Pharmacokinetic Herb-Drug Interactions of Glipizide with Andrographis paniculata (Burm. f.) and Andrographolide in Normal and Diabetic Rats by Validated HPLC Method

Co-administered medicinal herbs can modify a drug’s pharmacokinetics (PK), effectiveness, and toxicity. Andrographis paniculata (Burm. f.) ethanolic extract (APE) and andrographolide (AND) (a potent CYP2C9 inducer/inhibitor) can alter the pharmacokinetic parameters of glipizide (GLZ). This study aimed to determine the potential pharmacokinetics of herb–drug interactions between GLZ and APE/AND in the plasma of normal and diabetic rats using the HPLC bioanalysis method. The glipizide bioanalytical method established with RP-HPLC/UV instrument was validated following the EMA guidelines. GLZ was administered alone and in combination with APE or AND to normal and diabetic rats. The GLZ pharmacokinetic parameters were estimated according to the correlation between concentration and sampling time using the PK solver program. A simple and rapid GLZ bioanalysis technique with a lower limit of quantitation of 25 ng/mL was developed and presented the following parameters: accuracy (error ≤ 15%), precision (CV ≤ 15%), selectivity, stability, and linearity (R² = 0.998) at concentrations ranging 25–1500 ng/mL. APE administration significantly improved the C_max and AUC_0–t/AUC_0–∞ GLZ values in normal and diabetic rats (p < 0.05). AND significantly reduced the bioavailability of GLZ in diabetic rats with small values of T 1/2, C_max, and AUC_0–t/AUC_0–∞ (p < 0.05). This combination can be considered in administering medications because it can influence the pharmacological effects of GLZ.     

Development of an LC-MS/MS Method for ARV-110, a PROTAC Molecule,and Applications to Pharmacokinetic Studies

ARV-110, a novel proteolysis-targeting chimera (PROTAC), has been reported to show satisfactory safety and tolerability for prostate cancer therapy in phase I clinical trials. However, there is a lack of bioanalytical assays for ARV-110 determination in biological samples. In this study, we developed and validated an LC-MS/MS method for the quantitation of ARV-110 in rat and mouse plasma and applied it to pharmacokinetic studies. ARV-110 and pomalidomide (internal standard) were extracted from the plasma samples using the protein precipitation method. Sample separation was performed using a C18 column and a mobile phase of 0.1% formic acid in distilled water–0.1% formic acid in acetonitrile (30:70, v/v). Multiple reaction monitoring was used to quantify ARV-110 and pomalidomide with ion transitions at m/z 813.4 → 452.2 and 273.8 → 201.0, respectively. The developed method showed good linearity in the concentration range of 2–3000 ng/mL with acceptable accuracy, precision, matrix effect, process efficiency, and recovery. ARV-110 was stable in rat and mouse plasma under long-term storage, three freeze-thaw cycles, and in an autosampler, but unstable at room temperature and 37 °C. Furthermore, the elimination of ARV-110 via phase 1 metabolism in rat, mouse, and human hepatic microsomes was shown to be unlikely. Application of the developed method to pharmacokinetic studies revealed that the oral bioavailability of ARV-110 in rats and mice was moderate (23.83% and 37.89%, respectively). These pharmacokinetic findings are beneficial for future preclinical and clinical studies of ARV-110 and/or other PROTACs.     

Enhanced Antioxidant and Anti-Inflammatory Effects of Self-Nano and Microemulsifying Drug Delivery Systems Containing Curcumin

