Pharmacokinetic studies of six major 2-(2-phenylethyl) chromones in rat plasma using ultra high performance liquid chromatography with tandem mass spectrometry after oral administration of agarwood ethanol extract.

In this study, a simple, quick, sensitive and reliable method utilizing ultra-high performance liquid chromatography with tandem mass spectrometry method was validated for simultaneous quantification of six main 2-(2-phenylethyl) chromones, including agarotetrol, isoagarotetrol, (5S,6R,7R,8S)-5,6,7,8-tetrahydroxy-(4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one, 8-chloro-2-(2-phenyl ethyl)-5,6,7-trihydroxy-5,6,7,8-tetrahydrochromone, 6,7-dimethoxy-2-(2-phenylethyl) chromone, and 2-(2-phenylethyl) chromone in rat plasma after oral administration of agarwood ethanol extract. Separation was performed on a Waters ACQUITY UPLC BEH C18 column (2.1 × 100 mm, 1.7 µm) using gradient elution with mobile phase of 0.2% formic acid-water and acetonitrile. The tandem mass was performed in the multiple reaction monitoring mode with positive ionization. The calibration curves indicated good linearity (r2  > 0.99) over the corresponding concentration range. The precision and accuracy were within the acceptable range. Mean absolute recoveries of all analytes were between 73.31% and 94.76%, and the relative standard deviations of matrix effects were not higher than 15%. The six analytes were proven to be stable during sample storage and analysis procedures. The validated method was successfully applied to pharmacokinetic study of six 2-(2-phenylethyl) chromones in rat after oral administration of agarwood ethanol extract for the first time. This study could serve as a reference and provide theoretical guidance for further pharmacodynamic research and clinical applications of agarwood.

Simultaneous bioanalysis and pharmacokinetic interaction study of acebrophylline, levocetirizine and pranlukast in Sprague-Dawley rats.

The combination of acebrophylline (ABP), levocetirizine (LCZ) and pranlukast (PRN) is used to treat allergic rhinitis, asthma, hay-fever and other conditions where patients experience difficulty in breathing. This study was carried out with the aim of developing and validating a reverse-phase high-performance liquid chromatographic bioanalytical method to simultaneously quantitate ABP, LCZ and PRN in rat plasma. The objective also includes determination of the pharmacokinetic interaction of these three drugs after administration via the oral route after individual and combination treatment in rat. Optimum resolution between the analytes was observed with a C18 Kinetex column (250 mm × 4.6 mm × 5 µm). The chromatography was performed in a gradient elution mode with a 1 mL/min flow rate. The calibration curves were linear over the concentration range of 100-1600 ng/mL. The intra- and inter-day precision and accuracy were found to be within acceptable limits as specified in US Food and Drug Administration guideline for bioanalytical method validation. The analytes were stable on the bench-top (8 h), after three freeze-thaw cycles, in the autosampler (8 h) and as a dry extract (-80°C for 48 h). The statistical results of the pharmacokinetic study in Sprague-Dawley rats showed a significant change in pharmacokinetic parameters for PRN upon co-administration of the three drugs.

A randomized phase I study to evaluate the safety, tolerability, pharmacokinetics and food-effect of Iguratimod in healthy adult volunteers.

