Cytochrome P450 3A4 Isoenzyme Research Articles

Effects of microplastics on key reproductive and biochemical endpoints of the freshwater microcrustacean Daphnia magna

Human activities have directly impacted the environment, causing significant ecological imbalances. From the different contaminants resulting from human activities, plastics are of major environmental concern. Due to their high use and consequent discharge, plastics tend to accumulate in aquatic environments. There, plastics can form smaller particles (microplastics, MPs), due to fragmentation and weathering, which are more prone to interact with aquatic organisms and cause deleterious effects, including at the basis of different food webs. This study assessed the effects of two microplastics (polyethylene terephthalate, PET; and polypropylene, PP; both of common domestic use) in the freshwater cladoceran species Daphnia magna. Toxic effects were assessed by measuring reproductive traits (first brood and total number of offspring), and activities of biomarkers involved in xenobiotic metabolism (phase I: cytochrome P-450 isoenzymes CYP1A1, 1A2 and 3A4; phase II/conjugation: glutathione S-transferases; and antioxidant defense (catalase)). Both MPs showed a potential to significantly reduce reproductive parameters in D. magna. Furthermore, PET caused a significant increase in some isoenzymes of CYP450 in acutely exposed organisms, but this effect was not observed in chronically exposed animals. Similarly, the activity of the antioxidant defense (CAT) was significantly increased in acutely exposed animals, but not in chronically exposed organisms. This pattern of effects suggests a possible mechanism of long-term adaptation to the presence of the tested MPs. In conclusion, the herein tested MPs have shown the potential to induce deleterious effects on D. magna mainly observed in terms of the reproductive outcomes. Changes at the biochemical level seems transient and are not likely to occur in long term, environmentally exposed crustaceans.

Effects of schisandra lignans on the absorption of protopanaxadiol-type ginsenosides mediated by P-glycoprotein and protopanaxatriol-type ginsenosides mediated by CYP3A4

Ethnopharmacological relevanceGinseng Radix et Rhizoma (GRR) and Schisandrae Chinensis Fructus (SCF) are frequently used as herb pairs in traditional herbal formulas especially for the synergetic beneficial effects on lung and heart. Shengmai-yin (SMY), a noted formula, was first published in the traditional Chinese medicine classic named Yixue Qiyuan written by Zhang Yuansu in the Jin Dynasty, and has been used for deficiency of both qi and yin, palpitation, shortness of breath and spontaneous sweating. In SMY, GRR, a sovereign herb, plays an essential role in tonifying lung and supplementing qi, and SCF as an adjuvant herb contributes to the effects of nourishing yin and promoting fluid production, both of which are traditionally used as invigorants in China, Korea, Japan, and Russia. However, the underlying compatibility mechanism of GRR-SCF has remained unknown. Aim of the studyIn order to explore the impact and underlying mechanism of schisandra chinensis extract (SCE) on the absorption of ginsenosides Rb1, Rc, Rb2 and Rd belonging to protopanaxdiol (PPD)-type and ginsenosides Rg1 and Re belonging to protopanaxtriol (PPT)-type, pharmacokinetic studies, molecular docking technique and single-pass intestinal perfusion (SPIP) experiment were conducted. Material and methodsPreliminarily, pharmacokinetic characteristics of ginseng extract (GE) in the presence and absence of SCE were studied. Thereafter, molecular docking was used to predict whether ginsenosides were P-glycoprotein (P-gp) or cytochrome P450 isoenzyme 3A4 (CYP3A4) substrates. Finally, the effects and underlying mechanism of SCE on the absorption of GE were further investigated by in situ SPIP experiment. ResultsOur findings indicated that SCE could increase exposure in vivo and the intestinal absorption of distinct ginsenosides. Additionally, we found that the PPD-type ginsenosides Rb1, Rc, Rb2, and Rd were substrates for P-gp, and the PPT-type ginsenosides Rg1 and Re were substrates for CYP3A4 rather than P-gp. SCE, which has been found with extensive inhibitory effects on P-gp and CYP3A4, could remarkably promote the intestinal absorption of ginsenosides Rg1, Re, Rb1, Rc, Rb2, and Rd, obtaining similar effects comparable with ketoconazole known as a classic dual inhibitor of P-gp and CYP3A4. ConclusionsThe study demonstrated that SCE could improve the absorption of GE, and revealed the underlying compatibility mechanism of GRR and SCF from the perspective of P-gp and CYP3A4-mediated interactions to some extent, which provided a certain scientific reference for the compatibility and clinical practice of GRR-SCF as common herb pairs in traditional prescriptions such as SMY. Moreover, this study also furnished a strategy for improving the oral bioavailability of different types of ginsenosides by drug combinations.

