Synthesis and Biological Evaluation of Novel Triazine Derivatives as Positive Allosteric Modulators of α7 Nicotinic Acetylcholine Receptors

Enhancing neuronal α7 nicotinic acetylcholine receptor (α7 nAChR) function can alleviate cognitive deficits. Here, we report the design, synthesis, and evaluation of N-(4-(trifluoromethoxy)phenyl)-1,3,5-triazin-2-amine derivatives 8-10 as a series of novel α7 nAChR positive allosteric modulators (PAMs). The representative compound 10e functions as a type I PAM with an EC50 of 3.0 μM and approximately 38-fold enhancement of α7 current in the presence of agonist acetylcholine (100 μM). It specifically enhances α7 current with high selectivity. Compound 10e shows good pharmacokinetic property in mice. Intraperitoneal injection of 10e (3 mg/kg) exhibits sufficient blood-brain barrier penetration in mice. Furthermore, 10e can also rescue the auditory gating deficit in mice with schizophrenia-like behavior. Molecular docking of 10e with homopentameric α7 nAChR reveals a new mode of action. These results support the potential of 10e for treatment for schizophrenia and Alzheimer's disease.

Constructing slow-release formulations of herbicide metribuzin using its co-extrusion with biodegradable polyester poly-ε-caprolactone

Different technologies to prepare long term pesticide forms include polymer coating, preparing composites and encapsulating pesticides in nanoparticles. A simple and low-cost method was proposed to obtain slow-release formulations by co-extrusion of a pesticide with a biodegradable polymer at a temperature above the melting points of both components. A herbicide metribuzin and low-melting polyester poly-ε-caprolactone were chosen for this work. Formulations containing 10%, 20%, and 40% herbicide were prepared. During 7 days of their exposition in water, it was released from 81% to 96% of initially loaded metribuzin; the highest release was detected for 40%-loaded forms. Biodegradation of the constructs and pesticide release were further studied in the model soil. Degradation rates of the specimens increased with an increase in pesticide content, from 9% to 20% over 14 weeks for the 10%/20%-loaded and the 40%-loaded specimens, respectively. The release of metribuzin reached, respectively, 37-38% and 55%. The herbicide content in soil was lower due to its partial degradation in soil; it reached 23-25% and 33%, respectively, from initially loaded into the polymer matrix. Release kinetics of metribuzin in water as in soil best fitted the First-order model. The used approach is promising for obtaining long-term release formulations for soil applications.

Discovery of Potent and Fast-Acting Antimalarial Bis-1,2,4-triazines

Novel 3,3'-disubstituted-5,5'-bi(1,2,4-triazine) compounds with potent in vitro activity against Plasmodium falciparum parasites were recently discovered. To improve the pharmacokinetic properties of the triazine derivatives, a new structure-activity relationship (SAR) investigation was initiated with a focus on enhancing the metabolic stability of lead compounds. These efforts led to the identification of second-generation highly potent antimalarial bis-triazines, exemplified by triazine 23, which exhibited significantly improved in vitro metabolic stability (8 and 42 μL/min/mg protein in human and mouse liver microsomes). The disubstituted triazine dimer 23 was also observed to suppress parasitemia in the Peters 4-day test with a mean ED50 value of 1.85 mg/kg/day and exhibited a fast-killing profile, revealing a new class of orally available antimalarial compounds of considerable interest.

Aerosol Inhalation Delivery of Triazavirin in Mice: Outlooks for Advanced Therapy Against Novel Viral Infections

Under pandemic-caused emergency, evaluation of the potential of existing antiviral drugs for the treatment of COVID-19 is relevant. Triazavirin, an antiviral drug developed in Russia for per-oral administration, is involved in clinical trials against SARS-CoV-2 coronavirus. This virus has affinity to epithelial cells in respiratory tract, so drug delivery directly in lungs may enhance therapeutic effect and reduce side effects for stomach, liver, kidneys. We elaborated ultrasonic method of triazavirin aerosol generation and investigated the inhalation delivery of this drug in mice. Mean particle size and number concentration of aerosol used in inhalation experiments are 560 nm and 4 × 105 cm-3, respectively. Aerosol mass concentration is 1.6 × 10-4 mg/cm3. Inhalation for 20 min in a nose-only chamber resulted in 2 mg/kg body delivered dose and 2.6 μg/mL triazavirin concentration in blood plasma. Elimination rate constant determined in aerosol administration experiments was ke = 0.077 min-1, which agrees with the value measured after intravenous delivery, but per-oral administration resulted in considerably lower apparent elimination rate constant of pseudo-first order, probably due to non-linear dependence of absorption rate on triazavirin concentration in gastrointestinal tract. The bioavailability of triazavirin aerosol is found to be 85%, which is about four times higher than for per-oral administration.

