CYP2C19 Activity Research Articles

Afro-Latin American Pharmacogenetics of CYP2D6, CYP2C9, and CYP2C19 in Dominicans: A Study from the RIBEF-CEIBA Consortium.

Background/Objectives: Research on pharmacogenetic variability in response to prescribed drugs and across ethnic groups is essential for personalized medicine, particularly in admixed and unstudied populations. For the first time, this study examines CYP2D6, CYP2C9, and CYP2C19 alleles and genotypes in 197 healthy volunteers from the Dominican Republic, as part of the RIBEF-CEIBA collaborative network. Methods: The analysis focuses on the participants' tri-hybrid genomic ancestry, with CYP alleles determined by real-time PCR and molecular ancestry inferred using 90 AIMs. Linear regression was used to associate ancestry components with CYP frequencies. Results: The average ancestry was 23.8% European, 42.6% Native American, and 33.6% African, the latter being higher than in most Latin American populations. Native American ancestry was also higher than expected. Predicted phenotype frequencies based on genotypes were 4.2% poor metabolizers (gPMs) and 3.6% ultrarapid metabolizers (gUMs) for CYP2D6, as well as 3% gPMs, 22.8% rapid metabolizers (gRMs), and 1.5% gUMs for CYP2C19. No gPM individuals were observed for CYP2C9. Certain alleles associated with decreased CYP2D6 activity (*17 and *29) and increased CYP2C19 activity (*17 and gUMs) were positively linked with African ancestry and negatively with Native American ancestry. Rare CYP2C9 alleles (*5 and *6) with clinical relevance were additionally found. Conclusions: These findings build on previous results from the RIBEF-CEIBA collaborative network, demonstrating differences in allele frequencies of CYP2D6, CYP2C9, and CYP2C19 in relation to genomic ancestry. In summary, ethnicity must be considered in the development of pharmacogenetic guidelines for clinical application, research, and regulation to avoid widening the biotechnology gap and to allow Personalized Medicine to reach the entire world population.

Inhibitory effects characteristics of polysaccharide of Polygonati Rhizome on cytochrome P450 enzymes.

As the major active ingredient of Polygonatum sibriricum Red., polysaccharide of Polygonati Rhizome (PSP) has been reported to possess various pharmacological activities, especially for the treatment of chronic disorders in the elderly. This study evaluated the effect of PSP on the activities of major cytochrome P450 enzymes (CYP450) isoforms, aiming to provide theoretical reference for its co-prescription with other drugs and prevent the risk of adverse drug-drug interaction. The activities of CYP450 isoforms were assessed in human liver microsomes with specific probe substances. Through Lineweaver-Burk fitting models, the effect of PSP on the activity of inhibited CYP450 isoforms was characterized by competitive and non-competitive models. Dose-dependent and time-dependent experiments were also performed to completely understand the inhibition. Among experimental isoforms, PSP significantly inhibited the activities of CYP2C9, 2D6, and 3A4 in a concentration-dependent manner with IC50 values of 14.01, 17.63, and 5.33 μM. The inhibition of CYP2C9 and 2D6 was best fitted with the competitive model with the Ki values of 7.15 and 8.92 μM, respectively, while the inhibition of CYP3A4 was non-competitive with the Ki value of 2.63 μM. Additionally, the inhibition of CYP3A4 by PSP also showed time-dependent characteristics with the inhibition parameters, KI of 1.273 μM-1 and Kinact of 0.036 min-1. PSP exerted moderate inhibition on CYP2C9 and 2D6 and strong inhibition of CYP3A4. The dosage of CYP2C9-, 2D6-, and 3A4-metabolized drugs should be adjusted when co-administrated with PSP and its sourced herbs.

Induction of cytochrome P450 via upregulation of CAR and PXR: a potential mechanism for altered florfenicol metabolism by macranthoidin B in vivo.

