Plasma Concentration Rate Research Articles

Development of a novel celecoxib-loaded nanosuspension using a wet media milling process.

To develop a novel celecoxib (CXB)-loaded drug delivery system, numerous nanosuspensions were prepared with various polymers and surfactants using a wet media milling process, and their particle sizes were subsequently determined. A 24 full factorial design was used to identify the most appropriate preparation conditions. Pharmacokinetics of the selected nanosuspension were performed in rats and compared with those of a drug powder and a commercial CXB-loaded product. Among the carriers investigated, copovidone and sodium lauryl sulphate gave the smallest particle size of the drug in the nanosuspension. In particular, the nanosuspension prepared with 5% CXB, 4% copovidone, and 0.1% sodium lauryl sulphate, under the appropriate conditions, showed a particle size of approximately 190 nm, which was physically stable for at least 8 weeks. This nanosuspension provided a significantly higher plasma concentration and AUC in rats as compared with the drug powder and the commercial product. Thus, this novel CXB-loaded nanosuspension is a promising candidate with excellent stability and enhanced oral bioavailability.

Development of an LC-MS/MS-based assay to determine artemitin in rat plasma and its application in a pharmacokinetic study.

Artemitin, a significant flavonol compound existing in Laggera pterodonta (DC.) Benth., Artemisia rupestris L, etc., is the subject of attention by researchers owing to its pharmacological activities (such as antioxidative, anti-inflammatory and antiviral). In this work, a highly sensitive and specific high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) assay combined with protein precipitation has been established and validated for determining artemitin concentration in rat plasma. Both artemitin and warfarin sodium (internal standard, IS) were separated on an Agela Venusil XBP Phenyl column through the isocratic elution mode of methanol-water containing 0.1% formic acid (80:20, v/v), at a flow rate of 0.4 mL/min. The MS/MS system was operated in a positive ion and ESI multiple reaction monitoring mode, and the multiple reaction monitoring transition was optimized as m/z 389.0 → 373.0 for artemitin and 309.2 → 163.0 for IS. The method showed good linearity in the range of 2.5-2000 ng/mL (R2 = 1.0000) and high sensitivity for artemitin with the lower limit of quantification of 2.5 ng/mL. The intra- and inter-day accuracies were 97.4-100.9 and 93.4-100.3%, respectively. The intra- and inter-day precisions were <4.8 and 6.5%, respectively. The extraction efficiency and absolute recovery were >66.5 and 71.3%, respectively. In addition, a good matrix effect of <9.5% was obtained. As a result, the method developed herein was successfully applied for the pharmacokinetic study of artemitin after an intravenous administration in rats.

Analysis of paclitaxel concentration in rat plasma by Raman spectrums combined with partial least square

Partial least square (PLS) combining with Raman spectroscopy was applied to develop predictive models for plasma paclitaxel concentration detection. In this experiment, 312 samples were scanned by Raman spectroscopy. High performance liquid chromatography (HPLC) was applied to determine the paclitaxel concentration in 312 rat plasma samples. Monte Carlo partial least square (MCPLS) method was successfully performed to identify the outliers and the numbers of calibration set. Based on the values of degree of approach ( D a ), moving window partial least square (MWPLS) was used to choose the suitable preprocessing method, optimum wavelength variables and the number of latent variables. The correlation coefficients between reference values and predictive values in both calibration set ( R c2) and validation set ( R p2) of optimum PLS model were 0.933 1 and 0.926 4, respectively. Furthermore, an independent verification test was performed on the prediction model. The results showed that the correlation error of the 20 validation samples was 9.36%±2.03%, which confirmed the well predictive ability of established PLS quantitative analysis model.

An optimized LC-MS/MS method for determination of HYNIC-3PRGD2, a new promising imaging agent for tumor targeting, in rat plasma and its application

