In Vitro-In Vivo Correlation of Tianeptine Sodium Sustained-Release Dual-Layer Tablets.

Tianeptine tablets are currently marketed to be designed for immediate-release tablets. The tianeptine has a short half-life, making it difficult to design for sustained-release tablets and achieve bioequivalence with the tianeptine immediate-release tablet (Stablon®). We established the in vitro-in vivo correlation (IVIVC) of three formulations of tianeptine sustained-release tablets according to their granule size. To evaluate sustained drug release, in vitro tests were performed in pH 1.2 media for 24 h. In vivo pharmacokinetic analysis was performed following oral administration of reference drug and test drug to beagle dogs. The dissolution profile revealed delayed release as the size of the granules increased. The dissolution results were confirmed in pharmacokinetic analysis, showing that the half-life was delayed as granule size increased. The final formulation and reference drug showed an equivalent area under the curve (AUC). Through this, IVIVC was established according to the size of the tianeptine sodium granules, which is the purpose of this study, and was used to predict in vivo pharmacokinetics from the formulation composition. This approach may be useful for determining optimal formulation compositions to achieve the desired pharmacokinetics when developing new formulations.

Rapid characterization and pharmacokinetic study of aristolochic acid analogues using ion mobility mass spectrometry.

Aristolochic acid analogues (AAAs), naturally existing in herbal Aristolochia and Asarum genera, were once widely used in traditional pharmacopeias because of their anti-inflammatory properties, but lately they were identified as potential nephrotoxins and mutagens. A method for rapid characterization of AAAs in serum was developed using ion mobility spectrometry coupled with mass spectrometry (IMS-MS). Five AAAs, containing four aristolochic acids and one aristolactam, were separated and identified within milliseconds. AAAs were separated in gas phase based on the difference of their ion mobility (K0), and then identified based on their K0 values, m/z, and product ions from MS/MS. Quantitative analysis of AAAs was performed using an internal standard with a satisfactory sensitivity. Limits of detection (signal-to-noise = 3) and quantification (signal-to-noise = 10) were 1-5 ng/mL and 3-8 ng/mL, respectively. The method was validated and successfully applied to the pharmacokinetics study of AAAs in rats, offering a promising way for fast screening and evaluation of AAAs in biological samples.

Rp-HPLC Determination of Quercetin in a Novel D-α-Tocopherol Polyethylene Glycol 1000 Succinate Based SNEDDS Formulation: Pharmacokinetics in Rat Plasma.

Despite its proven efficacy in diverse metabolic disorders, quercetin (QU) for clinical use is still limited because of its low bioavailability. D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS) is approved as a safe pharmaceutical adjuvant with marked antioxidant and anti-inflammatory activities. In the current study, several QU-loaded self-nanoemulsifying drug delivery systems (SNEDDS) were investigated to improve QU bioavailability. A reversed phase high performance liquid chromatography (RP-HPLC) method was developed, for the first time, as a simple and sensitive technique for pharmacokinetic studies of QU in the presence of TPGS SNEDDS formula in rat plasma. The analyses were performed on a Xterra C18 column (4.6 × 100 mm, 5 µm) and UV detection at 280 nm. The analytes were separated by a gradient system of methanol and phosphate buffer of pH 3. The developed RP-HPLC method showed low limit of detection (LODs) of 7.65 and 22.09 ng/mL and LOQs of 23.19 and 66.96 ng/mL for QU and TPGS, respectively, which allowed their determination in real rat plasma samples. The method was linear over a wide range, (30-10,000) and (100-10,000) ng/mL for QU and TPGS, respectively. The selected SNEDDS formula, containing 50% w/w TPGS, 30% polyethylene glycol 200 (PEG 200), and 20% w/w pumpkin seed oil (PSO), showed a globule size of 320 nm and -28.6 mV zeta potential. Results of the pharmacokinetic studies showed 149.8% improvement in bioavailability of QU in SNEDDS relative to its suspension. The developed HPLC method proved to be simple and sensitive for QU and TPGS simultaneous determination in rat plasma after oral administration of the new SNEDDS formula.