Macranthoidin B (MB) is a primary active component of Flos Lonicerae. In Chinese veterinary clinics, Flos Lonicerae is frequently used in combination with florfenicol to prevent and treat infections in livestock and poultry. However, potential interactions between Flos Lonicerae and florfenicol remain unclear. To systematically study these interactions, it is crucial to investigate the individual phytochemicals within Flos Lonicerae. Therefore, MB was selected for this study to assess its effect on the pharmacokinetics of florfenicol in vivo and to explore the underlying mechanisms involved. Male Sprague-Dawley rats were administered MB (60 mg/kg BW) or sterile water orally for 7 consecutive days. On the 8th day, a single oral dose of florfenicol (25 mg/kg BW) was given. Florfenicol pharmacokinetics were analyzed using ultra-high performance liquid chromatography. The hepatic expression levels of cytochrome P450 (CYP1A2, CYP2C11, CYP3A1), UDP-glucuronosyltransferase (UGT1A1), P-glycoprotein (P-gp), and nuclear receptors, including constitutive androstane receptor (CAR), pregnane X receptor (PXR), and retinoid X receptor alpha (RXRα), were quantified via reverse transcription-quantitative polymerase chain reaction and Western blotting (WB). Hepatic CYP1A2 and CYP2C11 activities were measured using a cocktail method. Additionally, the subcellular expression and localization of CAR, PXR, and RXRαin hepatocytes was assessed using WB and immunofluorescence staining. MB significantly reduces the AUC(0-∞) and MRT(0-∞) of florfenicol. MB also markedly upregulates the mRNA and protein expression of hepatic CYP1A2 and CYP2C11, along with their catalytic activities. Substantial upregulation of CAR and PXR proteins occurs in the hepatocyte nucleus, along with significant nuclear colocalization of the transcriptionally active CAR/RXRα and PXR/RXRαheterodimers, indicating MB-induced nuclear translocation of both CAR and PXR. These findings suggest that MB-induced alterations in florfenicol pharmacokinetics, particularly its accelerated elimination, may be due to increased expression and activities of CYP1A2 and CYP2C11, with CAR and PXR potentially involved in these regulatory effects. Further investigation is yet needed to fully elucidate the clinical implications of these interactions concerning the efficacy of florfenicol in veterinary medicine.

Improving CYP2C19 phenotyping using stereoselective omeprazole and 5-hydroxy-omeprazole metabolic ratios.

Omeprazole (OME) is a CYP2C19 phenotyping probe, marketed as a racemic (S)/(R) mixture or as an S-enantiomer. Both CYP2C19 and CYP3A4 enzymes mediate (R)-OME hydroxylation to (R)-5-hydroxyomeprazole, while (S)-OME is exclusively hydroxylated via CYP2C19. This study investigates OME and its 5-hydroxymetabolite enantiomers' pharmacokinetics using data from two studies involving healthy volunteers. In Study A, volunteers received OME alone in Session 1, OME combined with voriconazole and fluvoxamine in Session 2 and finally OME with rifampicin in Session 3. In Study B, volunteers received OME alone in Session 1, OME combined with voriconazole in Session 2 and finally OME with fluvoxamine in Session 3. Despite low metabolic ratio values of (S)-OME, detectable modulation of CYP2C19 activity suggests both (R)- and (S)-OME isomers could effectively assess CYP2C19 activity. Further research is needed for precise cut-offs in different phenotype groups.

Kinetics of the inhibition of CYP3A4 and CYP2C19 activity by jabara juice and identification of the responsible inhibitory components

Some citrus fruits are known to cause clinically significant drug interactions by inhibiting intestinal cytochrome P450 (CYP) enzymes. This in vitro study aimed to investigate the kinetics of the inhibition of CYP3A4 and CYP2C19 by the juice of jabara, a Japanese citrus fruit that does not contain furanocoumarins such as 6′,7′-dihydroxybergamottin, and to identify the inhibitory compound(s).CYP3A4 and CYP2C19 activity levels were determined in vitro using recombinant CYP preparations and their respective substrates. The ethyl acetate extract (EAE) of jabara juice was separated to isolate and identify the compound(s) that inhibited CYP3A4. Then, the time-dependent kinetics of the inhibition of CYP3A4 and CYP2C19 by the EAE and its inhibitory compound(s) were analyzed.The EAE of jabara juice was found to inhibit CYP3A4 in a time-dependent manner. Two flavonoids, 3,3′,4′,5,6,7,8-heptamethoxyflavone (HpMF) and 3,3′,4′,5,6,7-hexamethoxyflavone (HxMF), were identified as the responsible compounds. HpMF and HxMF inhibited CYP3A4 activity in a concentration- and time-dependent manner, with inhibition constants (KI) of 10.0 and 7.90 µM and maximal inactivation rate constants (kinact,max) of 0.00856 and 0.0134 min−1, respectively. The EAE did not inhibit CYP2C19, even when preincubation was employed. These findings imply that jabara juice may cause food-drug interactions via time-dependent inhibition of intestinal CYP3A4.