HYNIC-3PRGD2 is used to prepare a new 99mTc-radiolabeled tracer. HYNIC-3PRGD2, which has a high binding affinity for the integrin αvβ3 due to its special structure, has become a promising tumor imaging agent for diagnosis and monitor of the clinical response to therapeutic effects of anti-tumor agents. Here, we developed and validated a method for determination of HYNIC-3PRGD2 concentration in rat plasma using ultra-high performance liquid chromatography-tandem mass spectrometry system. Following sample extraction by methanol precipitation, satisfactory separation through chromatography was achieved on an hydrophilic reverse-phase C18 column AQ (2.1 mm × 100 mm, 2.7 μm) at a flow rate of 0.2 mL·min−1 with an gradient elution using mobile phase consisting of ultrapure water and acetonitrile fortified with 0.1% formic acid respectively. The calibration curve was developed over a linear range of 3.125–100 ng·mL−1 with the lower limit of quantification of 3.125 ng·mL−1. The HYNIC-3PRGD2 and its internal standard c(RGDfK)(RK5) were detected and quantified with the multiple reaction monitoring (MRM) mode on a triple-quadrupole tandem mass spectrometer. This method was successfully validated and applied for pharmacokinetic evaluation of HYNIC-3PRGD2 during pre-clinical experiments.

Species-specific susceptibility to cannabis-induced convulsions.

Background and PurposeNumerous claims are made for cannabis' therapeutic utility upon human seizures, but concerns persist about risks. A potential confounder is the presence of both Δ9‐tetrahydrocannabinol (THC), variously reported to be pro‐ and anticonvulsant, and cannabidiol (CBD), widely confirmed as anticonvulsant. Therefore, we investigated effects of prolonged exposure to different THC/CBD cannabis extracts on seizure activity and associated measures of endocannabinoid (eCB) system signalling.Experimental ApproachCannabis extract effects on in vivo neurological and behavioural responses, and on bioanalyte levels, were measured in rats and dogs. Extract effects on seizure activity were measured using electroencephalography telemetry in rats. eCB signalling was also investigated using radioligand binding in cannabis extract‐treated rats and treatment‐naïve rat, mouse, chicken, dog and human tissue.Key ResultsProlonged exposure to cannabis extracts caused spontaneous, generalized seizures, subserved by epileptiform discharges in rats, but not dogs, and produced higher THC, but lower 11‐hydroxy‐THC (11‐OH‐THC) and CBD, plasma concentrations in rats versus dogs. In the same rats, prolonged exposure to cannabis also impaired cannabinoid type 1 receptor (CB1 receptor)‐mediated signalling. Profiling CB1 receptor expression, basal activity, extent of activation and sensitivity to THC suggested interspecies differences in eCB signalling, being more pronounced in a species that exhibited cannabis extract‐induced seizures (rat) than one that did not (dog).Conclusions and ImplicationsSustained cannabis extract treatment caused differential seizure, behavioural and bioanalyte levels between rats and dogs. Supporting radioligand binding data suggest species differences in eCB signalling. Interspecies variations may have important implications for predicting cannabis‐induced convulsions from animal models.Linked ArticlesThis article is part of a themed section on 8th European Workshop on Cannabinoid Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.10/issuetoc

Simultaneous determination of gemcitabine prodrug, gemcitabine and its major metabolite 2′, 2′-difluorodeoxyuridine in rat plasma by UFLC-MS/MS

To improve bioavailability and provide resistance to deamination, an array of gemcitabine (dFdC) prodrugs carrying the acyl modifications has been successful in the optimization of pharmacokinetic properties of dFdC, but the reports about 4-N-carbobenzoxy-dFdC (Cbz-dFdC), a dFdC prodrug bearing alkyloxycarbonyl modification, are relatively rare. Notably, in vivo enzymatic hydrolysis was an absolutely essential factor for the activation of these prodrugs, which is correlated with the anti-tumor activity. Therefore, detailed metabolism studies of Cbz-dFdC should be carried out for a more authentic pharmacodynamic evaluation. In order to detect the pharmacokinetic characteristics of Cbz-dFdC, a selective, sensitive and accurate method for the simultaneous determination of Cbz-dFdC, along with dFdC and its major metabolite dFdU in rat plasma was developed and validated using UFLC–MS/MS techniques. Column was at 40 °C for separation using an eluent with acetonitrile and 0.1% formic acid, 1 mM ammonium formate at a flow rate of 0.2 mL/min. Detection was performed using ESI source in positive ion selected reaction monitoring mode by monitoring the following ion transitions m/z 398.1 → 202.2 (Cbz-dFdC), m/z 264.1 → 112.0 (dFdC), m/z 265.3 → 113.2 (dFdU) and m/z 246.1 → 112.0 (IS). Analytes were extracted by simple precipitation with acetonitrile containing internal standards followed by liquid-liquid extraction with ethyl acetate. The calibration curves of Cbz-dFdC, dFdC and dFdU were linear in the concentration range of 2 to 500 ng/mL, 2 to 500 ng/mL and 40 to 10,000 ng/mL, respectively. The assay ranges selected for the three analytes were appropriate and minimized the need for reanalysis. All the validation data, such as intra- and inter-day precision, accuracy, selectivity and stability, were within the required limits. In conclusion, the sensitive analytical assay was selective and accurate for the determination of rat plasma concentrations of Cbz-dFdC, dFdC and dFdU from a single LC–MS/MS analysis and well-suited to support pharmacokinetic studies.

