Cytochrome P450 3A4 Activity Research Articles

Use of 4β-Hydroxycholesterol Plasma Concentrations as an Endogenous Biomarker of CYP3A Activity: Clinical Validation in Individuals With Type 2 Diabetes.

The relevance of endogenous 4β-hydroxycholesterol (4β-OHC) plasma concentrations or of the 4β-OHC/total cholesterol concentration ratio (4β-OHC ratio) as surrogate markers of cytochrome P450 3A (CYP3A) activity was evaluated in individuals with (n=38) or without (n=35) type 2 diabetes (T2D). Midazolam was used as a comparator to validate exploratory measures of phenotypic CYP3A activity. Metabolic ratios of orally administered midazolam in nondiabetic and diabetic populations correlated significantly with 4β-OHC (rs =0.64 and 0.48; P≤0.003) and 4β-OHC ratio (rs =0.69 and 0.46; P≤0.003), respectively. Activity of CYP3A was lower in the T2D population compared with nondiabetic subjects; this decrease was reflected in 4β-OHC concentrations (24.33 vs. 12.58ng/mL; P<0.0001) and 4β-OHC ratio (0.13 vs. 0.09 (×104 ); P<0.0002). These results suggest that 4β-OHC should be considered as a valid, convenient, and easy to use endogenous biomarker of CYP3A activity in patients.

Erlotinib treatment induces cytochrome P450 3A activity in non‐small cell lung cancer patients

Erlotinib is a tyrosine kinase inhibitor used in the treatment of non-small cell lung cancer highly metabolized by the cytochrome P450 (CYP) 3A. Hence, CYP3A4 activity might be a useful predictor of erlotinib pharmacokinetics in personalized medicine. The effect of erlotinib on CYP3A activity was therefore studied in non-small cell lung cancer patients. The study included 32 patients scheduled for erlotinib monotherapy. CYP3A activity was assessed using quinine as a probe before and during erlotinib treatment. Plasma from blood samples drawn 16hours post quinine administration were analysed using HPLC with fluorescence detection to determine the quinine/3-OH-quinine ratio. Matched samples, available from 13 patients, showed an induction of CYP3A activity (P=0.003, Wilcoxon's signed rank test) after 2months of treatment. The quinine/3-OH-quinine ratio decreased from 20.2 (± 13.4) at baseline to 11.0 (± 4.34). Single-point samples, available from 19 patients, supported the decrease in ratio (P=0.007, Mann-Whitney U-test). Generally, females had a higher CYP3A activity both at baseline and after two months of treatment. Statistical analysis by gender also showed significant increase in CYP3A activity (males, n=10, P=0.001, and females, n=22, P=0.001). An induction of CYP3A activity was observed after 2months of erlotinib treatment which was also seen when subdividing based on gender. It could be important to take this into consideration for patients co-administering other CYP3A-metabolizing drugs during erlotinib treatment and also makes it difficult to use baseline CYP3A activity to predict erlotinib pharmacokinetics.

CYP3A suppression during diet-induced nonalcoholic fatty liver disease is independent of PXR regulation

Cytochrome P450 3A (CYP3A) activity is inhibited, and its expression is suppressed during many diseases, including nonalcoholic fatty liver disease (NAFLD). However, the mechanism is controversial. Here, we report that PXR may not take part in the downregulation of CYP3A during NAFLD. Hepatic CYP3A11 (major subtype of mouse CYP3A) mRNA and protein expression was significantly decreased in both mice fed a high-fat diet (HFD) for 8 weeks and palmitate (PA)-treated mouse primary hepatocytes. Similarly, in HepG2 cells, PA treatment significantly suppressed the CYP3A4 (major subtype of human CYP3A) mRNA level and promoter transcription activity. However, Western blotting analysis found an induction of PXR nuclear translocation during NAFLD in both in vivo and in vitro models. Moreover, immunofluorescence determination also found nuclear translocation effect of PXR by PA stimulation in HepG2 cells. In addition, the siRNA knockdown of PXR did not affect the suppressive effects of PA on the CYP3A4 promoter transcription activity and mRNA levels in HepG2 cells. Similarly, PXR knockdown also did not affect the suppressive effects of PA on CYP3A11 mRNA and protein expression levels in mouse primary hepatoctyes. Taken together, the results showed that the suppressive effect of CYP3A transcription was independent of PXR regulation.