High Burden of Ileus and Pneumonia in Clozapine-Treated Individuals With Schizophrenia: A Finnish 25-Year Follow-Up Register Study.

The authors used longitudinal biobank data with up to 25 years of follow-up on over 2,600 clozapine users to derive reliable estimates of the real-world burden of clozapine adverse drug events (ADEs). A total of 2,659 participants in the FinnGen biobank project had a schizophrenia diagnosis and clozapine purchases with longitudinal electronic health record follow-up for up to 25 years after clozapine initiation. Diseases and health-related events enriched during clozapine use were identified, adjusting for disease severity. The incidence and recurrence of ADEs over years of clozapine use, their effect on clozapine discontinuation and deaths, and their pharmacogenetics were studied. Median follow-up time after clozapine initiation was 12.7 years. Across 2,157 diseases and health-related events, 27 were enriched during clozapine use, falling into five disease categories: gastrointestinal hypomotility, seizures, pneumonia, other acute respiratory tract infections, and tachycardia, along with a heterogeneous group including neutropenia and type 2 diabetes, among others. Cumulative incidence estimates for ileus (severe gastrointestinal hypomotility) and pneumonia were 5.3% and 29.5%, respectively, 20 years after clozapine initiation. Both events were significantly associated with increased mortality among clozapine users (ileus: odds ratio=4.5; pneumonia: odds ratio=2.8). Decreased genotype-predicted CYP2C19 and CYP1A2 activities were associated with higher pneumonia risk. Clozapine-induced ileus and pneumonia were notably more frequent than has previously been reported and were associated with increased mortality. Two CYP genes influenced pneumonia risk. Pneumonia and ileus call for improved utilization of available preventive measures.

Nrf2 Ameliorates Atrial Fibrosis During Antithrombotic Therapy for Atrial Fibrillation by Modulating CYP2C9 Activity.

Anticoagulant therapy can significantly reduce the incidence of stroke and peripheral embolism events in patients with atrial fibrillation (AF). Although warfarin is widely used as an anticoagulant drug, a wrong dose can lead to increased risks of bleeding or blood clots. The aim of this study was to assess whether nuclear factor-erythroid-2-related factor 2 (Nrf2) can improve the efficacy of warfarin through the regulation of cytochrome P450 family 2 subfamily C member 9 (CYP2C9) using a rat model of AF. Results showed that AF significantly reduced Nrf2 in myocardial tissue of sham-operated rats. Furthermore, Nrf2 overexpression effectively reduced AF-induced atrial fibrosis by reducing collagen in the left atrium, inhibiting the expression of the fibrosis-related genes collagen I and transforming growth factor-β1 in rats with AF. Nrf2 overexpression can activate CYP2C9, decrease the serum concentration of warfarin, and decrease prothrombin time and international normalized ratio in AF rats. In this article, Nrf2 overexpression protects against fibrosis, increased survival in AF rats, and activated CYP2C9 expression, thus broadening the therapeutic range of warfarin in AF rats.

Synergistic Effect of Glibenclamide Combining With Vitexin on Type 2 Diabetes Mellitus Rats

Background & objectives: The combination of drugs with herbs is a prevalent treatment for metabolic and chronic diseases. This study combined glibenclamide with vitexin and performed in vivo and in vitro investigations, aiming to evaluate their synergistic effect on type 2 diabetes mellitus (T2DM). Materials and methods: T2DM rat models were established by injecting streptozotocin, and the sham group was injected with a normal saline solution as the control. A single dosage was orally performed with 10 mg/kg glibenclamide, while the co-administrated was conducted by the pre-treatment of 20 mg/kg vitexin for 7 d to avoid potential chemical interactions. The pharmacokinetics of glibenclamide was evaluated in both sham and T2DM rats. The blood glucose of T2DM rats was detected in the presence of different administration strategies. The metabolic stability of glibenclamide was assessed in rat liver microsomes. Results: Glibenclamide showed a significant hypoglycemic effect on T2DM rats, which was enhanced by the co-administration of vitexin. Vitexin significantly affected the pharmacokinetics of glibenclamide in both sham and T2DM rats, where the AUC0-t, Cmax, and t1/2 of glibenclamide significantly increased, and the clearance rate decreased. Moreover, vitexin increased the in vitro half-life and decreased intrinsic clearance of glibenclamide in rat liver microsomes. The previously reported inhibitory effect of vitexin on CYP2C9 activity was hypothesized as the mechanism underlying the interaction. Conclusion: Co-administration of glibenclamide and vitexin would increase the systemic exposure and metabolic stability of glibenclamide and exert a synergistic effect on T2DM.

