffeine ratio in dried blood spots

“…We reported the −20 to +20% range in the Bland-Altman plots, because at least 67% of the observations must fall within this range for two methods to be considered as providing similar results according to the European Medicines Evaluation Agency (EMEA) guidelines (cross-validation acceptance criteria) and previous reports. [22][23][24] In addition, based on the US Food and Drug Administration (FDA) Bioequivalence Hearing, a difference of 20% is not considered clinically significant. 25 Normality was tested using the Kolmogorov-Smirnov test and significant outliers were identified by the ROUT method and removed (Q = 1%).…”

“…Linear regression and Bland–Altman plot were used to evaluate the relationship between the 6‐hydroxymelatonin/melatonin ratio from overnight urine samples and first morning voids. For the Bland–Altman analysis, the average of the ratios in 12‐h (overnight) and first morning voids urine samples at each session were measured and the percentage of difference was calculated as follows:We reported the −20 to +20% range in the Bland–Altman plots, because at least 67% of the observations must fall within this range for two methods to be considered as providing similar results according to the European Medicines Evaluation Agency (EMEA) guidelines (cross‐validation acceptance criteria) and previous reports 22–24 . In addition, based on the US Food and Drug Administration (FDA) Bioequivalence Hearing, a difference of 20% is not considered clinically significant 25 …”

Pharmacokinetic and Pharmacodynamic Drug–Drug Interactions: Research Methods and Applications

“…Recent studies have evaluated the safety of the Basel cocktail in patients with liver injury, which is conducive to timely adjustment of drug use in patients with liver cirrhosis [ 23 ]. In addition, the stability of the Basel cocktail was strengthened through deglucuronidation of the plasma samples, thus strengthening its practicability [ 24 ]. The safety of the Geneva cocktail has been verified in people from three different geographic origins by Rollason [ 25 ].…”