Functional and Structural Insights into Human PPARα/δ/γ Subtype Selectivity of Bezafibrate, Fenofibric Acid, and Pemafibrate.

Among the agonists against three peroxisome proliferator-activated receptor (PPAR) subtypes, those against PPARα (fibrates) and PPARγ (glitazones) are currently used to treat dyslipidemia and type 2 diabetes, respectively, whereas PPARδ agonists are expected to be the next-generation metabolic disease drug. In addition, some dual/pan PPAR agonists are currently being investigated via clinical trials as one of the first curative drugs against nonalcoholic fatty liver disease (NAFLD). Because PPARα/δ/γ share considerable amino acid identity and three-dimensional structures, especially in ligand-binding domains (LBDs), clinically approved fibrates, such as bezafibrate, fenofibric acid, and pemafibrate, could also act on PPARδ/γ when used as anti-NAFLD drugs. Therefore, this study examined their PPARα/δ/γ selectivity using three independent assays-a dual luciferase-based GAL4 transactivation assay for COS-7 cells, time-resolved fluorescence resonance energy transfer-based coactivator recruitment assay, and circular dichroism spectroscopy-based thermostability assay. Although the efficacy and efficiency highly varied between agonists, assay types, and PPAR subtypes, the three fibrates, except fenofibric acid that did not affect PPARδ-mediated transactivation and coactivator recruitment, activated all PPAR subtypes in those assays. Furthermore, we aimed to obtain cocrystal structures of PPARδ/γ-LBD and the three fibrates via X-ray diffraction and versatile crystallization methods, which we recently used to obtain 34 structures of PPARα-LBD cocrystallized with 17 ligands, including the fibrates. We herein reveal five novel high-resolution structures of PPARδ/γ-bezafibrate, PPARγ-fenofibric acid, and PPARδ/γ-pemafibrate, thereby providing the molecular basis for their application beyond dyslipidemia treatment.

Comparative Bioavailability Study of Solid Self-Nanoemulsifying Drug Delivery System of Fenofibric Acid in Healthy Male Subjects.

OBJECTIVE: This study aimed to evaluate the effect of solid self-nanoemulsifying drug delivery system (S-SNEDDS) formation on the bioavailability of fenofibric acid. SUBJECT AND METHODS: Three formulations of fenofibric acid, namely, S-SNEDDS containing medium-chain triglyceride (FS1), S-SNEDDS containing long-chain triglyceride (FS2), and FSt as tablet of innovator product, were used in this study. Bioavailability study was conducted in 12 Indonesian healthy male subjects after a single-dose administration of each formulation with three-way crossover design. Blood samples were collected from 0 to 72 h after drug administration and then analyzed using the high-performance liquid chromatography method. Data were statistically analyzed using the ANOVA and the Wilcoxon signed-rank test using a p value of 0.05. Dissolution test was carried out with USP dissolution apparatus using three medium (pH 1.2, 4.5 and 6.8). RESULTS: The rates of absorption of fenofibric acid from S-SNEDDS FS1 and FS2 were significantly increased about 1.78 and 2.40 times, respectively, relative to FSt. Tmax values of FS1 and FS2 were shorter than FSt, namely, 0.96 ± 0.438 h (FS1), 0.71 ± 0.445 h (FS2), and 1.71 ± 0.840 h (FSt), respectively. Meanwhile, the Cmax and AUC values of FS1, FS2, and FSt were found to be not significantly different with a p value of >0.05. S-SNEDDS formation increased the dissolution rate in acid medium. CONCLUSIONS: S-SNEDDS increased the dissolution rate in acid medium and absorption rate of fenofibric acid but did not increase the extent of fenofibric acid absorption.

Visualizing the Journey of Fenofibrate through the Rat Gastrointestinal Tract by Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging.