Inhibitory effects of cuminaldehyde on human liver cytochrome P450 enzymes

This work explored the influence of cuminaldehyde on the metabolic activity of four primary human cytochrome P450 (CYP) enzymes. Human liver microsomes (HLM) with and without cuminaldehyde were incubated with specific substrates of different CYP enzymes. The influence of cuminaldehyde on “CYP1A2, CYP2C9, CYP2D6 and CYP3A4” activities was examined. The formation of specific metabolites was analyzed by HPLC analytical methods. It was observed that cuminaldehyde appears to have a negligible influence on CYP1A2 activity. However, CYP2C9 activity was significantly and potently inhibited by cuminaldehyde at all investigated concentrations. It was found that cuminaldehyde (1 µM) inhibited the most CYP2C9 enzyme activity with 64.87 % inhibition followed by CYP3A4 (38.90 %), CYP2D6 (25.76 %) and CYP1A2 (4.99 %). Inhibition of both CYP2D6 and CYP3A4 enzyme activity was observed in response to cuminaldehyde concentrations. Findings of the current investigation indicate that herb-drug interactions are very possible when cuminaldehyde is concurrently taken with medicines predominantly metabolized by CYP2C9 and CYP3A4. Cuminaldehyde should be tested further to examine how it affects CYP2C9 and CYP3A4-metabolized drugs.

Effects of diphenhydramine on crayfish cytochrome P450 activity and antioxidant defence mechanisms: First evidence of CYP2C- and CYP3A-like activity in marbled crayfish

Growing evidence has reported that diphenhydramine (DPH), an ionisable antihistamine, is widely present in surface waters across the world. Relative to vertebrates studied, its impact on invertebrates, particularly concerning cytochrome P450 (CYP) metabolism and oxidative stress, remains poorly understood. In this study, we aimed to investigate the effects of 2, 20, and 200 µg/L DPH on marbled crayfish (Procambarus virginalis) after 96-h exposure. Specifically, we assessed CYP activity, antioxidant enzyme responses, and acetylcholinesterase (AChE) activity in gills, muscle, and hepatopancreas. The crayfish CYP metabolised fluorogenic CYP-metabolic substrates of 7-benzyloxy-4-trifluoromethylcoumarin (BFC) and dibenzylfluorescein (DBF), which evidenced the activity of CYP2C and CYP3A isoforms, well known in mammalian detoxification metabolism. Both BFC and DBF dealkylations showed a positive correlation with each other but were negatively correlated to water and haemolymph DPH concentrations. Exposure to 200 µg/L DPH elicited an apparent inhibition trend, albeit not significant, in BFC- and DBF-transformation activities in crayfish. Other tested 7-benzyloxyresorufin and 7-pentoxyresorufin substrates were poorly metabolised, suggesting their relatively low activity or the lack of mammalian-like CYP1A and CYP2B isoforms in marbled crayfish. The significant modulation of antioxidant enzymes was demonstrated in gills and hepatopancreas. The exposure to DPH did not alter the activity of AChE. Integrated biomarker response version 2 showed the highest cumulative effect of DPH exposure on gills, implying that gill tissue is the most reliable matrix for evaluating DPH toxicity. Activities of glutathione peroxidase and glutathione-S-transferase were the most deviated determinants among the investigated biomarkers, providing insights into the DPH toxicity in crayfish. This study brought the first insight into utilising the fluorogenically active substrates BFC and DBF to demonstrate the CYP involvement in the detoxification metabolism in marbled crayfish. Further, our results provided information on valuable antioxidant defence mechanisms and biomarker responses for a future DPH toxicity assessment in aquatic organisms.

Association of Polymorphic Cytochrome P450 Enzyme Pathways with Falls in Multimedicated Older Adults

