Pharmacokinetics of omeprazole and its metabolites in three phases of menstrual cycle

Performance Verification of CYP2C19 Enzyme Abundance Polymorphism Settings within the Simcyp Simulator v21

Physiologically based pharmacokinetic (PBPK) modeling has a number of applications, including assessing drug−drug interactions (DDIs) in polymorphic populations, and should be iteratively refined as science progresses. The Simcyp Simulator is annually updated and version 21 included updates to hepatic and intestinal CYP2C19 enzyme abundance, including addition of intermediate and rapid metabolizer phenotypes and changes to the ultra-rapid metabolizer enzyme abundance, with implications for population clearance and DDI predictions. This work details verification of the updates with sensitive CYP2C19 substrates, omeprazole and lansoprazole, using available clinical data from literature. Multiple assessments were performed, including recovery of areas under the concentration-time curve (AUC) and Cmax from compiled datasets for each drug, recovery of victim DDI ratios with CYP2C19 and/or CYP3A4 inhibition and recovery of relative exposure between phenotypes. Simulated data were within respective acceptance criteria for >80% of omeprazole AUC values, >70% of lansoprazole AUC and Cmax, >60% of AUC and Cmax DDI ratios and >80% of exposure ratios between different phenotypes. Recovery of omeprazole Cmax was lower (>50−70% within 2-fold) and possibly attributed to the variety of formulations used in the clinical dataset. Overall, the results demonstrated that the updated data used to parameterize CYP2C19 phenotypes reasonably described the pharmacokinetics of omeprazole and lansoprazole in genotyped or phenotyped individuals.

Studies on CYP3A activity during the menstrual cycle as measured by urinary 6β-hydroxycortisol/cortisol

The 6β-OH-cortisol/cortisol ratio (6β-OHC/C) in urine is an endogenous marker of drug-metabolizing enzyme cytochrome P450 3A (CYP3A). The primary aim of this single center, prospective, non-interventional cohort study, was to investigate the variability of 6β-OHC/C during the menstrual cycle. In addition, possible associations between the CYP3A activity and sex hormones, gut microbiota metabolite trimethylamine-N-Oxide (TMAO) and microRNA-27b, respectively, were investigated. Serum and urinary samples from healthy, regularly menstruating women followed for two menstrual cycles were analyzed. Twenty-six complete menstrual cycles including follicular, ovulatory, and luteal phase were defined based on hormone analyses in serum. 6β-OHC/C were analyzed in urine and sex hormones, TMAO and miRNA-27b were analyzed in serum at the same time points. 6β-OHC/C did not vary between the follicular, ovulatory, or luteal phases. There was a difference in the relative miRNA-27b expression between the follicular and ovulatory phase (p = .03). A significant association was found between 6β-OHC/C and progesterone during the follicular (p = .005) and ovulatory (p = .01) phases (n = 26 for each phase). In addition, a significant association was found between the ratio and TMAO during the ovulatory (p = .02) and luteal (p = .002) phases. 6β-OHC/C and gut microbiota TMAO were significantly associated (p = .003) when evaluating all values, for all phases (n = 78). Interestingly, the finding of an association between 6β-OHC/C in urine and levels of TMAO in serum suggest that gut microbiota may affect CYP3A activity.

Prediction of the Area under the Curve Using Limited-Point Blood Sampling in a Cocktail Study to Assess Multiple CYP Activities

A cocktail study is an in vivo evaluation method to assess multiple CYP activities via a single trial and single administration of a cocktail drug that is a combination of multiple CYP substrates. However, multiple blood samples are required to evaluate the pharmacokinetics of a CYP probe drug. A limited-point sampling method is generally beneficial in clinical studies because of the simplified protocol and reduced participant burden. The aim of this study was to evaluate whether a limited-point plasma concentration analysis of CYP substrates in a cocktail drug could predict their area under the curve (AUC). We created prediction models of five CYP substrates (caffeine, losartan, omeprazole, dextromethorphan, and midazolam) using multiple linear regressions from the data of two cocktail studies, and then performed predictability analysis of these models using data derived from data in the co-administration with inducer (rifampicin) and inhibitors (fluvoxamine and cimetidine). For the administration of inhibitors, the AUC prediction accuracy (mean absolute error (MAE)) were <39.5% in Model 1 and <26.2% in Model 2 which were created using 1- and 4-point sampling data. MAE shows larger values in the administration of inducer in compared with the administration of inhibitors. The accuracy of the prediction in Model 2 could be acceptable for screening of inhibitions. MAE for caffeine, dextromethorphan, and midazolam were acceptable in the model that used 4 sampling points from all data. The use of this method could reduce the burden on the subject and make it possible to evaluate each AUC in a minimally invasive manner.