Mapping the spatial distribution of a drug throughout the gastrointestinal tract (GIT) after oral ingestion can provide novel insights into the interaction between the drug, the oral drug delivery system, and the GIT. Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) is a molecular imaging technique that can analyze molecules in the cryosections of tissues, determining their localization with a spatial resolution of 10-100 µm. The overall aim of this study was to use MALDI-MSI to visualize the distribution and spatial location of a model prodrug (fenofibrate) through the rat GIT. Furthermore, the distribution and spatial colocalization of taurocholate and phospholipids in the rat GIT in relation to fenofibrate were investigated. Rats were given a fenofibrate suspension of 10 mg/mL by oral gavage. Blood samples were drawn, and the rats were euthanized at three different time points. The GIT was collected and frozen, and MALDI-MSI was applied on cross sections of the stomach and intestine. Fenofibrate was detected by MALDI-MSI throughout the GIT, which also revealed that fenofibrate was hydrolyzed to the active drug fenofibric acid already in the stomach. Furthermore, the presence of lyso-phosphatidylcholine (lyso-PC) and taurocholate was confirmed in the lumen of the small intestine. MALDI-MSI was shown to be a useful qualitative tool for localizing parent prodrugs and active drugs, with a possibility for gaining insight into not only the location for activation but also the role of endogenous molecules in the process.

Fenofibrate-Loaded Biodegradable Nanoparticles for the Treatment of Experimental Diabetic Retinopathy and Neovascular Age-Related Macular Degeneration.

Fenofibrate is a peroxisome proliferator-activated receptor α (PPARα) agonist and has been shown to have therapeutic effects on diabetic retinopathy (DR). However, the effects of fenofibrate through systemic administration are not as potent as desired due to inefficient drug delivery to the retina. The present study aimed to explore the sustained therapeutic effects of fenofibrate-loaded biodegradable nanoparticles (NP) on both DR and neovascular age-related macular degeneration (AMD). Fenofibrate was successfully encapsulated into poly(lactic- co-glycolic acid) (PLGA) NP (Feno-NP), and Feno-NP were optimized by varying polymer composition to achieve high drug loading and prolonged drug release. The Feno-NP made of PLGA 34 kDa demonstrated a drug content of 6% w/w and a sustained drug release up to 60 days in vitro. Feno-NP (PLGA 34 kDa) was selected for following in vivo studies, and one single intravitreal (IVT) injection of Feno-NP into rat eyes with a 30G fine needle maintained sustained fenofibric acid drug level in the eye for more than 60 days. The efficacy of Feno-NP in DR and neovascular AMD was investigated using streptozotocin (STZ)-induced diabetic rats, laser-induced choroidal neovascularization (CNV) rats, and very low-density lipoprotein receptor knockout ( Vldlr -/-) mice. Therapeutic effects of Feno-NP were evaluated by measuring electroretinogram (ERG), retinal vascular leakage, leukostasis, CNV size, and retinal levels of vascular endothelial growth factor (VEGF) and intracellular adhesion molecule-1 (ICAM-1). In diabetic rats, Feno-NP ameliorated retinal dysfunctions, reduced retinal vascular leakage, inhibited retinal leukostasis, and downregulated the overexpression of VEGF and ICAM-1 at 8 weeks after one IVT injection. In addition, Feno-NP reduced retinal vascular leakage and CNV formation in both CNV rats and Vldlr -/- mice. Moreover, no toxicity of Feno-NP or Blank-NP to retinal structure and function was detected. Feno-NP exhibited good physiochemical characteristics and controlled drug release profile, conferring prolonged beneficial effects on DR and neovascular AMD.

The effect of fenofibric acid on the pharmacokinetics and pharmacodynamics of warfarin in rats.