ObjectivesDose exposure is considered relevant for drug-associated falls in older adults, pointing to an importance of drug metabolism. Aim was to analyze individual factors altering drug metabolism such as enzyme saturation by drug exposure and pharmacogenetics in the context of drug-associated falls. DesignProspective population-based study (ActiFE-Ulm study). Setting and ParticipantsCommunity-dwelling older adults. MethodsFocus was laid on the metabolism by polymorphic cytochrome P450 (CYP) enzymes CYP2C19, 2C9, and 2D6. Relevant variants of pharmacogenes were analyzed. Logistic binary regression analysis was used to calculate odds ratios (ORs) and 95% CIs for falls observed prospectively over a 1-year period with drug metabolism characteristics. ResultsIn total, 1377 participants were included in the analysis. Although the phenotype predicted by the genotype was not, the use of drugs metabolized by CYP2C19 was associated with falls. Drugs not known as fall risk–increasing drugs (FRIDs; ie, non-FRIDs), but metabolized by CYP2C19, showed an OR of 1.46 (1.11-1.93) in adjusted analysis. Significant effect modification was observed for a reduced CYP2C19 activity phenotype with non-FRIDs metabolized by CYP2C19. Conclusions and ImplicationsThis study suggests an association between the occurrence of falls in older adults and the metabolic capacity of CYP2C19. Thus, an important step toward prevention of falls might be to personalize dosage and treatment length of the main drug classes known to be CYP2C19 substrates, such as many antidepressants, opioids, and sedatives, but also proton pump inhibitors in particular in poor and intermediate metabolizers.

The Impact of CYP 2C9 rs1799853 and rs1057910 Polymorphism on Plasma Losartan Metabolic Ratio in a Sample of Iraqi Hypertensive Patients

Background: The challenge associated with interindividual diversity in CYP2C9 enzyme activity is primarily related to genetic variations among individuals. Polymorphisms in the CYP2C9 gene can lead to different enzyme activity, affecting how individuals metabolize drugs. The understanding of interindividual diversity in CYP2C9 enzyme activity has implications for personalized medicine. Objective: To examine the impact of CYP2C9 gene polymorphisms (rs1799853 and rs1057910) on the losartan metabolism in Iraqi hypertensive patients. Methods: This prospective interventional study was conducted on a sample of hypertension patients from Babylon governorate, Iraq. All patients received 100 mg of losartan once daily. After 4 weeks, blood samples were obtained for genetic analysis and measuring losartan and its carboxylic acid (LCA) metabolite levels. The plasma losartan-to-LCA ratio is used as an indirect determinant of CYP2C9 activity within CYP2C9 SNP genotypes. Results: Two major allelic polymorphisms, CYP2C9 rs1799853 (T allele 15.5%) on exon 3 and rs1057910 (C allele 8.5%) on exon 7, have been identified among the patients. Plasma losartan/E3174 metabolic ratio was significantly higher in patients with a CT genotype of rs1799853 SNP (1.65) than in patients with a CC wild-type genotype (1.03). The losartan/E3174 metabolic ratio in heterozygous mutant AC genotypes of rs1057910 (1.18) was also higher than in those with wild-type AA genotypes (1.15); however, these differences are not statistically significant. Conclusions: The rs1799853 SNP variant, but not the rs1057910 SNP variant, significantly impacts CYP2C9 metabolic activity. The plasma losartan/E3174 metabolic ratio appears to be a practical and reliable measure for CYP2C9 activity.

Patient resuscitated after cardiopulmonary arrest exhibits abnormally increased phenytoin metabolic rate due to unknown factors: a case report

BackgroundFosphenytoin (FOS) is a prodrug of phenytoin (PHT) with a metabolism that exhibits Michaelis–Menten-type kinetics. Genetic polymorphisms of the metabolic enzymes of PHT make it challenging to predict its plasma concentrations. High plasma PHT concentrations are typically problematic, and several causes have been elucidated. In contrast, cases of patients with low PHT plasma concentrations that did not increase despite the administration of appropriate PHT doses have been reported, and the causes may include changes in plasma protein-binding rates, genetic mutations, and concomitant use of drugs that induce liver enzymes; however, even these factors do not explain the low PHT plasma concentrations in some cases.Case presentationWe encountered the case of a patient with plasma PHT concentrations that were continuously < 0.7 µg/mL after daily use of FOS for seizures that occurred after cardiopulmonary arrest. We analyzed the protein-unbound fraction, urinary metabolites, and related genes to investigate the cause. False negatives due to the measurement method, errors in dosage and administration method, and increased excretion of PHT were excluded. Hepatic metabolic activity of PHT increased to 4.6–6.1 times the normal level. The S/R ratio of 5-(p-hydroxyphenyl)-5-phenylhydantoin-glucuronide, a major PHT metabolite, was normal at 15.2, suggesting increased activities of CYP2C9 and CYP2C19. Furthermore, the protein-unbound fraction of PHT was 5.2–6.9%, CYP2C19*17 was wild type, and there was no concomitant drug use to induce both enzymes.ConclusionsThe low PHT plasma concentration in this patient was found to be caused by increased hepatic metabolic activity that could not be explained by known factors. Careful monitoring is necessary to consider the possibility of increased hepatic metabolic activity in similar cases.