Turmeric has been used for decades for its antioxidant and anti-inflammatory effect, which is due to an active ingredient isolated from the plant, called curcumin. However, the extremely poor water-solubility of curcumin often limits the bioavailability of the drug. The aim of our experimental work was to improve the solubility and thus bioavailability of curcumin by developing self-nano/microemulsifying drug delivery systems (SN/MEDDS). Labrasol and Cremophor RH 40 as nonionic surfactants, Transcutol P as co-surfactant and isopropyl myristate as the oily phase were used during the formulation. The average droplet size of SN/MEDDS containing curcumin was between 32 and 405 nm. It was found that the higher oil content resulted in larger particle size. The drug loading efficiency was between 93.11% and 99.12% and all formulations were thermodynamically stable. The curcumin release was studied at pH 6.8, and the release efficiency ranged between 57.3% and 80.9% after 180 min. The results of the MTT cytotoxicity assay on human keratinocyte cells (HaCaT) and colorectal adenocarcinoma cells (Caco-2) showed that the curcumin-containing preparations were non-cytotoxic at 5 w/v%. According to the results of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide dismutase (SOD) assays, SNEDDS showed significantly higher antioxidant activity. The anti-inflammatory effect of the SN/MEDDS was screened by enzyme-linked immunosorbent assay (ELISA). SNEDDS formulated with Labrasol as surfactant, reduced tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) levels below 60% at a concentration of 10 w/w%. Our results verified the promising use of SN/MEDDS for the delivery of curcumin. This study demonstrates that the SN/MEDDS could be promising alternatives for the formulation of poorly soluble lipophilic compounds with low bioavailability.     

A Rapid and Sensitive LC−MS/MS Method for the Quantitation of Physalin A with Special Consideration to Chemical Stability in Rat Plasma: Application to a Pharmacokinetic Study

Physalin A is a promising natural product with excellent anti-inflammatory and anti-tumor activities. However, the pharmacokinetic profile of physalin A is still unclear. In this study, a rapid and sensitive analytical method based on LC–MS/MS for the quantitation of physalin A in rat plasma with special consideration to its chemical stability was developed and validated. To avoid the degradation of physalin A, the separation of plasma was conducted at 4 °C directly after the blood samples were collected. Meanwhile, plasma samples were immediately precipitated with acetonitrile containing tolbutamide (internal standard, IS) and the pH of the supernatant was adjusted to 1.5 with formic acid. Chromatographic separation of physalin A and IS was achieved on an ACQUITY UPLC BEH-C18 column (2.1 × 50 mm, 1.7 μm) using 0.1% formic acid and acetonitrile as mobile phase delivered at 0.3 mL/min in a gradient elution mode. Physalin A and IS were detected through negative ion electrospray ionization in multiple reaction monitoring (MRM) mode. The MS/MS ion transitions for physalin A and IS were m/z 525.1–148.9 and m/z 269.8–169.9, respectively. The developed method showed good linearity over the range of 2.00–400 ng/mL. This method was successfully applied to the pharmacokinetic study of physalin A in rats following its intragastric administration and the findings were beneficial for future studies of physalin A.     

Development and Validation of a Chiral Liquid Chromatographic Assay for Enantiomeric Separation and Quantification of Verapamil in Rat Plasma: Stereoselective Pharmacokinetic Application

A novel, fast and sensitive enantioselective HPLC assay with a new core–shell isopropyl carbamate cyclofructan 6 (superficially porous particle, SPP) chiral column (LarihcShell-P, LSP) was developed and validated for the enantiomeric separation and quantification of verapamil (VER) in rat plasma. The polar organic mobile phase composed of acetonitrile/methanol/trifluoroacetic acid/triethylamine (98:2:0.05: 0.025, v/v/v/v) and a flow rate of 0.5 mL/min was applied. Fluorescence detection set at excitation/emission wavelengths 280/313 nm was used and the whole analysis process was within 3.5 min, which is 10-fold lower than the previous reported HPLC methods in the literature. Propranolol was selected as the internal standard. The S-(−)- and R-(+)-VER enantiomers with the IS were extracted from rat plasma by utilizing Waters Oasis HLB C18 solid phase extraction cartridges without interference from endogenous compounds. The developed assay was validated following the US-FDA guidelines over the concentration range of 1–450 ng/mL (r² ≥ 0.997) for each enantiomer (plasma) and the lower limit of quantification was 1 ng/mL for both isomers. The intra- and inter-day precisions were not more than 11.6% and the recoveries of S-(−)- and R-(+)-VER at all quality control levels ranged from 92.3% to 98.2%. The developed approach was successfully applied to the stereoselective pharmacokinetic study of VER enantiomers after oral administration of 10 mg/kg racemic VER to Wistar rats. It was found that S-(−)-VER established higher C_max and area under the concentration-time curve (AUC) values than the R-(+)-enantiomer. The newly developed approach is the first chiral HPLC for the enantiomeric separation and quantification of verapamil utilizing a core–shell isopropyl carbamate cyclofructan 6 chiral column in rat plasma within 3.5 min after solid phase extraction (SPE).     