A simple and sensitive HPLC–MS/MS method for quantification of eggmanone in rat plasma and its application to pharmacokinetics

Allosteric phosphodiesterase 4 (PDE4) inhibitors are highly sought after due to their important anti-inflammatory and anti-cancer therapeutic effects. We recently identified Eggmanone, an extraordinarily selective allosteric PDE4 inhibitor displaying favorable drug properties. However, a specific analytic method of Eggmanone in serum and its pharmacokinetics have not been reported yet. In this study, we developed a rapid and sensitive high performance liquid chromatography–mass spectrometric (HPLC–MS/MS) method to determine Eggmanone concentrations in rat plasma. This assay method was validated in terms of specificity, linearity, sensitivity, accuracy, precision, matrix effect, recovery and stability, and was applied to a pharmacokinetic study in rats following intravenous injection of Eggmanone at doses of 1 and 3 mg/kg. The lower limit of quantification (LLOQ) of this assay was 5 ng/mL and the linear calibration curve was acquired with R2 > 0.99 between 5 and 1000 ng/m. The intra-day and inter-day precision was evaluated with the coefficient of variations less than 11.09%, whereas the mean accuracy ranged from 98.38% to 105.13%. The assay method exhibited good recovery and negligible matrix effect. The samples were stable under all the experimental conditions. The plasma concentrations of Eggmanone were detected and quantified over 24 h with the terminal elimination half-live of 3.57 ± 1.80 h and 5.92 ± 3.34 h for the low dose (1 mg/kg) and high dose (3 mg/kg) respectively. In summary, the present method provides a robust, fast and sensitive analytical approach for quantification of Eggmanone in plasma and was successfully applied to a pharmacokinetic study in rats.

Enalapril decreases rat plasma concentration of TMAO, a gut bacteria-derived cardiovascular marker

Introduction: Increased plasma level of trimethylamine N-oxide (TMAO), a bacterial metabolite of choline, is associated with an increased cardiovascular risk. Indoxyl sulfate, a bacterial metabolite of tryptophan, is thought to be associated with higher mortality in cardiorenal syndrome. We hypothesized that enalapril, a well-established drug reducing cardiovascular mortality, may affect the plasma level of gut bacteria-derived metabolites and gut bacteria composition.Materials and methods: 14–16-week-old Wistar rats were maintained either on water (controls) or water solution of enalapril for two weeks (5.3 or 12.6 mg/kg b.w.). Blood plasma and urine were analyzed for the concentration of TMAO and indoxyl sulfate using liquid chromatography coupled with triple-quadrupole mass spectrometry. Gut bacteria composition was analyzed with 16S rRNA gene sequence analysis.Results: Rats treated with enalapril showed a significantly lower plasma TMAO level and a trend towards higher 24 h urine excretion of TMA and TMAO. Plasma indoxyl level was similar between the groups. There was no significant difference between the groups in gut bacteria composition.Conclusions: Enalapril decreases rat plasma TMAO, but does not affect the plasma level of indoxyl sulfate and gut bacteria composition. The enalapril-induced decrease in plasma TMAO level may be of therapeutic and diagnostic importance.

Facile synthesis of boronic acid-functionalized magnetic metal-organic frameworks for selective extraction and quantification of catecholamines in rat plasma.

