Increased plasma concentrations of an antidyslipidemic drug pemafibrate co-administered with rifampicin or cyclosporine A in cynomolgus monkeys genotyped for the organic anion transporting polypeptide 1B1.

In vitro permeability and in vivo pharmacokinetics of pemafibrate were investigated in human intestinal and animal models untreated or pretreated with cyclosporine A or rifampicin to evaluate any drug interactions. Ratios of basal to apical apparent permeability (Papp) over apical to basal Papp in the presence of pH gradients decreased from 0.37 to 0.080 on rifampicin co-incubation, suggesting active transport of pemafibrate from basal to apical sides in intestinal models. Plasma concentrations of intravenously administered pemafibrate were enhanced moderately in control mice but only marginally in humanized-liver mice by oral pretreatment with rifampicin [an organic anion transporting polypeptide (OATP) 1B1 inhibitor] 1 h before the administration of pemafibrate. In three cynomolgus monkeys genotyped as wild-type OATP1B1 (2 homozygous and 1 heterozygous), oral dosing of cyclosporine A 4 h or rifampicin 1 h before pemafibrate administration significantly increased the areas under the plasma concentration-time curves (AUC) of intravenously administered pemafibrate by 4.9- and 7.4-fold, respectively. Plasma AUC values of three pemafibrate metabolites in cynomolgus monkeys were also increased by cyclosporine A or rifampicin. These results suggested that pemafibrate was actively uptaken in livers and rapidly cleared from plasma in cynomolgus monkeys; this rapid clearance was suppressible by OATP1B1 inhibitors.

Enhancing the oral bioavailability of simvastatin with silica-lipid hybrid particles: The effect of supersaturation and silica geometry.

Silica-lipid hybrid (SLH) microparticles are a solidified lipid-based drug delivery system under investigation for their aptitude to enhance the oral bioavailability of poorly water-soluble drugs. The cholesterol-lowering agent, simvastatin (SIM), is poorly water-soluble and undergoes extensive first pass metabolism, resulting in a low oral bioavailability of approximately 5%. Hence, the current pre-clinical studies investigated the application of SLH technology to SIM with a supersaturation approach, aiming to enhance bioavailability and drug loading capacity. Additionally, the effect of silica was explored by evaluating the performance of SLH fabricated with silica of different particle geometries. SLH microparticles with supersaturated SIM loading levels ranging from 100% to 400% above the equilibrium solubility were successfully fabricated using either Aerosil® 300 or Syloid® 244 silica. All SLH formulations existed as white free-flowing powders, consisting of spherical porous microparticles for Aerosil® 300, and aggregated irregular microparticles for Syloid® 244. During in vitro dissolution in pH 7.0 media, the SLH formulations performed up to 4.4-fold greater than pure SIM powder. Furthermore, in vivo oral pharmacokinetics in male Sprague-Dawley rats revealed that the SLH formulations enhanced the oral bioavailability of SIM up to 6.1-fold and 2.9-fold, in comparison to pure SIM powder and a commercially available formulation (Simvastatin Sandoz®), respectively. The greatest in vivo performance enhancement was observed for the SLH formulation manufactured with Syloid® 244 silica with a supersaturation level of 200%. SLH technology demonstrated to be a successful formulation strategy to significantly improve the oral bioavailability of SIM in rodents and therefore, has a strong potential to also improve the oral bioavailability of SIM in humans.

Electrosprayed Polymeric Nanospheres for Enhanced Solubility, Dissolution Rate, Oral Bioavailability and Antihyperlipidemic Activity of Bezafibrate.

BACKGROUND: Bezafibrate is a BCS class II drug as it presents very low solubility in water; therefore, its bioavailability after oral administration is very poor. The aim of this work was to enhance solubility and dissolution rate of bezafibrate in water in order to enhance its oral bioavailability. METHODS: Several formulations were prepared using PVP K30 and Cremophor ELP employing the solvent-evaporation method and the electrospraying technique. Solubility, release rate, bioavailability in male Sprague Dawley rats, and lipid profile attributes in Wistar rats were assessed in comparison with bezafibrate plain powder. Solid-state characterization was carried out using X-ray diffraction (XRD) analysis, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). RESULTS: All the formulations exerted positive effect towards the desired goal. In particular, the optimized formulation furnished about 14-fold enhanced solubility and 85.48 ± 10.16% drug was released in 10 min as compared with bezafibrate alone (4.06 ± 2.59%). The drug existed in the amorphous state in the prepared sample as confirmed by XRD and DSC, whilst no drug-excipient interactions were observed through FTIR analysis. Moreover, SEM revealed smooth-surfaced spherical particles of the optimized formulation. A 5.5-fold higher oral bioavailability was achieved with the optimized formulation in comparison with bezafibrate plain powder. Also, TG, LDL and TC were decreased, and HDL was increased considerably in HFD-treated rats. CONCLUSION: The optimized formulation consisting of bezafibrate, PVP K30 and cremophor ELP (1/12/1.5, w/w/w) might be a capable drug delivery system for orally administering poorly water-soluble bezafibrate with improved bioavailability and antihyperlipidemic effects.