1. Case reports have shown that coadministration of fenofibric acid (FA) could increase bleeding risks of warfarin, but the mechanisms remained unknown. We therefore investigated the pharmacokinetic and pharmacodynamic interaction between warfarin and FA in rats. 2. Rats received warfarin alone (2 mg/kg) or coadministered with FA (100 mg/kg). FA significantly increased the exposure to warfarin, and decreased that to 7-hydroxywarfarin in rats nearly by two-fold, meanwhile increased Cmax and prolonged t1/2 of warfarin. Anticoagulant activity significantly increased, with prothrombin time (PT) up to 199 ± 33 s in coadministered group (approximately ten-fold compared with rats received warfarin alone). Incubation experiments illustrated FA inhibited CYP2C6 and CYP3A1/2 with the IC50 values of 6.98 and 16.14 µM, and inhibited the metabolism of warfarin (Ki value of 2.21 µM). Meanwhile, FA decreased the plasma protein binding of warfarin in vitro. 3. Our data suggested that the altered pharmacokinetics and pharmacodynamics of warfarin in rats was primarily attributed to the inhibition of metabolism. Anticoagulant activity monitoring or warfarin dose lowering needs to be considered when patients are coadministered with FA.

Anti-inflammatory activity of anti-hyperlipidemic drug, fenofibrate, and its phase-I metabolite fenofibric acid: in silico, in vitro, and in vivo studies.

Fenofibrate, an anti-hyperlipidemic drug and its phase-I biotransformed metabolite fenofibric acid, was studied for COX-1 (PDB ID: 3N8Y) and COX-2 (PDB ID: 1PXX) inhibition potentials in silico and in vitro for their effects on human recombinant COX-2 enzyme isolated from a Baculovirus expression system in sf21 cells (EC 1.14.99.1) using a conventional spectrophotometric assay. Furthermore, the compounds were also screened for their anti-inflammatory potentials in vivo using carrageenan-induced paw oedema method in Wistar rats. The test compounds fenofibric acid, fenofibrate, and the standard drug diclofenac exhibited binding energies of - 9.0, - 7.2, and - 8.0 kcal mol-1, respectively, against COX-2 and - 7.2, - 7.0, and - 6.5 kcal mol-1, respectively, against COX-1. In in vitro studies, both the test compounds inhibited COX-2 enzyme activity. Fenofibric acid showed an IC50 value of 48 nM followed by fenofibrate (82 nM), while diclofenac showed an IC50 value of 58 nM. Furthermore, under in vivo conditions in carrageenan-induced paw oedema rodent model, fenofibric acid exhibited relatively potent anti-inflammatory activity compared with fenofibrate. Hence, we conclude that fenofibric acid and fenofibrate are not only anti-hyperlipidemic but also shows potent anti-inflammatory activity, which may have an additional impact in the treatment of diabetic complications, viz., hyperlipidemia and inflammation leading to atherosclerosis.

C/EBP-ß Is Differentially Affected by PPARα Agonists Fenofibric Acid and GW7647, But Does Not Change Apolipoprotein A-I Production During ER-Stress and Inflammation.

Increasing apolipoproteinA-I (apoA-I) production may be anti-atherogenic. Thus, there is a need to identify regulatory factors involved. Transcription of apoA-I involves peroxisome-proliferator-activated-receptor-alpha (PPARα) activation, but endoplasmic reticulum (ER) -stress and inflammation also influence apoA-I production. To unravel why PPARα agonist GW7647 increased apoA-I production compared to PPARα agonist fenofibric acid (FeAc) in human hepatocellular carcinoma (HepG2) and colorectal adenocarcinoma (CaCo-2) cells, gene expression profiles were compared. Microarray analyses suggested CCAAT/enhancer-binding-protein-beta (C/EBP-ß) involvement in the FeAc condition. Therefore, C/EBP-ß silencing and isoform-specific overexpression experiments were performed under ER-stressed, inflammatory and non-inflammatory conditions. mRNA expression of C/EBP-ß, ATF3, NF-IL3 and GDF15 were upregulated by FeAc compared to GW7647 in both cell lines, while DDIT3 and DDIT4 mRNA were only upregulated in HepG2 cells. This ER-stress related signature was associated with decreased apoA-I secretion. After ER-stress induction by thapsigargin or FeAc addition, intracellular apoA-I concentrations decreased, while ER-stress marker expression (CHOP, XBP1s, C/EBP-ß) increased. Cytokine addition increased intracellular C/EBP-ß levels and lowered apoA-I concentrations. Although a C/EBP binding place is present in the apoA-I promoter, C/EBP-ß silencing or isoform-specific overexpression did not affect apoA-I production in inflammatory, non-inflammatory and ER-stressed conditions. Therefore, C/EBP-ß is not a target to influence hepatic apoA-I production. J. Cell. Biochem. 118: 754-763, 2017. © 2016 Wiley Periodicals, Inc.