Pharmacokinetics and anticoccidial activity of ethanamizuril in broiler chickens

The treatment effect of ethanamizuril (EZL) to broiler chickens experimentally infected with 8 × 104Eimeria tenella was evaluated. On the third day after infection, the broiler chickens were treated with EZL by gavage at doses of 2, 4, and 8 mg/kg body weight (bw) for once. For double administration, the challenged broiler chickens were administered EZL at doses of 1, 2, 4, and 8 mg/kg bw by gavage continually on the third day and fourth day and once a day. Throughout the experimental period, performance parameters including body weight gain, mortality, cecal lesion score, bloody diarrhoea and oocyst output were recorded. The anticoccidial efficacy was evaluated using the anticoccidial index (ACI). Meanwhile, the concentrations of EZL in chicken cecal contents were measured, and the data were analyzed with a non-compartmental model. The results indicated that EZL showed good anticoccidial activity at single dose of 4 mg/kgbw, with the corresponding ACI of 175.73. When the challenged chickens were treated with EZL under double administration, the EZL showed a medium level of anticoccidial activity at a dose of 2 mg/kg bw, with the corresponding ACI of 162.48. The maximum concentrations (Cmax) of EZL in content were 2.43 ± 1.16, 4.28 ± 1.56, and 8.57 ± 1.33 mg/kg after the chickens were administrated at doses of 2, 4, and 8 mg/kg bw, respectively. The respective areas under the curve were 36.93 ± 8.91, 96 ± 16.31, and 262.76 ± 51.52 mg/kg h. The respective half-lives (T1/2) were 10.82 ± 2.02, 10.53 ± 2.23, and 10.60 ± 1.50 h. The results show that when the concentrations of EZL in chicken cecal contents reached 4.28 ± 1.56 mg/kg, there is a significant therapeutic effect on chicken coccidiosis.

Pharmacokinetics, Activity, and Residue Elimination of R- and S-Diclazuril in Broiler Chickens

Diclazuril (DIC) is widely used as a racemic mixture to prevent and treat coccidiosis in farm animals, while the pharmacokinetics, bioactivity, and toxicity of DIC enantiomers are not known at all. This study first established a simple, sensitive, and reliable liquid chromatography tandem mass spectrometry method for separation of R-DIC and S-DIC and their analyses. Then, it was applied to investigate the stereoselective pharmacokinetics and residual elimination of individual enantiomers, and their anticoccidial activity was also evaluated in broiler chickens. The results indicated that the area under the concentration-time curve (AUC) and elimination half-life (t_1/2β) were significantly different (p < 0.05) for two enantiomers in chicken plasma. The AUC and t_1/2β of S-DIC were approximately 2 and 1.4 times those of R-DIC, respectively. The residual elimination of DIC enantiomers in chicken tissues was also stereoselective. The concentrations of S-DIC in chicken muscle and liver were greater than those of R-DIC, and it is the opposite in the kidney. There was no significant difference (p > 0.05) in the anticoccidial activity of racemate and enantiomers when a single enantiomer in feed was added above 0.5 mg kg^-1. However, the anticoccidial activity of R-DIC (0.25 mg kg^-1) was significantly higher (p < 0.05) than that of S-DIC (0.25 mg kg^-1) in the diet. It should be mentioned that in chicken small intestine and cecum, the enantiomerization rate of each enantiomer in the infection group was faster than that in the uninfected group.

