Preliminary Pharmacokinetic Study Research Articles

EXTH-78. WP1874, A HIGHLY POTENT UNIQUE DNA BINDING AGENT WITH ENHANCED CNS UPTAKE

Abstract As part of our drug discovery program, we have developed structure-based modular designs of unique DNA-binding agents. The approach combines DNA intercalating and DNA “minor-groove-binding” modules. We have discovered compound WP1244 that potentially binds up to 10 bp long sequences of DNA. The unique and intriguing feature of WP1244 is its high CNS uptake combined with the picomolar to low nanomolar cytotoxicity against ependymoma and glioblastoma multiforme (GBM) cell lines and demonstrated in vivo activity in the orthotopic model of GBM. To improve water solubility and develop an IV formulation, we have synthesized WP1874, a mesylate salt of WP1244, and initiated its preclinical characterization. WP1874, similarly to its parental compound, shows high cytotoxicity in ependymoma, GBM, and medulloblastoma cell lines with IC50 in low nanomolar range and it was up to 100 to 200 times more potent than doxorubicin. Interestingly, WP1874 does not appear to be cytotoxic against normal kidney cells (VeroC1008) with IC50 > 10 μM. Preliminary pharmacokinetic and biodistribution studies performed in CD-1 mice with intact brains revealed enhanced penetration of WP1874 to the brain with Cmax 1.5-fold greater than in plasma. Respectively, WP1874 Cmax in the brain was 2.3 ug/g (~2.0 μM) vs. 1.5 μg/ml (1.3 μM) in plasma. Acute toxicity in intravenously administered WP1874 was LD50 >15mg/kg. No mortalities or any apparent toxicity symptoms were recorded for six intravenous weekly doses of WP1874 at 2.5 or 5 mg/kg in CD-1, Balb/c, or nude athymic mice. Intraperitoneal administration was well-tolerated up to 5 mg/kg given three times a week for four cycles. High CNS uptake, excellent cytotoxicity against different brain cancer cell lines, and low toxicity in vivo and in vitro against normal cells warrant further investigation of WP1874 as a mechanically unique potential anticancer agent against CNS malignancies.

Prec-O2-02 - Anti-tumor effect of anti-apoptosis clone 11 protein-derived peptides on Sézary syndrome malignant CD4+ T lymphocytes

Sézary syndrome (SS) is a rare, aggressive leukemic form of cutaneous T-cell lymphoma characterized by generalized erythroderma, lymphadenopathy and circulating malignant CD4+ T cells (Sézary cells). Sézary syndrome evolves very quickly, patients are severely immunocompromised and their quality of life is drastically impaired. SS prognosis remains dismal despite recent therapeutic advances. AAC-11 (Anti-Apoptosis Clone 11, also known as Api5) is a survival scaffold protein that is widely expressed in cancer cells. Recent data indicate that AAC-11 might to be one of the central molecules involved in cancer cell progression and survival. Therefore, its inactivation might constitute an attractive approach for developing novel cancer therapeutics. AAC-11 contains a heptad leucine repeat domain that constitutes a protein-protein interaction motif, allowing its interaction with several apoptosis regulatory proteins. Loss-of-function mutations of the heptad leucine repeat motif are responsible for a defect in the interaction with its binding partners and associated with an abolition of the survival properties of AAC-11. We have recently described cell penetrating peptides based on the fusion of penetratin and a portion of the heptad leucine repeat region of AAC-11 that can induce cancer cells death. This effect is not observed in normal cells, suggesting high therapeutic indices. Here we evaluated the anti-tumor effect of a novel AAC-11-derived peptide, termed RT39, in the context of Sézary syndrome. Our results demonstrate that RT39 exerts an efficient and specific cytotoxic activity towards Sézary cells, while sparring the other immune cell populations, both <i>ex vivo</i> on primary patient cells and <i>in vivo</i> in preclinical Sézary syndrome murine models. Mechanistic studies revealed that RT39 induces membranolysis of Sézary cells by means of binding to p21-activated kinase 1 (PAK1) in the context of Sézary cells plasma membrane, where PAK1 is overexpressed. Preliminary pharmacokinetic studies in mice indicated that, after intravenous, subcutaneous or intraperitoneal administration, the half-life of the peptide is of the order of 30 minutes, but the elimination phase is very prolonged with high AUCs, indicative of durable exposure. Along with excellent tolerability in mice, our preclinical results support the development of RT39 as a new therapeutic strategy in Sézary syndrome.