UPLC-MS/MS method for gemfibrozil determination in plasma with application to a pharmacokinetic study in healthy Brazilian volunteers.

Gemfibrozil (GFZ) is a derivative of fibric acid and is used in the treatment of dyslipidemia. GFZ may affect the metabolism of various drugs, including statins, by inhibiting the sinusoidal influx transporter OATP1B1 and also CYP2C9 and CYP2C8 enzymes. This study presents the development and validation of a rapid, simple, sensitive and reproducible method of GFZ analysis in human plasma using UPLC-MS/MS. The method was applied in a pharmacokinetic study following administration of multiple doses of 600 mg GFZ every 12 h in healthy volunteers (n = 15). GFZ was separated on a C18 column using a mixture of 0.01% formic acid and acetonitrile (40:60, v/v) as the mobile phase at a flow rate of 0.4 mL/min. The method showed linearity in the range from 0.01 µg/mL to 100 µg/mL plasma. The coefficients of variation and the relative standard errors of the accuracy and precision analyses were <15%. The method allowed quantification of plasma concentrations of GFZ in the dose interval of the sixth day of administration of multiple oral doses of GFZ every 12 h. The pharmacokinetic parameters are presented as mean (95% CI): area under the plasma concentration versus time curve 88.84 (72.72-104.96) µg·h/mL, steady state mean plasma concentration 7.40 (6.06-8.75) µg/mL, minimum plasma concentration 1.24 (0.87-1.61) µg/mL, maximum plasma concentration 26.73 (21.31-32.15) µg/mL, time to reach maximum plasma concentration 2.28 (1.42-3.13) h, elimination half-life 2.81 (2.22-3.40) h, apparent total clearance 7.72 (5.85-9.58) L/h, apparent distribution volume 33.97 (18.41-49.53) L. In conclusion, the method for analysis of GFZ in human plasma showed sensitivity, linearity, precision and accuracy compatible with application in pharmacokinetic studies of multiple oral dose of 600 mg GFZ every 12 h.

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.

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.

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.

Preclinical pharmacokinetic study of a novel lipid-lowering agent, IMM-H007.

OBJECTIVE: To investigate the pharmacokinetic characteristics of absorption, distribution, metabolism, and excretion in vivo after oral administration and sublingual venous injection of the small molecule IMM-H007 in hamsters. MATERIALS AND  METHODS: Pharmacokinetic characteristics, including absorption, distribution, metabolism, and excretion, were studied in vivo by LC-MS/MS after oral administration and sublingual venous injection of IMM-H007 in hamsters. Furthermore, IMM-H007 stability in artificial gastric juices, artificial intestinal juices, and Tris-HCl buffer was also analyzed. RESULTS: There was no significant matrix or impurity interference in golden hamster whole blood as shown using MS/MS analysis to detect the existence of these substances. IMM-H007, Ml, and MP exhibited good linearity in the range of 1-500 ng/mL, 2-1000 ng/mL, and 10-5000 ng/mL, respectively. The matrix effect was 71.93-105.49%, and IMM-H007, M1, and MP were stable during the process of sample disposal. These results illustrate that the HPLC MS/MS analytic method is simple, reliable, and sensitive and exhibits high specificity and which meets the clinical pharmacokinetic requirements of IMM-H007. IMM-H007 is rapidly absorbed through the oral route in hamsters. The Cmax and AUC(0-t) of the Ml and MP metabolites in male and female hamsters were increased with increasing dosage and were proportional to the dose. In addition, T1/2 and MRT(0-t) were significantly prolonged with increasing dosage, exhibiting linear dynamic characteristics and no significant gender differences. Bioavailability in male and female golden hamsters after oral administration of IMM-H007 was calculated using the sum of Ml and MP, resulting in 6.97% and 8.95%, respectively. IMM-H007 and its metabolites were stable in Tris-HCl buffer, artificial gastric juices, and artificial intestinal juices. CONCLUSIONS: We provide an experimental basis for elucidating the material pharmacodynamics actions of IMM-H007 and predicting its potential drug interactions.