An Efficient UPLC-MS/MS Method for the Determination of Pyrroloquinoline Quinone in Rat Plasma and Its Application to a Toxicokinetic Study

Pyrroloquinoline quinone (PQQ) is a powerful antioxidant coenzyme existing in diet, benefiting growth, development, cognition function, and the repair of damaged organs. However, a method for detecting PQQ in vivo was rarely described, limiting the research on the bioanalysis and metabolic properties of PQQ. In this study, a novel, simple, and efficient ultra-high performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to quantify the concentration of PQQ in rat plasma. Detection through mass spectrometry was operated by multiple reaction monitoring (MRM) in negative electrospray ionization mode with ion transitions m/z 328.99→197.05 for PQQ and m/z 280.04→195.04 for the internal standard. The calibration curves were linear up to 10,000 ng/mL, with a lower limit of quantitation of 10 ng/mL. Inter-run and intra-run precision ranged from 1.79% to 10.73% and accuracy ranged from −7.73% to 7.30%. The method was successfully applied to a toxicokinetic study in Sprague–Dawley rats after the oral administration of PQQ disodium salt at doses of 250 mg/kg, 500 mg/kg, and 1000 mg/kg. The toxicokinetic parameters were subsequently analyzed, which may provide valuable references for the toxicokinetic properties and safety evaluation of PQQ.     

Pharmacokinetics and metabolism of ulixertinib in rat by liquid chromatography combined with electrospray ionization tandem mass spectrometry

The purpose of this study was to develop and validate a simple and sensitive liquid chromatography tandem mass spectrometry method for the determination of ulixertinib in rat plasma. The plasma samples were precipitated with acetonitrile and then separated on a C₁₈ column with water containing 0.1% formic acid and acetonitrile as mobile phase at a flow rate of 0.3 mL/min. Analytes were monitored on a TSQ Vantage triple quadrupole tandem mass spectrometer operated in positive electrospray ionization mode. Selected reaction monitoring transitions were m/z 433.1→262.1 for ulixertinib and m/z 450.1→260.1 for internal standard. The assay achieved good linearity over the concentration range of 0.1‐1000 ng/mL with correlation coefficient > 0.9991. The validated assay has been successfully applied to pharmacokinetic study of ulixertinib in rat after oral and intravenous administration. The results revealed that ulixertinib showed high exposure in rat plasma, low clearance, moderate oral bioavailability (45.13%), and dose‐independent pharmacokinetic profiles over the oral dose range of 1‐15 mg/kg. In addition, six metabolites from rat plasma and hepatocytes were detected and structurally identified by ultra‐high performance liquid chromatography combined with high‐resolution mass spectrometry. The metabolic pathways of ulixertinib referred to hydroxylation and dealkylation and glucuronidation.     

Determination of cefdinir levels in rat plasma and urine by high‐performance liquid chromatography–tandem mass spectrometry: application to pharmacokinetics after oral and intravenous administration of cefdinir

A selective and sensitive liquid chromatography tandem mass spectrometry method (LC‐MS/MS) was developed and validated for the determination of cefdinir in rat plasma and urine. Following a simple protein precipitation using methanol, chromatographic separation was achieved with a run time of 10 min using a Synergi 4 µ polar‐RP 80A column (150 × 2.0 mm, 4 µm) with a mobile phase consisting of 0.1% formic acid in water and methanol (65:35, v/v) at a flow rate of 0.2 mL/min. The protonated precursor and product ion transitions for cefdinir (m/z 396.1 → 227.2) and cefadroxil, an internal standard (m/z 364.2 → 208.0) were monitored in the multiple reaction monitoring in positive ion mode. The calibration curves for plasma and urine were linear over the concentration range 10–10,000 ng/mL. The lower limit of quantification was 10 ng/mL. All accuracy values were between 95.1 and 113.0% and the intra‐ and inter‐day precisions were <13.0% relative standard deviation. The stability under various conditions in rat plasma and urine was also found to be acceptable at three concentrations. The developed method was applied successfully to the pharmacokinetic study of cefdinir after oral and intravenous administration. Copyright © 2013 John Wiley & Sons, Ltd.     