Microdosed midazolam for the determination of cytochrome P450 3A activity: Development and clinical evaluation of a buccal film

Cytochrome P450 3A (CYP3A) isozymes metabolize about 50% of all marketed drugs. Their activity can be modulated up to 400-fold, which has great impact on individual dose requirements for CYP3A substrates. The activity of CYP3A can be monitored using the CYP3A substrate midazolam. To avoid pharmacological midazolam effects during phenotyping, a microdosing approach is preferred. However, the preparation of microdosed dosage forms remains a challenge. Fast dissolving buccal films are therefore proposed to facilitate this task.It was the aim of the present study to clinically evaluate a novel buccal film containing microdoses of midazolam for assessment of CYP3A activity.In a randomized, open-label crossover design, the pharmacokinetics of midazolam and its active hydroxy-metabolite, 1′‑OH‑midazolam, was assessed in 12 healthy volunteers after administration of single microdoses of midazolam (30 μg) as buccal film or buccal solution.The buccal film did rapidly disintegrate, was well tolerated, and no adverse events occurred. The film and the solution showed very similar midazolam plasma concentration-time profiles but were not bioequivalent according to EMA and FDA guidelines. For Cmax, AUC0-12h, and AUC0-∞ the geometric mean ratios of film to solution, with their 90% confidence intervals in parentheses, were 1.15 (1.00–1.32), 1.16 (1.04–1.28), and 1.19 (1.08–1.31), respectively. As a proxy for CYP3A activity, molar metabolic ratios of midazolam and 1′‑OH‑midazolam were analyzed over time, which revealed good correlations already 1 h or 2 h after application of the film or the solution, respectively.The tested midazolam buccal film is a convenient dosage form that facilitates administration of a phenotyping probe considerably and may potentially be used in special patient populations such as pediatric patients.Clinical Trials.gov Identifier: NCT03204578

Study Protocol for a Pilot, Open-Label, Prospective, and Observational Study to Evaluate the Pharmacokinetics of Drugs Administered to Patients during Extracorporeal Circulation; Potential of In Vivo Cytochrome P450 Phenotyping to Optimise Pharmacotherapy.

Pharmacokinetic alterations of medications administered during surgeries involving cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO) have been reported. The impact of CPB on the cytochrome P450 (CYP) enzymes’ activity is the key factor. The metabolic rates of caffeine, dextromethorphan, midazolam, omeprazole, and Losartan to the CYP-specific metabolites are validated measures of in vivo CYP 1A2, 2D6, 3A4, 2C19, and 2C9 activities, respectively. The study aim is to assess the activities of major CYPs in patients on extracorporeal circulation (EC). This is a pilot, prospective, open-label, observational study in patients undergoing surgery using EC and patients undergoing laparoscopic cholecystectomy as a control group. CYP activities will be measured on the day, and 1–2 days pre-surgery/3–4 days post-surgery (cardiac surgery and Laparoscopic cholecystectomy) and 1–2 days after starting ECMO, 1–2 weeks after starting ECMO, and 1–2 days after discontinuation from ECMO. Aforementioned CYP substrates will be administered to the patient and blood samples will be collected at 0, 1, 2, 4, and 6 h post-dose. Major CYP enzymes’ activities will be compared in each participant on the day, and before/after surgery. The CYP activities will be compared in three study groups to investigate the impact of CYPs on EC.

Midazolam Limited Sampling Strategy With a Population Pharmacokinetic Approach to Simultaneously Estimate Cytochrome P450 (CYP) 3A Constitutive, Inhibition, and Induction/Activation Conditions in Healthy Adults.

