Engineered Fenofibrate as Oxidation-Sensitive Nanoparticles with ROS Scavenging and PPARα-Activating Bioactivity to Ameliorate Nonalcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in western countries and China. Fenofibrate (FNB) can activate peroxisome proliferator-activated receptor α (PPARα) to increase fatty acid oxidation and ameliorate NAFLD. However, the application of FNB is limited in clinic due to its poor water solubility and low oral bioavailability. In this study, FNB-loaded nanoparticles (FNB-NP) based on a reactive oxygen species (ROS)-responsive peroxalate ester derived from vitamin E (OVE) and an amphiphilic conjugate 1,2-distearoyl-sn-glycerol-3-phosphoethanolamine-N-[methoxy(poly(ethylene glycol))-2000] (DSPE-PEG) were developed to enhance the preventive effects of FNB against NAFLD. In in vitro studies, FNB-NP displayed a high encapsulation efficiency of 97.25 ± 0.6% and a drug loading efficiency of 29.67 ± 0.1%, with a size of 197.0 ± 0.2 nm. FNB released from FNB-NP was dramatically accelerated in the medium with high H2O2 concentrations. Moreover, FNB-NP exhibited well storage stability and plasma stability. In pharmacokinetic (PK) studies, FNB-NP, compared with FNB crude drug, significantly increased the AUC0→t and AUC0→∞ of the plasma FNB acid by 3.3- and 3.4-fold, respectively. In pharmacodynamics (PD) studies, compared with an equal dose of FNB crude drug, FNB-NP more significantly reduced hepatic lipid deposition via facilitating FNB release in the liver and further upregulating PPARα expression in NAFLD mice. Meanwhile, oxidative stress in NAFLD was significantly suppressed after FNB-NP administration, suggesting that OVE plays a synergistic effect on antioxidation. Therefore, ROS-sensitive FNB delivery formulations FNB-NP enhance the preventive effects of FNB against NAFLD and could be further studied as a promising drug for the treatment of NAFLD in clinic.

Maximizing the Oral Bioavailability of Poorly Water-Soluble Drugs Using Novel Oil-Like Materials in Lipid-Based Formulations.

Lipid-based formulations, such as self-microemulsifying drug-delivery systems (SMEDDSs), are promising tools for the oral delivery of poorly water-soluble drugs. However, failure to maintain adequate aqueous solubility after coming into contact with gastrointestinal fluids is a major drawback. In this study, we examined the use of a novel cinnamic acid-derived oil-like material (CAOM) that binds drugs with a high affinity through π-π stacking and hydrophobic interactions, as an oil core in a SMEDDS for the oral delivery of fenofibrate in rats. The use of the CAOM in the SMEDDS resulted in an unprecedented enhancement in fenofibrate bioavailability, which exceeded the bioavailability values obtained using SMEDDSs based on corn oil, a conventional triglyceride oil, or Labrasol, an enhancer of intestinal permeation. Further characterization revealed that the CAOM SMEDDS does not alter the intestinal permeability and has no inhibitory activity on P-glycoprotein-mediated drug efflux. The results reported herein demonstrate the strong potential of CAOM formulations as new solubilizers for the efficient and safe oral delivery of drugs that have limited water solubility.

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.

Pharmacological screening of fenofibrate-loaded solid dispersion in fructose-induced diabetic rat.

OBJECTIVES: Hyperlipidaemia is a common phenomenon in diabetes mellitus. Fenofibrate (FF) is a good candidate for the treatment of lipid abnormalities in patients with type 2 diabetes. But the bioavailability as well as therapeutic efficacy of this drug is limited to its dissolution behaviour. Here, the authors assess the therapeutic efficacy of a newly formulated solid dispersion of fenofibrate (SDF) having enhanced dissolution profiles in contrast to pure FF using fructose-induced diabetic rat model. METHODS: Fructose-induced diabetic rat model was developed to assess the pharmacological efficacy of the formulated SDF, and the results were compared with the effects of conventional FF therapy. KEY FINDINGS: The 14 days treatment showed better improvement in lipid-lowering potency of SDF than pure FF. SDF containing one-third dose of pure FF showed similar effect in terms of triglyceride, total cholesterol and low-density lipoprotein lowering efficacy, whereas increased high-density lipoprotein at same extent. The similar dose of SDF produced more prominent effect than FF. Histological studies also demonstrated the enhanced lipid clearance from liver by SDF than FF that was concordant with the biochemical results. CONCLUSIONS: This newly formulated SDF would be a promising alternative for conventional fenofibrate in treating hyperlipidaemia.