Enhanced Solubility and Bioavailability of Dolutegravir by Solid Dispersion Method: In Vitro and In Vivo Evaluation-a Potential Approach for HIV Therapy.

Being a candidate of BCS class II, dolutegravir (DTG), a recently approved antiretroviral drug, possesses solubility issues. The current research was aimed to improve the solubility of the DTG and thereby enhance its efficacy using the solid dispersion technique. In due course, the miscibility study of the drug was performed with different polymers, where Poloxamer 407 (P407) was found suitable to move forward. The solid dispersion of DTG and P407 was formulated using solvent evaporation technique with a 1:1 proportion of drug and polymer, where the solid-state characterization was performed using differential scanning calorimetry, Fourier transform infrared spectroscopy and X-ray diffraction. No physicochemical interaction was found between the DTG and P407 in the fabricated solid dispersion; however, crystalline state of the drug was changed to amorphous as evident from the X-ray diffractogram. A rapid release of DTG was observed from the solid dispersion (>95%), which is highly significant (p<0.05) as compared to pure drug (11.40%), physical mixture (20.07%) and marketed preparation of DTG (35.30%). The drug release from the formulated solid dispersion followed Weibull model kinetics. Finally, the rapid drug release from the solid dispersion formulation revealed increased Cmax (14.56 µg/mL) when compared to the physical mixture (4.12 µg/mL) and pure drug (3.45 µg/mL). This was further reflected by improved bioavailability of DTG (AUC: 105.99±10.07 µg/h/mL) in the experimental Wistar rats when compared to the AUC of animals administered with physical mixture (54.45±6.58 µg/h/mL) and pure drug (49.27±6.16 µg/h/mL). Therefore, it could be concluded that the dissolution profile and simultaneously the bioavailability of DTG could be enhanced by means of the solid dispersion platform using the hydrophilic polymer, P407, which could be projected towards improved efficacy of the drug in HIV/AIDS.

Simultaneous Quantification and Pharmacokinetic Study of Five Homologs of Dalbavancin in Rat Plasma Using UHPLC-MS/MS.

Dalbavancin is a novel semisynthetic glycopeptide antibiotic that comprises multiple homologs and isomers of similar polarities. However, pharmacokinetic studies have only analyzed the primary components of dalbavancin, namely B0 and B1. In this study, an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed to simultaneously determinate and investigate the five homologous components of dalbavancin, namely, A0, A1, B0, B1, and B2, in rat plasma. In this method, methanol was used to precipitate plasma, and a triple-bonded alkyl chromatographic column was used for molecule separation, using 0.1% formic acid-acetonitrile as the mobile phase for gradient elution. Targeted homologs were analyzed by a triple quadrupole mass spectrometer using positive electrospray ionization in multiple reaction monitoring mode. The linearity range was 50-2500 ng/mL with a high correlation coefficient (r2 > 0.998). This method was successfully applied in the pharmacokinetic analysis of dalbavancin hydrochloride to investigate dalbavancin components in rats.

Comparative pharmacokinetics study of anastrozole after single administration and combination with celecoxib.

1. There are numerous investigations demonstrating that the cyclooxygenase-2 (COX-2) inhibitors might enhance the efficiency of anastrozole in breast cancer. Hence, this study was conducted to investigate the comparative pharmacokinetics of anastrozole after single administration and combination with celecoxib. 2. A simple protein precipitation procedure was adopted for the sample preparation with satisfactory extraction recovery for both anastrozole and the internal standard, and then anastrozole was separated and analysed on an ACQUITY BEH UPLC C18 column (50 × 2.0 mm, 1.7 µm, Waters) within 2 min. The calibration curves showed good linarites (r = 0.994). Intra- and inter-day precision were within 4.93 and 13.83%, respectively. The mean extraction recoveries across QC levels were within 91.4%, and the matrix effects were within 94.5%. 3. Results showed that the method was reliable to determine anastrozole in rat plasma. Compared with rats in single administration group, no significant difference was found in the combination group. It is workable to use celecoxib combined with anastrozole in clinical therapy.