Precise determination of the endogenous catecholamines, dopamine (DA), epinephrine (E) and norepinephrine (NE) faces substantial challenges due to their low physiological concentrations in plasma. We synthesized, for the first time, a magnetic metal–organic framework (MIL-100) composite with boronic acid-functionalized pore-walls (denoted as MG@MIL-100-B composite) using a metal–ligand-fragment coassembly (MLFC) strategy. The composites were then applied as an effective magnetic solid-phase extraction (SPE) sorbent for determination of trace catecholamine concentrations in rat plasma through coupling with HPLC-MS/MS. The obtained nano-composites exhibited high magnetic responsivity, uniform mesopores, large specific surface area, and boronic acid-functionalized inner pore-walls. Catecholamines in rat plasma were extracted through interaction between the cis-diol structures and the boronic acid groups in the MG@MIL-100-B composites. Extraction conditions were optimized by studying SPE parameters including adsorption and desorption time, elution solvent type, pH conditions and adsorbent amount. With our approach, the detection limits (S/N = 3) were as low as 0.005 ng mL−1 for DA and E, and 0.02 ng mL−1 for NE. Intra- and inter-day precision ranged from 2.84–6.63% (n = 6) and 5.70–11.44% (n = 6), respectively. Recoveries from spiking experiments also showed satisfactory results of 94.40–109.51%. Finally, the MG@MIL-100-B composites were applied successfully to determine catecholamine concentrations in rat plasma.

Investigation of the synergistic effects of haloperidol combined with Calculus Bovis Sativus in treating MK-801-induced schizophrenia in rats.

Clinical studies that focused on treating schizophrenia showed that Calculus Bovis Sativus (CBS), a substitute of Calculus Bovis, when used in combination with haloperidol could significantly lower the dosage of haloperidol compared with treatment with haloperidol alone, whereas efficacy was maintained. The aim of this study was to investigate the synergetic anti-schizophrenia effects in rats using CBS in combination with haloperidol. An open field test was conducted to verify the pharmacodynamic effects of a combination treatment of CBS and haloperidol on MK-801-induced schizophrenic rats. Rat plasma concentrations of intragastric haloperidol and intravenous haloperidol were determined after oral administration of a single dose or 1-week of pretreatment with CBS (50 mg/kg). The pharmacodynamic data showed a significant decrease in locomotor activity and an increase in the percentage of the central distance when haloperidol was concomitantly administered with CBS compared with haloperidol administration alone. The AUC0-∞ and Cmax of haloperidol in the orally coadministered groups were significantly higher compared with the oral treatment with haloperidol alone. In conclusion, oral coadministration of CBS with haloperidol resulted in a synergistic effect in rats. The enhanced oral bioavailability of haloperidol when combined with CBS might be attributed to the interaction between them.

Regulation of the kynurenine metabolism pathway by Xiaoyao San and the underlying effect in the hippocampus of the depressed rat

Ethnopharmacological relevanceXiaoyao San (XYS) is a classic Chinese herbal formula for treatment of depression. The present study aimed to investigate the antidepressant effects of XYS in a rat model of chronic unpredictable mild stress (CUMS) and the underlying mechanisms. Materials and methodsA CUMS rat model of depression was established via 4 weeks of unpredictable stimulation. Then the rats were orally administered paroxetine and XYS for 2 weeks with continued stress. Behavioral assessments, including an open field test (OFT), sucrose preference test (SPT) and forced swim test (FST), were conducted to evaluate the antidepressant effects of XYS. The concentrations in rat plasma of tryptophan (Trp) and its metabolic products, including kynurenine (Kyn) and quinolinic acid (QUIN), were determined using high performance liquid chromatography tandem mass spectrometry with electrochemical detection (HPLC-MS/MS). The mRNA and protein levels in rat hippocampus of depression-related brain derived neurotrophic factor (BDNF), cyclic AMP response element binding protein (CREB) and nerve cell adhesion molecule (NCAM) were determined by real-time qPCR and Western blot, respectively. Enzyme Linked Immunosorbent Assay (ELISA) was used to detect the activities of indoleamine 2,3-dioxygenase (IDO) and kynurenine-3-monooxygenase (KMO) in rat plasma. ResultsThe results showed that a successful CUMS rat model was established through 4 weeks of continuous unpredictable stimulation, as indicated by the significant decrease in locomotor activity and increase in immobility time in the OFT, reduction in body weight and food intake etc. Compared with the normal group, the concentrations of Kyn and QUIN had significantly (p < 0.05) decreased at day 28 in the control group, but then improved after drug treatment with paroxetine and XYS. There were no obvious changes in the activities of IDO and KMO. Compared with the normal group, the mRNA of NCAM, CREB and BDNF were significantly down-regulated (p < 0.001) in the control group, BDNF gene was up-regulated by paroxetine or XYS treatment, NCAM and CREB gene did not change in XYS group, protein expressions of BDNF and CREB were significantly increased, and NCAM was significantly reduced (p < 0.05). ConclusionsXYS reversed the abnormalities of the tryptophan-kynurenine metabolic pathways in depressed rats and achieved an excellent antidepressant effect. Its direct impact may be observed as changes in biological indicators in rat hippocampus tissue.