The elucidation of key factors for oral absorption enhancement of nanocrystal formulations: In vitro-in vivo correlation of nanocrystals.

Nanocrystal formulation is a well-established approach for improving oral absorption of poorly water-soluble drugs. However, it is difficult to predict the in vivo performance of nanocrystal formulations from in vitro dissolution studies. The object of the present study was to investigate the in vitro-in vivo correlation of nanocrystal formulations of different particle sizes. A microsuspension and three nanosuspensions with different particle sizes for model drugs, fenofibrate and megestrol acetate, were prepared. In the comparison between the microsuspension and the nanosuspension having the smallest particle sizes, drug permeation rates from the nanosuspension were about 3-fold higher in the dissolution-permeation study. On the other hand, the solubility enhancement effect due to nanocrystal formation was only up by 1.4-fold, suggesting that nanocrystal formulations dramatically improved not the solubility but the apparent permeability. The oral absorption rate in rats increased with particle size reduction. There were positive and very strong correlations (R2 > 0.95) between the in vitro permeation rate and in vivo maximum absorption rate. We concluded that the enhanced permeability rate due to nanocrystal formation is the main factor for improving oral absorption, and the in vitro dissolution-permeation study could be useful for predicting oral absorption enhancement of nanocrystal formulations.

Analysis of a Skeletal Muscle Injury and Drug Interactions in Lovastatin- and Fenofibrate-Coadministered Dogs.

Because dogs are widely used in drug development as nonrodent experimental animals, using a dog model for drug-induced adverse reactions is considered to be relevant for an evaluation and investigation of a mechanism and a biomarker of clinical drug-induced adverse reactions. Skeletal muscle injury occurs by various drugs, including statins and fibrates, during drug development. However, there is almost no report of a dog model for drug-induced skeletal muscle injury. In the present study, we induced skeletal muscle injury in dogs by oral coadministration of lovastatin (LV) and fenofibrate (FF) for 4 weeks. Increases in plasma levels of creatine phosphokinase, myoglobin, miR-1, and miR-133a and degeneration/necrosis of myofibers in skeletal muscles but not in the heart were observed in LV- and FF-coadministered dogs. Plasma levels of lovastatin lactone and lovastatin acid were higher in LV- and FF-coadministered dogs than LV-administered dogs. Taken together, FF coadministration is considered to affect LV metabolism and result in skeletal muscle injury.

Improvement of the dissolution rate and bioavailability of fenofibrate by the supercritical anti-solvent process.

The purpose of this study was to improve solubility and oral bioavailability of fenofibrate via solid dispersion (SD) using a supercritical anti-solvent (SAS) process with amphipathic polymers P407 and TPGS. Solid dispersion techniques have been widely used to enhance the solubility and dissolution profiles of poorly soluble drugs. Fenofibrate is classified as a Biopharmaceutics Classification System class II compound because of its low solubility and high gastrointestinal permeability. Two copolymers were selected based on solubility and dissolution tests. Their physicochemical properties were compared with those prepared by conventional solvent evaporation (CSE). The SD formulations containing fenofibrate were successfully prepared using the SAS and CSE methods. The dissolution rate (%) of fenofibrate at 60 min was significantly improved compared with the solution of raw fenofibrate (19.5% ±â€¯3.7%) by 95.1% ±â€¯2.5% and 93.7% ±â€¯4.1% using the SAS and the CSE process, respectively. This approximately four-fold increase in dissolution rate indicates that oral bioavailability can be enhanced. In addition, pharmacokinetic study was analyzed using the area under the curve (AUC) and Cmax values of SAS-SD and CSE-SD in rats. The AUC was 2.1 times higher and Cmax was 1.9 times higher in SAS-SD, indicating higher concentrations of fenofibrate in the blood. In a pharmacodynamic study to evaluate the efficacy of the drug in hyperlipidemic rat models, SAS-SD showed strong lipid-lowering effects including cholesterol (1.9-fold) and triglycerides (3.3-fold), than CSE-SD. Taken together, these results suggested that SAS-SD has excellent potential as a formulation for the poorly soluble drug fenofibrate.