Eco-Friendly UPLC–MS/MS Method for Determination of a Fostamatinib Metabolite,Tamatinib, in Plasma: Pharmacokinetic Application in Rats

Fostamatinib is a prodrug of the active metabolite tamatinib, which is a spleen tyrosine kinase (Syk) inhibitor used in the treatment of primary chronic adult immune thrombocytopenia and rheumatoid arthritis. A highly sensitive, rapid, reliable, and green method was developed and validated using ultra-performance liquid chromatography and tandem mass spectrometry (UPLC–MS/MS) for quantification of tamatinib in rat plasma. Ibrutinib was used as internal standard and liquid–liquid extraction was applied using tert-butyl methyl ether. The analyte was separated on an Acquity^TM CSH C₁₈ (2.1 mm × 100 mm, 1.7 µm) column using mobile phase consisting of 10 mM ammonium acetate and acetonitrile (10:90) and the flow rate was 0.25 mL/min. Electrospray ionization (ESI) was carried out in positive mode. Quantitation of tamatinib and the IS was performed using multiple reaction monitoring mode with precursor-to-product transitions of m/z 471.1 > 122.0 and m/z 441.1 > 84.0, respectively. The calibration range was 0.1–1000.0 ng/mL and the linearity of the method was ≥0.997. The developed method greenness was investigated. All principal parameters for the method, including linearity, accuracy, precision, recovery, and stability, were within acceptable ranges. Tamatinib pharmacokinetic study in rats was successfully carried out using the developed method.     

Polymerized Whey Protein Concentrate-Based Glutathione Delivery System: Physicochemical Characterization,Bioavailability and Sub-Chronic Toxicity Evaluation

Glutathione (GSH) is a powerful antioxidant, but its application is limited due to poor storage stability and low bioavailability. A novel nutrient encapsulation and delivery system, consisting of polymerized whey protein concentrate and GSH, was prepared and in vivo bioavailability, antioxidant capacity and toxicity were evaluated. Polymerized whey protein concentrate encapsulated GSH (PWPC-GSH) showed a diameter of roughly 1115 ± 7.07 nm (D₅₀) and zeta potential of 30.37 ± 0.75 mV. Differential scanning calorimetry (DSC) confirmed that GSH was successfully dispersed in PWPC particles. In vivo pharmacokinetics study suggested that PWPC-GSH displayed 2.5-times and 2.6-fold enhancement in maximum concentration (C_max) and area under the concentration–time curve (AUC) as compared to free GSH. Additionally, compared with plasma of mice gavage with free GSH, significantly increased antioxidant capacity of plasma in mice with PWPC-GSH was observed (p < 0.05). Sub-chronic toxicity evaluation indicated that no adverse toxicological reactions related to oral administration of PWPC-GSH were observed on male and female rats with a diet containing PWPC-GSH up to 4% (w/w). Data indicated that PWPC may be an effective carrier for GSH to improve bioavailability and antioxidant capacity.     

LC‐ESI‐MS/MS analysis of quercetin in rat plasma after oral administration of biodegradable nanoparticles

A simple, rapid and sensitive LC‐MS/MS method was developed and validated for the determination of free quercetin in rat plasma, using fisetin as internal standard. The detection was performed by negative ion electrospray ionization under selected reaction monitoring. Chromatographic separation (isocratic elution) was carried out using acetonitrile–10 m m ammonium formate (80:20, v/v) with 0.1% v/v formic acid. The lower limit of quantification (4.928 ng/mL) provided high sensitivity for the detection of quercetin in rat plasma. The linearity range was from 5 to 2000 ng/mL. Intra‐ and inter‐day variability (RSD) of quercetin extraction from rat plasma was <4.19 and 1.37% with accuracies of 98.77 and 99.67%. The method developed was successfully applied for estimating free quercetin in rat plasma, after oral administration of quercetin‐loaded biodegradable nanoparticles (QLN) and quercetin suspension. QLN (C_max, 1277.34 ± 216.67 ng/mL; AUC, 17,458.25 ± 3152.95 ng hr/mL) showed a 5.38‐fold increase in relative bioavailability as compared with quercetin suspension (C_max, 369.2 ± 108.07 ng/mL; AUC, 3276.92 ± 396.67 ng hr/mL). Copyright © 2015 John Wiley & Sons, Ltd.     