Pharmacokinetic Drug-Drug Interactions: A Systematic Review of the Cytochrome P450 (CYP) Isoenzyme 3A4

The cytochrome P450 (CYP) isoenzyme 3A4 or CYP3A4 is a major drug-metabolizing enzyme that has the potential to cause pharmacokinetic drug-drug interactions. Primary research studies have demonstrated CYP3A4-mediated drug-drug interactions through a variety of mechanisms. However, there has been no review during the last 10 years of pharmacokinetic drug-drug interactions mediated by CYP3A4 isoenzymes. It is necessary to systematically review the pharmacokinetic drug-drug interactions mediated by CYP3A4. Source review of articles were retrieved from the PubMed and Scopus databases. The preparation of keywords through the population, intervention, comparison, and outcomes (PICO) method written based on the Boolean operator. Reporting the results of the paper search is presented in the Prisma version 1 2020 flowchart. The risk of bias assessment used COHORT tools and Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) tools. Data was analyzed narratively. Pharmacokinetic drug interactions are mediated by CYP3A4 through the mechanism of induction, activation, inhibition, and inactivation. Induction or activation of CYP3A4 can cause an increase in CYP3A4 expression, so that the drug is metabolized more quickly and has the potential to lose drug efficacy. Inhibition and inactivation of CYP3A4 causes plasma drug levels to increase and drug elimination time to last longer. CYP3A4 plays a major role in the bioactivation of drugs that cause hepatotoxicity through the formation of reactive metabolites. The use of drugs needs to be monitored to avoid pharmacokinetic drug interactions.

Drug interactions between ALK inhibitors and warfarin with concurrent use of bucolome: a case report

BackgroundAlectinib, crizotinib, and ceritinib, are anaplastic lymphoma kinase-tyrosine kinase inhibitors (ALK-TKIs) that exhibit high protein binding, and their metabolism is associated with the cytochrome P450 (CYP) isoenzymes 2C9 or 3A4. The plasma protein binding rate of warfarin, which is used to prevent and treat venous thromboembolism, is also high. Warfarin is a racemate of S-warfarin and R-warfarin, which are metabolized by CYP2C9 and CYP3A4, respectively. Reports on the drug interactions between each of the above-mentioned ALK-TKIs and warfarin with concurrent use of bucolome are currently lacking.Case presentation.We report a case of a patient receiving warfarin and bucolome, whose international normalized ratio (INR) increased after sequential treatment with alectinib, crizotinib, and ceritinib. The patient was a 61-year-old man with a history of aortic valve regurgitation, who was receiving warfarin treatment following aortic valve replacement. Bucolome, which can enhance the effect of warfarin, was also used simultaneously. The patient was diagnosed with primary lung adenocarcinoma, and ALK rearrangement was detected during second-line chemotherapy. After progression of the disease with chemotherapy, sequential treatment with alectinib, crizotinib, and ceritinib was initiated. Pretreatment INR values were in the therapeutic range (target INR of 2–3) but increased to supratherapeutic levels each time after initiation of alectinib, crizotinib, or ceritinib treatment. Adjustment of warfarin dose or discontinuation of bucolome were necessary to maintain the therapeutic INR range. There were no serious bleeding events or substantial changes in dietary intake.Displacement of plasma protein binding or competitive inhibition of metabolism by alectinib, crizotinib, and ceritinib could increase the plasma concentration of the unbound form of warfarin, resulting in high INR values. In addition, alectinib, crizotinib, and ceritinib might cause displacement of bucolome from plasma proteins, followed by displacement of warfarin or inhibition of warfarin metabolism caused by the unbound form of bucolome.ConclusionsClose monitoring of INR and adjustment of warfarin dosage are needed during treatment with alectinib, crizotinib, or ceritinib in patients who receive warfarin with concurrent use of bucolome.

Impact of Concomitant Use of Azoles on Bortezomib-related Adverse Drug Reactions Using JADER.