Prospective Trial on the Pharmacokinetics of Clopidogrel in Hemodialysis Patients

IntroductionPatients undergoing hemodialysis (HDP) exhibit extensive cardiovascular risk. The widely prescribed anti-platelet agent clopidogrel is metabolically activated by cytochrome enzymes, which may be impaired by uremia and chronic low-grade inflammation, typically present in HDP. We conducted a prospective multicenter study to investigate the pharmacokinetics and pharmacodynamics of clopidogrel in HDP and healthy volunteers (HV). MethodsWe enrolled HDP receiving long-term clopidogrel (75mg) and pantoprazole treatment (40 mg). HV received a loading dose of 300 mg clopidogrel, followed by 75 mg once daily. Pantoprazole, a substrate and probe drug of CYP2C19, was administered intravenously (40 mg). Plasma concentrations were quantified by mass spectrometry. Pharmacokinetics were calculated, and a population pharmacokinetic model was developed. The primary endpoint was the maximum concentration of clopidogrel’s active metabolite (Cmax_CAM). Platelet aggregation was measured using ADP-induced whole-blood aggregometry. ResultsSeventeen HDP and 16 HV were included. Cmax_CAM was significantly lower in HDP compared to HV (median [IQR] 12.2 [4.6-23.4] vs. 24.7 [17.8-36.5] ng/mL, p=0.02). The Cmax ratio of CAM to prodrug was 8.5-fold lower in HDP, and an 82.7% reduced clopidogrel clearance, including CAM formation, was found using population pharmacokinetic modeling. ADP-induced platelet aggregation at 120 min was significantly higher in HDP than in HV (median [IQR]: 26 [14-43] vs. 12 [11-18] U, p=0.004. Pantoprazole terminal half-life was ∼1.7-fold higher in HDPs compared to HVs. ConclusionOur data demonstrate an altered metabolism of clopidogrel in HDP in the context of lower CYP2C19 activity, with potential implications for other substances metabolized by this enzyme.

Evaluation of In Vitro Metabolism- and Transporter-Based Drug Interactions with Sunscreen Active Ingredients.

The aim of this study was to examine the ability of sunscreen active ingredients to inhibit in vitro drug metabolism via cytochrome P450 (CYP) enzymes and drug uptake transporters. Metabolism assays with human liver microsomes were conducted for CYP2C9, CYP2D6 and CYP3A4 using probe substrates warfarin, bufuralol and midazolam, respectively. Uptake transporter assays with transfected cell lines were conducted for OAT3, OCT2 and OATP1B1 with probe substrates estrone-3-sulfate, metformin and rosuvastatin, respectively. Six sunscreen active ingredients, avobenzone, enzacamene, oxybenzone, octinoxate, trolamine, and homosalate, were evaluated up to their aqueous solubility limits in the assays. None of the sunscreen active ingredients inhibited CYP2D6 or CYP3A4 activities in the microsomes at concentration ranges up to tenfold higher than their known clinical total plasma levels. Only enzacamene, oxybenzone and trolamine were found to be inhibitory to CYP2C9 activity with IC50 values of 14.76, 22.46 and 154.7µM, respectively. Avobenzone, enzacamene, homosalate and octinoxate were not inhibitory to the uptake transporters at the evaluated concentrations. Oxybenzone was inhibitory to OAT3 and OCT2 with IC50 values of 39.93 and 42.77µM, respectively. Trolamine also inhibited uptake in OAT3 and OCT2 transfected cells with IC50 values of 448.1 and 1376μM, respectively. Although enzacamene, oxybenzone and trolamine inhibited CYP2C9 and the renal transporters OAT3 and OCT2 in vitro, their IC50 values exceeded total plasma levels found in clinical studies. Therefore, it is unlikely that these sunscreen active ingredients in sunscreen products will inhibit the metabolism or transport of co-administered drugs in consumers.