Comparison of Nociceptive Effects of Buprenorphine, Firocoxib, and Meloxicam in a Plantar Incision Model in Sprague–Dawley Rats

Due to their reduced frequency of dosing and ease of availability, NSAIDs are generally preferred over opioids for rodent analgesia. We evaluated the efficacy of the highly COX2-selective NSAID firocoxib as compared with meloxicam and buprenorphine for reducing allodynia and hyperalgesia in rats in a plantar incision model of surgical pain. After a preliminary pharmacokinetic study using firocoxib, Sprague-Dawley rats (n = 12 per group, 6 of each sex) were divided into 6 groups: no surgery (anesthesia only), saline (surgery but no analgesia), buprenorphine (0.05 mg/kg SC every 8 h), meloxicam (2 mg/kg SC every 24 h), and 2 dosages of firocoxib (10 and 20 mg/kg SC every 24 h). The nociception assays were performed by using von Frey and Hargreaves methodology to test mechanical allodynia and thermal hyperalgesia. These assays were performed at 24 h before and at 20, 28, 44, and 52 h after start of surgery. None of the analgesics used in this study produced significantly different responses in allodynia or hyperalgesia from those of saline-treated rats. In the Hargreaves assay, female saline-treated rats experienced significantly greater hyperalgesia than did males. These findings add to a growing body of literature suggesting that commonly used dosages of analgesics may not provide sufficient analgesia in rats experiencing incisional pain.

ML365 inhibits TWIK2 channel to block ATP-induced NLRP3 inflammasome.

Dysregulation of NLRP3 inflammasome results in uncontrolled inflammation, which participates in various chronic diseases. TWIK2 potassium channel mediates potassium efflux that has been reported to be an essential upstream mechanism for ATP-induced NLRP3 inflammasome activation. Thus, TWIK2 potassium channel could be a potential drug target for NLRP3-related inflammatory diseases. In the present study we investigated the effects of known K2P channel modulators on TWIK2 channel expressed in a heterologous system. In order to increase plasma membrane expression and thus TWIK2 currents, a mutant channel with three mutations (TWIK2I289A/L290A/Y308A) in the C-terminus was expressed in COS-7 cells. TWIK2 currents were assessed using whole-cell voltage-clamp recording. Among 6 known K2P channel modulators tested (DCPIB, quinine, fluoxetine, ML365, ML335, and TKDC), ML365 was the most potent TWIK2 channel blocker with an IC50 value of 4.07 ± 1.5 μM. Furthermore, ML365 selectively inhibited TWIK2 without affecting TWIK1 or THIK1 channels. We showed that ML365 (1, 5 μM) concentration-dependently inhibited ATP-induced NLRP3 inflammasome activation in LPS-primed murine BMDMs, whereas it did not affect nigericin-induced NLRP3, or non-canonical, AIM2 and NLRC4 inflammasomes activation. Knockdown of TWIK2 significantly impaired the inhibitory effect of ML365 on ATP-induced NLRP3 inflammasome activation. Moreover, we demonstrated that pre-administration of ML365 (1, 10, 25 mg/kg, ip) dose-dependently ameliorated LPS-induced endotoxic shock in mice. In a preliminary pharmacokinetic study conducted in rats, ML365 showed good absolute oral bioavailability with F value of 22.49%. In conclusion, ML365 provides a structural reference for future design of selective TWIK2 channel inhibitors in treating related inflammatory diseases.