We have previously described a midazolam limited sampling strategy employing a population pharmacokinetic (PK) approach to estimate constitutive cytochrome P450 (CYP) 3A activity. This study evaluated expansion of this approach to estimate CYP3A constitutive, inhibitory, and induction activities. Midazolam concentrations (n = 4441) from adults (n = 152) were obtained from previous studies after single, oral, or intravenous administration with intensive sample collection. Data were fit to a 2-compartment population PK model that incorporated CYP3A conditions as covariates for clearance (CL), volume of distribution, and bioavailability (F). Limited sampling models using single- or 2-time point concentrations were compared with full PK profiles using the empiric Bayesian post hoc estimations of midazolam area under the plasma concentration-time curve derived from the population PK model. Ketoconazole, rifampin, and pleconaril were significant covariates of CL, while ketoconazole, rifampin, and grapefruit juice were significant covariates for F. Typical midazolam CL and F estimates were 32.9 L/h and 0.31 for the constituent state, while the ratio of inducer/inhibitor for midazolam CL and CL/F for the induced/inhibited (rifampin/ketoconazole) states were 14.2 and 85.3. Upon comparison to the population PK model, the majority of evaluated single- and 2-time point limited sampling models estimated area under the plasma concentration-time curve had unacceptable r2 and/or unacceptable bias and precision. Exclusively during CYP3A inhibitory conditions, the 4- and 6-hour limited sampling model had acceptable limits of r2 , bias, and precision. Consequently, development of a single- or 2-time point midazolam limited sampling model for general, widespread use to simultaneously evaluate various CYP3A conditions remains elusive.

Ultrasensitive near-infrared fluorescent probe with large stokes shift for real-time tracing of CYP1A1 in living cells and zebrafish model

Human cytochrome P450 1A1 (CYP1A1) enzyme is involved in the oxidation of various procarcinogenes into active carcinogenic metabolites in the phase I of biotransformation and initiates the carcinogenic process. Here, a novel ultrasensitive CYP1A1-specific fluorescent probe (DPCl) was investigated deeply which has O-chloroethyl group as a trigger for CYP1A1 activity and a dicyanoisophorone derivative fluorophore with a 673 nm emission. The size of the O-chloroethyl group is suitable for the cavity volume of the active sites of CYP1A1 and the lipophilicity and polarity of the group make the probe suitable for oriented at the actives sites. Hence, this near-infrared fluorescent probe reveals ultrasensitive sensitivity (minimum detectable limit is 0.026 nM), excellent specificity, and low toxicity in the process of target enzyme monitoring under simulated physiological condition, living cells and zebrafish. The success of this strategy is rely on intermediate product (DPOH) after dechloroethylation of DPCl is NIR-illuminant platform with a prominent Stokes Shift (118 nm), which is the first report of a NIR fluorescent probe for detecting CYP1A1. Anyhow, this probe provides support for clinical studies of CYP1A1 cell screening inhibitors and real-time tracking of enzyme activity in vivo.

Liposome mediated-CYP1A1 gene silencing nanomedicine prepared using lipid film-coated proliposomes as a potential treatment strategy of lung cancer

The occurrence of lung cancer is linked with tobacco smoking, mainly through the generation of polycyclic aromatic hydrocarbons (PAHs). Elevated activity of cytochrome P4501A1 (CYP1A1) plays an important role in the metabolic processing of PAHs and its carcinogenicity. The present work aimed to investigate the role of CYP1A1 gene in PAH-mediated growth and tumor development in vitro and using an in vivo animal model. RNAi strategy was utilized to inhibit the overexpression of CYP1A1 gene using cationic liposomes generated using a lipid film-coated proliposome microparticles. Treatment of PAH-induced human alveolar adenocarcinoma cell line with cationic liposomes carrying CYP1A1 siRNA resulted in down regulation of CYP1A1 mRNA, protein as well as its enzymatic activity, triggering apoptosis and inhibiting multicellular tumor spheroids formation in vitro. Furthermore, silencing of CYP1A1 gene in BALB/c nude xenografts inhibited tumor growth via down regulation of CYP1A1 expression. Altogether, our findings showed that liposome-based gene delivery technology is a viable and stable approach for targeting cancer causing genes such as CY1PA1. This technology facilitated by the use of sugar particles coated with lipid films has demonstrated ability to generate anticancer effects that might be used in the future for therapeutic intervention and treatment of lung cancer.