A Comprehensive Study on the Chemical Constituents and Pharmacokinetics of Erzhi Formula and Jiawei Erzhi Formula Based on Targeted and Untargeted LC-MS Analysis.

BACKGROUND: Erzhi formula (EZF) is a traditional Chinese medicine prescription, which has been widely used in the treatment of osteoporosis and premature ovarian failure. OBJECTIVE: To enhance curative effects, the other two herbal medicines, including Spatholobi Caulis (SC) and Achyranthes bidentata Blume (ABB), were added into the original EZF formula to obtain two new Jiawei-EZF (JW-EZF) preparations. To clarify the effect of the compatibility of herbs for original formulas, the chemical constituents and bioactive compounds in vivo were detected. METHODS: An efficient and sensitive targeted and untargeted UHPLC/ESI-Q-Orbitrap MS method, together with mass defect filter and precursor ion list, was established firstly for the profiling of different EZF formulas. Furthermore, eleven absorbed compounds (apigenin, luteoloside, luteolin, oleuropein, wedelolactone, acteoside, specnuezhenide, 11-methyloleoside, ecliptasaponin A, formononetin, and ß-ecdysone) were simultaneously quantified in rat plasma. RESULTS: A total of 124, 162, and 177 compounds were identified or tentatively identified in EZF, JW-3-EZF (EZF+SC) and JW-4-EZF (EZF+SC+ABB), respectively. 110 compounds were found to be common constituents in the three formulas. Moreover, 66 prototypes were unambiguously identified in the rats' plasma after oral administration of the three formulas using the same strategy. 11 out of the 66 absorbed components were simultaneously quantitated in the pharmacokinetic (PK) study. Compared to the original EZF, the plasma AUC(0-24h) and AUC(0-∞) of apigenin, 11-methyloleoside, luteolin, luteoloside, wedelolactone, and acteoside were found to be significantly increased after oral administration of JW-3-EZF, and plasma AUC(0-24h) and AUC(0-∞) of apigenin, wedelolactone, and acteoside, were also found to be significantly increased after JW-4-EZF administration. CONCLUSION: The combined qualitative and quantitative methods were used to provide a potential approach to the characterization and quality control of the Traditional Chinese Medicine (TCM) and its preparations.

Gut microbiota mediates the pharmacokinetics of Zhi-zi-chi decoction for the personalized treatment of depression.

ETHNOPHARMACOLOGICAL RELEVANCE: Zhi-zi-chi decoction (ZZCD), from "Treatise on Febrile Diseases", is a typical traditional Chinese medicine herb pair, which consists of Gardeniae Fructus (GF) and Semen Sojae Praeparatu (SSP). In clinical research, ZZCD was widely used to fight depression, remove annoyance. Many studies have reported that gut microbiota is critical target for the influence of depress through gut-brain axis, and our previously studies have found that ZZCD exhibiting antidepressant effect was through the gut-brain axis. However, the specific mechanism by which gut microbiota mediates the pharmacokinetics parameters of active compounds from ZZCD during the process of depression treatment has not yet been studied. AIM OF THE STUDY: To explore the differences in pharmacokinetics characters of bioactive iridoids from ZZCD and study the changes of gut microbiota at different stages of depression with the personalized medicine of ZZCD. MATERIALS AND METHODS: A new strategy exploring the relationship among disease phenotypes (D), intestinal microbiota (I), enzymes (E) and traits of metabolism (T) named as "DIET" was established. Firstly, a fast, selective and sensitive ultra-performance liquid chromatography coupled with tandem mass spectrometer (UPLC-MS/MS) was established and validated to quality the main bioactive compounds from ZZCD and compare the pharmacokinetics and bioavailability of different iridoids prototypes and metabolites from ZZCD between normal and chronic unpredictable mild stress rats. Subsequently, the activity of corresponding metabolic enzymes of anti-depressive compounds, ß-glucosidases and sulfotransferases, were analyzed by ρ-nitrophenyl-ß -D-glucopyranoside and sulfotransferases ELISA kits, respectively. Finally, 16S rRNA gene sequencing was adopt to analyze intestinal bacteria composition for the treatment of depression by ZZCD. RESULTS: The antidepressant effect of ZZCD was promoted due to the increased exposures and reduced eliminations of anti-depressive compounds, especially geniposide and genipin 1-gentiobioside, under the depression state. With the ZZCD treatment, the depression was improved, but the exposures of anti-depressive compounds from ZZCD gradually decreased. Meanwhile, there were the corresponding decreased trends on the activity of ß-glucosidases and sulfotransferases. With the consumption of ZZDC and the improvement of depression, the exposures of anti-depressive iridoid glycosides decreased and the activity of metabolism enzymes restored. Meanwhile, the dysbiosis of pathogenic bacteria (Bacteroidota) induced by depression was ameliorated and the probiotics (Firmicutes) at the phylum and genus level raised, the two phyla are closely related to the production of ß-glucosidase and sulfotransferases. CONCLUSIONS: It is the first proposed that ZZCD could personalized to treat depression at different stages targeting gut microbiota and gut microbiome could emerged as a potential diagnostic and therapeutic biomarker in depression.