Effect investigation of coumarin constituents in Angelica dahurica on pharmacokinetics of docetaxel by LC-MS

The study was aimed to establish a liquid chromatography-tandem mass spectrometric method for the determination of the docetaxel concentration in rat plasma, and study the effect of coumarin constituents (imperatorin, isoimperatorin and oxypeucedanin) in Angelica dahurica on pharmacokinetics of docetaxel.Plasma was precipitated with acetonitrile and determined by LC-MS method with Paclitaxel as an internal standard. The specificity, linearity, range, accuracy, precision and stability of the method were suitable for the determination of docetaxel in plasma.Six sprague-dawley rats in each group received intragastric administration of docetaxel (50 mg•kg⁻¹), oxypeucedanin (8 mg•kg⁻¹) combined with docetaxel (50 mg•kg⁻¹), imperatorin (15 mg•kg⁻¹) combined with docetaxel (50 mg•kg⁻¹), and isoimperatorin(15 mg•kg⁻¹) combined with docetaxel (50 mg•kg⁻¹).Their drug plasma concentration was determined by LC-MS with Paclitaxel as an internal standard to draw plasma concentration-time curve, and the phamacokinetic parameters were calculated by DAS 2.0. The results showed that the phamacokinetic parameters of docetaxel all had notable changes when combined with imperatorin, isoimperatorin, and oxypeucedanin, respectively. The phamacokinetic parameters AUC and Cmax were significantly increased, indicating that coumarin constituents in Angelica dahurica could promote the oral bioavailability of docetaxel, and their effects were in the following order: oxypeucedanin> isoimperatorin> imperatorin.

Sex-specific risk assessment of PFHxS using a physiologically based pharmacokinetic model.

Perfluorohexanesulfonate (PFHxS), which belongs to the group of perfluoroalkyl and polyfluoroalkyl substances (PFASs), has been extensively used in industry and subsequently detected in the environment. Its use may be problematic, as PFHxS is known to induce neuronal cell death, and has been associated with early onset menopause in women and with attention deficit/hyperactivity disorder. Due to these impending issues, the aim of this study is to develop and evaluate a physiologically based pharmacokinetic (PBPK) model for PFHxS in male and female rats, and apply this to a human health risk assessment. We conducted this study in vivo after the oral or intravenous administration of PFHxS in male (dose of 10mg/kg) and female rats (dose of 0.5-10mg/kg). The biological samples consisted of plasma, nine tissues, urine, and feces. We analyzed the sample using ultra-liquid chromatography coupled tandem mass spectrometry (UPLC-MS/MS). Our findings showed the tissue-plasma partition coefficients for PFHxS were highest in the liver. The predicted rat plasma and tissue concentrations using a simulation fitted well with the observed values. We extrapolated the PBPK model in male and female rats to a human PBPK model of PFHxS based on human physiological parameters. The reference doses of 0.711µg/kg/day (male) and 0.159µg/kg/day (female) and external doses of 0.007µg/kg/day (male) and 0.006µg/kg/day (female) for human risk assessment were estimated using Korean biomonitoring values. This study provides valuable insight into human health risk assessment regarding PFHxS exposure.

Preparation and characterization of solid dispersion of novel dual antiplatelet agent BF061 for oral use

Combined antiplatelet therapy has been widely used to treat arterial thrombotic diseases with improved efficacy and safety. In our pursuit to seek more efficacious and safer antiplatelet drugs, we developed a novel antiplatelet agent BF061 targeting both P2Y12 and phosphodiesterase. In FeCl3 induced mouse mesenteric arterial thrombosis model, BF061 intravenous administration effectively prevented thrombus formation similarly to clopidogrel with significantly less bleeding. BF061 oral administration is ineffective due to low plasma concentration. To increase BF061 plasma concentration, we developed several solid dispersions (SD) of BF061. Among them, a mixture of BF061/Soluplus (1:5) prepared by hot-melt extrusion significantly enhanced BF061 plasma concentration in rats after oral administration. Differential scanning calorimetry (DSC) and X-ray powder diffraction (PXRD) demonstrated the formation of amorphous BF061. Using rat arterio-venous (A-V) shunt arterial thrombosis model, BF061 SD1 100 mg/kg oral administration prevented thrombosis similarly to clopidogrel (10 mg/kg, p.o.). Notably, at the doses achieving antithrombotic effects similar to clopidogrel, BF061 SD1 oral administration did not significantly increase bleeding time in rats (15.9 ± 3.7 min, compared to 11.2 ± 1.0 min in saline group), in contrast to the significantly increased bleeding time in clopidogrel group (more than 60 min). In conclusion, we successfully prepared a solid dispersion of an efficacious and safe antiplatelet agent for oral use. Given the success of combined antiplatelet therapy in clinical practice and the bleeding concern, BF061 which targets both P2Y12 and phosphodiesterase without significant bleeding deserves further development.