OBJECTIVE: The aim of this study was to investigate the safety, maximum tolerated dose and pharmacokinetics (PK) of iguratimod and the effect of food on PK parameters in healthy adult volunteers. METHODS: This phase 1 study consisted of four parts. Part 1 was a single-ascending dose (3.125, 6.25, 12.5, 25, 50, 75 mg) study to assess the maximum tolerated dose and safety of iguratimod. Part 2 was a single-ascending dose study to analyze the pharmacokinetic (PK) parameters of iguratimod; subjects were divided into three groups, with each group receiving iguratimod at a different dose (25, 50 or 75 mg). Part 3 was designed to compare the pharmacokinetic parameters of iguratimod between single-dose and multiple-dose administration; subjects were divided into two groups, with one group receiving a single dose of 50 mg on day 1 and the other group receiving a multiple dose of 50 mg, once every day, until a stable plasma concentration had been achieved. The aim of part 4 was to evaluate the effect of food on the pharmacokinetic parameters of iguratimod; subjects were divided into two groups, namely a fed group and a fasted group, with each group receiving a single 50 mg dose of iguratimod on day 1. Following a 14-day washout period, the two groups were crossed-over and received a single dose of 50 mg iguratimod on day 15. RESULTS: In part 1 of the study, iguratimod at doses ranging from 3.125 to 50 mg were well tolerated, with most adverse effects (AEs) being mild; no severe AEs occurred. In part 2, there were no significant differences in Tmax, T1/2, Ka and V/F among volunteers receiving doses of 25, 50 and 75 mg iguratimod. The Cmax and AUC0-last in volunteers receiving 75 mg iguratimod were higher than those in volunteers receiving 25 and 50 mg. The Cmax was linear from 25 to 75 mg, with a correlation coefficient (r 2) of 0.9808. The AUC0-last was also linear from 25 to 75 mg, with an r 2 of 0.9839. In part 3, in subjects receiving multiple doses of 50 mg, the T1/2 was 10.25 h, Tmax was 3.63 h, Cmax was 1.88 mg/L, AUC0-last was 31.88 mg/L h, Vd was 1.16 L and Ka was 0.87 1/h.There were no significant differences in the Cmax, AUC0-last, Ka and V/F between the single-dose and multiple-dose groups; there were, however, significant differences in Tmax and T1/2 between the two groups. In part 4, there were no significant differences in T1/2, AUC0-last, Ka and V/F between the fed group and fasted group; however, food may promote the absorption of iguratimod. CONCLUSIONS: The maximum tolerated dose for iguratimod was confirmed to be 50 mg. The ingestion of food was able to increase the peak concentration of iguratimod and shorten the time to peak concentration. Therefore, based on our results, iguratimod can be administered with food. The PK profile and metabolic effects of iguratimod support further clinical development for its application in treating autoimmune diseases.

Development and validation of a sensitive UHPLC-MS/MS method for quantitative analysis of farrerol in rat plasma: Application to pharmacokinetic and bioavailability studies.

Farrerol is a 2,3-dihydro-flavonoid isolated from rhododendron. In this study, a sensitive and selective ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the determination of farrerol in rat plasma. Liquid-liquid extraction by ethyl ether was used for sample preparation. Chromatographic separation was achieved on an Agilent UHPLC XDB-C18 column (2.1 × 100 mm, 1.8 µm) with water and methanol (30:70, v/v) as the mobile phase. An electrospray source was applied and operated in negative ion mode; selection reaction monitoring was used for quantification using target fragment ions m/z 299 → 179 for farrerol and m/z 267 → 252 for internal standard. Calibration plots were linear in the range of 2.88-1440 ng/mL for farrerol in rat plasma. Intra- and inter-day precisions were <11.6%, and the accuracy ranged from -13.9 to 11.9%. The UHPLC-MS/MS method was successfully applied in pharmacokinetics and bioavailability studies of farrerol in rats.

Pharmacokinetic interactions in mice between irinotecan and MBL-II-141, an ABCG2 inhibitor.

PURPOSE: The chromone derivative MBL-II-141, specifically designed to inhibit ABCG2, was previously demonstrated to combine strong inhibition potency, low toxicity and good efficiency in reversing resistance to irinotecan in a xenografted mouse model. Here, the pharmacokinetic interactions in mice between irinotecan, its active metabolite SN-38 and MBL-II-141 were characterized quantitatively in the blood and in the brain. METHODS: Compartmental models were used to fit the data. Goodness-of-fit was assessed by simulation-based diagnostic tools. RESULTS: Irinotecan increased the MBL-II-141 apparent clearance and Vss 1.5-fold, probably by increasing the MBL-II-141 unbound fraction. MBL-II-141 decreased the total apparent clearance of irinotecan by 23%, by decreasing its biliary clearance. MBL-II-141 increased 3-fold the brain accumulation of irinotecan, as a result of the rise of systemic exposure combined with the inhibition of ABCG2-mediated efflux at the blood-brain barrier. Finally, SN-38 exposure was increased by 1.16-fold under treatment with MBL-II-141, owing to the higher irinotecan exposure with increased metabolism towards the formation of SN-38. CONCLUSIONS: These results may help to anticipate the pharmacokinetic interactions between MBL-II-141 and other ABCG2 substrates. The irinotecan-MBL-II-141 interaction is also expected to occur in humans. Copyright © 2017 John Wiley & Sons, Ltd.

Polysaccharide enhances Radix Saposhnikoviae efficacy through inhibiting chromones decomposition in intestinal tract.