Pharmacokinetics, Bioequivalence, and Safety Studies of Pantoprazole Sodium Enteric-Coated Tablets in Healthy Subjects

This study aimed to evaluate the bioequivalence of 2 pantoprazole sodium enteric-coated tablet formulations, a generic formulation and a branded formulation, and to investigate their pharmacokinetic and safety profiles. The study was designed as a single-center, randomized, open-label, single-dose, dual-period, and 2-sequence crossover trial, and was divided into fasting and postprandial human bioequivalence trials. In the first trial, 36 subjects were fasted overnight before they were given generic or branded tablets (during 2 separate administration periods). Separately, 42 subjects were provided a high-fat meal 1 hour before the drugs were administered. Blood specimens of each subject were obtained up to 24 hours after drug administration. No significant differences were observed between the pharmacokinetic profiles of the generic and branded pantoprazole sodium enteric-coated tablets. Bioequivalence was evaluated using 90% confidence intervals for the ratio of test/reference log area under the concentration-time curve over 24 hours, log area under the concentration-time curve to infinity (AUC_0-∞ ), and log peak concentration (C_max ). The 90% confidence intervals of the least squares geometric mean ratio of C_max , area under the concentration-time curve from time zero to the last measurable concentration (AUC_0-t ), and AUC_0-∞ of 36 subjects in the fasting trial and of 40 of 41 subjects in the postprandial trial (C_max [41], AUC_0-t [41], and AUC_0-∞ [40]) were in accordance with the bioequivalence criteria. No severe adverse effects were detected. The generic and branded pantoprazole sodium enteric-coated tablets were considered bioequivalent with similar safety profiles.

Evaluation of potential herbal-drug interactions of a standardized propolis extract (EPP-AF®) using an in vivo cocktail approach

ETHNOPHARMACOLOGICAL RELEVANCE

Propolis has been employed extensively in many cultures since ancient times as antiseptic, wound healing, anti-pyretic and others due to its biological and pharmacological properties, such as immunomodulatory, antitumor, anti-inflammatory, antioxidant, antibacterial, antiviral, antifungal, antiparasite activities. But despite its broad and traditional use, there is little knowledge about its potential interaction with prescription drugs.

AIM OF THE STUDY

The main objective of this work was to study the potential herbal-drug interactions (HDIs) of EPP-AF® using an in vivo assay with a cocktail approach.

MATERIALS AND METHODS

Subtherapeutic doses of caffeine, losartan, omeprazole, metoprolol, midazolam and fexofenadine were used. Sixteen healthy adult volunteers were investigated before and after exposure to orally administered 125 mg/8 h (375 mg/day) EPP-AF® for 15 days. Pharmacokinetic parameters were calculated based on plasma concentration versus time (AUC) curves.

RESULTS

After exposure to EPP-AF®, it was observed decrease in the AUC^0-∞ of fexofenadine, caffeine and losartan of approximately 18% (62.20 × 51.00 h.ng/mL), 8% (1085 × 999 h.ng/mL) and 13% (9.01 × 7.86 h.ng/mL), respectively, with all 90% CIs within the equivalence range of 0.80-1.25. On the other hand, omeprazole and midazolam exhibited an increase in AUC^0-∞ of, respectively, approximately 18% (18.90 × 22.30 h.ng/mL) and 14% (1.25 × 1.43 h.ng/mL), with the upper bounds of 90% CIs slightly above 1.25. Changes in pharmacokinetics of metoprolol or its metabolite α-hydroxymetoprolol were not statistically significant and their 90% CIs were within the equivalence range of 0.80-1.25.

CONCLUSIONS

In conclusion, our study shows that EPP-AF® does not clinically change CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A activities, once, despite statistical significant, the magnitude of the changes in AUC values after EPP-AF® were all below 20% and therefore may be considered safe regarding potential interactions involving these enzymes. Besides, to the best of our knowledge this is the first study to assess potential HDIs with propolis.

Alterations in Xenobiotic-Metabolizing Enzyme Activities across Menstrual Cycle in Healthy Volunteers

The purpose of the study was to determine whether the in vivo activities of drug-metabolizing enzymes CYP1A2 and CYP2A6, xanthine oxidase (XO), and N-acetyltransferase-2 (NAT2) vary across the menstrual cycle. Forty-two healthy women were studied at early follicular phase (EFP: 2nd to 4th days), late follicular phase (LFP: 10th to 12th days), and luteal phase (LP: 19th to 25th days) of a single menstrual cycle, and blood and urine samples were collected at each phase. Spot urine samples obtained 6 hours following 200-mg caffeine administration were used to determine caffeine metabolite ratios (CMRs); blood samples were used to determine CYP1A2*1F (rs762551) and CYP1A2*1C (rs2069514) polymorphisms and the hormonal profile (estradiol, progesterone, and luteinizing and follicle-stimulating hormones) at EFP, LFP, and LP. CMR and hormone variations were analyzed at three levels (EFP, LFP, LP) using one-way repeated-measures analysis of variance. CYP1A2 activity was lower and that of CYP2A6 and NAT2 were higher at LFP compared with EFP and LP. Enzyme alterations were significant in volunteers (n = 21) whose hormonal profiles at EFP, LFP, and LP corresponded to expected levels, but not in volunteers (n = 15) with presumed early or late sampling around LFP. No significant difference was detected in any enzyme activity in presumed anovulatory volunteers (n = 6). The reduction of CYP1A2 activity at LFP was not associated with smoking or CYP1A2*1F polymorphism. XO and NAT2 (fast acetylators) activities remained unaltered. It is suggested that drug-metabolizing enzyme activities are altered across the menstrual cycle. Selection of appropriate sampling periods verified by hormonal assessment and identification of anovulatory cycles are decisive factors in disclosing altered enzyme activity across the menstrual cycle.