Absolute oral bioavailability of fenofibric acid and choline fenofibrate in rats determined by ultra-performance liquid chromatography tandem mass spectrometry.

Choline fenofibrate is the choline salt of fenofibric acid, which releases free fenofibric acid in the gastrointestinal tract. To estimate the absolute oral bioavailability of fenofibric acid and choline fenofibrate, a novel and sensitive UPLC-MS/MS method with liquid-liquid extraction procedure was developed for the determination of fenofibric acid in rat plasma. The separation was achieved on a Phenomenex Kinetex C18 column (50 × 2.1 mm, 2.6 µm) containing 2 mm ammonium acetate-methanol with a gradient elution program. Validations of this method including specificity, sensitivity (limit of quantification, 5 ng/mL), linearity (0.005-10 µg/mL), accuracy (within ±4.3%), precision (intra- and inter-day coefficient of variation <11.3%), recovery (94.9-105.2% for fenofibric acid), matrix effect, stability and dilution, were all within acceptable limits. This method successfully supported the determination of fenofibric acid and choline fenofibrate. The absolute oral bioavailability was 93.4% for choline fenofibrate and 40.0% for fenofibric acid. These results suggested that choline fenofibrate and fenofibric acid had a better in vivo pharmacokinetic behavior than that of fenofibrate. The two new orally administrated pharmaceuticals, fenofibric acid and choline fenofibrate, can be developed as alternatives to fenofibrate.

Mechanistic Studies on the Photoallergy Mediated by Fenofibric Acid: Photoreactivity with Serum Albumins.

The photoreactivity of fenofibric acid (FA) in the presence of human and bovine serum albumins (HSA and BSA, respectively) has been investigated by steady-state irradiation, fluorescence, and laser flash photolysis (LFP). Spectroscopic measurements allowed for the determination of a 1:1 stoichiometry for the FA/SA complexes and pointed to a moderate binding of FA to the proteins; by contrast, the FA photoproducts were complexed more efficiently with SAs. Covalent photobinding to the protein, which is directly related to the photoallergic properties of the drug, was detected after long irradiation times and was found to be significantly higher in the case of BSA. Intermolecular FA-amino acid and FA-albumin irradiations resulted in the formation of photoproducts arising from coupling between both moieties, as indicated by mass spectrometric analysis. Mechanistic studies using model drug-amino acid linked systems indicated that the key photochemical step involved in photoallergy is formal hydrogen atom transfer from an amino acid residue to the excited benzophenone chromophore of FA or (more likely) its photoproducts. This results in the formation of caged radical pairs followed by C-C coupling to give covalent photoaducts.

Comparisons of pharmacokinetics and NO-releasing of nitrofibriate and fenofibrate after oral administration in rats.

Nitrofibriate, a new compound of hypolipidemic, is modified based on fenofibrate. Both of them are used for prevention and treatment of cardiovascular diseases. In this study, an accurate and sensitive analytical method of reversed-phase high-performance liquid chromatography was developed to determine fenofibric acid, which is an active metabolite of both nitrofibriate and fenofibrate in rat plasma. This method was validated and successfully applied to pharmacokinetic study of nitrofibriate and fenofibrate after oral administration. The results suggested that the pharmacokinetic behavior of nitrofibriate followed a nonlinear process, while fenofibrate was linear, demonstrating that the two drugs were different in pharmacokinetic behaviors. Moreover, the effect of fenofibrate and nitrofibriate on releasing NO in rat serum was explored. This study showed that nitrofibriate, as a nitric oxide donor, could slowly release nitric oxide in vivo. This study provided a biopharmaceutical basis for further study of nitrofibriate.