Vegetative but not reproductive stage of Saposhnikovia divaricate (Turxz.) schischk possesses pharmacological activities. However, our recent study showed that reproductive S. divaricate supplemented with polysaccharide showed evidently elevated pharmacological activities and increased cimifugin content in rat serum. The aims of present study were to assess the influence of polysaccharides on the chromones pharmacological activities in Radix Saposhnikoviae (RS), the dried root of vegetative stage of S. divaricate, and to explore the underlying mechanisms. Only cimifugin was detected in the plasma of chromone treated animals and RS polysaccharide significantly increased the plasma content of cimifugin. It was shown that neither cimifugin absorption nor glycoside components transformation in simulated digestive fluid was affected by RS polysaccharide. However, a significant promotion of transformation of cimifugin to more stable prime-O-glucosylcimifugin (PGCN) by RS polysaccharide, and a protective effect of polysaccharide on chromone components were observed in small intestine solutions. Meanwhile, RS polysaccharide produced a significant elevation of cimifugin and PGCN concentration in vivo. Based on these findings, we concluded that RS polysaccharide could greatly increase the content of cimifugin, which might be related to its degradation-proof effect on cimifugin, via transforming cimifugin to comparatively more stable PGCN and spatial structure protection.

Improving dissolution and oral bioavailability of pranlukast hemihydrate by particle surface modification with surfactants and homogenization.

The present study was carried out to develop an oral formulation of pranlukast hemihydrate with improved dissolution and oral bioavailability using a surface-modified microparticle. Based on solubility measurements, surface-modified pranlukast hemihydrate microparticles were manufactured using the spray-drying method with hydroxypropylmethyl cellulose, sucrose laurate, and water and without the use of an organic solvent. The hydrophilicity of the surface-modified pranlukast hemihydrate microparticle increased, leading to enhanced dissolution and oral bioavailability of pranlukast hemihydrate without a change in crystallinity. The surface-modified microparticles with an hydroxypropylmethyl cellulose/sucrose laurate ratio of 1:2 showed rapid dissolution of up to 85% within 30 minutes in dissolution medium (pH 6.8) and oral bioavailability higher than that of the commercial product, with approximately 2.5-fold and 3.9-fold increases in area under the curve (AUC 0 → 12 h) and peak plasma concentration, respectively. Therefore, the surface-modified microparticle is an effective oral drug delivery system for the poorly water-soluble therapeutic pranlukast hemihydrate.

Pharmacokinetics, Tissue Distribution and Plasma Protein Binding Studies of Rohitukine: A Potent Anti-hyperlipidemic Agent.

Rohitukine (RH) is a chromone alkaloid considered as one of the major active component of Dysoxylum binectariferum, exhibiting diverse pharmacological activities such as anti-hyperlipidemic, anti-cancer, anti-inflammatory, immuno-modulatory, anti-leishmanial, anti ulcer and anti-fertility. There's still a lack of information of RH, inclusive of pharmacokinetics, tissue distribution and excretion, in vivo studies in experimental animals, such as hamster and rats. In this study, a selective and sensitive bioanalytical method was developed and validated using HPLC-UV system. The assay was applied to estimate pharmacokinetics, tissue distribution and excretion of RH in hamster at 50 mg/kg oral dose. It rapidly reached systemic circulation and distributed to various tissues, and highest concentration was observed in liver. The pharmacokinetic parameters such as clearance (CL/F) was 3.95±0.9 L/h/kg, volume of distribution (Vd/F) was 17.34±11.34 L/kg and elimination half-life was 2.62±1.34 h. RH shows moderate protein binding ~ 60% and found stable in gastro-intestinal fluid, a property that favors oral administration.

Analysis and pharmacokinetic study of polyphyllin H in beagle dog plasma after oral administration of Rhizoma Paridis extracts by LC-MS/MS.

A highly sensitive, rapid assay method has been developed and validated for the analysis of polyphyllin H in beagle dog plasma with liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the positive-ion mode. The assay procedure involves extraction of polyphyllin H and ginsenoside Re (IS) from beagle dog plasma. Chromatographic separation was carried out on an Agilent Zorbax XDB-C18 (100 × 2.1 mm, 1.8µm) column by isocratic elution with acetonitrile and water (50:50, v/v) at a flow rate of 0.25 mL/min with a total run time of 2.5 min. The MS/MS ion transitions monitored were m/z 869.60 → 869.60 for polyphyllin H and m/z 969.60 → 969.60 for IS. [corrected] Linear responses were obtained for polyphyllin H ranging from 1 to 50 ng/mL. The intra-and inter-day precisions (RSDs) <1.77 and 3.39% and the extraction recovery ranged from 91.89 to 93.33% with RSD <2.68%. Stability studies showed that polyphyllin H was stable in the preparation and analytical process. The results indicated that the validated method was successfully used to determine the concentration-time profiles of polyphyllin H.