A phase 1b study of the MET inhibitor capmatinib combined with cetuximab in patients with MET-positive colorectal cancer who had progressed following anti-EGFR monoclonal antibody treatment

Background Overcoming resistance to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) in patients with KRAS wildtype (WT) metastatic colorectal cancer (mCRC) could help meet the needs of patients with limited treatment options. Methods In this phase 1b study, patients with N/KRAS WT, MET-positive mCRC who had progressed following anti-EGFR mAb treatment received escalating oral doses of capmatinib (150, 300, and 400 mg) twice daily plus weekly intravenous cetuximab (at the approved dose). The primary objective was to establish a recommended dose for expansion (RDE) of capmatinib in combination with cetuximab. Safety, preliminary activity, pharmacokinetics, and pharmacodynamics were also explored. Results Thirteen patients were enrolled. No patients experienced a dose-limiting toxicity at investigated doses; the RDE was established as capmatinib 400 mg twice daily plus cetuximab. All patients experienced adverse events (AEs) suspected to be related to the study treatment. Five patients (38.5%) reported study-drug-related AEs of grade 3/4 in severity. No patients achieved a complete or partial response according to RECIST v1.1; however, tumor shrinkage of 29-44% was observed in 4 patients. Conclusions Capmatinib plus cetuximab was well tolerated. Preliminary signs of activity were observed. Further investigation is warranted to obtain efficacy data and refine predictive biomarkers of response. Clinical trial registration NCT02205398.

Stimuli-responsive graphene-based hydrogel driven by disruption of triazine hydrophobic interactions

The study reported here concerns the preparation of a novel graphene-diaminotriazine (G-DAT) nanocomposite hydrogel for application in the drug delivery field. The hybrid nature of this material is founded on two key elements: the presence of the DAT backbone induced the formation of hydrophobic regions that allowed efficient loading of a series of drugs of increasing hydrophobicity (Metronidazole, Benzocaine, Ibuprofen, Naproxen and Imipramine), while simultaneously endowing swelling-induced pH-responsiveness to the hydrogel. Additionally, the incorporation of graphene was found to interfere with these hydrophobic domains through favourable non-covalent interactions, thus leading to the partial disruption of these aggregates. As a consequence, graphene facilitated and enhanced the release of model hydrophobic drug Imipramine in a synergistic manner with the pH trigger, and increased the swelling capacities and improved mechanical performance. This hybrid hydrogel can therefore be envisaged as a proof-of-concept system for the release of hydrophobic compounds in the field of drug delivery.

In Vitro, In Silico, and In Vivo Assessments of Pharmacokinetic Properties of ZM241385

Parkinson’s disease is one of the most common neurodegenerative diseases. Adenosine regulates the response to other neurotransmitters in the brain regions related to motor function. In the several subtypes of adenosine receptors, especially, adenosine 2A receptors (A_2ARs) are involved in neurodegenerative conditions. ZM241385 is one of the selective non-xanthine A2AR antagonists with high affinity in the nanomolar range. This study describes the in vitro and in vivo pharmacokinetic properties of ZM241385 in rats. A liquid chromatography-quadrupole time-of-flight mass spectrometric (LC-qToF MS) method was developed for the determination of ZM241385 in rat plasma. In vivo IV administration studies showed that ZM241385 was rapidly eliminated in rats. However, the result of in vitro metabolic stability studies showed that ZM241385 had moderate clearance, suggesting that there is an extra clearance pathway in addition to hepatic clearance. In addition, in vivo PO administration studies demonstrated that ZM241385 had low exposure in rats. The results of semi-mass balance studies and the in silico PBPK modeling studies suggested that the low bioavailability of ZM241385 after oral administration in rats was due to the metabolism and by liver, kidney, and gut.

Antitubercular Triazines: Optimization and Intrabacterial Metabolism

The triazine antitubercular JSF-2019 was of interest due to its in vitro efficacy and the nitro group shared with the clinically relevant delamanid and pretomanid. JSF-2019 undergoes activation requiring F420H2 and one or more nitroreductases in addition to Ddn. An intrabacterial drug metabolism (IBDM) platform was leveraged to demonstrate the system kinetics, evidencing formation of NO⋅ and a des-nitro metabolite. Structure-activity relationship studies focused on improving the solubility and mouse pharmacokinetic profile of JSF-2019 and culminated in JSF-2513, relying on the key introduction of a morpholine. Mechanistic studies with JSF-2019, JSF-2513, and other triazines stressed the significance of achieving potent in vitro efficacy via release of intrabacterial NO⋅ along with inhibition of InhA and, more generally, the FAS-II pathway. This study highlights the importance of probing IBDM and its potential to clarify mechanism of action, which in this case is a combination of NO⋅ release and InhA inhibition.