An LC‐MS/MS method for determination of curculigoside with anti‐osteoporotic activity in rat plasma and application to a pharmacokinetic study

A rapid, simple, selective and sensitive LC‐MS/MS method was developed for the determination of curculigoside in rat plasma. The analytical procedure involves extraction of curculigoside and syringin (internal standard, IS) from rat plasma with a one‐step extraction method by protein precipitation. The chromatographic resolution was performed on an Agilent XDB‐C₁₈ column (4.6 × 50 mm, 5 µm) using an isocratic mobile phase of methanol with 0.1% formic acid and H₂O with 0.1% formic acid (45:55, v/v) at a flow rate of 0.35 mL/min with a total run time of 2.0 min. The assay was achieved under the multiple‐reaction monitoring mode using positive electrospray ionization. Method validation was performed according to US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over 4.00–4000 ng/mL (R = 0.9984) for curculigoside with a lower limit of quantification of 4.00 ng/mL in rat plasma. The intra‐ and inter‐day precisions and accuracies were 3.5–4.6 and 0.7–9.1%, in rat plasma, respectively. The validated LC‐MS/MS method was successfully applied to a pharmacokinetic study of curculigoside in rats after a single intravenous and oral administration of 3.2 and 32 mg/kg. The absolute bioavailability of curculigoside after oral administration was 1.27%. Copyright © 2013 John Wiley & Sons, Ltd.     

Development and Verification of a Precolumn Derivatization LC-MS/MS Method for the Pharmacokinetic Study of Houttuynine of Houttuynia Essential Oil

Houttuynia essential oil (HEO) has excellent antiviral, anti-inflammatory, and other pharmacological effects, but the lack of effective analytical methods to quantify HEO in plasma has hindered its better clinical monitoring. Houttuynine (Hou) is one of the main active ingredients and quality control substances of HEO, so the pharmacokinetic study of HEO could be conducted by determining Hou blood concentration. Hou is active and not stable in plasma, which makes its blood concentration difficult to measure. In this work, a novel liquid chromatography tandem mass spectrometry (LC-MS/MS) method for Hou determination in rat blood was established that involves Hou being derivatized with 2, 4-dinitrophenylhydrazine to form a stable compound to prevent degradation. Herein, p-Tolualdehyde-2,4-dinitrophenylphenylhydrazone was selected as an internal standard substance and the LC-MS/MS method was evaluated for selectivity, precision, accuracy, calibration limit, matrix effect, recovery, and stability. Good linearity (r² = 0.998) was reached in the range of 2–2000 ng/mL, and the lower limit of quantification of Hou was determined to be 2 ng/mL. The mean intra-assay accuracy ranged from 77.7% to 115.6%, whereas the intra-assay precision (relative standard deviation, RSD) was below 11.42%. The matrix effect value for Hou in rat plasma was greater than 75%, and for the internal standard (IS) it was 104.56% ± 3.62%. The extraction recovery of Hou were no less than 90%, and for the IS it was 96.50% ± 4.68%. Our method is sensitive and reliable and has been successfully applied to the pharmacokinetic analysis of Hou in rats given HEO via gavage and injection.     

Determination of pterostilbene in rat plasma by a simple HPLC‐UV method and its application in pre‐clinical pharmacokinetic study

A simple HPLC‐UV method was developed and validated for the quantification of pterostilbene (3,5‐dimethoxy‐4'‐hydroxy‐trans‐stilbene), a pharmacologically active phytoalexin in rat plasma. The assay was carried out by measuring the UV absorbance at 320 nm. Pterostilbene and the internal standard, 3,5,4'‐trimethoxy‐trans‐stilbene eluted at 5.7 and 9.2 min, respectively. The calibration curve (20–2000 ng/mL) was linear (R² > 0.997). The lower limits of detection and of quantification were 6.7 and 20 ng/mL, respectively. The intra‐ and inter‐day precisions in terms of RSD were all lower than 6%. The analytical recovery ranged from 95.5 ± 3.7 to 103.2 ± 0.7% while the absolute recovery ranged from 101.9 ± 1.1 to 104.9 ± 4.4%. This simple HPLC method was subsequently applied in a pharmacokinetic study carried out in Sprague–Dawley rats. The terminal elimination half‐life and clearance of pterostilbene were 96.6 ± 23.7 min and 37.0 ± 2.5 mL/min/kg, respectively, while its absolute oral bioavailability was 12.5 ± 4.7%. Pterostilbene appeared to have better pharmacokinetic characteristics than its natural occurring analog, resveratrol. Copyright © 2009 John Wiley & Sons, Ltd.     