Development of a particle swarm optimization-backpropagation artificial neural network model and effects of age and gender on pharmacokinetics study of omeprazole enteric-coated tablets in Chinese population.

BACKGROUND: The effects of age and gender were explored on pharmacokinetics study of omeprazole enteric-coated tablets in Chinese population and a plasma concentration prediction model was developed. All the data (demographic characteristics and results of clinical laboratory tests) were collected from healthy Chinese subjects in pharmacokinetics study using 20 mg omeprazole enteric-coated tablets. A noncompartmental method was used to calculate pharmacokinetic parameters, and 47 subjects were divided into two groups based on the calculation of the median age. Pharmacokinetic data from the low-age and high-age groups or male and female groups were compared by Student t-test. After a total of 12 variables were reconstruct and convert into independent or irrelative variables by principal component analysis, particle swarm optimization (PSO) was used to construct a backpropagation artificial neural network (BPANN) model. RESULT: The model was fully validated and used to predict the plasma concentration in Chinese population. It was noticed that the Cmax, AUC0-t, AUC0-∞ and t1/2 values have significant differences when omeprazole was administered by low-age groups or high-age groups while there were slight or no significant differences of pharmacokinetic data were found between male and female subjects. The PSO-BPANN model was fully validated and there was 0.000355 for MSE, 0.000133 for the magnitude of the gradient, 50 for the number of validation checks. The correlation coefficient of training, validation, test groups were 0.949, 0.903 and 0.874. CONCLUSION: It is necessary to pay attention to the age and gender effects on omeprazole and PSO-BPANN model could be used to predict omeprazole concentration in Chinese subjects to minimize the associated morbidity and mortality with peptic ulcer. TRIAL REGISTRATION: The study was registered in China Drug Clinical Trial Registration and Information Publicity Platform ( http://www.chinadrugtrials.org.cn ), the registration number was CTR20170876, and the full date of registration was 04/AUG/2017.

Development and Validation of a LC-MS/MS Method for Quantification of Mobocertinib (TAK-788) in Plasma and its Application to Pharmacokinetic Study in Rats.