Metabolism, Distribution, and Excretion of Ethanamizuril in Chickens

Ethanamizuril(N-{4-[4-(3,5-dioxo-4,5-dihydro-3H-[1,2,4]triazin-2-yl)-2-methyl-phenoxy]-phenyl}-acetamide, EZL) is a new anticoccidiosis compound and belongs to the class of triazines. In this study, the metabolism, distribution, and excretion of EZL were evaluated in chickens after administration of EZL at a single dosage. According to the relevant drug biotransformation rules, the exact molecular mass detection, the fragmentation characteristics, and the retention times, a total of five metabolites were identified in vivo in chickens, including two phase I metabolites and three phase II conjugated metabolites. The major metabolic pathways of EZL in chickens were deacetylation, hydroxylation, and glucuronidation. Regarding ¹⁴C-tissue residues after administration, kidney was considered to be the target tissue, as ¹⁴C-tissue residues could be detected at 240 h postdose. DeacetylEZL (M3) was the main metabolite, accounting for 68.65% and 25.62% of ¹⁴C in kidney at 6 and 24 h, respectively. In heart, muscle, skin+fat, and lung tissues, EZL was the main radioactive substance accounting for 94.88%, 97.32%, 96.23%, and 91.3% of ¹⁴C, respectively. In the liver, EZL and M3 were 20.76% and 54.65% of ¹⁴C, respectively. In chicken tissues the ratio of M5 was too low to be quantitated and it was mainly detected in chicken fecal and bile samples. In chicken excreta, EZL, M3, and glucuronidation of EZL (M5) accounted for 7.02%, 12.33%, and 10.32% of the dose, respectively and were eliminated primarily. This study presents the first detection of EZL metabolites, which is helpful for further understanding of the metabolic mechanism and in vivo intermediate processes of EZL. The results of this study will be good bases for better understanding EZL's anticoccidiosis mechanism and will serve as a helpful reference for assessing the risks to animals and humans.

1,3,5-Tris-(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione: kinetic studies and phototransformation products

1,3,5-Tris-(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione (TDBP-TAZTO) is an emerging brominated flame retardant which is widely used in several plastic materials (electric and electronic equipment, musical instruments, automotive components). However, until today, no photochemical studies as well as the identification of possible phototransformation products (PTPs) were described in literature. Therefore, in this study, UV-(C) and simulated sunlight irradiation experiments were performed to investigate the photolytic degradation of TDBP-TAZTO and to identify relevant PTPs for the first time. The UV-(C) irradiation experiments show that the photolysis reaction follows a first-order kinetic model. Based on this, the photolysis rate constant k as well as the half-life time t_1/2 were calculated to be k = (41 ± 5 × 10^-3) min^-1 and t_1/2 = (17 ± 2) min. In comparison, a minor degradation of TDBP-TAZTO and no formed phototransformation products were obtained under simulated sunlight. In order to clarify the photochemical behavior, different chemicals were added to investigate the influence on indirect photolysis: (i) H₂O₂ for generation of hydroxyl radicals and (ii) two quenchers (2-propanol, sodium azide) for scavenging oxygen species which were formed during the irradiation experiments. Herein, nine previously unknown PTPs of TDBP-TAZTO were detected under UV-(C) irradiation and identified by HPLC-(HR)MS. As a result, debromination, hydroxylation, and dehydrobromination reactions could be presumed as the main degradation pathways by high-resolution mass spectrometry. The direct as well as the OH radical-induced indirect photolysis were observed. Graphical abstract .

Preclinical pharmacokinetics, disposition, and translational pharmacokinetic/pharmacodynamic modeling of savolitinib, a novel selective cMet inhibitor

Savolitinib is a novel small-molecule selective cMet inhibitor. This work characterized its pharmacokinetics in preclinical phase, established the preclinical relationships between PK, cMet modulation and anti-tumor efficacy. In vitro and in vivo animal studies were performed for PK characterization. Savolitinib showed good absorption, moderate tissue distribution, low to intermediate clearance, and low accumulation. Hepatic oxidative metabolism followed by urinary and biliary excretions was the major elimination pathway. Based on preclinical PK data, human PK profiles were predicted using empirical methods. Pharmacodynamic studies for evaluating cMet inhibition and anti-tumor efficacy were conducted in nude mice bearing Hs746t xenograft. PK/PD models were built to link the PD measurements to nude mouse PK. The established integrated preclinical PK/PD model contained a two-compartment non-linear PK model, a biomarker link model and a tumor growth transit model. The IC₅₀ of cMet inhibition and the concentration achieving half of the maximal Hs746t tumor reduction by savolitinib were equal to 12.5 and 3.7 nM (free drug), respectively. Based on the predicted human PK data, as well as the established PK/PD model in nude mouse, the human PD (cMet inhibition) profiles were also simulated. This research supported clinical development of savolitinib. Understanding the preclinical PK/PD relationship of savolitinib provides translational insights into the cMet-targeted drug development.

