WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Numerous cocktails using concurrent administration of several cytochrome P450 (CYP) isoform‐selective probe drugs have been reported to investigate drug–drug interactions in vivo.• This approach has several advantages: characterize the inhibitory or induction potential of compounds in development toward the CYP enzymes identified in vitro in an in vivo situation, assess several enzymes in the same trial, and have complete in vivo information about potential CYP‐based drug interactions. WHAT THIS STUDY ADDS • This study describes a new cocktail containing five probe drugs that has never been published.• This cocktail can be used to test the effects of a new chemical entity on multiple CYP isoforms in a single clinical study: CYP1A2 (caffeine), CYP2C9 (warfarin), CYP2C19 (omeprazole), CYP2D6 (metoprolol), and CYP3A (midazolam) and was designed to overcome potential liabilities of other reported cocktails.AIMS To assess the pharmacokinetics (PK) of selective substrates of CYP1A2 (caffeine), CYP2C9 (S‐warfarin), CYP2C19 (omeprazole), CYP2D6 (metoprolol) and CYP3A (midazolam) when administered orally and concurrently as a cocktail relative to the drugs administered alone.METHODS This was an open‐label, single‐dose, randomized, six‐treatment six‐period six‐sequence William's design study with a wash‐out of 7 or 14 days. Thirty healthy male subjects received 100 mg caffeine, 100 mg metoprolol, 0.03 mg kg−1 midazolam, 20 mg omeprazole and 10 mg warfarin individually and in combination (cocktail). Poor metabolizers of CYP2C9, 2C19 and 2D6 were excluded. Plasma samples were obtained up to 48 h for caffeine, metoprolol and omeprazole, 12 h for midazolam, 312 h for warfarin and the cocktail. Three different validated liquid chromatography tandem mass spectrometry methods were used. Noncompartmental PK parameters were calculated. Log‐transformed Cmax, AUClast and AUC for each analyte were analysed with a linear mixed effects model with fixed term for treatment, sequence and period, and random term for subject within sequence. Point estimates (90% CI) for treatment ratios (individual/cocktail) were computed for each analyte Cmax, AUClast and AUC.RESULTS There was no PK interaction between the probe drugs when administered in combination as a cocktail, relative to the probes administered alone, as the 90% CI of the PK parameters was within the prespecified bioequivalence limits of 0.80, 1.25.CONCLUSION The lack of interaction between probes indicates that this cocktail could be used to evaluate the potential for multiple drug–drug interactions in vivo.
We investigated whether a single plasma midazolam concentration could serve as an accurate predictor of total midazolam clearance, an established in-vivo probe measure of cytochrome P450 3A (CYP3A) activity. In a retrospective analysis of data from 224 healthy volunteers, non-compartmental pharmacokinetic parameters were estimated from plasma concentration-time curves following intravenous (IV) and/or oral administration. Based on statistical moment theory, the concentration at the mean residence time (MRT) should be the best predictor of the total area under the curve (AUC). Following IV or oral midazolam administration, the average MRT was found to be approximately 3.5 h, suggesting that the optimal single sampling time to predict AUC was between 3 and 4 h. Since a 4-h data point was common to all studies incorporated into this analysis, we selected this time point for further investigation. The concentrations of midazolam measured 4 h after an IV or oral dose explained 80 and 91% of the constitutive interindividual variability in midazolam AUC, respectively. The 4-h midazolam measurement was also an excellent predictor of drug-drug interactions involving CYP3A induction and inhibition. Compared with baseline values, the direction and magnitude of change in midazolam AUC and the 4-h concentration were completely concordant for all study subjects. We conclude that a single 4-h midazolam concentration following IV or oral administration represents an accurate marker of CYP3A phenotype under constitutive and modified states. Moreover, the single-point approach offers an efficient means to phenotype and identify individuals with important genetic polymorphisms that affect CYP3A activity.
Transporter-mediated drug-drug interactions (DDIs) are a major cause of drug toxicities. Using published genome-wide association studies (GWAS) of the human metabolome, we identified 20 metabolites associated with genetic variants in organic anion transporter, OATP1B1 (P < 5 × 10 ). Of these, 12 metabolites were significantly higher in plasma samples from volunteers dosed with the OATP1B1 inhibitor, cyclosporine (CSA) vs. placebo (q-value < 0.2). Conjugated bile acids and fatty acid dicarboxylates were among the metabolites discovered using both GWAS and CSA administration. In vitro studies confirmed tetradecanedioate (TDA) and hexadecanedioate (HDA) were novel substrates of OATP1B1 as well as OAT1 and OAT3. This study highlights the use of multiple datasets for the discovery of endogenous metabolites that represent potential in vivo biomarkers for transporter-mediated DDIs. Future studies are needed to determine whether these metabolites can serve as qualified biomarkers for organic anion transporters. Quantitative relationships between metabolite levels and modulation of transporters should be established.