Zerumbone, a Bioactive Sesquiterpene, Ameliorates Diabetes-Induced Retinal Microvascular Damage through Inhibition of Phospho-p38 Mitogen-Activated Protein Kinase and Nuclear Factor-κB Pathways.

Zerumbone ameliorates retinal damage by blocking advanced glycation end products and their receptor system in streptozotocin-diabetic rats. Because of the multiple factors involved in diabetic retinopathy (DR) etiology, the mechanisms of zerumbone that are mainly responsible for its ameliorative effect on DR need to be further clarified. In the present study, zerumbone (20 mg or 40 mg/kg) or fenofibric acid (100 mg/kg) was orally administered to diabetic rats by intragastric gavage once daily for three consecutive months. Zerumbone displayed similar characteristics to fenofibric acid in reducing retinal vascular permeability and leukostasis in diabetic rats. Fundus photographs showed that large retinal vessel diameters were decreased in zerumbone-treated diabetic rats. Zerumbone not only down-regulated the gene expression of retinal angiogenic parameters, but also reduced the expression of inflammatory cytokines and chemokines in the retina of diabetic rats. Moreover, zerumbone reduced the p38 MAPK phosphorylation and abrogated the nuclear translocation of NF-κB p65 in the retina of diabetic rats. In conclusion, treatment of diabetic rats with zerumbone attenuates the severity of retinal inflammation and angiogenesis, via inhibition of p38 MAPK and NF-κB signaling pathways. These benefits of zerumbone for DR appear to be linked to its antihyperglycemic and antihyperlipidemic effects.

Endoplasmic reticulum stress involved in high-fat diet and palmitic acid-induced vascular damages and fenofibrate intervention.

Fenofibrate (FF) is widely used to lower blood lipids in clinical practice, but whether its protective effect on endothelium-dependent vasodilatation (EDV) in thoracic aorta is related with endoplasmic reticulum (ER) stress remains unknown. In this study, female Sprauge Dawley rats were divided into standard chow diets (SCD), high-fat diets (HFD) and HFD plus FF treatment group (HFD + FF) randomly. The rats of latter two groups were given HFD feeding for 5 months, then HFD + FF rats were treated with FF (30 mg/kg, once daily) via gavage for another 2 months. The pathological and tensional changes, protein expression of eNOS, and ER stress related genes in thoracic aorta were measured. Then impacts of palmitic acid (PA) and FF on EDV of thoracic aorta from normal female SD rats were observed. Ultimately the expression of ER stress related genes were assessed in primary mouse aortic endothelial cells (MAEC) treated by fenofibric acid (FA) and PA. We found that FF treatment improved serum lipid levels and pathological changes in thoracic aorta, accompanied with decreased ER stress and increased phosphorylation of eNOS. FF pretreatment also improved EDV impaired by different concentrations of PA treatment. The dose- and time-dependent inhibition of cell proliferation by PA were inverted by FA pretreatment. Phosphorylation of eNOS and expression of ER stress related genes were all inverted by FA pretreatment in PA-treated MAEC. Our findings show that fenofibrate recovers damaged EDV by chronic HFD feeding and acute stimulation of PA, this effect is related with decreased ER stress and increased phosphorylation of eNOS.

Beneficial effects of fenofibric acid on overexpression of extracellular matrix components, COX-2, and impairment of endothelial permeability associated with diabetic retinopathy.