Vortioxetine Derivatives with Amino Acid as Promoiety: Synthesis, Activity, Stability and Preliminary Pharmacokinetic Study

Vortioxetine (Vot) is an effective antidepressant with unique mechanisms exerting multi-target effects. However, severe side-effects such as nausea and vomiting are commonly experienced under conditions of long-term administration. Eight amino acid modified Vot derivatives were designed and prepared in this study. Similar or lower binding affinities of the modified compounds to the serotonin transporter (SERT) than Vot was observed in the 4-(4-(dimethylamino)-styrl)-N-methylpyridinium (ASP+) uptake assay on RBL-2H3 cells. Additionally, the majority of derivatives remained sufficiently stable in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF), indicating achievement of intestinal absorption in the modified form. Afterwards, all derived compounds exhibited slower hepatic clearance and a longer half-life, compared to the parent drug Vot. Notably, threonine-modified 3f exhibited significantly lower activity to SERT, serine-modified 3e showed the fastest degradation rate in rat plasma, with hydrolysis to an extent of 50% in 10 min, and better pharmacokinetic properties in rat, including Cmax, t1/2, and especially AUC0-t, which was ∼3-fold higher relative to the parent compound. Although, no clear understanding of SARs has been obtained, modification of Vot with amino acids containing hydroxyl groups may be beneficial to reduce the gastrointestinal side effect of Vot or obtain better pharmacokinetic properties, providing some ideas for the further study in the future.

EPCT-19. A PHASE I STUDY OF RIBOCICLIB AND EVEROLIMUS FOLLOWING RADIATION THERAPY IN CHILDREN WITH NEWLY DIAGNOSED NON-BIOPSIED DIFFUSE PONTINE GLIOMAS (DIPG) AND RB+ BIOPSIED DIPG AND HIGH GRADE GLIOMAS (HGG)

Genomic aberrations in the cell cycle and mTOR pathways have been reported in diffuse pontine gliomas (DIPG) and high-grade gliomas (HGG). Dual inhibition of CDK4/6 (ribociclib) and mTOR (everolimus) has strong biologic rationale, non-overlapping single-agent toxicities, and adult clinical experience. The maximum tolerated dose (MTD) and/or recommended phase two dose (RP2D) of ribociclib and everolimus administered during maintenance therapy following radiotherapy was determined in the phase I study as a rolling 6 design. Ribociclib and everolimus were administered once daily for 21 days and 28 days, respectively starting two-four weeks post completion of radiotherapy. All HGG patients and any DIPG patient who had undergone biopsy were screened for RB protein by immunohistochemistry. Eighteen eligible patients enrolled (median age 8 years; range: 2–18). Six patients enrolled at dose levels 1,2, and 3 without dose limiting toxicities (DLT). Currently, five patients are enrolled at dose level 3 expansion cohort. The median number of cycles are 4.5 (range: 1–20+). Among the expansion cohort, one dose limiting toxicity included a grade 3 infection and one patient required a dose reduction in course 3 due to grade 3 ALT and grade 4 hypokalemia. The most common grade 3/4 adverse events included neutropenia. Preliminary pharmacokinetic studies on 12 patients suggest an impact of ribociclib on everolimus pharmacokinetics. The MTD/RP2D of ribociclib and everolimus following radiotherapy in newly diagnosed DIPG and HGG is anticipated to be 170 mg/m2/day x 21 days and 1.5 mg/ m2/day every 28 days which is equivalent to the adult RP2D.

Comparable Intestinal and Hepatic First-Pass Effect of YL-IPA08 on the Bioavailability and Effective Brain Exposure, a Rapid Anti-PTSD and Anti-Depression Compound.