Development of a gastric retentive system as a sustained-release formulation of pranlukast hydrate and its subsequent in vivo verification in human studies.

Pranlukast hydrate was demonstrated in a human site-of-absorption study to have extremely poor absorption properties in the lower gastrointestinal tract. The ratios of AUC0-24 in the distal small bowel and colon compared to stomach delivery were approximately 1/7 and 1/70, respectively. As a consequence, a gastroretentive double-layered tablet formulation (gastric swelling system; GSS), consisting of a swelling layer and a drug release layer, was developed for once-daily dosing. To study the gastric retention of the optimized GSS, an in vivo gamma scintigraphic study was carried out in nine healthy volunteers. The transit profiles demonstrated that the GSS was retained in the stomach for more than 10h. The plasma profile was prolonged, especially following administration after an evening meal. The human data validated the design concept and suggest that GSS could be a promising approach for the development of sustained-release formulation for drugs with a limited absorption window in the upper small bowel.

Determination of sec-O-glucosylhamaudol in rat plasma by gradient elution liquid chromatography-mass spectrometry.

Sec-O-glucosylhamaudol is one of the major bioactive compounds of the Saposhnikoviae Radix. A simple and selective liquid chromatography-mass spectrometry (LC-MS) method for determination of sec-O-glucosylhamaudol in rat plasma was developed. After addition of carbamazepine as internal standard (IS), protein precipitation with acetonitrile-methanol (9:1, v/v) was used as sample preparation. Chromatographic separation was achieved on a Zorbax SB-C18 (2.1mm×150mm, 5µm) column with acetonitrile-0.1% formic acid in water as mobile phase with gradient elution. Electrospray ionization (ESI) source was applied and operated in positive ion mode; selective ion monitoring (SIM) mode was used for quantification using target fragment ions m/z 439 for sec-O-glucosylhamaudol and m/z 237 for the IS. Calibration plots were linear over the range of 50-8000ng/mL for sec-O-glucosylhamaudol in rat plasma. Mean recovery of sec-O-glucosylhamaudol in plasma was in the range of 74.8-83.7%. Intra-day and inter-day precision were both <15%. This method was successfully applied in pharmacokinetic study after intravenous administration of 2.5mg/kg sec-O-glucosylhamaudol in rats.

[Studies on effects of calycosin-7-O-ß-D-glucoside on prim-O-glucosylcimifugin and cimifugin in vivo pharmacokinetics].

Study on the effects of Astragali Radix main active flavone calycosin-7-O-ß-D-glucoside on Saposhnikoviae Radix main active ingredients prim-O-glucosylcimifugin and cimifugin, a UPLC-MS/MS method for simultaneous determination of prim-O-glucosylcimifugin and cimifugin in rat plasma was established, and the comparative pharmacokinetics of prim-O-glucosylcimifugin and cimifugin after oral administration of prim-O-glucosylcimifugin and calycosin-7-O-ß-D-glucoside-prim-O-glucosylcimifugin to rats were carried out, which might be conductive in exploring the rationality of Astragali Radix - Saposhnikoviae Radix herb couple. Twelve male SD rats were divided into two groups. Prim-O-glucosylcimifugin and cimifugin in rat plasma of different time points after oral administration of prim-O-glucosylcimifugin and calycosin-7-O-ß-D-glucoside - prim-O-glucosylcimifugin to rats were determinated. And the main pharmacokinetic parameters were investigated using DAS 3. 2. 4. The established method was rapid, accurate and sensitive for simultaneous determination of prim-O-glucosylcimifugin and cimifugin in rat plasma. The analysis was performed on a Waters Acquity BEH C18 column (2.1 mm x 100 mm, 1.7 µm) with the mixture of acetonitrile and 0.1% formic acid/water as mobile phase, and the gradient elution at a flow rate of 0.3 mL x min(-1). The analytes were detected by tandem mass spectrometry with the electrospray ionization (ESI) source and in the multiple reaction monitoring (MRM) mode. Compared with prim-O-glucosylcimifugin group, the AUC(0-t)., and AUC(0-∞) of p-O-glucosylcimifugin as well as the C(max) of cimifugin significantly increased (P < 0.05) in calycosin-7-O-ß-D-glucoside-prim-O-glucosylcimifugin group. Calycosin-7-O-ß-D-glucoside could enhance the absorption of prim-O-glucosylcimifugin and cimifugin and improve the bioavailability, explaining preliminarily the rationality of Astragali Radix-Saposhnikoviae Radix herb couple.