Supramolecular self-assembly of triazine-based small molecules: targeting the endoplasmic reticulum in cancer cells

The endoplasmic reticulum (ER) is one of the most important organelles controlling myriads of cellular functions including protein folding/misfolding/unfolding, calcium ion homeostasis and lipid biosynthesis. Subsequently, due to its functional dysregulation in cancer cells, it has emerged as an interesting target for anti-cancer therapy. However, specific targeting of the ER in cancer cells remains a major challenge due to the lack of ER-selective chemical tools. Furthermore, for performing multiple cellular functions the ER is dependent on the nucleus through complicated cross-talk. Herein, we have engineered a supramolecular self-assembled hexameric rosette structure from two small molecules: tri-substituted triazine and 5-fluorouracil (5-FU). This rosette structure consists of an ER-targeting moiety with a fluorescence tag, an ER-stress inducer and a nuclear DNA damaging drug simultaneously, which further self-assembled into an ER-targeting spherical nano-scale particle (ER-NP). These ER-NPs internalized into HeLa cervical cancer cells by macropinocytosis and specifically localized into the ER to induce ER stress and DNA damage leading to cell death through apoptosis. Interestingly, ER-NPs initiated autophagy, inhibited by a combination of ER-NPs and chloroquine (CQ) to augment cancer cell death. This work has the potential to exploit the concept of supramolecular self-assembly into developing novel nano-scale materials for specific sub-cellular targeting of multiple organelles for future anti-cancer therapy.

Determination of a astragaloside IV derivative LS-102 in plasma by ultra-performance liquid chromatography-tandem mass spectrometry in dog plasma and its application in a pharmacokinetic study

BACKGROUND

Astragalosidic acid (LS-102) is a new water-soluble derivative of astragaloside IV - a major effective component isolated from the Chinese herb Astragali Radix. Our previous study showed that LS-102 exhibited potent cardiovascular activity.

PURPOSE

The objective of this study was to investigate the pharmacokinetic properties of LS-102 after single-dose, oral administration in beagle dogs by developing and validating an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method.

METHOD AND RESULT

The chromatographic separation was performed on a Acquity HSS C₁₈ column (100 mm × 2.1 mm, 1.8 µm) by a gradient elution using a mobile phase consisting of water and acetonitrile at a flow rate of 0.35 ml/min. The analytes were detected with a triple quadrupole tandem mass spectrometry in multiple reaction monitoring mode. Method validation revealed a wide linearity over the range of 2.0-10,000 ng/ml together with satisfactory intra- and inter-day precision, accuracy, and recovery. Stability testing showed that LS-102 spiked into dog plasma was stable for 4 h at room temperature, for up to 2 weeks at -80 °C, and during three freeze-thaw cycles. The method was effectively and successfully applied to the pharmacokinetics of LS-102 after oral administration (5, 10 and 20 mg/kg) to beagle dogs. Peak plasma concentrations are attained within approximately 2 h after oral administration with a half-life ranging from 1.55 h to 4.49 h. The plasma concentration-time curve of LS-102 after oral administration presents the phenomenon of a double-peak absorption phase. The peak concentration and area under the concentration-time curve of LS-102 seemed to increase with the increasing doses proportionally, that suggesting linear pharmacokinetics in dogs. Meanwhile, the doxorubicin (Dox)-injured H9c2 cell model was prepared by incubating the cells in 1 µM Dox for 24 h. MTT assay and LDH release measurement showed that LS-102 protected against Dox-induced cardiomyocyte death.

CONCLUSION

The obtained results may help to guide the further pre-clinical research of LS-102 as a potentially novel cardioprotective agent.