YL-IPA08, exerting rapid antidepressant-like and anxiolytic-like effects on behaviors by translocator protein (TSPO) mediation, is a novel compound that has been discovered and developed at our institute. Fit-for-purpose pharmacokinetic properties is urgently needed to be discovered as early as possible for a new compound. YL-IPA08 exhibited low bioavailability (∼6%) during the preliminary pharmacokinetics study in rats after oral administration. Our aim was to determine how metabolic disposition by microsomal P450 enzymes in liver and intestine limited YL-IPA08’s bioavailability and further affected brain penetration to the target. Studies of in vitro metabolic stability and permeability combined with in vivo oral bioavailability, panel CYP inhibitor co-administration via different routes, and double cannulation rats were conducted to elucidate the intestinal and hepatic first-pass effect of YL-IPA08 on bioavailability. Unbound brain-to-plasma ratio (K p,uu) in rats was determined at steady state. Results indicated that P450-mediated elimination appeared to be important for its extensive first-pass effect with comparative contribution of gut (35%) and liver (17%), and no significant species difference was observed. The unbound concentration of YL-IPA08 in rat brain (6.5 pg/ml) was estimated based on K p,uu (0.18) and was slightly higher than in vitro TSPO-binding activity (4.9 pg/ml). Based on the onset efficacy of YL-IPA08 toward TPSO in brain and K p,uu, therapeutic human plasma concentration was predicted to be ∼27.2 ng/ml would easily be reached even with unfavorable bioavailability.

LC-MS/MS quantification of progesterone in ovariectomized miniature swine and its application for preliminary pharmacokinetic study of a novel vaginal sustained release system

Objective We here established a simple, fast, robust and sensitive LC-MS/MS method and validated as well for the quantitative analysis of progesterone (PGT) in ovariectomized (OVX) miniature swine plasma. The method was successfully applied to characterize the pharmacokinetics of a progesterone vaginal drug delivery system. Methods Megestrol acetate was utilized as an internal standard (IS). The separation and detection of PGT from endogenous interference was performed successfully by liquid chromatography with gradient elution and mass spectrometry equipped with positive ESI source using MRM mode. The EVA intravaginal rings (IVRs) were manufactured by hot-melt extrusion (HME), afterward were administrated vaginally to OVX minipigs to evaluate PK study. Results The calibration curve for swine plasma samples across the concentration ranged between 0.25 ng/mL and 100 ng/mL. The intra- and inter-assay accuracy and precision were lower than ±5% and 5.88%, respectively. Recoveries of PGT and IS were ranging from 114–119% and 96.5–112%, respectively. In vitro study showed that the EVA IVRs release 18 mg/day of PGT continuously over 7 days, and corresponding mean PGT plasma concentration in OVX minipigs (CAVG) was 4.892 ng/mL. Conclusion All the study produced reliable results for the measurement of PGT concentration in miniature swine plasma and the method was successfully applied to a PK study for PGT vaginal ring in miniature pigs, which may lay the foundation for further research on the progesterone preparations intended for in assisted reproductive technology.

Salting‐out assisted liquid–liquid extraction method optimized by design of experiments for the simultaneous high‐performance liquid chromatography analysis of perampanel and stiripentol in mouse matrices

We report a high-performance liquid chromatography method development able to simultaneously determine perampanel and stiripentol, two third-generation antiepileptics whose therapeutic spectrum can potentially be extended, in several mouse matrices. A salting-out assisted liquid-liquid extraction optimized by a design of experiments approach was adopted for sample preparations. Isopropanol and magnesium sulfate were the extraction solvent and salting-out agent, respectively. Both drugs and internal standard (terbinafine) were separated using a LiChroCART® Purospher Star column (C18 , 55×4mm; 3μm) isocratically pumped with mobile phase [1% triethylamine in water (pH 2.5) and acetonitrile (53:47, v/v)] at 1mL/min. Stiripentol and terbinafine were detected by fluorescence at 254/372nm and perampanel at 275/430nm. Good linearity was demonstrated for perampanel at 1-500ng/mL range in brain, 2-2000ng/mL in liver and 1-2000ng/mL in plasma and kidney (r2 ≥0.9922), and for stiripentol between 10 and 2000ng/mL in brain and 10 and 20000ng/mL in the remaining matrices (r2 ≥0.9917). Precision (CV ≤15%) and accuracy (bias ±15%) were also verified, with obtained recovery values consistent with those predicted by the experimental design. This method was applied in preliminary pharmacokinetic studies to quantify perampanel or stiripentol after oral administration to mice, showing to be a promising bioanalytical tool to support future nonclinical in vivo pharmacokinetic studies.