In the Fenofibric Acid (FA) Intervention and Event Lowering in Diabetes (FIELD) study, FA, a lipid-lowering drug, has been shown to significantly reduce macular edema in diabetic patients. In the present study, we investigated whether FA reduces vascular permeability by inhibiting cyclooxygenase-2 (COX-2), a critical mediator of inflammation, and reducing overexpression of fibronectin (FN) and collagen IV (Coll IV), two basement membrane (BM) components upregulated in diabetic retinopathy. Rat retinal endothelial cells (RRECs) were grown in normal (N:5 mM glucose) or high glucose (HG:30 mM glucose) medium with or without FA for 7 days. Total protein isolated from these cells was assessed for FN, Coll IV, COX-2, and zonula occludens-1 (ZO-1), a tight junction protein, using Western blot analysis. In addition, the distribution and localization of ZO-1 was determined by immunofluorescence microscopy, and cell monolayer permeability was studied by in vitro permeability (IVP) assay. RRECs grown in HG medium showed significant increase in FN, Coll IV, and COX-2 expression (179%, 144%, 139% of N respectively), and a decrease in ZO-1 expression (48% of N) compared to those of N cells. Cells grown in HG medium supplemented with FA significantly reduced FN, Coll IV, and COX-2 expression by 47%, 32%, and 34% respectively, with concomitant increase in ZO-1 expression by 42%. In parallel studies, IVP assays showed a significant increase (139% of N) in cell monolayer permeability in RRECs grown in HG medium, which was significantly reduced with FA treatment. Additionally, immunostaining results indicated FA prevents HG-induced downregulation of ZO-1. The findings indicate that the beneficial effect of FA in reducing excess permeability is mediated, at least in part, by downregulating abnormal overexpression of BM components and inflammatory factors and preventing compromised tight junctions associated with diabetic retinopathy.

Human in vivo regional intestinal permeability: quantitation using site-specific drug absorption data.

Application of information on regional intestinal permeability has been identified as a key aspect of successful pharmaceutical product development. This study presents the results and evaluation of an approach for the indirect estimation of site-specific in vivo intestinal effective permeability (Peff) in humans. Plasma concentration-time profiles from 15 clinical studies that administered drug solutions to specific intestinal regions were collected and analyzed. The intestinal absorption rate for each drug was acquired by deconvolution, using historical intravenous data as reference, and used with the intestinal surface area and the dose remaining in the lumen to estimate the Peff. Forty-three new Peff values were estimated (15 from the proximal small intestine, 11 from the distal small intestine, and 17 from the large intestine) for 14 active pharmaceutical ingredients representing a wide range of biopharmaceutical properties. A good correlation (r(2) = 0.96, slope = 1.24, intercept = 0.030) was established between these indirect jejunal Peff estimates and jejunal Peff measurements determined directly using the single-pass perfusion double balloon technique. On average, Peff estimates from the distal small intestine and large intestine were 90% and 40%, respectively, of those from the proximal small intestine. These results support the use of the evaluated deconvolution method for indirectly estimating regional intestinal Peff in humans. This study presents the first comprehensive data set of estimated human regional intestinal permeability values for a range of drugs. These biopharmaceutical data can be used to improve the accuracy of gastrointestinal absorption predictions used in drug development decision-making.

Effects of fenofibric acid on carotid intima-media thickness in patients with mixed dyslipidemia on atorvastatin therapy: randomized, placebo-controlled study (FIRST).