Hypoglycemic and hypolipidemic effect of Vaccinium myrtillus L. leaf and Phaseolus vulgaris L. seed coat extracts in diabetic rats.

OBJECTIVES: The aim of this study was to examine the hypoglycemic and hypolipidemic effects of Vaccinium myrtillus L. leaf (VLE) and Phaseolus vulgaris L. seed coat (PCE) plant extracts, containing polyphenolic compounds, on carbohydrate and lipid metabolism in Wistar rats with streptozotocin (STZ) and high-fructose diet (HFD)-induced diabetes. METHODS: Male Wistar rats with STZ and HFD-induced diabetes were fed with or without VLE or PCE for 50 d. At different intervals, blood glucose and body weight were recorded. Blood samples were used to determine glycated hemoglobin (HbA) and parameters of lipid profile in serum. Additionally, the levels of serum diene conjugates and malondialdehyde were assessed. RESULTS: Results of HbA and blood glucose level analysis showed the ameliorative effect of VLE on carbohydrate metabolism in diabetic rats. Of the eight diabetic animals treated with bilberry leaf extract, four had normal HbA levels. A significant reduction was observed in VLE group in blood glucose level compared with control diabetic rats (level of hyperglycemia decreased to normal values in 50% of animals versus 0% in the control diabetic group). VLE treatment normalized parameters of lipid metabolism. There was no significant difference from the same parameters in the intact control group. Administration of PCE significantly (P < 0.05) decreased the levels of plasma triacylglycerol (0.81 ± 0.06 mmol/L) and low-density lipoprotein (0.74 ± 0.10 mmol/L) in blood serum compared with the diabetic control group (1.36 ± 0.13 and 1.85 ± 0.30, respectively). Moreover, VLE and PLE showed an antioxidant effect on diene compounds in the blood serum of rats. A significant decrease was found in the plasma diene conjugate levels in PLE group (1.16 ± 0.11 nmol/mL) compared with control diabetic rats (2.09 ± 0.21 nmol/mL; P < 0.05). There was no significant difference from the same parameter in the VLE and intact control groups. CONCLUSIONS: The set of results that was obtained in the present study reveals lipid-lowering and antioxidant action related to the administration of VLE and PCE in Wistar rats with diabetes, induced by STZ, in combination with a high-carbohydrate diet. VLE to a certain extent also reduced hyperglycemia in diabetic animals.

Improved pharmacokinetics and antihyperlipidemic efficacy of rosuvastatin-loaded nanostructured lipid carriers.

In the present study, rosuvastatin calcium-loaded nanostructured lipid carriers were developed and optimized for improved efficacy. The ROS-Ca-loaded NLC was prepared using melt emulsification ultrasonication technique and optimized by Box-Behnken statistical design. The optimized NLC composed of glyceryl monostearate (solid lipid) and capmul MCM EP (liquid lipid) as lipid phase (3% w/v), poloxamer 188 (1%) and tween 80 (1%) as surfactant. The mean particle size, polydispersity index (PDI), zeta potential (ζ) and entrapment efficiency (%) of optimized NLC formulation was observed to be 150.3 ± 4.67 nm, 0.175 ± 0.022, -32.9 ± 1.36 mV and 84.95 ± 5.63%, respectively. NLC formulation showed better in vitro release in simulated intestinal fluid (pH 6.8) than API suspension. Confocal laser scanning showed deeper permeation of formulation across rat intestine compared to rhodamine B dye solution. Pharmacokinetic study on female albino Wistar rats showed 5.4-fold increase in relative bioavailability with NLC compared to API suspension. Optimized NLC formulation also showed significant (p < 0.01) lipid lowering effect in hyperlipidemic rats. Therefore, NLC represents a great potential for improved efficacy of ROS-Ca after oral administration.

Effects of type 2 diabetes mellitus on the pharmacokinetics of berberine in rats.