Simple and fast UPLC-MS method for quantifying the anti-inflammatory candidate 5′-methoxynobiletin in rat plasma: Validation and application in a preliminary pharmacokinetic study

This study presents the development and validation of a fast and simple bioanalytical ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) method intended for quantifying the anti-inflammatory candidate 5′-methoxynobiletin (5′-MeONB) in rat plasma. Standard of 5′-MeONB was purified from A. conyzoides extract by using preparative HPLC. After a pretreatment of plasma samples with acetonitrile, chromatographic separations were efficiently achieved with a C18 column using a 9 min gradient system of 0.1% aqueous formic acid and acetonitrile as eluent. Drug candidate 5′-MeONB and chrysin (internal standard, IS) detection were carried out using ESI+ through the extracted ion chromatograms approach, monitored at m/z 433.1494 (for 5′-MeONB, tR:1.78 min) and m/z 255.0657 (for IS, tR:1.57 min). Method was validated according to US FDA guidelines, presenting linearity (R2 > 0.999) over concentration range of 30–750 ng/mL. Relative standard deviation (RSD) of repeatability and intermediary precision respectively ranged between 1.93–3.65% and 2.16–7.54%, considering lower limit of quantitation (30 ng/mL) and quality control (90, 360 and 600 ng/mL) samples, while accuracy was between 82.51 and 109.44%. Moreover, no interference from plasma endogenous substances, no carryover effect, and no influence of extraction method even in hemolyzed blood samples were observed. Sample stability in auto-sampler and long-term −80 °C storage, as well as matrix effect were within acceptable limits. For the first time, using the validated UPLC-MS bioanalytical method, the plasma pharmacokinetics of 5′-MeONB following 2 mg/kg intravenous bolus dosing to Wistar rats was characterized allowing the determination of the parameters describing drug distribution and elimination.

Preparation, optimization and preliminary pharmacokinetic study of curcumin encapsulated turmeric oil microemulsion in zebra fish

The present investigation aimed to develop curcumin loaded turmeric oil microemulsion for brain targeting. An effort has been made to investigate the role of functional components in developing brain targeted formulation which could enhance the bioavailability and uptake of drug in the brain upon oral administration. Preliminary studies like solubility study, emulsification study and construction of the pseudo ternary phase diagram were performed for screening components. The formulation was optimized by using extreme vertices mixture design. The optimized formulation was characterized for appearance, stability to centrifugation, dilution potential, globule size, zeta potential and drug content. Furthermore, ex-vivo permeation in chicken gut sac non everted technique and pharmacokinetic study in adult zebra fishes were carried out. The optimized formulation was found to clear, yellow-colored with the absence of phase separation and precipitation denoted the stability of formulation to centrifugation and dilution. The mean globule size, polydispersity index, zeta potential and drug content was observed as 29.13± 0.12 nm, 0.23 ± 0.01,-12.33 ± 1.37 mV and 99.10±3.91 %, respectively. Ex vivo permeation study revealed 2.41 fold enhancement in the steady-state flux when compared to curcumin solution. Furthermore, optimized formulation showed shorter Tmax (5 min) and higher AUC(0-∞) (7.93 μg/brain*min) compared to the curcumin solution which showed similar Tmax and AUC(0-∞) of 2.78 μg/brain*min after oral administration to zebra fishes revealing 3.97 fold enhancement. The results revealed enhanced ex vivo oral absorption and enhanced in vivo brain pharmacokinetics of curcumin via functional microemulsion in the zebra fish model.