Effect of molecular weight of hypromellose on mucin diffusion and oral absorption behavior of fenofibrate nanocrystal.

We investigated the effect of variation in the molecular weight of hypromellose (HPMC) on the oral absorption of fenofibrate (FFB) nanocrystal. Four types of HPMC with different molecular weights and sodium dodecyl sulfate (SDS) were used as dispersion stabilizers for FFB nanocrystal suspension. Wet-milling of FFB crystal with HPMC and SDS formed diamond-shaped FFB nanocrystals with approximately 150 nm diameter. HPMC was strongly adsorbed onto the FFB nanocrystal interface, and the amount of HPMC adsorbed was not dependent on the molecular weight of HPMC. However, the decrease in the molecular weight of adsorbed HPMC led to an improvement in the permeability of FFB nanocrystal through the mucin layer. The decrease in molecular weight of HPMC enhanced the flexibility of FFB nanocrystal interface and effectively inhibited its interaction with mucin. This led to faster diffusion of FFB nanocrystal through mucin. In vivo oral absorption studies showed rapid FFB absorption from FFB nanocrystal formulations using HPMC of low molecular weights. The present study revealed that the molecular weight of the dispersion stabilizer for drug nanocrystal formulation should be taken into consideration to achieve improved absorption of poorly water-soluble drugs after oral administration.

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.

Pharmacokinetics and bioequivalence of two fenofibrate choline formulations in healthy subjects under fed and fasted condition
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OBJECTIVE: The objective of this study was to evaluate the pharmacokinetics and bioequivalence of two formulations (the original capsule ("reference") and the new tablet ("test") formulations) of 135-mg choline fenofibrate under fed and fasted conditions. MATERIALS AND METHODS: This was an open-label, randomized, single-dose, crossover bioequivalence study in healthy Korean males. A total of 40 individuals were separately enrolled in the high-fat fed and the fasting study, respectively, and were randomized in a 1:1 ratio into two sequences. Serial blood samples were collected over 72 hours after drug administration. Plasma concentrations of fenofibric acid were determined by a validated LC-MS/MS method. Pharmacokinetic (PK) parameters were estimated using noncompartmental methods. RESULTS: Overall, 37 and 35 individuals completed the fed and the fasting study, respectively, as planned. The estimated Cmax, AUC0-∞, and AUC0-last were comparable between the test and the reference formulations in both fed and fasting studies (p > 0.05). The 90% confidence intervals for the geometric mean ratios of Cmax, AUC0-∞, and AUC0-last were 0.92 - 1.06, 0.95 - 1.01, and 0.95 - 1.01 in the fed study; and 0.94 - 1.12, 0.94 - 1.00, and 0.94 - 1.00 in the fasting study, respectively. For both formulations, tmax was significantly prolonged under fed condition compared to fasting condition (p < 0.0001); all other PK parameters were comparable between the fed and the fasting studies (p > 0.05). CONCLUSION: The reference and the test formulations of 135 mg choline fenofibrate show comparable pharmacokinetic profiles of fenofibric acid under both fed and fasted conditions and are considered bioequivalent.
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Effects of Polymer/Surfactant as Carriers on the Solubility and Dissolution of Fenofibrate Solid Dispersion.