Azoles are widely used for prophylaxis in patients with haematologic malignancies and are well known as selective cytochrome P450 isoenzyme 3A4 inhibitors. Although the interaction between bortezomib and azoles has been reported, most previous studies were case reports or small clinical studies. Hence, we conducted a pharmacoepidemiological study to elucidate the impact of azoles on bortezomib-related adverse reactions, using the Japanese adverse drug event report database (JADER). We extracted 19,567 reports on patients prescribed bortezomib and/or azoles. We classified cases into three groups, namely bortezomib, bortezomib and azoles, and azoles groups. We estimated the odds ratios (OR) for the impact of concomitant azole use on five bortezomib-related adverse drug reactions (peripheral neuropathy, thrombocytopenia, neutropenia, leukopenia, and interstitial lung disease) using logistic regression. The OR for peripheral neuropathy in the 'bortezomib and azoles' group was higher than that in the bortezomib group [OR=2.02, 95% confidence interval (CI)=1.32-3.08]. The magnitude of the interaction was stronger with itraconazole than that with fluconazole (itraconazole, OR=3.22, 95% CI=1.78-5.70; fluconazole, OR=1.56, 95% CI=0.86-2.72). We found an association between concomitant administration of azoles with bortezomib and peripheral neuropathy. Azoles may enhance bortezomib-induced peripheral neuropathy based on their pharmacokinetic properties.

PSAT052 Iatrogenic Cushing's Syndrome With a Remote History of Synthetic Glucocorticoid Use in the Setting of a CYP3A4 Inhibitor – Location Matters

Abstract Introduction The most common cause of Cushing's syndrome is iatrogenic due to the exogenous administration of glucocorticoids (GCs). Exogenous GCs disrupt the hypothalamic-pituitary-adrenal (HPA) axis by reducing ACTH production, thereby suppressing cortisol production by the adrenal gland. The degree of HPA axis suppression and recovery varies by the formulation, dose, duration, frequency, timing, and location of GC administration. It is also well known that the clearance of GCs is delayed by inhibitors of cytochrome P450 (CYP) 3A4 isoenzyme. Here we report a case in which a patient on cobicistat developed iatrogenic Cushing's syndrome (ICS) even with a remote history of GC use. Clinical Case A 34-year-old male with Human Immunodeficiency Virus (HIV) on cobicistat and a history of a motor vehicle accident was referred for evaluation of ICS. The patient was started on triamcinolone epidural injections after the accident and developed a ruddy face, weight gain, posterior neck fat redistribution, and purple abdominal striae. He received a total of nine injections over three months at an unknown dose with the last injection being given two years ago. His symptoms improved after stopping the regimen. He received no GCs again until four months prior to presentation when he completed a 4 mg methylprednisolone taper and the cushingoid phenotype returned. Biochemical workup was consistent with HPA axis suppression: morning cortisol <0.5 mcg/dL (4-22 mcg/dL), ACTH <5 pg/mL (6-50 pg/mL), and DHEAS 18 mcg/dL (106-464 mcg/dL). Synthetic glucocorticoid screen was positive for methylprednisolone 5.3 mcg/dL (n <0.10 mcg/dL) and triamcinolone 0.29 mcg/dL (n <0.1 mcg/dL). The patient denied any surreptitious GC use. We concluded the patient still had unmetabolized triamcinolone even after two years due to drug interactions from cobicistat, which is a CYP3A4 inhibitor. Moreover, epidural triamcinolone has the longest half-life, 523 hours, compared to oral or intraarticular injections. Clinical Lesson: GCs are primarily metabolized in the liver by CYP3A4. Very few cases have been reported with the use of cobicistat and the cushingoid phenotype typically appears within 3-6 months of the GC use. However, our patient had detectable triamcinolone and return of ICS two years after epidural injections. It is not enough to know whether a patient received GCs; it is also essential to know how it was given and the location of the injection as the half-lives vary depending on said location. This case reinforces the importance of pharmacovigilance and performing a thorough medication reconciliation, as even a remote history of steroid use in the setting of CYP3A4 inhibitors could lead to ICS. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

Development of a Fast and Highly Sensitive UPLC–MS/MS Technique for Simultaneous Estimation of Artemether and Dihydroartemisinin with its Application to Pharmacokinetic and Biodistribution Studies

