Pharmacokinetics and phenotyping properties of the Basel phenotyping cocktail combination capsule in healthy male adults

Abstract

Aims: We compared the phenotyping metrics of a combination capsule formulation to its individual components of the newly composed Basel phenotyping cocktail. Moreover, we investigated a reduced sampling regimen for clinical applications.

Methods: We performed in vitro experiments and a crossover pharmacokinetic study in twelve healthy male subjects to compare the Basel phenotyping cocktail capsule containing 6 cytochrome P450 (CYP) probe drugs with individual administration of the same drugs. Parent compounds and selected metabolites were determined by liquid chromatography-tandem mass spectrometry. Metabolic ratios (MR) for are under the curve (AUC) and single time point measurements and their correlation were determined.

Results: Experiments with human liver microsomes and primary human hepatocytes in 3D co-culture confirmed that flurbiprofen is a suitable CYP2C9 substrate. Both cocktail formulations (capsule and individual probe drug administration) were well-tolerated and yielded reproducible MRs, which were almost identical. Correlations between single time point ratios and the corresponding AUC ratios depended on the sampling time point and the concentration time curve of the probe drugs. The MR of the capsule (Spearman rank correlation coefficient, R_s : 0.77-0.97) as well as the individual components (R_s : 0.69-0.99) correlated best at 6 h post-treatment considering all 6 CYPs. Moreover, the 2-h time points of the capsule agreed suitably with the AUC; however, the MR of omeprazole could not be determined for 10 out of 12 subjects.

Conclusion: The capsule is easy to swallow, well tolerated and provides reliable estimates for CYP activity. The optimal sampling point for the capsule formulation is 6 h after intake.

Keywords: Basel phenotyping cocktail; combination capsule formulation; cytochrome P450 (CYP); liquid chromatography-tandem mass spectrometry; metabolic ratio.

Figure 1

Formation of phase I metabolites of probe substrates of the Basel phenotyping cocktail: paraxanthine (CYP1A2); 8′‐hydroxyefavirenz (CYP2B6); 5′‐hydroxyomeprazole (CYP2C19); α‐hydroxymetoprolol (CYP2D6); and 1′‐hydroxymidazolam (CYP3A4). The corresponding parent drugs were incubated with 3D‐cultured primary human hepatocytes in the absence (open circle) or in the presence of flurbiprofen (grey circle). Data represent mean values ± standard deviation of at least 3 independent experiments

Figure 2

Plasma concentration–time curves of parent and metabolite for each probe drug and formulation of the Basel phenotyping cocktail from 0 to 12 h post‐dose. Filled grey circles and filled grey squares represent mean ± standard deviation of parent compound and metabolite, respectively, of the capsule formulation. Open circles and open squares represent mean ± standard deviation of parent compound and metabolite, respectively, of the individual components of the Basel phenotyping cocktail

Figure 3

Metabolic ratios calculated for individual sampling time points. Grey and open circles and error bars represent mean ± standard deviation of single time point metabolic ratios from capsule formulation and individually administered components, respectively

Figure 4

Box and whiskers plot of the spearman rank correlation coefficients (R_s) determined for 6 cytochrome P450 (CYP) isoforms. Correlation was assessed for the relationship between area under the curve up to 12 h and each single time point (1–12 h) after treatment with the combination capsule or the individual components (n = 12). Both formulations show a good correlation at 6 h post‐treatment for all CYPs. Boxes represent the interquartile ranges and the line in the middle of the box is plotted at the median. Whiskers represent the maximum and minimum values

Figure 5

Box and whiskers plot of metabolic ratios of the 6‐h time points and the area under the curve up to 12 h for each probe drug and formulation (capsule and individual components) of the Basel phenotyping cocktail. The number in the squares (01–12) correspond to the study participant identifier. Subjects 03 and 10 are smokers shown by bold numbers in the plots of CYP1A2. Colours indicate the genotype of the study participants: Ultra‐rapid metabolizer (white), extensive metabolizer (light grey), intermediate metabolizer (grey), and poor metabolizer (black). In the case of CYP 1A2 and 2C19 white squares stand for extensive/ultra‐rapid metabolizers and rapid metabolizers, respectively. Subjects 01 and 09 were not genotyped which is highlighted by dashed square frames. The genotype of CYP3A4 was not determined. Largest differences between the metabolic ratios of capsule and individual components were observed for midazolam and caffeine. Boxes represent the interquartile ranges and the line in the middle of the box is plotted at the median. Whiskers represent the maximum and minimum values