The purpose of this work is to investigate the effects of polymer/surfactant as carriers on the solubility and dissolution of fenofibrate solid dispersions (FF SDs) with the aid of systematic research on the physicochemical properties of the polymer/surfactant system and further highlight the importance of studying polymer/surfactant interaction in the preformulation. The critical micelle concentration (CMC) of sodium lauryl sulfate (SLS) and critical aggregation concentration (CAC) of polymer/SLS solutions were obtained through conductivity measurement. Meanwhile, surface tension, viscosity, morphology, and wettability of polymer/SLS with different weight ratios of SLS were analyzed to screen out the suitable content of SLS (weight%, 5% in carriers) incorporated in SDs. Polymer/SLS coprecipitate and FF SDs were prepared by the solvent evaporation method. The results from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis showed that FF was molecularly dispersed in SDs. Compared to the solubility of FF in povidone/SLS (PVP/SLS) solutions, the increment of FF solubility in copovidone/SLS (VA64/SLS) solutions was due to the formation of free SLS micelles, which have been confirmed by transmission electron microscopy (TEM). Particularly, the wettability of FF SDs and physical mixtures (PMs) was also determined by the sessile drop technique. A linear relationship between the wettability of carriers and that of FF SDs was found, which revealed the significant role of carriers on the surface composition of FF SDs. As the molecular weight of PVP increased, the wettability of carriers decreased, thus leading to the reduction of the dissolution rate of SDs. Although the presence of SLS did not enhance the dissolution of FF SDs, it increased the amount of drug released at the initial stage. All these results indicated that the polymer/SLS interaction would affect the performance of SDs; hence, it was necessary to study their properties in the preformulation.

Fenofibrate modified-release pellets with lag phase and high oral bioavailability.

PURPOSE: Fenofibrate and statin combination therapy is highly recommended by the current clinical guidelines for treatment of mixed dyslipidemia. In this study, an innovative delayed-release preparation of fenofibrate was designed to reduce the risk of muscle toxicity, caused by simultaneous administration of this combination therapy, by altering the pharmacokinetic profile of fenofibrate, as well as to improve the oral bioavailability of the modified-release formulation. METHODS: Micronized fenofibrate was used to prepare drug-loaded cores via a powder layering process before multiparticulate pellet coating. Different coating formulations (Eudragit® RS PO/E100, Eudragit® RS PO/RL PO, Eudragit® NE30D/HPMC, and EC/HPMC) were screened, and their in vitro release was compared with the commercial sustained-release pellets Lipilfen®. Two optimized formulations were evaluated in beagle dogs using two commercial preparations of fenofibrate (the immediate-release preparation Lipanthyl® and the sustained-release pellets Lipilfen®) as references. RESULTS: The in vivo release of fenofibrate from R1 and R2 selected from in vitro tests exhibited a lag phase, and then rapid and complete drug release. The relative bioavailabilities of R1 and R2 were 100.4% and 201.1%, respectively, which were higher than that of Lipilfen® (67.2%). CONCLUSION: The modified fenofibrate pellets developed showed enhanced bioavailability and delayed-release properties. They have the potential to improve safety and compliance when co-administrated with statins. This is the first report of a delayed-release fenofibrate preparation.

Fenofibrate Solid Dispersion Processed by Hot-Melt Extrusion: Elevated Bioavailability and Its Cell Transport Mechanism.

BACKGROUND: Fenofibrate (FNB) is an effective drug for the treatment of hypertriglyceridemia, hypercholesterolemia as well as mixed hyperlipidemia. However, due to its poor aqueous solubility, FNB has the problem of poor oral absorption followed by low bioavailability. OBJECTIVE: The aim of this research was to construct FNB amorphous solid dispersion employing PVP VA64 as the carrier by hot-melt extrusion method, in order to improve the oral bioavailability. Additionally, the cell transport experiment was conducted to further investigate the mechanism of promoted osmotic absorption. METHODS: The physical state of the obtained solid dispersion was characterized using SEM, DSC and XRD. Besides, in vitro Caco-2 cells were used to evaluate the cytotoxicity of the carrier and mimic gastrointestinal drug permeation. At last, in vitro dissolution test and in vivo bioavailability study were also carried out. RESULTS: The prepared FNB solid dispersion was found to be an amorphous state after hot-melt extrusion process. In vitro cytotoxicity test on Caco-2 cells confirmed the excellent biocompatibility of the carrier PVP VA64. Besides, transwell cell transport assay and in vitro dissolution test revealed that FNB released from amorphous solid dispersion was equipped with an improved transmembrane transport and dissolution rate. Moreover, pharmacokinetic study in beagle dogs showed that comparing with commercial micronized product Lipanthyl®, the oral bioavailability of FNB solid dispersion was significantly enhanced (2.45 fold). CONCLUSION: In conclusion, PVP VA64 can be regarded as a promising polymer to enhance the bioavailability of poorly water-soluble drugs such as FNB processed by hot-melt extrusion. Besides, investigations on the mechanism of the enhanced penetration are expected to lay a foundation on the subsequent development of effective and practical solid dispersion.