Background: Artemether (ART) has been recognized as a potent and rapidly acting antimalarial agent metabolized by cytochrome P450 isoenzyme 3A4 into a more active form dihydroartemisinin (DHA). Hence, it was required to study the pharmacokinetics and biodistribution of ART and DHA for the optimization of dose. Objectives: The current research aims to develop an ultra-performance liquid chromatographytandem mass spectrometry (UPLC-MS/MS) technique with high sensitivity for quantification of ART and DHA simultaneous in the biological fluid. Methods: An isocratic elution mode was applied for delivery of mobile phase (A) ammonium acetate (2mM) in UPLC grade water and (B) acetonitrile (20:80, v/v) comprising 0.1% v/v formic acid in each solvent system with the rate of flow maintained at 400 μL/min. For analyte detection and parent to daughter ion transition tracking, multiple reaction monitoring system was adopted. Artemisinin was selected as the internal standard (IS) for its structural similarity with the analytes. Results: The linearity range of the calibration curve was between 0.5-200 ng/mL. The regression equation indicated r2 = 0.996 for ART and r2 = 0.997 for DHA. Precision and accuracy set in terms of relative error (RE%: ±15) and relative standard deviation (RSD%: ±15) expressed in percentage were within the acceptability range. The % recoveries were within the acceptable limit (90–110%). The detection and quantification limits of the analyte were 0.2 ng/mL and 0.5 ng/mL, respectively. Conclusion: The method demonstrated a useful technique for quantification of ART and DHA for evaluating the pharmacokinetics and biodistribution studies in rat plasma following orally administered nanoformulation.

Formulation Development and Characterization of Darunavir and Ritonavir Sustained Release Tablets Using Quality by Design Approach

Darunavir is a nonpeptidic inhibitor of protease and is primarily metabolized by cytochrome P450 3A (CYP3A) isoenzymes. It is usually coadministered with low-dose ritonavir (Darunavir/r). Ritonavir is an inhibitor of CYP3A isoenzymes and pharmacologically enhances Darunavir which leads to increased plasma concentrations of darunavir and allows for daily lower dose. Here, we have developed combination SR formulation of Darunavir and Ritonavir and evaluated. In vitro drug release of all formulations was carried out in dissolution medium 900ml of pH 3.0, 0.05 M Sodium Phosphate Buffer + 2% Tween 20 for 75 RPM USP II apparatus (paddle). The results shown that, all the formulations of matrix tablets shown the good release of drug from trialed formulations however all formulations were not releasing the drug in enough amount. In matrix tablets F6, the release of drug shows NLT 80%. So, the formulation F6 have been considered as suitable for the SR tablet of Darunavir and Ritonavir. Tablets were also evaluated though Quality by Design (QbD) method.

Formulation Development and Characterization of Darunavir and Ritonavir Sustained Release Tablets using Quality by Design Approach

Darunavir is a nonpeptidic inhibitor of protease and is primarily metabolized by cytochrome P450 3A (CYP3A) isoenzymes. It is usually coadministered with low-dose ritonavir (Darunavir/r). Ritonavir is an inhibitor of CYP3A isoenzymes and pharmacologically enhances Darunavir which leads to increased plasma concentrations of darunavir and allows for daily lower dose. Here, we have developed combination SR formulation of Darunavir and Ritonavir and evaluated. In vitro drug release of all formulations was carried out in dissolution medium 900ml of pH 3.0, 0.05 M Sodium Phosphate Buffer + 2% Tween 20 for 75 RPM USP II apparatus (paddle). The results shown that, all the formulations of matrix tablets shown the good release of drug from trialed formulations however all formulations were not releasing the drug in enough amount. In matrix tablets F6, the release of drug shows NLT 80%. So, the formulation F6 have been considered as suitable for the SR tablet of Darunavir and Ritonavir. Tablets were also evaluated though Quality by Design (QbD) method.

Severe secondary hyperkalemia and arrhythmia from drug interactions between calcium\u2010channel blocker and voriconazole: a case presentation

BackgroundPatients with kidney disease may have concurrent hypertension and infection. Dihydropyridine calcium-channel blockers (CCB) are the most popular class of antihypertensive drugs used in clinical settings and can be metabolized by cytochrome P450 isoenzyme 3A4 (CYP3A4). Voriconazole is a commonly used antifungal treatment and a CYP3A4-inhibitor. Insufficient attention to drug interactions from the concomitant use of CCB and voriconazole may result in serious adverse reactions.Case presentationHere, we report a patient with acute kidney injury on stable anti-neutrophil cytoplasm antibody associated vasculitis who developed hyperkalemia resulting in sinus arrest with junctional escape rhythm attributed to drug interactions of CCB with voriconazole. This is a very rarely reported case and may be an under-recognized complication. After continuous renal replacement therapy and changing the anti-hypertensive drugs, symptoms, and laboratory abnormalities of the patient fully recovered.ConclusionsThis case warns us of severe consequences of drug interactions. Co-prescription of CYP3A4-inhibitors with calcium-channel blockers increases the risk of hypotension and acute kidney injury, which may further induce hyperkalemia and arrhythmia.