Sensitive liquid chromatography/tandem mass spectrometry method for the determination of two novel highly lipophilic anticancer drug candidates in rat plasma and tissues.

A simple and sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for determination of two highly lipophilic anticancer drug candidates, LG1980 and GH501, in rat plasma and tissues (liver, kidney and femur bones). LG1980 and GH501 were extracted from rat plasma and tissue homogenates using liquid-liquid extraction. The method provided a linear range of 1.0-200.0 ng/mL for GH501 in plasma and LG1980 in plasma and liver. For both analytes in other tissue homogenates the linear range was 2.0-400.0 ng/mL. The method was validated with precision within 15% relative standard deviation, accuracy within 15% relative error and a consistent recovery. This method has been successfully applied in two preclinical studies for LG1980 and GH501 to determine their concentrations in rat plasma, liver, kidney and bone over 24 h after intravenous injection of compounds.

Gas chromatography/negative chemical ionization mass spectrometry of transfluthrin in rat plasma and brain.

Transfluthrin is a relatively non-toxic rapid-acting synthetic pyrethroid insecticide. It is widely used in household and hygiene products. A sensitive and accurate bioanalytical method is required for quantification of its concentration in plasma and its potential target organ, the brain for studies to assess its health effects and toxicokinetics in mammals. The samples were prepared by liquid-liquid extraction. Gas chromatography mass spectrometry (GC/MS) analysis was performed for the determination of transfluthrin in biological samples with an overall method run time of 15min. Transfluthrin was quantified using selected-ion monitoring (SIM) in the negative chemical ionization (NCI) mode. Chromatographic separation was achieved using a Zebron® ZB5-MS GC column operating with 1mL/min constant flow helium. Cis-Permethrin was used as the internal standard. The method was validated to be precise and accurate within the linear range of 1.0-400.0ng/mL in plasma and 4.0-400.0ng/mL in brain homogenate, based on a 100μL sample volume for both matrices. This method was applied to samples following administration of a 10mg/kg oral dose to male adult rats. The plasma concentrations were observed to be 11.70±5.69ng/mL and brain concentrations 12.09±3.15ng/g when measured 2h post-dose. A rapid GC/NCI-MS method was demonstrated to be sensitive, specific, precise and accurate for the quantification of transfluthrin in rat plasma and brain. The optimized method was successfully used to quantify the rat plasma and brain concentrations of transfluthrin 2h after the oral dosing of Sprague-Dawley rats.

BHX, a novel pyrazoline derivative, inhibits breast cancer cell invasion by reversing the epithelial-mesenchymal transition and down-regulating Wnt/\u03b2-catenin signalling

The novel pyrazoline derivative, BHX, has recently been shown to exhibit potent anti-tumour activity by blocking the Wnt/β-catenin signalling pathway. However, its effect on breast cancer growth and invasion are unknown. Our results show that BHX suppresses MDA-MB-231 cell viability and colony formation in a dose-dependent manner, and induces apoptosis and G0/G1 phase arrest. BHX-treated breast cancer cells showed morphological characteristics of cells undergoing apoptosis. Furthermore, BHX inhibited cell migration and invasion, which was associated with increased E-cadherin mRNA and protein expression, and down-regulation of SNAIL and vimentin. In addition, BHX induced the generation of intracellular ROS and decreased β-catenin protein and mRNA expression. We used a mouse xenograft model to investigate the effects of BHX in vivo, where the growth of MDA-MB-231 xenografted tumours was suppressed in nude mice treated continuously with BHX for 21 days. Finally, the rat plasma concentration of BHX was measured by ultra-performance liquid-chromatography tandem mass spectrometry and the pharmacokinetic parameters of BHX were processed by non-compartmental analysis. In conclusion, BHX merits further study as a novel therapeutic small molecule for the treatment of breast cancer.