Hot melt extrusion technology for improved dissolution, solubility and "spring-parachute" processes of amorphous self-micellizing solid dispersions containing BCS II drugs indomethacin and fenofibrate: Profiles and mechanisms.

Many strategies have been employed to improve oral drug delivery. One such approach involves the use of supersaturable delivery systems such as amorphous self-micellizing solid dispersions (SmSDs). SmSDs have attracted more attention recently, but little is known regarding the impact of production methods on profiles and internal mechanisms of final SmSDs in spite of its importance. In this study, amorphous SmSDs containing self-micellizing Soluplus® and BCS II drug (either indomethacin (IND) or fenofibrate (FEN)) were generated using various methods: solvent evaporation (SOL), freeze-drying (FD), microwave radiation-quench cooling (MQC), and hot melt extrusion (HME). Microscopic morphology, amorphous state, thermal behavior, dissolution/solubility, and "spring-parachute" data were used to assemble physicochemical profiles for SmSD systems prepared using each method. Analysis of intermolecular interactions, solubilization, and crystallization inhibition further uncovered internal mechanisms explaining observed physicochemical properties. Generally, SmSD/IND and SmSD/FEN systems generated using HME exhibited superior dissolution, solubility, and spring-parachute profiles. The superior advantages of HME-generated SmSD/IND systems were attributed to relatively stronger intermolecular interactions than observed in SmSD/IND systems fabricated using other methods. Moreover, self-micellizing Soluplus® carrier was able to solubilize IND or FEN and suppress drug crystallization from a supersaturated state, which seemed to be an important mechanism for the properties enhancement caused by SmSD/FENHME. This knowledge should be useful for guiding further development of self-micellizing solid dispersions and for gaining deeper understanding of how HME technology can improve supersaturable drug delivery based on SmSDs strategy.

Pharmacokinetic interactions and tolerability of berberine chloride with simvastatin and fenofibrate: an open-label, randomized, parallel study in healthy Chinese subjects.

PURPOSE: Fenofibrate (Fbt) is a prodrug that has been used to reduce low-density-lipoprotein cholesterol, triglycerides, and increase high-density-lipoprotein cholesterol. Simvastatin (Svt) is a classic lipid-lowering drug that is widely used in the treatment of hypercholesterolemia and hypertriglyceridemia, while berberine chloride (Bbr) is a novel hypolipidemic agent and its blood-lipid-reducing mechanism is distinct from traditional drugs. Currently, drug combination is the trend in treating hyperlipidemia to improve clinical efficacy. The purpose of this study was to evaluate drug interaction from the perspective of pharmacokinetics between Bbr and Fbt/Svt and the tolerability of combined administration in healthy Chinese subjects. METHODS: Healthy subjects (n=60) were randomly allocated to five treatment groups: Bbr alone, Fbt alone, Svt alone, Bbr plus Fbt, and Bbr plus Svt. The experiment was divided into two parts: single-dose administration and multiple-dose administration. Bbr, Fbt, and Svt were taken once every 8 hours, 24 hours, and 24 hours, respectively, over 7 days in the multidose group. Plasma samples were collected and liquid chromatography-mass spectrometry/mass spectrometry was used to detect drug concentrations. RESULTS: No serious adverse reactions or intolerance were observed throughout the trial. More importantly, the combined-administration groups did not show an increase in incidence of side effects. Coadministration of Fbt and Svt with Bbr had no significant effect on the pharmacokinetic parameters of Bbr, except time to maximum concentration, apparent volume of distribution, and apparent clearance. Concurrent coadministration of Bbr had no obvious impact on the pharmacokinetic behavior of Fbt or Svt. Additionally, there was no significant correlation between sex and pharmacokinetic results. CONCLUSION: All treatments were well tolerated. No clinically obvious pharmacokinetic interactions between Bbr and Fbt/Svt were observed with combined administration. The results demonstrated that Bbr can be coadministered safely with Fbt and Svt without dose adjustment.