A simple and selective UHPLC–MS/MS method for quantification of plantagoguanidinic acid in rat plasma and its application to a pharmacokinetic study

A simple, sensitive and specific UHPLC–MS/MS method for quantification of plantagoguanidinic acid (PGA) in rat plasma was applied to investigate the pharmacokinetic behavior in vivo , using protopine as internal standard. The chromatography was separated on a Phenomenex® Luna‐C₁₈ column (2.1 × 150 mm, 3.0 μm) within 7.0 min using a mobile phase consisting of acetonitrile–0.1% formic acid solution under gradient elution at a flow rate of 0.4 mL/min. Prepared samples were monitored by multiple reaction monitoring mode, with the target fragmentions m/z 226.2 → 84.2 for PGA and m/z 354.2 → 188.9 for IS in positive electrospray ionization. The calibration curve of PGA was linear throughout the range 1–1000 ng/mL (r = 0.9962). The lower limit of quantitation in plasma for PGA was 0.1 ng/mL, and the recovery was >88.6%. Intra‐ and interday accuracy ranged from −8.6 to 4.9%. Furthermore, this validated method was successfully used for a pre‐clinical pharmacokinetic study of PGA at a single dose of 20 and 5 mg/kg in rats via oral and intravenous administration. The study showed that PGA was absorpted rapidly and eliminated gradually with a greater absolute oral bioavailability of 70.1% in rats.     

Pharmacokinetics and bioavailability study of ginsenoside Rk1 in rat by liquid chromatography/electrospray ionization tandem mass spectrometry

Ginsenoside Rk1 (Rk1) exhibited various potent biological activities. However, its pharmacokinetic profile in vivo remains unclear. In the present study, a simple and sensitive liquid chromatography tandem mass spectrometry method was developed and validated for determination of Rk1 in rat plasma and applied in a pharmacokinetic study. The sample was precipitated with acetonitrile and separated on a Zorbax Eclipse XDB C18 column (50 × 2.1 mm, 1.8 μm). The mobile phase was composed of 0.1% formic acid in water and acetonitrile at a flow rate of 0.4 mL/min. Rk1 and internal standard (ginsenoside Rg3) were quantitatively monitored with precursor‐to‐product ion transitions of m/z 765.4 → 441.5 and m/z 783.5 → 621.4, respectively. The assay was linear over the concentration range of 5–1000 ng/mL (r > 0.99) with the LLOQ of 5 ng/mL. Other parameters including intra‐ and inter‐day precision and accuracy, extraction recovery and matrix effect were within the acceptable limits. The analyte was stable under the tested storage conditions. The validated method has been successfully applied to a pharmacokinetic study of Rk1 in rat plasma after intravenous (5 mg/kg) and oral (25 mg/kg, 50 mg/kg) administration. After oral administration, Rk1 could be detected in blood at 30 min and reached the highest concentration at 4.29~4.57 h. Our results demonstrated that Rk1 showed low clearance, moderate half‐life (3.09–3.40 h) and low bioavailability (2.87–4.23%). The study will provide information for the further application of Rk1.     

Determination of Mifepristone (RU-486) and Its Metabolites in Maternal Blood Sample after Pharmacological Abortion

The aim of the study was the development and validation of the UHPLC-QqQ-MS/MS method for the determination of mifepristone in human blood as well as the identification and quantification of its metabolites after self-induced pharmacological abortion. The metabolic pathway in humans was proposed after examination of an authentic casework. The fast and simple preanalytical procedure was successfully applied (pH9, tert-butyl-methyl ether). The validation parameters of the method were as follows: limit of quantification: 0.5 ng/mL; coefficients of determination: >0.999 (R²), intra- and inter-day accuracy and precision values did not exceed ± 13.2%. The recovery and matrix effect were in the range of 96.3–114.7% and from −3.0 to 14.7%, respectively. Toxicological analysis of the mother’s blood (collected the day after the pregnancy termination) revealed the presence of five compounds: mifepristone (557.4 ng/mL), N-desmethyl-mifepristone (638.7 ng/mL), 22-OH-mifepristone (176.9 ng/mL), N,N-didesmethyl-mifepristone (144.5 ng/mL) and N-desmethyl-hydroxy-mifepristone (qualitatively). To our knowledge, the study presented in this paper is the first report on the concentrations of mifepristone and its metabolites in maternal blood samples after performing a self-induced abortion. The established UHPLC-QqQ-MS/MS method is suitable for forensic toxicological analysis as well as in terms of clinical toxicology in future investigations (examination of pharmacokinetics, bioavailability and metabolism of RU-486).     