OBJECTIVE: To assess whether adding a fibrate to statin therapy reduces residual cardiovascular risk associated with elevated triglycerides and low high-density lipoprotein cholesterol, The Evaluation of Choline Fenofibrate (ABT-335) on Carotid Intima-Media Thickness (cIMT) in Subjects with Type IIb Dyslipidemia with Residual Risk in Addition to Atorvastatin Therapy (FIRST) trial evaluated the effects of fenofibric acid (FA) treatment on cIMT in patients with mixed dyslipidemia on atorvastatin. APPROACH AND RESULTS: This multicenter, double-blind, placebo-controlled study was performed in patients with mixed dyslipidemia (fasting triglycerides, ≥150 mg/dL; high-density lipoprotein cholesterol, ≤45 [men] or 55 mg/dL [women]; low-density lipoprotein cholesterol, ≤100 mg/dL once and averaging ≤105 mg/dL) and a history of coronary heart disease or risk equivalent. Patients on background atorvastatin (continued on starting dose or titrated to 40 mg, if needed) were randomized to FA 135 mg or placebo. The primary end point was rate of change from baseline through week 104 of the mean posterior-wall cIMT, measured by ultrasound. In patients with controlled low-density lipoprotein cholesterol while on atorvastatin background therapy, rate of change in posterior-wall cIMT was similar with FA plus atorvastatin (-0.006 mm/y) versus atorvastatin monotherapy (0.000 mm/y; P=0.22). FA plus atorvastatin was favored (P<0.05) in 5 of 24 prespecified subgroups: age ≥60 years, history of coronary artery disease, cIMT >0.795 mm, triglycerides 170 to 235 mg/dL, and statin use at entry. Adverse events were consistent with the known safety profiles of both drugs; however, FA plus atorvastatin was associated with a greater incidence of renal-related adverse events compared with atorvastatin monotherapy (6.5% versus 0.9%). CONCLUSIONS: Compared with atorvastatin monotherapy, FA plus atorvastatin did not further decrease cIMT progression in high-risk patients with mixed dyslipidemia.

The Lidose hard capsule formulation of fenofibrate is suprabioavailable compared to the nanoparticle tablet formulation under high-fat fed conditions.

PURPOSE: The therapeutic equivalence of multiple registered fenofibrate formulations, several of which are suprabioavailable and therefore marketed at lower dosage strengths than their reference products, is based on the results of bioequivalence studies. Most of these formulations show a higher bioavailability when taken with a high-fat meal. The relative bioavailability of two of these formulations, the 200 mg Lidose hard capsules and the 145 mg nanoparticle tablets, was assessed when taken with a high-fat meal. METHODS: In this single dose, 2-way, randomized, crossover study, 24 healthy subjects received a 200 mg fenofibrate Lidose hard capsule (Test) and a 145 mg nanoparticle tablet (Reference) under high-fat fed conditions. Plasma concentrations of fenofibric acid were measured up to 72 hours by using a validated LC-MS/MS method. RESULTS: The geometric mean ratios (Test/Reference) and the 90% confidence intervals for AUC0-t and Cmax were 1.37 (131.58 - 142.88) and 1.38 (124.60 - 152.93), respectively. The median (range) Tmax- values of fenofibric acid were 4.5 h (3.0 - 8.0 h) and 3.25 h (1.0 - 6.5 h) after administration of the Lidose hard capsule and the nanoparticle tablet, respectively. CONCLUSION: Under high-fat fed conditions the extent of fenofibrate absorption was 37% higher for the 200 mg Lidose hard capsule compared to the 145 mg nanoparticle tablet, which is exactly as expected based on a mg-to-mg weight basis. The results of the present study underline the importance of assessing bioequivalence of fenofibrate formulations under identical fed conditions, and preferentially after a high-fat meal as this condition represents the worst-case scenario. Furthermore, the results of this study demonstrate that the 145 mg nanoparticle tablet is not bioequivalent to the 200 mg Lidose hard capsule when administered under high-fat meal conditions.

Discovery and Synthesis of a Novel Series of Liver X Receptor Antagonists.

Fourteen novel compounds were prepared and their antagonistic activities against liver X receptors (LXR) α/ß were tested in vitro. Compound 26 had an IC50 value of 6.4 µM against LXRα and an IC50 value of 5.6 µM against LXRß. Docking studies and the results of structure-activity relationships support the further development of this chemical series as LXRα/ß antagonists.

A simple and sensitive method for the determination of fibric acids in the liver by liquid chromatography.