Alteration of drug-metabolizing enzyme activity in palliative care patients: Microdosed assessment of cytochrome P450 3A

Background: Cytochrome P450 3A is the most relevant drug-metabolizing enzyme in humans as it is involved in the elimination of 50% of marketed drugs. Nothing is known about the activity of cytochrome P450 3A in palliative care patients who have complicated symptoms often associated with a terminal illness. Aim: In order to improve drug dosing in end-of-life care and to avoid drug interactions, cytochrome P450 3A activity was determined in patients of a palliative care unit under real-life clinical conditions. Design: As midazolam is an established marker substance for cytochrome P450 3A activity, this single-arm prospective trial was designed to obtain a 4-h pharmacokinetic profile of midazolam after oral administration of a 10-µg dose from each enrolled patient. Plasma concentrations of midazolam and its primary metabolite 1′-hydroxy-midazolam were quantified by mass spectrometry techniques. Cytochrome P450 3A activity was calculated as partial metabolic clearance from a limited sampling area under the curve. All other drugs taken by the participating patients were considered, as well as recent blood test results and patients’ diagnoses. The trial was registered at German Clinical Trials Register (www.drks.de): DRKS00011753. Setting/participants: The trial was carried out at a university palliative care unit under real-life clinical conditions. Every patient admitted to the ward was screened for possible participation, independent of the individual performance status. Results: Partial metabolic clearance of midazolam in palliative care patients was 31.7 ± 32.1 L/h. This was a highly significant 40% reduction (p < 0.0001) in comparison with the cytochrome P450 3A activity of healthy subjects. Conclusion: Dosing of cytochrome P450 3A substrate drugs (e.g. macrolide antibiotics, benzodiazepines, calcium channel blockers) needs to be adjusted in palliative care patients; otherwise, escalation of debilitating symptoms due to drug interactions might occur.

Estimation of CYP3A4*1B single nucleotide polymorphism in patients with recurrent Major Depressive Disorder.

BackgroundMajor depression is the most common mental illness in the world. Failures in treatment may occur due to the presence of a subtype of depression called TRD (Treatment‐ Resistant Depression). CYP3A4 polymorphism (rs2740574) can increase the activity of Cytochrome P450 3A4, contributing to faster metabolism of xenobiotics and reduced response to treatment. The aim of the study was to assess the distribution of CYP3A4*1B in study and control group and to estimate the influence of particular genotypes on parameters such as: age at onset, severity of symptoms before treatment and on the effectiveness of therapy.MethodsTotal of 192 patients were enrolled in this study (102 patients suffering from recurrent Major Depression Disorder, 90 healthy blood donors). PCR Restriction Fragment Length Polymorphism method with MboII enzyme was performed. The presence of CYP3A4*1B allele was evaluated on the basis of agarose gel electrophoresis.ResultsThere was a tendency in frequency of genotypes distribution in the study group in comparison with the control group (p = 0.050). There were no statistically significant differences in the distribution mutant allele among these two groups, but there was a tendency for mutant allele to occur more often in the study group (p = 0.050). No significant correlations were found between the specific genotype and the studied parameters: age at onset (p = 0.232), severity of the symptoms (p = 0.946), and efficacy of treatment (p = 0.882).ConclusionThe study suggests that CYP3A4*1B polymorphism have no influence on the predisposition to depression, the severity of depressive symptoms and the efficiency of antidepressant therapy.

Doravirine and the Potential for CYP3A-Mediated Drug-Drug Interactions.