Metabolic activity of CYP2C19 and CYP2D6 on antidepressant response from 13 clinical studies using genotype imputation: a meta-analysis

Cytochrome P450 enzymes including CYP2C19 and CYP2D6 are important for antidepressant metabolism and polymorphisms of these genes have been determined to predict metabolite levels. Nonetheless, more evidence is needed to understand the impact of genetic variations on antidepressant response. In this study, individual clinical and genetic data from 13 studies of European and East Asian ancestry populations were collected. The antidepressant response was clinically assessed as remission and percentage improvement. Imputed genotype was used to translate genetic polymorphisms to metabolic phenotypes (poor, intermediate, normal, and rapid+ultrarapid) of CYP2C19 and CYP2D6. CYP2D6 structural variants cannot be imputed from genotype data, limiting the determination of metabolic phenotypes, and precluding testing for association with response. The association of CYP2C19 metabolic phenotypes with treatment response was examined using normal metabolizers as the reference. Among 5843 depression patients, a higher remission rate was found in CYP2C19 poor metabolizers compared to normal metabolizers at nominal significance but did not survive after multiple testing correction (OR = 1.46, 95% CI [1.03, 2.06], p = 0.033, heterogeneity I2 = 0%, subgroup difference p = 0.72). No metabolic phenotype was associated with percentage improvement from baseline. After stratifying by antidepressants primarily metabolized by CYP2C19, no association was found between metabolic phenotypes and antidepressant response. Metabolic phenotypes showed differences in frequency, but not effect, between European- and East Asian-ancestry studies. In conclusion, metabolic phenotypes imputed from genetic variants using genotype were not associated with antidepressant response. CYP2C19 poor metabolizers could potentially contribute to antidepressant efficacy with more evidence needed. Sequencing and targeted pharmacogenetic testing, alongside information on side effects, antidepressant dosage, depression measures, and diverse ancestry studies, would more fully capture the influence of metabolic phenotypes.

Inflammation altered correlation between CYP2C19 genotype and CYP2C19 activity in patients receiving voriconazole.

Voriconazole is the cornerstone of the treatment and prevention of fungal infections. While there is a good correlation between CYP2C19 genotype and voriconazole exposure during prophylactic treatment, no correlation was found in patients with invasive aspergillosis. Proinflammatory cytokines result in inhibition of CYP2C19 enzyme activity (and may result in phenoconversion). Here we investigated the relationship between inflammation, CYP2C19 genotype-predicted-phenotype, and CYP2C19 activity in patients receiving voriconazole. Data were obtained from two prospective studies investigating voriconazole treatment (NCT02074462 and NCT00893555). Dose-corrected voriconazole plasma concentration and C-reactive protein (CRP) were used as proxies for CYP2C19 activity and inflammation, respectively. After data extraction and synthesis, data from 39 patients with paired voriconazole and CRP measurements were available. The distribution of CYP2C19 genotype-predicted metabolizer phenotypes was 31% intermediate (IM), 41% normal (NM), and 28% rapid metabolizer (RM). During inflammation, dose-corrected voriconazole levels were increased by 245%, 278%, and 486% for CYP2C19 NMs IMs and RMs, respectively. Patients with moderate or high CRP levels (>50 mg/L) were phenoconverted to a lower metabolizer phenotype irrespective of their CYP2C19 genotype. In a subgroup analysis of eight patients with longitudinal data available with and without inflammation, the pattern of the dose-corrected voriconazole and CRP measurements were similar, with CYP2C19 activity following decreasing or increasing CRP levels. In conclusion, voriconazole plasma concentrations increase during inflammation due to downregulation of CYP2C19 activity. While this effect appears largest for CYP2C19 RMs, no clinically relevant differences were observed between the CYP2C19 genotypes.

Phenotype-Genotype Correlation Applying a Cocktail Approach and an Exome Chip Analysis Reveals Further Variants Contributing to Variation of Drug Metabolism.

Although great progress has been made in the fine-tuning of diplotypes, there is still a need to further improve the predictability of individual phenotypes of pharmacogenetically relevant enzymes. The aim of this study was to analyze the additional contribution of sex and variants identified by exome chip analysis to the metabolic ratio of five probe drugs. A cocktail study applying dextromethorphan, losartan, omeprazole, midazolam, and caffeine was conducted on 200 healthy volunteers. CYP2D6, 2C9, 2C19, 3A4/5, and 1A2 genotypes were analyzed and correlated with metabolic ratios. In addition, an exome chip analysis was performed. These SNPs correlating with metabolic ratios were confirmed by individual genotyping. The contribution of various factors to metabolic ratios was assessed by multiple regression analysis. Genotypically predicted phenotypes defined by CPIC discriminated very well the log metabolic ratios with the exception of caffeine. There were minor sex differences in the activity of CYP2C9, 2C19, 1A2, and CYP3A4/5. For dextromethorphan (CYP2D6), IP6K2 (rs61740999) and TCF20 (rs5758651) affected metabolic ratios, but only IP6K2 remained significant after multiple regression analysis. For losartan (CYP2C9), FBXW12 (rs17080138), ZNF703 (rs79707182), and SLC17A4 (rs11754288) together with CYP diplotypes, and sex explained 50% of interindividual variability. For omeprazole (CYP2C19), no significant influence of CYP2C:TG haplotypes was observed, but CYP2C19 rs12777823 improved the predictability. The comprehensive genetic analysis and inclusion of sex in a multiple regression model significantly improved the explanation of variability of metabolic ratios, resulting in further improvement of algorithms for the prediction of individual phenotypes of drug-metabolizing enzymes.