Abstract 1825: Tumor-targeted knockdown of KRAS mutants with novel Centyrin:siRNA conjugates

Abstract KRAS has been the quintessential undruggable oncogene for many years. Although there have been recently described small molecule inhibitors of KRAS, these molecules only target a specific mutant form, KRAS G12C. The KRAS G12C mutation represents just 12% of the total number of KRAS mutants across many different tumor types including CRC, NSCLC, and PDAC. We have taken a novel approach to decrease all KRAS mRNA and protein mutants using Centyrin:siRNA drug conjugates which should have applicability across a broader group of patients. Centyrins are a new class of small, stable and highly soluble proteins engineered to bind antigens with high affinity. Centyrins facilitate internalization of macromolecules, including siRNA, into cells and enable trafficking through endosomes and into the cytoplasm. Centyrins are engineered by consensus design from human tenascin C with each domain having a MW of approximately 10 kilodaltons. We have rationally designed a bispecific Centyrin conjugate which targets EpCAM and CD71 to deliver an optimized, chemically modified pan-KRAS siRNA into epithelial derived tumors. EpCAM and CD71 (the transferrin receptor) were selected due to their higher levels of expression on tumors versus normal tissue and the targeting of these receptors with a bispecific molecule enhances both potency of siRNA delivery and selectivity to tumor cells. In addition, Centyrin:siRNA conjugate candidates contain a domain to extend in vivo exposure. The designed Centyrin:siRNA drug conjugates exhibit potencies for knockdown of KRAS mRNA and protein at nM concentrations across various KRAS mutant tumor cell lines, resulting in potent inhibition of proliferation. We report activity on tumor cell lines harboring all of the most common KRAS mutants including G12D (HPAF-II), G12V (SW620), G12S (A549), G12C (H358, MIA PaCa-2), G13D (H1944), and Q61H (H460). This activity is specific for cells expressing EpCAM and CD71 and synergy of the bispecific versus the monospecific Centyrin has been demonstrated. The effect of the Centyrin:siRNA conjugate is specific for KRAS with no effect on the closely related homologs NRAS or HRAS. Pulse washout experiments suggest that in vitro treatment of cells for only 6-24 hours resulted in maximal knockdown of KRAS mRNA up to at least 72 hours. Preliminary pharmacokinetic studies have demonstrated good exposure (~100-400nM) of the siRNA in tumors in a xenograft model. Current efforts are aimed at demonstration of in vivo efficacy in multiple xenograft models with optimization of dose and scheduling. These novel Centyrin:siRNA conjugates have great potential to treat the many patients with KRAS mutations. Citation Format: Russell C. Addis, Robert Kolakowski, Swapnil Kulkarni, Joshua Gorsky, Rebecca Meyer, Yao Xin, Evana Mortezavi, Karyn T. O'Neil, Steven G. Nadler. Tumor-targeted knockdown of KRAS mutants with novel Centyrin:siRNA conjugates [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1825.

Ergogenic Effect of BCAAs and L-Alanine Supplementation: Proof-of-Concept Study in a Murine Model of Physiological Exercise.

Background: Branched-chain amino acids (BCAAs: leucine, isoleucine, valine) account for 35% of skeletal muscle essential amino acids (AAs). As such, they must be provided in the diet to support peptide synthesis and inhibit protein breakdown. Although substantial evidence has been collected about the potential usefulness of BCAAs in supporting muscle function and structure, dietary supplements containing BCAAs alone may not be effective in controlling muscle protein turnover, due to the rate-limiting bioavailability of other AAs involved in BCAAs metabolism. Methods: We aimed to evaluate the in vivo/ex vivo effects of a 4-week treatment with an oral formulation containing BCAAs alone (2:1:1) on muscle function, structure, and metabolism in a murine model of physiological exercise, which was compared to three modified formulations combining BCAAs with increasing concentrations of L-Alanine (ALA), an AA controlling BCAAs catabolism. Results: A preliminary pharmacokinetic study confirmed the ability of ALA to boost up BCAAs bioavailability. After 4 weeks, mix 2 (BCAAs + 2ALA) had the best protective effect on mice force and fatigability, as well as on muscle morphology and metabolic indices. Conclusion: Our study corroborates the use of BCAAs + ALA to support muscle health during physiological exercise, underlining how the relative BCAAs/ALA ratio is important to control BCAAs distribution.