Identifying and understanding potential drug-drug interactions (DDIs) are vital for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. This article discusses DDIs between doravirine, a nonnucleoside reverse transcriptase inhibitor (NNRTI), and cytochrome P450 3A (CYP3A) substrates and drugs that modulate CYP3A activity. Consistent with previously published in vitro data and DDI trials with the CYP3A substrates midazolam and atorvastatin, doravirine did not have any meaningful impact on the pharmacokinetics of the CYP3A substrates ethinyl estradiol and levonorgestrel. Coadministration of doravirine with CYP3A inhibitors (ritonavir or ketoconazole) increased doravirine exposure approximately 3-fold. However, these increases were not considered clinically meaningful. Conversely, previously published trials showed that coadministered CYP3A inducers (rifampin and rifabutin) decreased doravirine exposure by 88% and 50%, respectively (K. L. Yee, S. G. Khalilieh, R. I. Sanchez, R. Liu, et al., Clin Drug Investig 37:659-667, 2017 [https://doi.org/10.1007/s40261-017-0513-4]; S. G. Khalilieh, K. L. Yee, R. I. Sanchez, R. Liu, et al., J Clin Pharmacol 58:1044-1052, 2018 [https://doi.org/10.1002/jcph.1103]), while doravirine exposure following prior efavirenz administration led to an initial reduction in doravirine exposure of 62%, but the reduction became less pronounced with time (K. L. Yee, R. I. Sanchez, P. Auger, R. Liu, et al., Antimicrob Agents Chemother 61:e01757-16, 2017 [https://doi.org/10.1128/AAC.01757-16]). Overall, the coadministration of doravirine with CYP3A inhibitors and substrates is, therefore, supported by these data together with efficacy and safety data from clinical trials, while coadministration with strong CYP3A inducers, such as rifampin, cannot be recommended. Concomitant dosing with rifabutin (a CYP3A inducer less potent than rifampin) is acceptable if doravirine dosing is adjusted from once to twice daily; however, the effect of other moderate inducers on doravirine pharmacokinetics is unknown.

Biomarker Discovery for Cytochrome P450 1A2 Activity Assessment in Rats, Based on Metabolomics.

Cytochrome P450 1A2 (CYP1A2) is one of the major CYP450 enzymes (CYPs) in the liver, and participates in the biotransformation of various xenobiotics and endogenous signaling molecules. The expression and activity of CYP1A2 show large individual differences, due to genetic and environmental factors. In order to discover non-invasive serum biomarkers associated with hepatic CYP1A2, mass spectrometry-based, untargeted metabolomics were first conducted, in order to dissect the metabolic differences in the serum and liver between control rats and β-naphthoflavone (an inducer of CYP1A2)-treated rats. Real-time reverse transcription polymerase chain reaction and pharmacokinetic analysis of phenacetin and paracetamol were performed, in order to determine the changes of mRNA levels and activity of CYP1A2 in these two groups, respectively. Branched-chain amino acids phenylalanine and tyrosine were ultimately focalized, as they were detected in both the serum and liver with the same trends. These findings were further confirmed by absolute quantification via a liquid chromatography–tandem mass spectrometry (LC-MS/MS)-based targeted metabolomics approach. Furthermore, the ratio of phenylalanine to tyrosine concentration was also found to be highly correlated with CYP1A2 activity and gene expression. This study demonstrates that metabolomics can be a potentially useful tool for biomarker discovery associated with CYPs. Our findings contribute to explaining interindividual variations in CYP1A2-mediated drug metabolism.

Anti-tumor properties of methoxylated analogues of resveratrol in malignant MCF-7 but not in non-tumorigenic MCF-10A mammary epithelial cell lines

Resveratrol is a plant-derived polyphenol that is known for its anti-inflammatory and anti-tumorigenic properties in in vitro and in vivo models. Recent studies show that some resveratrol analogues might be more potent anti-tumor agents, which may partly be attributed to their ability to activate the aryl hydrocarbon receptor (AHR). Here, the anti-tumorigenic properties of resveratrol and structural analogues oxyresveratrol, pinostilbene, pterostilbene and tetramethoxystilbene (TMS) were studied in vitro, using in the malignant human MCF-7 breast cancer cell line and non-tumorigenic breast epithelial cell line MCF-10A.Cell viability and migration assays showed that methoxylated analogues of resveratrol are more potent anti-tumorigenic compounds than resveratrol and its hydroxylated analogue oxyresveratrol, with 2,3’,4,5’-tetramethoxy-trans-stilbene (TMS) being the most potent compound. TMS decreased MCF-7 tumor cell viability with 50% at 3.6 μM and inhibited migration with 37.5 ± 14.8% at 3 μM. In addition, TMS activated the AHR more potently (EC50 in a reporter gene assay 2.0 μM) and induced AHR-mediated induction of cytochrome P450 1A1 (CYP1A1) activity (EC50 value of 0.7 μM) more than resveratrol and the other analogues tested. Cell cycle analysis showed that TMS induced a shift in cell cycle status from the G1 to the G2/M phase causing a cell cycle arrest in the MCF-7 cells, while no effect of TMS was observed in the non-tumorigenic MCF-10A mammary epithelial cell line. Gene expression analysis showed that 3 μM TMS increased gene expression of CYP1A1 (289-fold), CYP1B1 (5-fold) and Nqo1 (2-fold), and decreased gene expression of IL-8 (3-fold) in MCF-7 cells. In MCF-10A cells, 10 μM TMS also increased gene expression of CYP1A1 (5-fold) and CYP1B1 (2-fold), but decreased gene expression of Nqo1 (1.4-fold) in contrast to MCF-7 cells.TMS displays more potent anti-tumorigenic properties and activates the AHR more effectively than resveratrol. In addition, this is the first study to show that TMS, but not resveratrol, selectively inhibits the cell cycle of breast tumor cells and not the non-tumorigenic cells. Our study provides more insight in the anti-tumor properties of the methoxylated analogues of resveratrol in breast cells in vitro.