AIM AND OBJECTIVE: An analytical method for the determination of mobocertinib, an investigational tyrosine kinase inhibitor, was developed and optimized by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) in rat plasma. MATERIALS AND METHODS: Plasma samples were pretreated by the protein precipitation method with a methanol solution of osimertinib as the internal standard (IS). Chromatographic separation was performed using an Inertsil ODS-3 column (50 mm × 4.6 mm, I.D. 5 µm) with the temperature maintained at 40°C. The mobile phase consisted of water (containing 0.1% formic acid) and methanol in a gradient mode at a flow rate of 0.5 mL/min. Mass spectrometric detection was carried out in the selected reaction monitoring (SRM) mode with positive electrospray ionization, and the mass transitions of mobocertinib and osimertinib were m/z 587.01 → 71.88 and m/z 499.80 → 71.94, respectively. The method was validated in terms of selectivity, linearity, accuracy and precision, extraction recovery and matrix effect, stability and carryover as per the guidelines for bioanalytical method validation (FDA, 2018). The method was applied to the pharmacokinetic study of mobocertinib in rats by oral gavage at the doses of 2, 6, and 18 mg/kg. A total of 216 plasma samples from 18 rats were analyzed. RESULTS: The results showed good linearity over the range of 1-1000 ng/mL (R2 = 0.9957). The intra-batch accuracy was within 94.65-102.59% and the precision was within 5.49-10.46%. The inter-batch accuracy was within 97.08-102.25% with a precision of 7.54-10.13%. The extraction recovery and matrix factor were acceptable for the bioanalysis of mobocertinib. Additionally, mobocertinib was found to be stable under the detected conditions. Mobocertinib showed linear pharmacokinetic characteristics following oral administration to rats at 2.0-18.0 mg/kg. CONCLUSION: The developed and validated method was successfully employed in the pharmacokinetic study in rats following oral administration of mobocertinib at the doses of 2, 6, and 18 mg/kg.

An Efficient Method for the Differentiation of Human iPSC-Derived Endoderm toward Enterocytes and Hepatocytes.

The endoderm, differentiated from human induced pluripotent stem cells (iPSCs), can differentiate into the small intestine and liver, which are vital for drug absorption and metabolism. The development of human iPSC-derived enterocytes (HiEnts) and hepatocytes (HiHeps) has been reported. However, pharmacokinetic function-deficiency of these cells remains to be elucidated. Here, we aimed to develop an efficient differentiation method to induce endoderm formation from human iPSCs. Cells treated with activin A for 168 h expressed higher levels of endodermal genes than those treated for 72 h. Using activin A (days 0-7), CHIR99021 and PI-103 (days 0-2), and FGF2 (days 3-7), the hiPSC-derived endoderm (HiEnd) showed 97.97% CD-117 and CD-184 double-positive cells. Moreover, HiEnts derived from the human iPSC line Windy had similar or higher expression of small intestine-specific genes than adult human small intestine. Activities of the drug transporter P-glycoprotein and drug-metabolizing enzyme cytochrome P450 (CYP) 3A4/5 were confirmed. Additionally, Windy-derived HiHeps expressed higher levels of hepatocyte- and pharmacokinetics-related genes and proteins and showed higher CYP3A4/5 activity than those derived through the conventional differentiation method. Thus, using this novel method, the differentiated HiEnts and HiHeps with pharmacokinetic functions could be used for drug development.

Development and validation of a simple and sensitive LC-MS/MS method for quantification of ampicillin and sulbactam in human plasma and its application to a clinical pharmacokinetic study.

Ampicillin-sulbactam is a broad-spectrum combination antibiotic used for a variety of clinical applications, including as a prophylactic agent to reduce the risk of surgical site infection. The pharmacokinetics of ampicillin-sulbactam after redosing during prolonged surgeries remains incompletely understood. In anticipation of further studying the intra-operative pharmacokinetics of this drug, we have developed a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of ampicillin and sulbactam. The plasma samples were prepared using a simple protein precipitation method. Gradient chromatographic elution was used to separate analytes, and MS/MS analysis was performed in negative ionization mode for both analytes via multiple reaction monitoring (MRM). All validation parameters were evaluated under a good laboratory practice (GLP) environment. For both ampicillin and sulbactam, the lower limit of quantitation (LLOQ) was established as 0.25 µg/mL. The calibration curve ranged from 0.25 to 200 µg/mL for ampicillin and 0.25-100 µg/mL for sulbactam. Inter- and intra-day precisions for both analytes were ≤11.5 % for quality controls and ≤17.4 % for LLOQ; accuracies ranged from -11.5 to 12.5% for 3 quality control levels and -18.1-18.7% for LLOQ. In addition to sensitivity, accuracy and precision, 13 other parameters were also validated for both analytes, and the results met the acceptance criteria. Our method was successfully applied to quantify ampicillin and sulbactam concentrations in patients undergoing surgery.