A human liver cytochrome P-450 (P-450) IIIA4 cDNA clone was inserted behind an alcohol dehydrogenase promoter in the plasmid vector pAAH5 and expressed in Saccharomyces cerevisiae (D12 and AH22 strains). A cytochrome P-450 with typical spectral properties was expressed at a level of approximately 8 x 10(5) molecules/cell in either strain of yeast. The expressed P-450 IIIA4 had the same apparent monomeric Mr as the corresponding protein in human liver microsomes (P-450NF) and could be isolated from yeast microsomes. Catalytic activity of the yeast microsomes toward putative P-450 IIIA4 substrates was seen in the reactions supported by cumene hydroperoxide but was often lower and variable when supported by the physiological donor NADPH. The catalytic activity of purified P-450 IIIA4 was also poor in some systems reconstituted with rabbit liver NADPH-P-450 reductase and best when both the detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate and a lipid extract (from liver or yeast microsomes) or L-alpha-1,2-dilauroyl-sn-glycero-3-phosphocholine were present. Under these conditions the expressed P-450 IIIA4 was an efficient catalyst for nifedipine oxidation, 6 beta-hydroxylation of testosterone and cortisol, 2-hydroxylation of 17 beta-estradiol and 17 alpha-ethynylestradiol, N-oxygenation and 3-hydroxylation of quinidine, 16 alpha-hydroxylation of dehydroepiandrosterone 3-sulfate, erythromycin N-demethylation, the 10-hydroxylation of (R)-warfarin, the formation of 9,10-dehydrowarfarin from (S)-warfarin, and the activation of aflatoxins B1 and G1, sterigmatocystin, 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (both + and - diastereomers), 3,4-dihydroxy-3,4-dihydrobenz[a]anthracene, 3,4-dihydroxy-3,4-dihydro-7, 12-dimethylbenz[a]anthracene, 9,10-dihydroxy-9,10-dihydrobenzo[b]fluoranthene, 6-aminochrysene, and tris(2,3-dibromopropyl) phosphate to products genotoxic in a Salmonella typhimurium TA1535/pSK1002 system where a chimeric umuC' 'lacZ plasmid is responsive to DNA alkylation. Reaction rates were stimulated by 7,8-benzoflavone and inhibited by rabbit anti-P-450 IIIA (anti-P-450NF), troleandomycin, gestodene, and cimetidine. Evidence was obtained that rates of reduction of ferric P-450 IIIA4 in yeast microsomes and the reconstituted systems are slow and at least partially responsible for the lower rates of catalysis seen in these systems (relative to liver microsomes). The results of these studies with a defined protein clearly demonstrate the ability of P-450 IIIA4 to catalyze regio- and stereoselective oxidations with a diverse group of substrates, and this enzyme appears to be one of the most versatile catalysts in the P-450 family.
Background Type 2 inflammation is common in numerous atopic/allergic diseases and can be identified by elevated biomarker levels. Dupilumab, a fully human monoclonal antibody, blocks the shared receptor component for interleukin‐4 and interleukin‐13, key and central drivers of type 2 inflammation. Objective Assessment of dupilumab effect on type 2 inflammatory biomarkers in atopic dermatitis (AD), asthma, chronic rhinosinusitis with nasal polyps (CRSwNP) and eosinophilic esophagitis (EoE). Methods Data were extracted from three randomized placebo‐controlled trials of dupilumab in AD (NCT02277743, N = 671; NCT02277769, N = 708; NCT02260986, N = 740); and one each in asthma (NCT02414854, N = 1902); CRSwNP (NCT02898454, N = 448); and EoE (NCT02379052, N = 47). Biomarkers assessed were serum thymus and activation‐regulated chemokine (TARC), plasma eotaxin‐3, serum total immunoglobulin E (IgE), serum periostin and blood eosinophil count. Results Dupilumab versus placebo significantly suppressed most type 2 inflammatory biomarker levels across all studies/indications where data were assessed. Reductions in serum TARC, plasma eotaxin‐3 and serum periostin occurred rapidly, whereas reductions in serum total IgE were more gradual. Across diseases, at the end of treatment, median percentage change from baseline in TARC levels ranged from −24.8% to −88.6% (placebo +2.6% to −53.6%); −38.2% to −51.5% (placebo +8.3% to −0.16%) in eotaxin‐3; −24.8% to −76.7% (placebo +8.3% to −4.4%) in total IgE; and −13.6% to −41.1% (placebo +10.1% to −6.94%) in periostin levels. Blood eosinophil responses to dupilumab varied by disease, with minimal changes in AD in the SOLO studies (median percentage change from baseline to end of treatment: 0% [95% CI: −15.8, 0]); transient increases followed by decreases to below‐baseline levels in asthma (−14.6% [−20.0, −7.7]) and CRSwNP (−29.4% [−40.0, −16.3]); and significant decreases in EoE (−50.0% [−50.0, −33.3]). Conclusion and clinical relevance Dupilumab reduced levels of type 2 biomarkers across clinical studies in patients with AD, asthma, CRSwNP and EoE.
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