Safety, Tolerability, and Pharmacokinetics of the Novel Anti-influenza Agent Baloxavir Marboxil in Healthy Adults: Phase I Study Findings

Background and Objective

Baloxavir marboxil, a prodrug that is metabolized to baloxavir acid, suppresses viral replication by inhibiting cap-dependent endonuclease. This first-in-human phase I study evaluated the safety, tolerability, and pharmacokinetics of baloxavir marboxil/baloxavir acid in healthy Japanese volunteers (Study 1), while food effects were evaluated in a separate phase I, crossover study in healthy Japanese volunteers (Study 2).

Methods

Study 1 participants were randomized to single-dose oral baloxavir marboxil (6, 20, 40, 60, or 80 mg; n = 6 per dose) or placebo (n = 10), while Study 2 participants (n = 15) received single-dose oral baloxavir marboxil 20 mg in fasted, fed, and before-meal states.

Results

Baloxavir marboxil was well tolerated; there were few treatment-emergent adverse events and no serious adverse events/deaths. The mean plasma baloxavir acid concentration 24 h after single-dose (C₂₄) oral baloxavir marboxil 6 mg was 6.92 ng/mL, exceeding the target C₂₄ (6.85 ng/mL) estimated in nonclinical studies. In Study 1, baloxavir acid exposure demonstrated dose-proportional increases in the fasted state, with maximum plasma concentration generally attained within 3.5 h. Terminal elimination half-life ranged from 49 to 91 h. In Study 2, exposure was decreased and apparent clearance increased in the fed and before-meal states versus the fasted state; however, exposure exceeded the target C₂₄ in all states.

Conclusion

Single-dose oral baloxavir marboxil was well tolerated, had a favorable safety profile, and had favorable pharmacokinetic characteristics, including a long half-life, supporting single oral dosing. The baloxavir acid area under the plasma concentration-time curve decreased with food intake by approximately 40%.

Antibiotics may increase triazine herbicide exposure risk via disturbing gut microbiota

BACKGROUND

Antibiotics are commonly used worldwide, and pesticide is a kind of xenobiotic to which humans are frequently exposed. The interactive impact of antibiotics on pesticides has rarely been studied. We aim to investigate the effects of antibiotics on the pesticide exposure risk and whether gut microbiota altered by antibiotics has an influence on pesticide bioavailability. Furthermore, we explored the mechanisms of gut microbiota affecting the fate of pesticides in the host.

RESULTS

The oral bioavailability of triazine herbicides significantly increased in the rats treated with ampicillin or antibiotic cocktails. The antibiotic-altered gut microbiota directly influenced the increased pesticide bioavailability through downregulating hepatic metabolic enzyme gene expression and upregulating intestinal absorption-related proteins.

CONCLUSIONS

Antibiotics could increase the pesticide bioavailability and thereby may increase the pesticide exposure risk. The antibiotic-altered gut microbiota that could alter the hepatic metabolic enzyme gene expression and intestinal absorption-related proteome was a critical cause of the increased bioavailability. This study revealed an undiscovered potential health impact of antibiotics and reminded people to consider the co-exposed xenobiotics when taking antibiotics.

Pharmacokinetics and safety of Enasidenib following single oral doses in Japanese and Caucasian subjects

The aim of this study was to assess and compare the pharmacokinetics (PK) and safety of Enasidenib in healthy adult male Japanese subjects to healthy adult male Caucasian subjects. This was a phase 1, single dose study to evaluate the PK and safety of Enasidenib in healthy adult male Japanese subjects relative to healthy adult male Caucasian subjects. A total of 62 subjects (31 Japanese and 31 Caucasian) were enrolled into three dose cohorts (single doses of 50 mg, 100 mg, or 300 mg Enasidenib). Blood samples for PK assessment were collected up to 672 hours postdose. Safety was evaluated throughout the study. In the present study, we found that PK exposures of Enasidenib and its metabolite AGI-16903 for Caucasian and Japanese subjects were comparable at the 50, 100, and 300 mg dose levels, demonstrated by that the 90% confidence intervals (CIs) of geometric mean ratios for AUCs and Cmax between these two populations generally contained 100% from all three treatment cohorts. In conclusion, PK exposures of Enasidenib and its metabolite AGI-16903 for Caucasians and Japanese subjects were comparable and Enasidenib was safe and well tolerated with no apparent differences between Japanese and Caucasian subjects when administered as single oral doses of 50 mg, 100 mg, and 300 mg.