Self-microemulsifying drug-delivery system for improved oral bioavailability of pranlukast hemihydrate: preparation and evaluation.

The purpose of the present investigation was to develop and evaluate a self-microemulsifying drug delivery system (SMEDDS) for improving the oral absorption of a pranlukast hemihydrate (PLH), a very poorly water-soluble drug. An efficient self-microemulsifying vehicle for PLH was selected and optimized using solubility testing and phase diagram construction. The formulations were characterized by assessing self-emulsification performance, droplet size analysis, in vitro drug release characteristics and formulation stability studies. Optimized formulations for in vitro dissolution and bioavailability assessment were Triethylcitrate (TEC; 10%), Tween 20 (50%), Span 20 (25%), triethanolamine (5%), and benzyl alcohol (10%). The SMEDDS readily released the lipid phase to form a fine oil-in-water microemulsion with a narrow distribution size. Saturated solubilities of PLH from SMEDDS in water, pH 4.0 and 6.8, were over 150 times greater than that of plain PLH. The release of 100% PLH from SMEDDS was considerably greater compared to only 1.12% in simulated intestinal fluid (pH 6.8) from plain PLH after 2 hours. The PLH suspension with 0.5% sodium carboxymethylcellulose or 3% PLH-loaded SMEDDS was administrated at a dose of 40 mg/kg as PLH to fasted rats. The absorption of PLH from SMEDDS resulted in about a threefold increase in bioavailability compared with plain PLH aqueous suspension. Our studies illustrated that the potential use of the new SMEDDS can be used as a possible alternative to oral delivery of a poorly water-soluble drug such as PLH.

Development of an SPE-HPLC-MS method for simultaneous determination and pharmacokinetic study of bioactive constituents of Yu Ping Feng San in rat plasma after oral administration.

ETHNOPHARMACOLOGICAL RELEVANCE: Yu Ping Feng San (YPFS, in Chinese: Jade Windscreen Powder), a well-known traditional Chinese medicine, is commonly used to cure the diseases of respiratory systems and immune systems. AIM OF THE STUDY: A selective and sensitive high-performance liquid chromatography coupled with mass spectrometry method (HPLC-MS) was developed and validated for simultaneous quantification of cycloastragenol, formononetin, calycosin, 4'-O-ß-glucopyranosyl-5-O-methylvisamminol (GMV) and cimifugin in rat plasma after oral administration of Yu Ping Feng San decoction. MATERIALS AND METHODS: Plasma samples were extracted via solid-phase extraction (SPE), separated on a Zorbax SB-C18 column, detected by single quadruple mass spectrometry with an electrospray ionization interface, and quantified using selected ion monitoring mode. The current SPE-HPLC-MS assay was validated for linearity, intra-day and inter-day precisions, accuracy, extraction recovery and stability. The method was applied to a comparative pharmacokinetic study after administration of Yu Ping Feng San to rats at different doses (10, 20 and 40g/kg). RESULTS: The calibration curves were linear over the ranges 0.50-50ng/mL and 17.36-1736ng/mL. Intra- and inter-day precisions (relative standard deviations) were from 0.45% to 10.95%, and accuracy (relative recovery) from 95% to 115%. The extraction recoveries were greater than 88.42% for all analytes. Dose-dependence was shown for some constituents in the drug concentration-time profiles. Among all the active ingredients detected, cimifugin had the highest blood concentration (881-1510ng/mL), and cycloastragenol had the longest retention time in the rat body (15.06-20.44h). CONCLUSION: This analytical method is a selective, sensitive, precise, accurate, and reliable assay for simultaneous determination of cycloastragenol, calycosin, formononetin, GMV, and cimifugin in rat plasma.

Enhance the dissolution rate and oral bioavailability of pranlukast by preparing nanosuspensions with high-pressure homogenizing method.