Effects of triptolide on pharmacokinetics of fenofibrate in rats and its potential mechanism.

Triptolide and fenofibrate are often used together for the treatment of nephrotic syndrome in Chinese clinics. This study investigates the effects of triptolide on the pharmacokinetics of fenofibrate in rats and it potential mechanism. The pharmacokinetics of fenofibrate (20 mg/kg) with or without triptolide pretreatment (2 mg/kg/day for seven days) were investigated. Additionally, the inhibitory effects of triptolide on the metabolic stability of fenofibrate were investigated using rat liver microsome incubation systems. The results indicated that the Cmax (35.34 ± 7.52 vs. 30.43 ± 6.45 µg/mL), t1/2 (6.17 ± 1.15 vs. 4.90 ± 0.82 h) and AUC(0-t) (468.12 ± 35.84 vs. 416.35 ± 32.68 mg h L-1) of fenofibric acid decreased significantly (p < .05). The Tmax of fenofibric acid increased significantly (p < .05) from 5.12 ± 0.36 to 6.07 ± 0.68 h. Additionally, the metabolic stability of fenofibrate was prolonged from 35.8 ± 6.2 to 48.6 ± 7.5 min (p < .05) with the pretreatment of triptolide. In conclusion, these results indicated that triptolide could affect the pharmacokinetics of fenofibric acid, possibly by inhibiting the metabolism of fenofibrate in rat liver when they were co-administered.

Effect of Surfactant-Bile Interactions on the Solubility of Hydrophobic Drugs in Biorelevant Dissolution Media.

Biorelevant dissolution media (BDM) methods are commonly employed to investigate the oral absorption of poorly water-soluble drugs. Despite the significant progress in this area, the effect of commonly employed pharmaceutical excipients, such as surfactants, on the solubility of drugs in BDM has not been characterized in detail. The aim of this study is to clarify the impact of surfactant-bile interactions on drug solubility by using a set of 12 surfactants, 3 model hydrophobic drugs (fenofibrate, danazol, and progesterone) and two types of BDM (porcine bile extract and sodium taurodeoxycholate). Drug precipitation and sharp nonlinear decrease in the solubility of all studied drugs is observed when drug-loaded ionic surfactant micelles are introduced in solutions of both BDM, whereas the drugs remain solubilized in the mixtures of nonionic polysorbate surfactants + BDM. One-dimensional and diffusion-ordered 1H NMR spectroscopy show that mixed bile salt + surfactant micelles with low drug solubilization capacity are formed for the ionic surfactants. On the other hand, separate surfactant-rich and bile salt-rich micelles coexist in the nonionic polysorbate surfactant + bile salt mixtures, explaining the better drug solubility in these systems. The nonionic alcohol ethoxylate surfactants show intermediate behavior. The large dependence of the drug solubility on surfactant-bile interactions (in which the drug molecules do not play a major role per se) highlights how the complex interplay between excipients and bile salts can significantly change one of the key parameters which governs the oral absorption of poorly water-soluble drugs, viz. the drug solubility in the intestinal fluids.

Phase separation of supersaturated solution created from amorphous solid dispersions: Relevance to oral absorption.