Quantitative prediction of hepatic CYP3A activity using endogenous markers in healthy subjects after administration of CYP3A inhibitors or inducers

Accurate prediction of cytochrome P450 (CYP) 3A activity in the early stage of drug development and in clinical practice is important. This study aimed to evaluate the previously constructed CYP3A activity prediction model after administration of CYP3A inhibitors and inducers and to modify the model for better prediction of CYP3A activity. Healthy male subjects received the following study drugs during three study periods: midazolam alone (control phase); midazolam with 200 mg of itraconazole (CYP3A inhibition phase); and midazolam with 150 mg of rifampicin (CYP3A induction phase). We quantified the concentrations of several endogenous CYP3A markers in both urine and plasma using gas chromatography-mass spectrometry. The urinary markers, including 6β-hydroxy (OH)-cortisol/cortisol, 6β-OH-cortisone/cortisone, 16α-OH-dehydroepiandrosterone (DHEA)/DHEA, 16α-OH-androstenedione (A-dione)/A-dione and 7β-OH-DHEA/DHEA, were significantly correlated with midazolam clearance in both the CYP3A inhibition and induction phases. We constructed a statistical prediction model after integrating data from a previous study to predict midazolam clearance as follows: Ln(midazolam clearance) = 2.5545 + 0.3988 × ln(7β-OH-DHEA/DHEA) + 0.1984 × ln(16α-OH-DHEA/DHEA) + 0.5031 × ln(6β-OH-cortisol/cortisol) – 0.1261 [ln(7β-OH-DHEA/DHEA) × ln(6β-OH-cortisol/cortisol)] (r2 = 0.75). We suggest that quantitating endogenous markers in vivo coupled with the statistical prediction model may be useful for predicting CYP3A parameters.

Decreased Cytochrome P450 3A activity in palliative patients with haematological diseases: Potential impact on supportive drug therapies

Cytochrome P450 3A (CYP3A) is the most relevant drug-metabolizing enzyme in human beings involved in the elimination of about 50% of the marketed drugs. Comprehensive in vivo data of CYP3A activity in palliative patients with haematological diseases are missing. Therefore, CYP3A activity was determined under real-life clinical conditions in patients to gain knowledge about dose adjustments for supportive therapies and symptom management in haematology. The single-arm, prospective trial obtained a 4-hours pharmacokinetic profile of midazolam after oral administration of a microdose as marker substance from each enrolled patient. Plasma concentrations of midazolam and its primary metabolite 1'-hydroxy-midazolam were quantified by mass spectrometry techniques. CYP3A activity was calculated as partial metabolic clearance from an established limited sampling area under the curve. All other drugs taken by the participating patients were considered as well as recent laboratory test results and the patients' diagnoses. Partial metabolic clearance of midazolam in patients with haematological diseases was highly variable (36.9±52.7L/h). In comparison with the CYP3A activity of healthy individuals, this was a highly significant 30% reduction of activity (P<0.0001). Dosing of major CYP3A substrate drugs needs to be reduced in palliative patients with haematological diseases, otherwise escalation of debilitating symptoms due to drug interactions might occur.