Hypothesis for a partially non urinary elimination of tranexamic acid in haemorrhagic caesarean section: Traces pilot pharmacokinetic study: Pharmacokinetics of tranexamic acid in obstetrics

BackgroundIn previous studies, the choice of doses of tranexamic acid was empirically defined as no pharmacokinetic study had been conducted in haemorrhagic caesarean section. ObjectiveThe objective was to build a pharmacokinetic model in patients receiving a single 0.5, 1 or 2 g intravenous bolus. MethodA preliminary monocentric open study was performed in the Lille centre. Blood samples and one urinary sample were collected in the 6 h following the injection. Nine patients were included. Tranexamic acid concentration was measured using liquid chromatography system coupled with tandem mass spectrometry. We used Monolix 2019R1 for population pharmacokinetic modelling. A structural model was constructed followed by the investigation of potential covariates. ResultsData were best described with a two-compartment model with a double first-order elimination from the central compartment. The model was improved when the variable ideal weight per dose was affected as a covariate for the apparent volume of distribution. Assuming a dose of 1 g and a height of 160 cm, the pharmacokinetic parameters were estimated at 10.26 L.h−1 for total clearance, 11.5 L for the volume of the central compartment, 15.8 L for the volume of the second compartment, a diffusional clearance of 30.36 L.h−1 , and a urinary excretion fraction of 25.8%. ConclusionsThe population pharmacokinetic model of tranexamic acid in haemorrhagic caesarean section was successfully established in our tiny sample of patients. The results of this preliminary TRACES pharmacokinetic study suggested that elimination of tranexamic acid is partially non urinary in contrast with healthy patients.

Rapid fluorometric determination of ticagrelor in tablets and rat plasma: Application to pharmacokinetics study.

The new antiplatelet drug ticagrelor has been determined based on its native fluorescence properties. These properties were studied and optimized to develop fast, simple and sensitive spectrofluorimetric method. The study included two approaches. The first approach is depending on measuring the native fluorescence at 300nm after excitation at 222nm. While the second approach combined synchronous and derivative scanning modes to measure ticagrelor at 286nm using Δ λ=100nm. Ticagrelor was measured in aqueous solution starting from the concentration of 200 to 5000ng/mL in both native and first derivative synchronous approaches. The developed methods were validated in accordance with ICH guidelines to be acceptable for quality control laboratories. Lowest concentrations that could be quantitated using the native and first derivative synchronous methods were 189 and 151ng/mL while lowest detectable concentrations were 63 and 50ng/mL, respectively. Moreover, the derivative synchronous fluorimetric approach was utilized to determine ticagrelor at 286nm in presence of other commonly co- administered drugs and the results demonstrate the enhanced selectivity of the proposed method. The same approach was also used to determine ticagrelor in rat plasma with acceptable recoveries. A preliminary pharmacokinetic study in rats was conducted and could be used to monitor plasma ticagrelor levels in humans.

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.

Niacin as a dietary supplement for improving mare fertility: A preliminary pharmacokinetic study

Niacin as a dietary supplement for improving mare fertility: A preliminary pharmacokinetic study

A novel LC–MS/MS analytical method for detection of articaine and mepivacaine in blood and its application to a preliminary pharmacokinetic study