Formulation Development and Characterization of Darunavir and Ritonavir Immediate Release Tablets using Quality by Design approach

Darunavir is a nonpeptidic inhibitor of protease and is primarily metabolized by cytochrome P450 3A (CYP3A) isoenzymes. It is usually Coad ministered with low-dose ritonavir (Darunavir/r). Ritonavir is an inhibitor of CYP3A isoenzymes and pharmacologically enhances Darunavir which leads to increased plasma concentrations of darunavir and allows for daily lower dose. Here, we have developed combination IR formulation of Darunavir and Ritonavir and evaluated. In vitro drug release of all formulations was carried out in dissolution medium 900ml of pH 3.0 0.05 M Sodium Phosphate Buffer + 2% Tween 20 for 75 Min USP II apparatus (paddle). The results shown that, all the formulations of matrix tablets shown the good release of drug from trialed formulations however all formulations were not releasing the drug in enough amount. In matrix tablets F8, the release of drug shows 99%. So, the formulation F8 has been considered as suitable for the immediate release of Darunavir and Ritonavir. Tablets were also evaluated for physic chemical properties, dissolution studies and though Quality by Design (QbD) method.

Commiphora myrrha (Nees) Engl. resin extracts induce phase-I cytochrome P450 2C8, 2C9, 2C19, and 3A4 isoenzyme expressions in human hepatocellular carcinoma (HepG2) cells

Commiphora myrrha (Nees) Engl. (C. myrrha) resin is the most Middle Eastern herbal medicine used against numerous diseases. After being decocted or macerated, this resin is widely consumed among Saudi Arabian patients who are already under prescribed medication. Despite its popularity, no studies have been reported on potential modulation effects of these resin extracts on drug metabolism. Therefore, we studied C. myrrha resin extracts on the expression of cytochrome P450 (CYP) drug-metabolizing isoenzyme in human hepatocellular carcinoma cell line HepG2. The C. myrrha extracts were prepared by sonication and boiling, resembling the most popular traditional preparations of maceration and decoction, respectively. Both boiled and sonicated aqueous extracts were fingerprinted using high-performance liquid chromatography equipped with ultra-violet detector (HPLC-UVD). The viability of HepG2 cells treated with these aqueous extracts was determined using CellTiter-Glo® assay in order to select the efficient and non-toxic resin extract concentrations for phase-I metabolic CYP isoenzyme expression analysis. The isoenzyme gene and protein expression levels of CYP 2C8, 2C9, 2C19, and 3A4 were assessed using reverse transcription-quantitative polymerase chain reaction and Western blot technologies. The HPLC-UVD fingerprinting revealed different chromatograms for C. myrrha boiled and sonicated aqueous extracts. Both aqueous extracts were toxic to HepG2 cells when tested at concentrations exceeding 150 µg/ml of the dry crude extract. The CYP 2C8, 2C9, and 2C19 mRNA expression levels increased up to 4.0-fold in HepG2 cells treated with either boiled or sonicated C. myrrha aqueous extracts tested between 1 and 30 µg/ml, as compared with the untreated cells. However, CYP3A4 mRNA expression level exceeded the 2.0-fold cutoff when the cells were exposed to 30 µg/ml of C. myrrha extracts. The up-regulation of CYP mRNA expression levels induced by both boiled and sonicated C. myrrha aqueous extracts was confirmed at the CYP protein expression levels. In conclusion, both sonicated and boiled C. myrrha aqueous extracts modulate CYP 2C8, 2C9, 2C19, and 3A4 gene expression at clinically-relevant concentrations regardless of preparation methods. Further in vitro and in vivo experiments are required for CYP isoenzyme activity assessment and the establishment of herb-drug interaction profile for these traditional medicinal resin extracts.

Interaction of Isatin with Cytochrome P450 Isoenzymes: Investigation by Means of Spectral and Electrochemical Methods The role of Isatin in Cytochromes P450 Ligand-Protein Binding Events

In the present study, the effects of endogenous non-peptide bioregulator isatin (indole-2,3-dione) cytochrome P450 isoenzymes 3A5, 3A4, 2C19, 2E1, and 5A1 were investigated for the first time by means of electrochemical methods. Absorption spectroscopy and electrochemical methods have shown that isatin does not interact with heme as the active center of cytochrome P450 isoenzymes. Isatin has no significant effect on the electrocatalysis of cytochrome P450 3A4 (CYP3A4) in the presence of testosterone chosen as the substrate. Direct electrochemistry of thromboxane synthase (CYP5A1 or TBXAS1) has been investigated using protein film voltammetry. Reversible electrochemical signals of CYP5A1 were observed with midpoint potential of − 0.294 ± 0.012 V (vs Ag/AgCl). The results obtained indicate the existence of the binding sites for isatin on the protein surface of the investigated cytochromes P450, which differ from the active substrate-binding center. For CYP3A4 Arg375, Arg105, and Arg440; for CYP3A5 Arg375 and Arg105; and for CYP2C19 Arg433 were revealed as conserved “hot” amino acid residues involved in the binding of isatin while aligning CYP’s sequences.