Dissolution of amorphous solid dispersions (ASDs) is a complicated process, which may involve phase separation from the supersaturated state and formation of a colloidal phase. However, relevance of the phase separation behavior to oral absorption from ASDs is still not well understood. We investigated phase separation of a supersaturated fenofibrate (FEN) solution in the presence of polymers, in vitro dissolution of FEN ASDs, and their in vivo absorption. The supersaturation behavior was assessed based on turbidity measurement in an artificial supersaturation system, where FEN ethanol solutions were added to aqueous polymer solutions. The phase separation concentration of FEN was ca. 1 µg/mL regardless of the presence/absence of the polymer, which was approximately 10-fold the equilibrium solubility. In the presence of 0.1% Tween 80 in the media, the phase separation concentration depended on the polymer species, presumably due to differences in their inhibitory effect of crystallization. The degrees of supersaturation achieved by the ASDs were similar to those found in the artificial system, suggesting that the artificial system works for comprehending the effect of polymer species on supersaturation ability for designing ASDs. A robust in vitro-in vivo correlation was achieved using the paddle and the flow-through cell methods by employing non-sink and pH-shift conditions. However, the phase separation concentration may rather be a good and simple indicator to estimate the absorption-enhancing ability of the polymeric excipients for ASDs, if the absorption is limited by solubility.

Development of a tin oxide carrier with mesoporous structure for improving the dissolution rate and oral relative bioavailability of fenofibrate.

BACKGROUND: Biopharmaceutics classification system class II drugs have low solubility, which limits their extent and speed of absorption after oral administration. Over the years, mesoporous materials have been widely used to increase the dissolution rate and oral relative bioavailability of poorly water-soluble drugs. OBJECTIVES: In order to improve the dissolution rate and increase oral relative bioavailability of the poorly water-soluble drugs, a tin oxide carrier (MSn) with a mesoporous structure was successfully synthesized. METHODS: In this study, MSn was synthesized using mesoporous silica material (SBA-15) as the template. Fenofibrate (FNB) was adsorbed into the channels of MSn by an adsorption method. Characterizations of the pure FNB, MSn, physical mixture of the drug and MSn (PM; 1:1) and FNB-loaded MSn (FNB-MSn) samples were carried out by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption, powder X-ray diffractometer (PXRD), differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy. Cytotoxicity assay (MTT) was used to evaluate the cytotoxicity of MSn. In vitro dissolution studies were performed to investigate the dissolution rate of FNB-MSn. In vivo pharmacokinetic studies were used to investigate the changes of plasma drug concentrations of FNB-MSn tablets and commercial FNB tablets in rabbits. RESULTS: Detailed characterization showed that FNB in the channels of MSn was present in an amorphous state. The in vitro release tests demonstrated that MSn with a good biocompatibility could effectively enhance the dissolution rate of FNB. Pharmacokinetic results indicated that MSn significantly increased the oral relative bioavailability of FNB. CONCLUSION: MSn can be regarded as a promising carrier for an oral drug delivery system.

Combined effects of the drug distribution and mucus diffusion properties of self-microemulsifying drug delivery systems on the oral absorption of fenofibrate.

We present the absorption improvement mechanism of fenofibrate (FFB), a Biopharmaceutics Classification System (BCS) class II drug, from self-microemulsifying drug delivery systems (SMEDDS), centered on improving the diffusion of FFB through the unstirred water layer (UWL). Four SMEDDS formulations containing Labrafac™ lipophile WL 1349 (WL1349) or Labrafil® M 1944CS (M1944) oils and NIKKOL HCO-40 (HCO40) or NIKKOL HCO-60 (HCO60) surfactants were prepared. Every SMEDDS formulation formed microemulsion droplets of approximately 30 nm. In vitro tests showed that the microemulsion droplets containing M1944 had relatively small FFB solubilization capacities, causing larger amounts of FFB to be dissolved in the bulk water phase, compared to the droplets containing WL1349. The diffusivity of the microemulsion droplets through the mucin solution layer was enhanced when using HCO40 compared to HCO60. The oral absorption in rats was the highest when using the SMEDDS formulation containing M1944 and HCO40. High FFB distribution in the bulk water phase and fast diffusion of microemulsion droplets through the mucus layer contributed to the efficient delivery of FFB molecules through the UWL to the epithelial cells, leading to enhanced FFB absorption.