PURPOSE: Pranlukast, one of the potential therapeutic tools in the treatment of asthma, has limited clinical applications due to its poor water solubility. The study is aimed to provide a platform for better utilizing pranlukast with enhancement of the dissolution rate and, thus, the oral bioavailability of pranluka'st by preparing nanosuspensions through high-pressure homogenization method. METHOD: Poloxamer407 and PEG200 were chosen as stabilizer and surfactant. The formulation was investigated systematically with the dissolution tests as predominant method. Nanosuspensions were prepared by programmed high-pressure homogenization method. The product was characterized by particle size analysis, TEM and XRD are evaluated by in vitro dissolution tests and in vivo absorption examination. In addition, nanosuspensions with only pranlukast were prepared and compared with formulated nanosuspensions. RESULTS: The optimal values of formulation were 0.5% (w/v) pranlukast with 0.375% (w/v) Poloxamer407, 0.375% (w/v) PEG200 and the screened programming homogenizing procedure parameters were 680 bar for the first 15 circles, 1048 bar for the next 9 circles and 1500 bar for the last 9 circles. Nanosuspensions of 318.2 ± 7.3 nm, -29.3 ± 0.8 mV were obtained. The XRD analysis indicated no change of crystalline occurred in the process of homogenization. The in vitro dissolution behavior of nanosuspensions exhibited complete release in 30 min with a remarkable fast dissolution rate. The in vivo bioavailability of formulated pranlukast nanosuspensions demonstrated its enhancement of fast onset of therapeutic drug effects with 4.38-fold improved compared to that of raw crystals. CONCLUSION: The study provides a feasible, practical thinking of industry development in the clinical use of pranlukast.

Comparative pharmacokinetics of prim-O-glucosylcimifugin and cimifugin by liquid chromatography-mass spectrometry after oral administration of Radix Saposhnikoviae extract, cimifugin monomer solution and prim-O-glucosylcimifugin monomer solution to rats.

A sensitive and reliable liquid chromatography-mass spectrometry method has been developed and validated for simultaneous determination of cimifugin and prim-O-glucosylcimifugin in rat plasma after oral administration of Radix Saposhnikoviae (RS) extract, prim-O-glucosylcimifugin monomer solution and cimifugin monomer solution. Plasma samples were pretreated by protein precipitation with acetonitrile containing the internal standards puerarin and daidzein. LC separation was achieved on a Zorbax SB-C(18) column (150 × 4.6 mm i.d., 5 µm) with 0.1% formic acid in water and methanol by isocratic elution. The detection was carried out in select-ion-monitoring mode with a positive electrospray ionization interface. The fully validated method was successfully applied to the pharmacokinetic study of the analytes in rats. A bimodal phenomenon appeared in the concentration-time curve of prim-O-glucosylcimifugin and cimifugin after oral administration of RS extract. Prim-O-glucosylcimifugin mainly transformed to cimifugin when it was absorbed into blood. Both absorption and elimination of cimifugin after oral administration of RS were longer than after administration of single cimifugin. The pharmacokinetic parameters (AUC(0-t) , AUC(0-∞) and t(1/2) ) of prim-O-glucosylcimifugin and cimifugin by giving cimifugin monomer solution, prim-O-glucosylcimifugin monomer solution and RS extract had significant differences (P < 0.05).

Application of dissolution/permeation system for evaluation of formulation effect on oral absorption of poorly water-soluble drugs in drug development.

PURPOSE: The aim of the present study is to evaluate the formulation effect on the oral absorption of poorly water-soluble drugs using a dissolution/permeation system (D/P system). METHODS: This D/P system, consisting of apical and basal chambers and a Caco-2 cell monolayer mounted between chambers, can be used to perform simultaneous analysis of drug dissolution and permeation process of drugs applied as various dosage forms. Oral administration study with rats was also performed for both drugs as the same dosage forms. RESULTS: When danazol, a low-soluble and high-permeable drug, was applied to the D/P system as various formulations, dissolved and permeated amounts were significantly high compared with those from a suspension form. On the other hand, whereas the dissolved amount of pranlukast, a low-soluble and low-permeable drug, was significantly increased by formulations, there were no significant changes observed in the permeated amount between suspension and formulation. The oral availability of danazol was significantly increased by formulations but not pranlukast, which corresponded well to in vitro evaluations. CONCLUSION: These results indicated that the D/P system might be applicable for selection of formulation on the basis of physicochemical drug properties.

Pharmacokinetics of cimifugin in rat plasma after oral administration of the extract of Saposhnikovia divaricatae root. Determination of cimifugin by high performance liquid chromatography coupled with solid phase extraction.