Administration of Vitamin D Metabolites Affects RNA Expression of Xenobiotic Metabolising Enzymes and Function of ABC Transporters in Rats

From studies on different species and in cell culture systems, it has been suggested that vitamin D metabolites might affect the metabolism and elimination of xenobiotics. Although most studies performed on rodents and cell cultures report an upregulation of respective enzymes and transporters, data from the literature are inconsistent. Especially results obtained with sheep differ from these observations. As vitamin D metabolites are widely used as feed additives or therapeutics in livestock animals, we aimed to assess whether these differences indicate species-specific responses or occurred due to the very high dosages used in the rodent studies. Therefore, we applied treatment protocols to rats that had been used previously in sheep or cattle. Forty-eight female rats were divided into three treatment and corresponding placebo groups: (1) a single intraperitoneal injection of 1,25-(OH)2D3 or placebo 12 h before sacrifice; (2) daily supplementation with 25-OHD3 by oral gavage or placebo for 10 days; and (3) a single intramuscular injection of vitamin D3 10 days before sacrifice. In contrast to a previous study using sheep, treatment of rats with 1,25-dihydroxyvitamin D3 did not result in an upregulation of cytochrome P450 3A isoenzymes (CYP3A), but a decrease was found in hepatic and intestinal expressions. In addition, a downregulation of P-glycoprotein (P-gp) and breast cancer resistance protein was found in the brain. Taken together, the stimulating effects of vitamin D metabolites on the expression of genes involved in the metabolism and elimination of xenobiotics reported previously for rodents and sheep could not be reproduced. In contrast, we even observed a negative impact on the expression of CYP3A enzymes and their most important regulator, the pregnane X receptor. Most interestingly, we could demonstrate an effect of treatment with 25-hydroxyvitamin D3 and vitamin D3 on the functional activity of ileal P-glycoprotein (P-gp) using the Ussing chamber technique.

Metabolic Disposition of [Women 14 C] Ulipristal Acetate in Healthy Premenopausal

Introduction: Ulipristal acetate (UPA) is a novel selective progesterone receptor modulator for the treatment of benign gynaecological conditions such as uterine myoma. The disposition of [ 14 C] UPA was determined in five healthy premenopausal women after administration of a single oral dose of 20 mg (59 μCi). Materials and Methods: The single dose study allocated 5 healthy women of reproductive age to receive a single radio labelled dose of 20 mg (59 μCi) UPA. After dosing, blood, plasma, urine and faecal samples were collected for up to 11 days and analysed for concentrations of radioactivity. UPA metabolite profiles in plasma were determined by high-performance liquid chromatography with radioactivity flow detection; metabolite structures were confirmed by liquid chromatography-mass spectrometry. Results: UPA was rapidly absorbed, exhibiting a mean peak plasma concentration of 141 ng/mL at 0.7 hours post-dose. Plasma radioactivity maxima were observed 0.9 hours post-dose at 281ng equivalents/mL. The total mean recovery of the radioactive dose in excreta was 78.8%, with the majority recovered in faeces (72.5%) and only a small fraction (6.4%) in urine. UPA was extensively metabolised. Radio-chromatograms of plasma revealed that oxidative demethylation was the major metabolic pathway, most likely via cytochrome P450 isoenzyme3A4. At peak plasma radioactivity, the majority of circulating radioactivity was constituted by parent (58.0%), N-monodemethylated UPA (PGL4002 (20.5%)) and N-didemethylated UPA (PGL4004) eluting together with PGL4002+2H (8.3%). Unchanged UPA was not present in faeces, but PGL4002, hydroxylated PGL4004 and UPA +2H, UPA +2O -2H, as well as acetylated or glucuronidated UPA were identified. Conclusion: After oral administration in healthy premenopausal women, UPA was rapidly absorbed, extensively metabolized via oxidative demethylation, and excreted predominantly in faeces.