Pharmacokinetic study and brain tissue analysis of Zolmitriptan loaded chitosan nanoparticles in rats by LC-MS method.

INTRODUCTION: Migraine has recently become a major interest to the neuroscientists. Zolmitriptan is an effective medicine used in the treatment of migraine. The nasal spray was prepared from Zolmitriptan loaded chitosan nanoparticles and evaluated for pharmacokinetic properties. METHODS: In this study male Wistar albino rats weighing between 200 and 250 g were taken and divided into 4 groups with 6 rats in each group. Nasal spray containing Zolmitriptan loaded Chitosan nanoparticles were administered nasally (using specific inhalation mask) at a dose of 0.5 mg/kg as a test formulation and compared with the control groups which received either water for injection or marketed standard drug (Zolmist) or standard drug solution at a same dose. The pharmacokinetic parameters such as Cmax, Tmax, and brain tissue analyses for accumulation of drug were performed for Zolmitriptan by LC-MS method. RESULTS: Amount of drug in the plasma from the test formulation, standard marketed drug (Zolmist) and standard drug solution was found to be 41.37 ±â€¯2.31, 34.76 ±â€¯4.22 and 23.74 ±â€¯2.42 ng/ml at 10 min respectively, which indicated significantly (p < 0.05) greater amount of drug being delivered from the test formulation compared to the both standard groups. The amount of the drug (Zolmitriptan) present in brain tissue (Olfactory lobe) was found to be 15 ±â€¯0.08, 13 ±â€¯0.14 and 8 ±â€¯0.13 ng/g at 60 min for test formulation, marketed standard and standard drug solution respectively which indicates significantly (p < 0.05) higher amount of drug absorption in brain tissue from the test formulation compared to both the standard groups. CONCLUSION: Pharmacokinetics studies of nasal spray containing Zolmitriptan loaded chitosan nanoparticles proved rapid onset of action in animals and is promising in treatment of migraine.

Putative multiple reaction monitoring strategy for the comparative pharmacokinetics of postoral administration Renshen-Yuanzhi compatibility through liquid chromatography-tandem mass spectrometry.

BACKGROUND: Exploring the pharmacokinetic (PK) changes of various active components of single herbs and their combinations is necessary to elucidate the compatibility mechanism. However, the lack of chemical standards and low concentrations of multiple active ingredients in the biological matrix restrict PK studies. METHODS: A putative multiple reaction monitoring strategy based on liquid chromatography coupled with mass spectrometry (LC-MS) was developed to extend the PK scopes of quantification without resorting to the use of chemical standards. First, the compounds studied, including components with available reference standard (ARS) and components lacking reference standard (LRS), were preclassified to several groups according to their chemical structures. Herb decoctions were then subjected to ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry analysis with appropriate collision energy (CE) in MS2 mode. Finally, multiple reaction monitoring transitions transformed from MS2 of ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry were used for ultrahigh-performance liquid chromatography coupled with triple quadrupole mass spectrometry to obtain the mass responses of LRS components. LRS components quantification was further performed by developing an assistive group-dependent semiquantitative method. RESULTS: The developed method was exemplified by the comparative PK process of single herbs Radix Ginseng (RG), Radix Polygala (RP), and their combinations (RG-RP). Significant changes in PK parameters were observed before and after combination. CONCLUSION: Results indicated that Traditional Chinese Medicine combinations can produce synergistic effects and diminish possible toxic effects, thereby reflecting the advantages of compatibility. The proposed strategy can solve the quantitative problem of LRS and extend the scopes of PK studies.

Preclinical Pharmacokinetics Study of a Novel Intravenous Anesthetic ET-26 Hydrochloride.