Fibrates are used in biochemical and pharmacological studies as bioactive tools. Nevertheless, most studies have lacked information concerning the concentrations of fibric acids working inside tissues because a simple and sensitive method is not available for their quantitation. This study aimed to develop a simple and sensitive bioanalytical method for the quantitation of clofibric, bezafibric and fenofibric acids in samples of very small portions of tissues. Fibric acids were extracted into n-hexane-ethyl acetate from tissue homogenates (10 mg of liver, kidney or muscle) or serum (100 µL) and were derivatized with 4-bromomethyl-6,7-dimethoxycoumarin, followed by HPLC with fluorescence detection. These compounds were separated isocratically on a reversed phase with acetonitrile-water. Standard analytical curves were linear over the concentration range of 0.2-20 nmol/10 mg of liver. Precision and accuracy were within acceptable limits. Recovery from liver homogenates ranged from 93.03 to 112.29%. This method enabled the quantitation of fibric acids in 10 mg of liver from rats treated with clofibric acid, bezafibric acid or fenofibrate. From these analytical data, it became clear that there was no large difference in ratio of acyl-CoA oxidase 1 (Acox1) mRNA level to fibric acid content in the liver among the three fibric acids, suggesting that these three fibric acids have similar potency to increase expression of the Acox1 gene, which is a target of peroxisome proliferator-activated receptor α. Thus, the proposed method is a simple, sensitive and reliable tool for the quantitation of fibric acids working in vivo inside livers.

Rare APOA5 promoter variants associated with paradoxical HDL cholesterol decrease in response to fenofibric acid therapy.

Individuals with mixed dyslipidemia, including high triglycerides (TGs) and low high density lipoprotein cholesterol (HDL-C), have increased risk for coronary events. We examined the effect of rare genetic variants in the APOA5 gene region on plasma HDL-C, apolipoprotein A-I (apoA-I), and TG response to fenofibric acid monotherapy and in combination with statins. The APOA5 gene region was sequenced in 1,612 individuals with mixed dyslipidemia in a randomized trial of fenofibric acid alone and in combination with statins. Student's t-test and rare variant burden tests were used to examine plasma HDL-C, apoA-I, and TG response. Rare APOA5 promoter region variants were associated with decreased HDL-C and apoA-I levels in response to fenofibric acid therapy; rare missense variants were associated with increased TG response to combination therapy. Further study is needed to examine the effect of these rare variants on coronary outcomes in this population in response to fenofibric acid monotherapy or combined with statins.

The human liver fatty acid binding protein T94A variant alters the structure, stability, and interaction with fibrates.

Although the human liver fatty acid binding protein (L-FABP) T94A variant arises from the most commonly occurring single-nucleotide polymorphism in the entire FABP family, there is a complete lack of understanding regarding the role of this polymorphism in human disease. It has been hypothesized that the T94A substitution results in the complete loss of ligand binding ability and function analogous to that seen with L-FABP gene ablation. This possibility was addressed using the recombinant human wild-type (WT) T94T and T94A variant L-FABP and cultured primary human hepatocytes. Nonconservative replacement of the medium-sized, polar, uncharged T residue with a smaller, nonpolar, aliphatic A residue at position 94 of the human L-FABP significantly increased the L-FABP α-helical structure content at the expense of ß-sheet content and concomitantly decreased the thermal stability. T94A did not alter the binding affinities for peroxisome proliferator-activated receptor α (PPARα) agonist ligands (phytanic acid, fenofibrate, and fenofibric acid). While T94A did not alter the impact of phytanic acid and only slightly altered that of fenofibrate on the human L-FABP secondary structure, the active metabolite fenofibric acid altered the T94A secondary structure much more than that of the WT T94T L-FABP. Finally, in cultured primary human hepatocytes, the T94A variant exhibited a significantly reduced extent of fibrate-mediated induction of PPARα-regulated proteins such as L-FABP, FATP5, and PPARα itself. Thus, while the T94A substitution did not alter the affinity of the human L-FABP for PPARα agonist ligands, it significantly altered the human L-FABP structure, stability, and conformational and functional response to fibrate.