CONTEXT: Berberine is an active alkaloid isolated from Rhizoma coptidis [Coptis chinensis Franch. (Ranunculaceae)] that is widely used for the treatment of diabetes, hyperlipidemia and hypertension. However, the pharmacokinetics of berberine in normal rats and type 2 diabetes mellitus (T2DM) model rats are not clear. OBJECTIVE: This study compares the pharmacokinetics of berberine between normal and T2DM model rats. MATERIALS AND METHODS: The T2DM model rats were fed with high fat diet for 4 weeks, induced by low-dose (30 mg/kg) streptozotocin for 72 h and validated by determining the peripheral blood glucose level. Rats were orally treated with berberine at a dose of 20 mg/kg and then berberine concentration in rat plasma was determined by employing a sensitive and rapid LC-MS/MS method. RESULTS: The significantly different pharmacokinetic behaviour of berberine was observed between normal and T2DM model rats. When compared with the normal group, Cmax, t1/2 and AUC(0-t) of berberine were significantly increased in the model group (17.35 ± 3.24 vs 34.41 ± 4.25 µg/L; 3.95 ± 1.27 vs 9.29 ± 2.75 h; 151.21 ± 23.96 vs 283.81 ± 53.92 µg/h/L, respectively). In addition, oral clearance of berberine was significantly decreased in the model group (134.73 ± 32.15 vs 62.55 ± 16.34 L/h/kg). DISCUSSION AND CONCLUSION: In T2DM model rats, the pharmacokinetic behaviour of berberine was significantly altered, which indicated that berberine dosage should be modified in T2DM patients.

Novel genipin crosslinked atorvastatin loaded sericin nanoparticles for their enhanced antihyperlipidemic activity.

The objective of this study was to demonstrate the therapeutic as well as biopolymer like characteristics of naturally occurring sericin protein for development of nanoparticulate system of atorvastatin (Atr) to improve therapeutic effect and to reduce toxicity. The sericin encapsulated atorvastatin nanoparticles (Seri-Atr NPs) were prepared by desolvation method utilizing genipin (Gn) as a natural and nontoxic crosslinker. The optimized NPs exhibited small particle size (166±0.30nm), high entrapment efficiency (91±0.69%) and uniform spherical shape with sustained release profile. Moreover, the results of pharmacokinetic studies indicated an increase in AUC0-∞ of NPs (1189.74±52.3hng/ml) compared with Atr (501.84±66hng/ml). The cellular uptake of NPs suggested an interaction of negatively charged particles with the cell surface and considerable reduction in systemic toxicity. Histopathology studies also demonstrated the therapeutic potential of sericin and cytocompatibility. Hence, genipin crosslinked sericin based nanoparticles represents a promising nanoplatform for improved therapeutic efficiency of Atr.

In Vivo Performance of Fenofibrate Formulated With Ordered Mesoporous Silica Versus 2-Marketed Formulations: A Comparative Bioavailability Study in Beagle Dogs.

The present study aims to evaluate the in vitro and in vivo performance of ordered mesoporous silica (OMS) as a carrier for the poorly water-soluble compound fenofibrate. Fenofibrate was loaded into OMS via incipient wetness impregnation to obtain a 29% drug load and formulated into capsules. Two capsule dosage forms (containing 33.5 and 16.75 mg fenofibrate, respectively) were compared with the commercially available forms-Lipanthyl(®) (fenofibrate microcrystals) and Tricor(®) (fenofibrate nanocrystals). In vitro dissolution tests showed that the amount of fenofibrate released from Lipanthyl(®) and Tricor(®) was approximately 30%, whereas approximately 66% and 60% of the drug was released from OMS capsules containing 33.5 and 16.75 mg of fenofibrate, respectively. Storage of OMS capsules loaded with 33.5 mg of fenofibrate at 25°C/60% relative humidity (RH) or 40°C/75% RH did not alter the release kinetics, nor the physical state of the compound, pointing the stability of the present formulation. The in vivo study in dogs confirmed satisfying level of safety and tolerability of fenofibrate-OMS formulation (eq. 33.5 mg) with the potential to improve the absorption of fenofibrate. Though some variability in the data, this formulation is promising to be further investigated in a clinical trial setting.

Effect of magnesium carbonate on the solubility, dissolution and oral bioavailability of fenofibric acid powder as an alkalising solubilizer.