Lead Optimization Generates CYP11B1 Inhibitors of Pyridylmethyl Isoxazole Type with Improved Pharmacological Profile for the Treatment of Cushing's Disease.

Cushing's disease, characterized by elevated plasma cortisol levels, can be controlled by inhibition of 11β-hydroxylase (CYP11B1). The previously identified selective and potent CYP11B1 inhibitor 5-((5-methylpyridin-3-yl)methyl)-2-phenylpyridine Ref 7 (IC50= 2 nM) exhibited promutagenic potential as well as very low oral bioavailability in rats (F = 2%) and was therefore modified to overcome these drawbacks. Successful lead optimization resulted in similarly potent and selective 5-((5-methoxypyridin-3-yl)methyl)-3-phenylisoxazole 25 (IC50 = 2 nM, 14-fold selectivity over CYP11B2), exhibiting a superior pharmacological profile with no mutagenic potential. Furthermore, compound 25 inhibited rat CYP11B1 (IC50 = 2 μM) and showed a high oral bioavailability (F = 50%) and sufficient plasma concentrations in rats, providing an excellent starting point for a proof-of-principle study.

Invitro and invivo cytochrome P450 3A enzyme inhibition by Aframomum melegueta and Denniettia tripetala extracts.

To evaluate the invitro and invivo inhibitory effects of two commonly used herbs, Aframomum melegueta (A.melengueta) and Dennettia tripetala (D.tripetala) on CYP 3A enzymes. Invitro inhibition of the enzymes were assessed with microsomes extracted from female albino rats using erythromycin-N-demethylation assay (EMND) method while their invivo effects were measured by estimating simvastatin plasma concentrations in rats. Pharmacokinetic parameters were determined using non-compartmental analysis as implemented in WinNonlin pharmacokinetic program. EMND assay with intestinal microsomes indicated that aqueous extracts of D.tripetala and A.melengueta significantly (P<0.05) inhibited intestinal CYP 3A activity at both 50μg and 100μg concentrations. Petroleum ether extract of D.tripetala and ethanol extracts of A.melengueta inhibited intestinal CYP3A activity at 100μg but not at 50μg concentrations. All the extracts showed an invitro dose dependent CYP 3A inhibition with liver microsomes. Invivo analysis showed that pre-treatment with the extracts enhanced systemic absorption of simvastatin with reductions in metabolizing enzymes activity as indicated in significant increases in maximal concentration, area under curve, area under moment curve and mean resident time of simvastatin (P<0.05). Herbal preparations containing these plants' extracts should be used with caution especially in patients on CYP450 3A substrate medications.

Pharmacokinetics and correlation between in vitro release and in vivo absorption of bio-adhesive pellets of panax notoginseng saponins

The present study was designed to prepare and compare bio-adhesive pellets of panax notoginseng saponins (PNS) with hydroxy propyl methyl cellulose (HPMC), chitosan, and chitosan : carbomer, explore the influence of different bio-adhesive materials on pharmacokinetics behaviors of PNSbio-adhesive pellets, and evaluate the correlation between in vivo absorption and in vitro release (IVIVC). In order to predict the in vivo concentration-time profile by the in vitro release data of bio-adhesive pellets, the release experiment was performed using the rotating basket method in pH 6.8 phosphate buffer. The PNS concentrations in rat plasma were analyzed by HPLC-MS-MS method and the relative bioavailability and other pharmacokinetic parameters were estimated using Kinetica4.4 pharmacokinetic software. Numerical deconvolution method was used to evaluate IVIVC. Our results indicated that, compared with ordinary pellets, PNS bio-adhesive pellets showed increased oral bioavailability by 1.45 to 3.20 times, increased Cmax, and extended MRT. What's more, the release behavior of drug in HPMC pellets was shown to follow a Fickian diffusion mechanism, a synergetic function of diffusion and skeleton corrosion. The in vitro release and the in vivo biological activity had a good correlation, demonstrating that the PNS bio-adhesive pellets had a better sustained release. Numerical deconvolution technique showed the advantage in evaluation of IVIVC for self-designed bio-adhesive pellets with HPMC. In conclusion, the in vitro release data of bio-adhesive pellets with HPMC can predict its concentration-time profile in vivo.