Development of a liquid chromatography–mass spectrometry method for determination of agrimol B in rat plasma: application to preclinical pharmacokinetics

A sensitive and accurate liquid chromatography coupled with mass spectrometry (LC‐MS) method was developed for the determination of agrimol B, a main active ingredient isolated from Agrimonia pilosa Ledeb., in rat plasma. Chromatographic separation was achieved on a Zorbax CN column (150 × 4.6 mm, 5 µm), with isocratic elution consisting of acetonitrile and water (15:85, v/v) at a flow rate of 0.6 mL/min. Agrimol B and dryocrassin ABBA, an internal standard (IS), were analyzed by selected ion monitoring at m/z transitions of 681.3 and 819.4, respectively. This assay exhibited a good linearity with a correlation coefficient >0.99 and showed no endogenous interference with the analyte and IS. The limit of quantification of agrimol B was 8.025 ng/mL with acceptable precision and accuracy. The method was successfully applied in the pharmacokinetic study of agrimol B in rats after intravenous (1 mg/kg) and oral (2, 5 and 10 mg/kg) doses of agrimol B. The absolute bioavailability of agrimol B was 16.4–18.0% in rat. Our study clarifies the pharmacokinetic behavior of agrimol B in animals. Copyright © 2014 John Wiley & Sons, Ltd.     

Development and validation of a cost-effective and sensitive bioanalytical HPLC-UV method for determination of lopinavir in rat and human plasma

A simple, sensitive and cost-effective HPLC-UV bioanalytical method for determination of lopinavir (LPV) in rat and human plasma was developed and validated. The plasma sample preparation procedure includes a combination of protein precipitation using cold acetonitrile and liquid–liquid extraction with n-hexane–ethyl acetate (7:3, v/v). A good chromatographic separation was achieved with a Phenomenex Gemini column (C₁₈, 150 mm × 2.0 mm, 5 μm) at 40°C with gradient elution, at 211 nm. Calibration curves were linear in the range 10–10,000 ng/mL, with a lower limit of quantification of 10 ng/mL using 100 μL of plasma. The accuracy and precision in all validation experiments were within the criteria range set by the guidelines of the Food and Drug Administration. This method was successfully applied to a preliminary pharmacokinetic study in rats following an intravenous bolus administration of LPV. Moreover, the method was subsequently fully validated for human plasma, allowing its use in therapeutic drug monitoring (TDM). In conclusion, this novel, simple and cost-efficient bioanalytical method for determination of LPV is useful for pharmacokinetic and drug delivery studies in rats, as well as TDM in human patients.     

LC Determination and Pharmacokinetic Study of Sinomenine in Dog Plasma

A simple HPLC method has been developed for determination of sinomenine in dog plasma and has been used to evaluate the pharmacokinetics of sinomenine tablets in dogs. Chromatographic separation was performed on a reversed-phase column with 0.78% (w/v) NaH₂PO₄-acetonitrile, 88:12 (v/v), as mobile phase, delivered at a flow rate of 1.5 mL min^?1. Detection was performed at 265 nm. The limit of quantification was 5.0 ng mL^?1. The calibration range was from 5.0 to 1000 ng mL^?1. The developed method was applied to pharmacokinetic studies of sinomenine sustained-release tablets (test preparation) and sinomenine conventional tablets (reference preparation) in six dogs. Pharmacokinetic data t _max, C _max, AUC _0-t , AUC _0-∞, and t _1/2 for both preparations were determined from plasma concentration-time profiles. The method was sufficiently sensitive, simple, and repeatable for use in pharmacokinetic studies.