To investigate the possibility of developing a novel oral pharmaceutical product using fenofibric acid instead of choline fenofibrate, the powder properties, solubility, dissolution and pharmacokinetics in rats of fenofibrate, choline fenofibrate and fenofibric acid were compared. Furthermore, the effect of magnesium carbonate, an alkalising agent on the solubility, dissolution and oral bioavailability of fenofibric acid was assessed, a mixture of fenofibric acid and magnesium carbonate being prepared by simple blending at a weight ratio of 2/1. The three fenofibrate derivatives showed different particle sizes and melting points with similar crystalline shape. Fenofibric acid had a significantly higher aqueous solubility and dissolution than fenofibrate, but significantly lower solubility and dissolution than choline fenofibrate. However, the fenofibric acid/magnesium carbonate mixture greatly improved the solubility and dissolution of fenofibric acid with an enhancement to levels similar with those for choline fenofibrate. Fenofibric acid gave lower plasma concentrations, AUC and Cmax values compared to choline fenofibrate in rats. However, the mixture resulted in plasma concentrations, AUC and Cmax values levels not significantly different from those for choline fenofibrate. Specifically, magnesium carbonate increased the aqueous solubility, dissolution and bioavailability of fenofibric acid by about 7.5-, 4- and 1.6-fold, respectively. Thus, the mixture of fenofibric acid and magnesium carbonate at the weight ratio of 2/1 might be a candidate for an oral pharmaceutical product with improved oral bioavailability.

Antidiabetic and hypolipidemic effects of adropinin streoptozotocin-induced type 2 diabetic rats.

BACKGROUND: To examine the effects of adropin on glucose and lipid metabolism in a rat model of Type 2 diabetes mellitus (T2DM). METHODS: T2DM were established using high-fat diet and streptozocin (STZ; 35 mg/kg/b.w.). Seven days after STZ induction, diabetic rats were randomly treated with adropin (2.1 µg/kg/day intraperitonealy) for 10 days. The study involved the evaluation of biochemical parameters, including blood glucose, total cholesterol (TC), triglycerides (TG), low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and gamma glutamyl transferase (GGT) activities. Additionally, Tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6) and inducible nitric oxide synthase (iNOS) mRNA gene expressions in pancreas tissue were determined by reverse transcription-polymerase chain reaction. RESULTS: The serum levels of insulin and adropin were determined by ELISA. Treatment with adropin showed a significant reduction in blood glucose levels, HbA1c (%), HOMA-IR and increase in HOMA-ß, serum insulin levels. In addition, intraperitoneal adropin application can reduce serum levels of TC, TG, LDL-C, and increase level of HDL-C. Adropin also effectively ameliorated the alterations in TNF-α, IL-6 and iNOS mRNA expression. CONCLUSION: The present study indicates that the adropin possesses antidiabetic and antidyslipidemic effects in T2DM (Tab. 2, Fig. 3, Ref. 32).

Lack of an Effect of Ritonavir Alone and Lopinavir-Ritonavir on the Pharmacokinetics of Fenofibric Acid in Healthy Volunteers.

STUDY OBJECTIVE: Because we previously observed a significant 41% reduction in gemfibrozil exposure after 2 weeks of lopinavir-ritonavir administration, we sought to determine the influence of lopinavir-ritonavir and ritonavir alone on the pharmacokinetics of fenofibric acid, an alternative to gemfibrozil for the treatment of elevated triglyceride levels. DESIGN: Open-label, single-sequence pharmacokinetic study. SETTING: Clinical Research Center at the National Institutes of Health. SUBJECTS: Thirteen healthy adult volunteers. INTERVENTION: Subjects received a single oral dose of fenofibrate 145 mg during three study phases: before ritonavir administration, after 2 weeks of administration of ritonavir 100 mg twice/day, and after 2 weeks of administration of lopinavir 400 mg-ritonavir 100 mg twice/day. MEASUREMENTS AND MAIN RESULTS: Serial blood samples were collected over 120 hours for determination of fenofibric acid concentrations. Fenofibric acid pharmacokinetic parameter values were compared before and after concomitant ritonavir or lopinavir-ritonavir administration. The geometric mean ratios (90% confidence intervals) for fenofibric acid area under the plasma concentration-time curve were 0.89 (0.77-1.01) after 14 days of ritonavir alone compared with baseline (p>0.05) and 0.87 (0.69-1.05) after 14 days of lopinavir-ritonavir compared with baseline (p>0.05). Study drugs were generally well tolerated; all adverse events were mild or moderate, transient, and resolved without intervention. CONCLUSION: In contrast to a significant interaction between gemfibrozil and lopinavir-ritonavir, neither lopinavir-ritonavir nor ritonavir alone altered the pharmacokinetics of fenofibric acid in healthy volunteers. These data suggest that fenofibrate remains an important option in human immunodeficiency virus-infected patients receiving common ritonavir-boosted therapy.