Interakcje wybranych leków kardiologicznych ze składnikami diety

The ageing society and the growing problem of fragility syndrome necessitate the long-term use of cardiac drugs, thereby increasing the risk from drug/food interactions. The aim of this study was to present the interaction between foods and those drugs used in the clinical practice of cardiologists. The effect of vitamin K antagonists is intensified by food and drink such as sage, camomile, parsley, aniseed, liquorice, ginger, ginseng, cranberry juice, and grapefruit juice, among others. However, products rich in vitamin K inhibit the therapeutic effect of coumarin derivatives. Due to the increased risk of bleeding, antiplatelet drugs should not be combined with dietary supplements containing Ginkgo biloba which inhibits platelet activating factor. The literature indicates the occurrence of a similar risk when combining antiplatelet drugs with garlic-containing supplements. Numerous scientific studies have looked at the impact of food on the absorption of antihypertensive drugs. The best known of these is grapefruit/grapefruit juice. It was recently found that grapefruit acts by interfering in the activity of cytochrome P450 3A4 (CYP3A4) enzyme. People who regularly take cardiac drugs are exposed to food/drug interactions, and should be aware of the possible complications. There is an urgent need to educate patients in the area of food/drug interactions. Therefore, a therapeutic team should be created consisting of a general practitioner, a cardiologist, a psychologist, a nurse and a dietician.

CYP1A2 contributes to alcohol-induced abnormal lipid metabolism through the PTEN/AKT/SREBP-1c pathway

Abnormal liver lipid metabolism results in a series of liver diseases and contributes to tumourigenesis. The expression and activity of Cytochrome P450 1A2 (CYP1A2) is significantly increased in alcoholic fatty liver according to our previous studies. In this study, we aimed to explore the role of CYP1A2 in lipid metabolism abnormalities induced by alcohol and to investigate the underlying mechanisms. L02 cells were treated with siRNA-CYP1A2 or fluvoxamine and then stimulated with 100 mM ethanol for 24 h. The levels of ALT and TGs in the siRNA-CYP1A2 and fluvoxamine groups were significantly lower than those in the normal control group after ethanol treatment, and the expression of SREBP-1c was decreased when CYP1A2 was inhibited, suggesting that CYP1A2 may contribute to alcohol-induced irregular lipid metabolism by regulating sterol regulatory element-binding protein-1c (SREBP-1c). The expression of phosphatase and tensin homologue deleted on chromosome ten (PTEN) was decreased in normal cells, and it was further reduced when the expression of CYP1A2 was downregulated. Overexpression of PTEN led to decreased expression of p-AKT and SREBP-1c, which were elevated in both the normal and transfected groups after ethanol stimulation. In contrast, when PTEN was inhibited by siRNA-PTEN or bpv, the expression of PTEN was reduced in each group after ethanol treatment, while the expression of p-AKT and SREBP-1c was increased significantly. These results demonstrate that CYP1A2 may participate in the abnormal lipid metabolism caused by alcohol stimulation through the PTEN/AKT/SREBP-1c pathway.

Effects of shuanghuanglian injection on the activities of CYP1A2, 2C11, 2D1 and 3A1/2 in rats in vivo and in vitro

Shuanghuanglian Injection (SHLI), one of the most popular herbal prescription in China, has been commonly used to treat pneumonia, tonsillitis, and other respiratory diseases caused by bacterium and virus. This study is to investigate the effects of SHLI on the activities of Cytochrome P450 (CYP) 1A2, 2C11, 2D1 and 3A1/2 in rats.Sixteen rats were randomly divided into two groups (SHLI-treated and blank control). They were administered SHLI or physiological saline for consecutive seven days. On day eight, 16 animals were administrated cocktail drugs as probe substrates of the four CYP in vivo. In addition, other four probe drugs were added, respectively, into incubation systems of rat liver microsomes (RLM) to assess the effects of SHLI on the four CYP isoforms in vitro.SHLI exhibited an inductive effect on CYP2C11 in vivo by decreasing Cmax, t1/2 and AUC0-∞ of tolbutamide, while the main pharmacokinetic parameters of caffeine, metoprolol and dapsone have no significant changes. In vitro study, SHLI showed no significant effects on the activities of CYP1A2, 2D1 and 3A1/2, but increasing the metabolism of tolbutamide in RLM.SHLI induced the activities of CYP2C11, but had no significant effects on the activities of CYP1A2, CYP2D1 and CYP3A1/2 in rats.