BACKGROUND: ET-26 hydrochloride is a novel intravenous anesthetic, approved for clinical trials, that produces a desirable sedative-hypnotic effect with stable myocardial performance and mild adrenocortical suppression in rats and beagle dogs. The objective of this study was to assess the absorption, distribution, metabolism, and excretion of ET-26 hydrochloride. METHODS: Hepatocytes from human, monkey, dog, rat, and mouse were used to determine the metabolites of ET-26 hydrochloride. Distribution and excretion were assessed in rats and pharmacokinetic studies were performed in beagle dogs. RESULTS: The metabolic pathway and proposed structure of metabolites were fully assessed resulting from the biotransformation reactions of hydrolysis, dehydrogenation, demethylation and glucuronic acid conjugation. The main distribution of the drug was in fat (15067 ± 801 ng/ml) and liver (13647 ± 1126 ng/ml), and the kidney was the primary excretion route (4.47%-11.94%). The Cmax after injection with 1.045 mg/kg, 2.09 mg/kg, and 4.18 mg/kg was 1476.5 ± 138.9 ng/ml, 2846.1 ± 223.3 ng/ml, and 6233.3 ± 238.9 ng/ml, respectively. The t1/2 of the drug was similar across dose groups at 74.8 ± 10.8 min to 81.4 ± 4.2 min. The AUC0-t values were 30208.1 ± 2026.5 min*ng/ml, 62712.8 ± 1808.3 min*ng/ml, and 130465.2 ± 7457.4 min*ng/ml, respectively. CONCLUSION: The metabolic pathway and the proposed structure of metabolites for ET-26 hydrochloride were fully assessed. The majority of distribution for ET-26 hydrochloride occurs in the fat and liver, while the primary route of excretion for ET-26 hydrochloride is through the kidney. In dogs, pharmacokinetic features of ET-26 hydrochloride had a linear relationship with dosage.

Levetiracetam.

A comprehensive profile of levetiracetam is presented in this chapter which includes its description, formula, elemental analysis, appearance, uses and applications. Different earlier studies included for example methods of synthesis are described with its typical structural schemes. The profile also listed the drug's physical characteristics indicating its solubility, X-ray powder diffraction pattern, thermal methods of analysis as well as its spectroscopic characteristics. Different methods of analysis which includes compendial method of analysis, as well as reported method of analysis which include spectrophotometry, spectrofluorometry, electrochemical method, chromatographic method, and immunoassay method of analysis. The study was include drug stability, clinical pharmacology, e.g., mechanism of action, pharmacokinetic study. Around 70 references are recorded as a proof of this chapter.

Simultaneous determination of nine coumarins in rat plasma by HPLC-MS/MS for pharmacokinetics studies following oral administration of Fraxini Cortex extract.

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of nine coumarins including aesculin, aesculetin, fraxin, fraxetin, scopoletin, isoscopoletin, 6-hydroxy-7,8-dimethoxy coumarin, 8-hydroxy-6,7-dimethoxy coumarin and umbelliferone in rat plasma using nodakenin as the internal standard (IS). The plasma samples were pretreated by a one-step direct protein precipitation with methanol. The chromatographic separation was carried out on a C18 column with a gradient mobile phase consisting of methanol and water (containing 0.05% acetic acid). All analytes and IS were quantitated through electrospray ionization in negative ion multiple reaction monitoring (MRM) mode. This method was fully validated in terms of the sensitivity, specificity, accuracy, precision (intra- and inter-day), matrix effect, recovery as well as the stability of the analyte under various conditions, and the results satisfied the requirements of biological sample measurement. The validated method was successfully applied to pharmacokinetic study of the nine coumarins in rat plasma after oral administration of Fraxini Cortex aqueous extract, among which the pharmacokinetics of four coumarins including fraxetin, isoscopoletin, 6-hydroxy-7,8-dimethoxy coumarin and 8-hydroxy-6,7-dimethoxy coumarin were studied for the first time.

Improvement of the Pharmacological Properties of Maize RIP by Cysteine-Specific PEGylation.