Combined effect of CYP2C19 and CYP2D6 genotypes on escitalopram serum concentration and its metabolic ratio in a European patient population.

The aim of the present study was to investigate the impact of CYP2D6 genotype on exposure and metabolism of escitalopram in patients stratified by CYP2C19 genotype in a large real-world population. Patients were included from a therapeutic drug monitoring service if they had measured serum concentration of escitalopram and the metabolite, N-desmethyl escitalopram, and performed CYP2C19 and CYP2D6 genotyping. Patients were divided into 16 combined genotype-predicted phenotype subgroups (poor [PM], intermediate [IM], normal [NM] and ultrarapid metabolizers [UM]) of CYP2C19/CYP2D6. The concentration-to-dose (CD) ratio and metabolite-to-parent ratio (metabolic ratio) of escitalopram were compared across subgroups using the Kruskal-Wallis test followed by Dunn's test with CYP2D6 NMs as the reference group. A total of 5067 patients were included in the study. A stepwise increase in escitalopram CD ratio by decreasing CYP2D6 activity was observed in all CYP2C19 subgroups, except for in CYP2C19 UMs. The percentage differences in escitalopram CD ratio between CYP2D6 PMs and NMs were 24% in CYP2C19 NMs (P < .001), 28% in CYP2C19 IMs (P < .001) and 31% in CYP2C19 PMs (P = .04). As for the CD ratio, CYP2D6 genotype effect on metabolic ratio increased stepwise by decreasing CYP2C19 metabolism. CYP2D6 genotype is of significant importance for the individual variation in escitalopram pharmacokinetics. The most relevant increase in escitalopram concentration is seen in individuals with decreased and/or absent CYP2C19 activity. By combining CYP2C19 and CYP2D6 genotypes, the optimal dose for patients may be predicted with greater precision than for CYP2C19 genotype alone.

Impact of obesity and roux-en-Y gastric bypass on the pharmacokinetics of (R)- and (S)-omeprazole and intragastric pH.

This study employed physiologically-based pharmacokinetic-pharmacodynamics (PBPK/PD) modeling to predict the effect of obesity and gastric bypass surgery on the pharmacokinetics and intragastric pH following omeprazole treatment. The simulated plasma concentrations closely matched the observed data from non-obese, morbidly obese, and post-gastric bypass populations. Obesity significantly reduces CYP3A4 and CYP2C19 activities, as reflected by the metabolic ratio [omeprazole sulphone]/[omeprazole] and [5-hydroxy-omeprazole]/[omeprazole]. The morbidly obese model accounted for the down-regulation of CYP2C19 and CYP3A4 to recapitulate the observed data. Sensitivity analysis showed that intestinal CYP3A4, gastric pH, small intestine bypass, and the delay in bile release do not have a major influence on omeprazole exposure. Hepatic CYP3A4 had a significant impact on the AUC of (S)-omeprazole, while hepatic CYP2C19 affected both (R)- and (S)-omeprazole AUC. After gastric bypass surgery, the activity of CYP3A4 and CYP2C19 is restored. The PBPK model was linked to a mechanism-based PD model to assess the effect of omeprazole on intragastric pH. Following 40 mg omeprazole, the mean intragastric pH was 4.3, 4.6, and 6.6 in non-obese, obese, and post-gastric bypass populations, and the daily time with pH >4 was 14.7, 16.4, and 24 h. Our PBPK/PD approach provides a comprehensive understating of the impact of obesity and weight loss on CYP3A4 and CYP2C19 activity and omeprazole pharmacokinetics. Given that simulated intragastric pH is relatively high in post-RYGB patients, irrespective of the dose of omeprazole, additional clinical outcomes are imperative to assess the effect of proton pump inhibitor in preventing marginal ulcers in this population.