High performance liquid chromatography (HPLC) coupled with the solid phase extraction method was developed for determining cimifugin (a coumarin derivative; one of Saposhnikovia divaricatae's constituents) in rat plasma after oral administration of Saposhnikovia divaricatae extract (SDE), and the pharmacokinetics of cimifugin either in SDE or as a single compound was investigated. The HPLC analysis was performed on a commercially available column (4.6 mm x 200 mm, 5 pm) with the isocratic elution of solvent A (Methanol) and solvent B (Water) (A:B=60:40) and the detection wavelength was set at 250 nm. The calibration curve was linear over the range of 0.100-10.040 microg/mL. The limit of detection was 30 ng/mL. At the rat plasma concentrations of 0.402, 4.016, 10.040 microg/mL, the intra-day precision was 6.21%, 3.98%, and 2.23%; the inter-day precision was 7.59%, 4.26%, and 2.09%, respectively. The absolute recovery was 76.58%, 76.61%, and 77.67%, respectively. When the dosage of SDE was equal to the pure compound calculated by the amount of cimifugin, it was found to have two maximum peaks while the pure compound only showed one peak in the plasma concentration-time curve. The pharmacokinetic characteristics of SDE showed the superiority of the extract and the properties of traditional Chinese medicine.

A sensitive liquid chromatography-mass spectrometry method for simultaneous determination of two active chromones from Saposhnikovia root in rat plasma and urine.

A sensitive and efficient liquid chromatography-mass spectrometry method was developed and validated for the simultaneous determination of two active chromones (prim-O-glucosylcimifugin and 4'-O-D-glucosyl-5-O-methylvisamminol) from Saposhnikovia root in rat plasma and urine. The plasma or urine samples were prepared by protein precipitation. Chromatographic separation of the two active chromones from matrix interferences was achieved on an Angilent TC-C(18) column with a mobile phase consisted of methanol, water and 0.1% formic acid. Puerarin was added as the internal standard. The method was validated with the concentration range 1.0-100 ng/mL in rat plasma and 10-1000 ng/mL in urine for prim-O-glucosylcimifugin, 1.5-150 ng/mL in plasma and 15-1500 ng/mL in urine for 4'-O-D-glucosyl-5-O-methylvisamminol. The lower limit of quantitation (LLOQ) of prim-O-glucosylcimifugin and 4'-O-D-glucosyl-5-O-methylvisamminol was 1.0 and 1.5 ng/mL in plasma, 10 and 15 ng/mL in urine, respectively. The intra- and inter-day precision across three validation days over the entire concentration range was lower than 9.0% as terms of relative standard deviation (R.S.D.). Accuracy determined at three quality control concentrations (2.0, 25 and 75 ng/mL for prim-O-glucosylcimifugin; 3.0, 37.5 and 112.5 ng/mL for 4'-O-D-glucosyl-5-O-methylvisamminol) ranged from -1.9 to 3.9% as terms of relative error (R.E.). The LC-ESI-MS method was further applied to assess pharmacokinetics and urine excretion of the two chromones after oral administration of Fangfeng extract to rats. Practical utility of this new LC-MS method was confirmed in pilot pharmacokinetic studies in rats following oral administration.

Determination of iguratimod in rat plasma by high performance liquid chromatography: method and application.

A high-performance liquid chromatographic method with UV detection has been developed for the determination of iguratimod (T-614) in rat plasma. Plasma was precipitated with acetonitrile after the addition of the internal standard (IS), N-[4-(2-formylaminoacetyl)-5-methoxy-2-phenoxyphenyl]-methanesulfonamide. The chromatographic separation was achieved on a reversed-phase C(18) column with the mobile phase acetonitrile-acetic acid aqueous solution, pH 4.5 (40:60, v/v), at a flow rate of 1 mL/min, and the UV detection wavelength was set at 257 nm. The calibration curve was linear over the range 0.10-50.0 microg/mL, and the lower limit of quantification was 0.10 microg/mL. The intra- and inter-day relative standard deviations were all less than 11.5%. The method has been successfully applied to study the pharmacokinetics of iguratimod in rats. A single 10 mg/kg dose of iguratimod was given to the rats by intragastric administration. The mean maximum plasma concentration of iguratimod for the six rats was 14.5 microg/mL, and the mean elimination half-life of iguratimod was 4.0 h.