To improve the pharmacological properties of maize ribosome-inactivating protein (maize RIP) for targeting HIV-infected cells, the previously engineered TAT-fused active form of maize RIP (MOD) was further engineered for cysteine-directed PEGylation. In this work, two potential antigenic sites, namely Lys-78 and Lys-264, were identified. They were mutated to cysteine residue and conjugated with PEG5k or PEG20k. The resultant PEG derivatives of MOD variants were examined for ribosome-inactivating activity, circulating half-life and immunogenicity. Our results showed that MOD-PEG conjugates had two- to five-fold lower biological activity compared to the wild-type. Mutation of the two sites respectively did not decrease the anti-MOD IgG and IgE level in mice, but the conjugation of PEG did dramatically reduce the antigenicity. Furthermore, pharmacokinetics studies demonstrated that attachment of PEG20k prolonged the plasma half-life by five-fold for MOD-K78C and 17-fold for MOD-K264C, respectively. The site-specific mutation together with PEGylation therefore generated MOD derivatives with improved pharmacological properties.

Assessment of the safety, targeting, and distribution characteristics of a novel pH-sensitive hydrogel.

In our previous study, we synthesized a pH-sensitive hydrogel based on poly (ɛ-caprolactone) (PCL), Pluronic (Poloxamer) and methacrylic acid (MAA) using UV-initiated free-radical polymerization. In the present study, we evaluated the safety of the obtained GMA-PCFC-GMA copolymer and a P(CFC-MAA-MEG) hydrogel both in vitro and in vivo. The pharmacokinetics study and distribution characteristics of dexamethasone in rat blood and mouse colon were investigated in detail. The in vitro toxicity of the GMA-PCFC-GMA copolymer was evaluated using a cell viability assay with HEK293 cells. An acute oral toxicity test was conducted by orally administering mice with a total of 10,000 mg/kg body weight of the P(CFC-MAA-MEG) hydrogel. The mice were then observed continuously for 14 days. After which, they were sacrificed and their blood collected for routine blood and serum chemistry tests. Pharmacokinetic and colonic tissue distribution studies were conducted using high-performance liquid chromatography to detect the concentration of dexamethasone in rat blood and mouse colon tissue. All of the results indicated that both the GMA-PCFC-GMA copolymer and P(CFC-MAA-MEG) hydrogel were nontoxic. Moreover, the hydrogel significantly enhanced the colon-targeting behavior of dexamethasone. These results suggested that the novel hydrogel has great potential in colon-targeted drug delivery.

Liquid chromatography tandem mass spectrometry in study of the pharmacokinetics of six steroidal saponins in rats.

A rapid, simple and sensitive high-performance liquid chromatography tandem mass spectrometry method was developed and validated for simultaneous determination of six main steroidal saponins in Paris polyphylla in rat plasma. Ginsenoside Rg3 was selected as the internal standard (IS). Plasma samples were pretreated with protein precipitation, and the separation was achieved on a reverse phase Agilent poroshell120 EC-C18 column using a gradient mobile phase system of acetonitrile-water containing 0.1% formic acid. The triple quadruple mass spectrometer was set in negative electrospray ionization mode and multiple reaction monitoring (MRM) was used for six steroidal saponins quantification. The precursors to produce ion transitions monitored for polyphyllin I, polyphyllin II, polyphyllin VI, polyphyllin VII, dioscin, gracillin and IS were m/z 899.5>853.4, 1059.5>1013.5, 783.4>737.4, 1075.5>1029.5, 913.5>867.4, 929.5>883.4 and 819.5>783.4, respectively. The intra- and inter-day precisions (RSD%) were less than 13% and the average extraction recoveries ranged from 85% to 97.0% for each analyte. Six steroidal saponins were proved to be stable during sample storage, preparation and analytical procedures. The established method was employed for simultaneous quantification and successfully used for the first time for the pharmacokinetics evaluation of the six main compounds after intragastric administration of P. polyphylla extract in Sprague-Dawley rats.