Local anaesthetics (LAs) are commonly used in surgery, especially in dentistry. They cause a transitory inhibition of nerve signal due to the blockade of the voltage-gated sodium channels. LAs are administrated alone or with vasoconstriction agents, such as adrenaline. Toxicity of LAs is associated to neurological and cardiovascular alterations. Tachycardia, arrhythmia, tremors, tonic-clonic seizure and respiratory depression (at high doses) are the main symptoms of intoxication by LAs. Lidocaine, articaine and mepivacaine are among the most used anaesthetics. This study aimed to fully validated a new method for the simultaneous detection of articaine and mepivacaine in whole blood. Sample treatment consisted in a liquid-liquid extraction with phosphate buffer (pH 8, 0.1 M) and ethyl-acetate. Analysis was performed by liquid chromatography-tandem mass spectrometry in multiple reaction monitoring mode (transitions: articaine, 285→8658 m/z; mepivacaine, 247→9870 m/z; lidocaine – internal standard –, 235→8658 m/z). The method proved to be highly sensitive with limit of quantifications for articaine and mepivacaine of 0.8 and 0.1 ng/mL, respectively. Accuracy and precision were always within the acceptance criteria. The new procedure was also successfully applied to a preliminary pharmacokinetics study.

Preparation, characterization and preliminary pharmacokinetic study of pH-sensitive Hydroxyapatite/Zein nano-drug delivery system for doxorubicin hydrochloride.

Zein nanoparticles (Zein NPs) were used as a hydroxyapatite (HA) biomineralization template to generate HA/Zein NPs. Doxorubicin hydrochloride (DOX) was loaded on HA/Zein NPs (HA/Zein-DOX NPs) to improve its pH-sensitive release, bioavailability and decrease cardiotoxicity. HA/Zein-DOX NPs were prepared by phase separation and biomimetic mineralization method. Particle size, polydispersity index (PDI), Zeta potential, transmission electron microscope, X-ray diffraction and Fourier-transform infrared spectroscopy of HA/Zein-DOX NPs were characterized. The nanoparticles were then evaluated in vitro and in vivo. The small PDI and high Zeta potential demonstrated that HA/Zein-DOX NPs were a stable and homogeneous dispersed system and that HA was mineralized on Zein-DOX NPs. HA/Zein-DOX NPs showed pH-sensitive release. Compared with free DOX, HA/Zein-DOX NPs increased cellular uptake which caused 7 times higher in-vitro cytotoxicity in 4T1 cells. Pharmacokinetic experiments indicated the t1/2β and AUC0- t of HA/Zein-DOX NPs were 2.73- and 3.12-fold higher than those of DOX solution, respectively. Tissue distribution exhibited HA/Zein-DOX NPs reduced heart toxicity with lower heart targeting efficiency (18.58%) than that of DOX solution (37.62%). In this study, HA/Zein-DOX NPs represented an antitumour drug delivery system for DOX in clinical tumour therapy with improved bioavailability and decreased cardiotoxicity.

Pharmacological Characterizations of anti-Dementia Memantine Nitrate via Neuroprotection and Vasodilation in Vitro and in Vivo.

We have previously designed and synthesized a series of novel memantine nitrates, and some of them have shown neuroprotective effects; however, the detailed mechanisms remain unknown. In this study, we demonstrated that MN-12, one of the memantine nitrates, concentration-dependently protected against glutamate-induced neurotoxicity in rat primary cultured cerebellar granule neurons (CGNs). Western blotting assays revealed that MN-12 might possess neuroprotective effects through the inhibition of ERK pathway and activation of PI3K/Akt pathway concurrently. Moreover, MN-12 concentration-dependently dilated precontracted rat middle cerebral artery through activation of NO-cGMP pathway ex vivo. In the 2-vessel occlusion (2VO) rat model, MN-12 alleviated the impairments of spatial memory and motor dysfunction possibly via neuroprotection and improvement of the cerebral blood flow. Furthermore, the results of preliminary pharmacokinetic studies showed that MN-12 might quickly distribute to the major organs including the brain, indicating that MN-12 could penetrate the blood-brain barrier. Taken together, MN-12 might provide multifunctional therapeutic benefits for dementia associated with Alzheimer's disease, vascular dementia, and ischemic stroke, via neuroprotection and vessel dilation to improve the cerebral blood flow.