Development of a hydrophilic interaction liquid chromatography-tandem mass spectrometric method for the determination of kinsenoside, an antihyperlipidemic candidate, in rat plasma and its application to pharmacokinetic studies.

Kinsenoside is a major bioactive constituent isolated from Anoectochilus formosanus and is investigated as an antihyperlipidemic candidate. In this study, a rapid, sensitive, and reliable bioanalytical method was developed for the determination of kinsenoside in rat plasma using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). The plasma sample was pretreated with 1% acetic acid, followed by protein precipitation with acetonitrile:methanol (70:30). Chromatographic separation was performed on a HILIC silica column (2.1mm×100mm, 3µm). The mobile phases consisted of 0.1% acetic acid in distilled water (solvent A) and 0.1% acetic acid in acetonitrile (solvent B). A gradient program was used at a flow rate of 0.2mL/min. For mass spectrometric detection, the multiple reaction monitoring mode was used; the MRM transitions were m/z 265.2→m/z 102.9 for kinsenoside and m/z 163.3→m/z 132.1 for the internal standard (IS) nicotine in the positive ionization mode. A calibration curve was constructed in the range of 2-500ng/mL. The intra- and interday precision and accuracy were within 5%. The HILIC-MS/MS method was specific, accurate, and reproducible and was successfully applied in a pharmacokinetic study of kinsenoside in rats.

Alteration of the intravenous and oral pharmacokinetics of valsartan via the concurrent use of gemfibrozil in rats.

The present study aimed to examine the potential pharmacokinetic drug interaction between valsartan and gemfibrozil. Compared with the control given valsartan (10 mg/kg) alone, the concurrent use of gemfibrozil (10 mg/kg) significantly (p < 0.05) increased the oral exposure of valsartan in rats. In the presence of gemfibrozil, the Cmax and AUC of oral valsartan increased by 1.7- and 2.5-fold, respectively. Consequently, the oral bioavailability of valsartan was significantly higher (p < 0.05) in the presence of gemfibrozil compared with that of the control group. Furthermore, the intravenous pharmacokinetics of valsartan (1 mg/kg) was also altered by pretreatment with oral gemfibrozil (10 mg/kg). The plasma clearance of valsartan was decreased by two-fold in the presence of gemfibrozil, while the plasma half-life was not altered. In contrast, both the oral and intravenous pharmacokinetics of gemfibrozil were not affected by the concurrent use of valsartan. The cellular uptake of valsartan and gemfibrozil was also investigated by using cells overexpressing OATP1B1 or OATP1B3. Gemfibrozil and gemfibrozil 1-O-ß glucuronide inhibited the cellular uptake of valsartan with IC50 values (µm) of 39.3 and 20.4, respectively, in MDCK/OATP1B1, while they were less interactive with OATP1B3. The cellular uptake of gemfibrozil was not affected by co-incubation with valsartan in both cells. Taken together, the present study suggests the potential drug interaction between valsartan and gemfibrozil, at least in part, via the OATP1B1-mediated transport pathways during hepatic uptake. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

A new in vitro lipid digestion - in vivo absorption model to evaluate the mechanisms of drug absorption from lipid-based formulations.

PURPOSE: In vitro lipid digestion models are commonly used to screen lipid-based formulations (LBF), but in vitro-in vivo correlations are in some cases unsuccessful. Here we enhance the scope of the lipid digestion test by incorporating an absorption 'sink' into the experimental model. METHODS: An in vitro model of lipid digestion was coupled directly to a single pass in situ intestinal perfusion experiment in an anaesthetised rat. The model allowed simultaneous real-time analysis of the digestion and absorption of LBFs of fenofibrate and was employed to evaluate the influence of formulation digestion, supersaturation and precipitation on drug absorption. RESULTS: Formulations containing higher quantities of co-solvent and surfactant resulted in higher supersaturation and more rapid drug precipitation in vitro when compared to those containing higher quantities of lipid. In contrast, when the same formulations were examined using the coupled in vitro lipid digestion - in vivo absorption model, drug flux into the mesenteric vein was similar regardless of in vitro formulation performance. CONCLUSION: For some drugs, simple in vitro lipid digestion models may underestimate the potential for absorption from LBFs. Consistent with recent in vivo studies, drug absorption for rapidly absorbed drugs such as fenofibrate may occur even when drug precipitation is apparent during in vitro digestion.