Hepatic CYP1A2 activity in liver tumors and the implications for preoperative volume-function analysis.

Dynamic liver function assessment by the [13C]methacetin maximal liver function capacity (LiMAx) test reflects the overall hepatic cytochrome P-450 (CYP) 1A2 activity. One proven strategy for preoperative risk assessment in liver surgery includes the combined assessment of the dynamic liver function by the LiMAx test, the volumetric analysis of the liver, and calculation of future liver remnant function. This so-called volume-function analysis assumes that the remaining CYP1A2 activity in any tumor lesion is zero. The here presented study aims to assess the remaining CYP1A2 activities in different hepatic tumor lesions and its consequences for the preoperative volume-function analysis in patients undergoing liver surgery. The CYP1A2 activity analysis of neoplastic lesions and adjacent nontumor liver tissue from resected tumor specimens revealed a significantly higher CYP1A2 activity (median, interquartile range) in nontumor tissues (35.5, 15.9-54.4 µU/mg) compared with hepatocellular adenomas (7.35, 1.2-32.5 µU/mg), hepatocellular carcinomas (0.18, 0.0-2.0 µU/mg), or colorectal liver metastasis (0.17, 0.0-2.1 µU/mg). In nontumor liver tissue, a gradual decline in CYP1A2 activity with exacerbating fibrosis was observed. The CYP1A2 activity differences were also reflected in CYP1A2 protein signals in the assessed hepatic tissues. Volume-function analysis showed a minimal deviation compared with the current standard calculation for hepatocellular carcinomas or colorectal liver metastasis (<1% difference), whereas a difference of 11.9% was observed for hepatocellular adenomas. These findings are important for a refined preoperative volume-function analysis and improved surgical risk assessment in hepatocellular adenoma cases with low LiMAx values. NEW & NOTEWORTHY The cytochrome P-450 (CYP) 1A2-dependent maximal liver function capacity test reflects the overall functional capacity of the liver. To which extent hepatocellular tumors harbor CYP1A2 activity and thus contribute to the maximal liver function capacity test outcome is unknown. We here show that hepatocellular adenomas but not hepatocellular carcinomas or colorectal liver metastasis contain significant residual CYP1A2 activity. These findings are important for an improved preoperative volume-function analysis and an accurate surgical risk assessment in hepatocellular adenoma cases.

Human placental extract ameliorates cytokine and cytokine receptor signaling in the rat hippocampus upon Benzo[a]Pyrene exposure

Benzo[alpha]Pyrene (B[a]P) causes toxicity via Cytochrome P450 1A1 (CYP1A1) metabolic activity in the brain. Studies have shown that neuronal IL-2 and TNF-α are associated with the hippocampus development and regulation, but their association with the CYP1A1 activity remains unidentified. Limited action of human placental extract (HPE) in the activation of tissue repair and wound healing is known, but their role in B[a]P clearance in the hippocampus is not known so far. Our study has focused on two novel concepts: (1) association of CYP1A1 activity with the inflammatory response in the brain hippocampus and (2) role of HPE in the immunomodulatory mechanisms in the hippocampus upon B[a]P exposure at cytokine receptor and nuclear level. Intrathecal administration of different concentrations of B[a]P and HPE into male wistar rat pups has been conducted. An increased CYP1A1 activity was observed in the presence of 0.25 μM B[a]P alone but in case of HPE followed by 0.25 μM B[a]P, it was equal to control. Herein we report that 5 μl of 0.1 gm HPE followed by 0.25 μM B[a]P administration enabled down-regulation of IL-2 and TNF-α levels in the hippocampus thereby modulating TNFR2 and IL2Rγc signals via NF-κB activation. Besides, localization of IL-2, TNF-α, IL2Rγc, TNFR1 and TNFR2 in the CA1, CA3 and DG regions of the hippocampus are also depicted. Altogether, these findings will project the clinical importance of HPE in the neuroinflammation suppression in the hippocampus developed due to B[a]P toxicity.