Statins significantly reduce mortality in patients receiving clopidogrel without affecting platelet activation and aggregation: a systematic review and meta-analysis

BackgroundCombination of statins and clopidogrel is frequently administered in patients with coronary artery disease (CAD). They are mainly activated and eliminated in the liver by cytochrome P450 isoenzyme 3A4 (CYP3A4). The aim was to clarify whether the coadministration of clopidogrel and statins attenuate respective efficacy.MethodsPubMed, Embase, the Cochrane Library, Web of Science and Clinical Trials. gov were searched for until August 2018. Randomized controlled trials (RCTs) and cohort studies were taken into quality evaluation. Data were pooled using random effect models to estimate standard mean difference (SMD) or risk ratio (RR) with 95% confidence interval (CI).ResultsIn total, 28 studies representing 25,267 participants were included. Statins reduce the mortality of patients administered clopidogrel (RR 0.54; 95% CI 0.40,0.74; p = 0.000), no differences were found in platelet aggregation (PA) (SMD 0.02; 95% CI -0.38,0.42; p = 0.920) and the expressions of P-selectin (SMD -0.04; 95% CI -0.14,0.05; p = 0.346), CD40L (SMD 0.09; 95% CI -0.29,0.48; p = 0.633), CD63 (SMD 0.09; 95% CI -0.01,0.19; p = 0.079) and PAC-1 (SMD 0.03; 95% CI -0.08,0.13; p = 0.633). Furthermore, CYP3A4 metabolized or non-CYP3A4 metabolized statins have no discrepancies in PA (SMD 0.13; 95% CI -0.31,0.58; p = 0.556), P-selectin (SMD 0.17; 95% CI -0.16,0.51; p = 0310), death (RR 0.89; 95% CI 0.38,2.07; p = 0.791), except for triglyceride (TG) (SMD -0.19; 95% CI –0.33,-0.06; p = 0.005).ConclusionsThis meta-analysis confirmed that statins reduce mortality in patients undergoing clopidogrel treatment without affecting platelet activation and aggregation.

Effect of Rifampin on the Pharmacokinetics of Ertugliflozin in Healthy Subjects

PurposeErtugliflozin is a selective sodium glucose cotransporter 2 inhibitor being developed for the treatment of type 2 diabetes mellitus. The primary enzyme involved in the metabolism of ertugliflozin is uridine diphosphate-glucuronosyltransferase (UGT) 1A9, with minor contributions from UGT2B7 and cytochrome P450 (CYP) isoenzymes 3A4, 3A5, and 2C8. Rifampin induces UGT1A9, UGT2B7, CYP3A4, and CYP3A5. Because concurrent induction of these enzymes could affect ertugliflozin exposure, this study assessed the effect of multiple doses of rifampin on the pharmacokinetic properties of single-dose ertugliflozin. MethodsTwelve healthy adult subjects were enrolled in this open-label, 2-period, fixed-sequence study and received ertugliflozin 15 mg on day 1 of period 1, followed by rifampin 600 mg once daily on days 1 to 10 in period 2. On day 8 of period 2, ertugliflozin 15 mg was coadministered with rifampin 600 mg. Plasma samples for ertugliflozin pharmacokinetic analysis were collected during 72 hours after dosing on day 1 of period 1 and day 8 of period 2 and analyzed using a validated HPLC-MS/MS method. Pharmacokinetic parameters were calculated using noncompartmental analysis of concentration-time data. Natural log transformed AUC0–∞ and Cmax of ertugliflozin were analyzed using a mixed-effects model with treatment as a fixed effect and subject as a random effect. FindingsAfter administration of ertugliflozin 15 mg alone or with rifampin, the Tmax was 1 hour. The mean t½ was 12.3 hours for ertugliflozin alone and 9.2 hours with steady-state rifampin. Geometric mean ratios for AUC0–∞ and Cmax were 61.2% (90% CI, 57.2%–65.4%) and 84.6% (90% CI, 74.2%–96.5%), respectively. Ertugliflozin was well tolerated when administered alone or with rifampin. ImplicationsCoadministration of ertugliflozin with rifampin decreased ertugliflozin AUC0–∞ and Cmax by 39% and 15%, respectively. The effect of the reduced exposure was evaluated using the ertugliflozin dose-response model. The model predicted that a 5-mg ertugliflozin dose after coadministration with rifampin is expected to maintain clinically meaningful glycemic efficacy. Therefore, no dose adjustment of ertugliflozin is recommended when ertugliflozin is coadministered with a UGT and CYP inducer, such as rifampin.

Concomitant use of statins and macrolide antibiotics and risk of serious renal events: A nationwide cohort study

BackgroundConcomitant use of statins metabolized by the cytochrome P450 isoenzyme 3A4 (CYP3A4) and CYP3A4-inhibiting macrolide antibiotics may confer an increased risk of renal failure. We investigated the risk of serious renal events associated with concomitant use of such statins and such macrolides. MethodsIn a nationwide register-based cohort study (Denmark, 1999–2017), we identified 906,423 new users (40–79 years old), of CYP3A4-metabolized statins. In propensity score-matched analyses, we compared the risk of serious renal events during episodes of concomitant use of statins and CYP3A4-inhibiting macrolides (n = 71,521) with episodes of use of statins alone (n = 285,488) and, as the primary analysis, with episodes of concomitant use of statins and an active comparator (penicillin V, n = 139,446). Using proportional hazards regression, we estimated hazard ratios (HRs) for serious renal events within 30 days of start of follow-up. ResultsWe observed 25 serious renal events during concomitant use of statins and macrolides (incidence rate [IR], 4.9 per 1000 person-years). Compared with use of statins alone (50 events; IR, 2.3), concomitant use of statins and macrolides was associated with a significantly increased risk of serious renal events (HR 2.16, 95% confidence interval [CI] 1.33, 3.49). Compared with concomitant use of statins and penicillin V (52 events; IR, 5.3), however, we observed no increased risk (HR 0.93, 95% CI 0.58, 1.49). ConclusionsIn this nationwide cohort study concomitant use of statins and macrolides was not associated with a significantly increased risk of serious renal events.

Pharmacokinetic interaction between bedaquiline and clofazimine in patients with drug-resistant tuberculosis.

Bedaquiline (BDQ) and clofazimine (CFZ) are both recommended for treating drug-resistant tuberculosis (DR-TB). As CFZ is an inhibitor of the cytochrome P450 isoenzyme 3A4 (CYP3A4) in vitro, and BDQ a substrate of CYP3A4, there is a potential for pharmacokinetic (PK) drug-drug interaction that may result in increased BDQ exposure when co-administered with CFZ, which could increase the toxicity of BDQ. We assessed the effect of co-administered CFZ on BDQ bioavailability, or on clearance of BDQ and its N-monodesmethyl metabolite (M2), in patients with DR-TB using a population PK model developed from data of patients with DR-TB. This was a secondary analysis of a study designed to explore drug-drug interactions between BDQ and antiretrovirals. Of 46 participants, 30 were on concomitant CFZ when intensive PK sampling of BDQ was done. CFZ did not have a statistically significant effect on BDQ bioavailability (-9.1%, 90%CI -22.8 to +7.1; P = 0.19) or on BDQ and M2 clearance (+12.2%, 90%CI -13.7 to +38; P = 0.32). We did not find a statistically significant PK drug-drug interaction between BDQ and CFZ, but cannot exclude a potentially clinically relevant interaction due to the wide confidence intervals of the estimated interaction effects.

Impact of enzalutamide and its main metabolite N‐desmethyl enzalutamide on pharmacokinetically important drug metabolizing enzymes and drug transporters

Enzalutamide is a new drug against castration-resistant prostate cancer. Recent data indicate profound induction of drug metabolizing enzymes (e.g. cytochrome P450 isoenzyme (CYP) 3A4) but comprehensive in vitro data on other CYP enzymes, drug conjugating enzymes or drug transporters is scarce. Moreover, the mechanisms of induction are poorly investigated and the effects of the active metabolite N-desmethyl enzalutamide are unknown. Using LS180 cells as an induction model and quantitative real-time reverse transcription polymerase chain reaction, our study demonstrated a concentration-dependent induction of CYP1A1, CYP1A2, CYP3A5, CYP3A4, UGT1A3, UGT1A9, ABCB1, ABCC2 and ABCG2 mRNA. Induction of CYP3A4 and ABCB1 was confirmed by Western blot analysis and is likely mediated by activation of the nuclear receptor pregnane x receptor, elucidated by a luciferase-based reporter gene assay. Enzalutamide's main active metabolite N-desmethyl enzalutamide exhibited only weak induction properties. mRNA expression of UGT2B7 was suppressed by enzalutamide and its metabolite. Both compounds are apparently not transported by P-glycoprotein (P-gp) or breast cancer resistance protein (BCRP). N-desmethyl enzalutamide more potently inhibited important drug transporters (P-gp, BCRP, OATPs) than enzalutamide. Taken together, the pharmacokinetics of concurrently administered drugs is likely altered during enzalutamide therapy. Levels of metabolically (mainly CYP3A4) eliminated drugs are expected to be decreased, whereas the abundance of compounds with solely transporter-determined pharmacokinetics (P-gp, OATPs) is likely enhanced.