Time course of reversal of valproate-mediated inhibition of lamotrigine

PURPOSE

Conversion to lamotrigine (LTG) monotherapy from sodium valproate (VPA) is complicated by the robust pharmacokinetic interaction between the two AEDs. This study examined changes in LTG serum concentrations immediately following VPA discontinuation.

METHODS

Ten healthy female and male adult subjects were initiated on LTG (Lamictal) 10 mg orally every morning for 30 days and VPA (Depakote ER) 500 mg orally every morning for 14 days. Morning trough (pre-dose) venous blood samples were obtained for determination of LTG and VPA concentrations on study days 14, 15, 16, 18, 20, 22, 24, 26, 28, and 30. Following the collection of the blood sample on day 15, VPA was discontinued.

RESULTS

Despite stable LTG dosage serum concentrations on study day 20, 22, 24, 26, and 28, all were significantly lower compared to baseline (p < 0.05).

CONCLUSIONS

These observations demonstrate that the pharmacokinetic interaction between LTG and VPA is reversible, and that de-inhibition appears to follow a predictable time course. Complete offset, or reversal of this interaction takes place 10-14 days after VPA discontinuation. Our data also confirms the observation that LTG oral clearance may be inhibited by very low concentrations of VPA. These data support the conversion algorithm suggested by the manufacturer, and provide guidance to the clinician. These data provide clinically useful information in developing a dosing algorithm for converting patients to LTG monotherapy.

Enasidenib in mutant IDH2 relapsed or refractory acute myeloid leukemia

Recurrent mutations in isocitrate dehydrogenase 2 (IDH2) occur in ∼12% of patients with acute myeloid leukemia (AML). Mutated IDH2 proteins neomorphically synthesize 2-hydroxyglutarate resulting in DNA and histone hypermethylation, which leads to blocked cellular differentiation. Enasidenib (AG-221/CC-90007) is a first-in-class, oral, selective inhibitor of mutant-IDH2 enzymes. This first-in-human phase 1/2 study assessed the maximum tolerated dose (MTD), pharmacokinetic and pharmacodynamic profiles, safety, and clinical activity of enasidenib in patients with mutant-IDH2 advanced myeloid malignancies. We assessed safety outcomes for all patients and clinical efficacy in the largest patient subgroup, those with relapsed or refractory AML, from the phase 1 dose-escalation and expansion phases of the study. In the dose-escalation phase, an MTD was not reached at doses ranging from 50 to 650 mg per day. Enasidenib 100 mg once daily was selected for the expansion phase on the basis of pharmacokinetic and pharmacodynamic profiles and demonstrated efficacy. Grade 3 to 4 enasidenib-related adverse events included indirect hyperbilirubinemia (12%) and IDH-inhibitor-associated differentiation syndrome (7%). Among patients with relapsed or refractory AML, overall response rate was 40.3%, with a median response duration of 5.8 months. Responses were associated with cellular differentiation and maturation, typically without evidence of aplasia. Median overall survival among relapsed/refractory patients was 9.3 months, and for the 34 patients (19.3%) who attained complete remission, overall survival was 19.7 months. Continuous daily enasidenib treatment was generally well tolerated and induced hematologic responses in patients for whom prior AML therapy had failed. Inducing differentiation of myeloblasts, not cytotoxicity, seems to drive the clinical efficacy of enasidenib. This trial was registered at www.clinicaltrials.gov as #NCT01915498.

Expression in grasses of multiple transgenes for degradation of munitions compounds on live-fire training ranges

The deposition of toxic munitions compounds, such as hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX), on soils around targets in live-fire training ranges is an important source of groundwater contamination. Plants take up RDX but do not significantly degrade it. Reported here is the transformation of two perennial grass species, switchgrass (Panicum virgatum) and creeping bentgrass (Agrostis stolonifera), with the genes for degradation of RDX. These species possess a number of agronomic traits making them well equipped for the uptake and removal of RDX from root zone leachates. Transformation vectors were constructed with xplA and xplB, which confer the ability to degrade RDX, and nfsI, which encodes a nitroreductase for the detoxification of the co-contaminating explosive 2, 4, 6-trinitrotoluene (TNT). The vectors were transformed into the grass species using Agrobacterium tumefaciens infection. All transformed grass lines showing high transgene expression levels removed significantly more RDX from hydroponic solutions and retained significantly less RDX in their leaf tissues than wild-type plants. Soil columns planted with the best-performing switchgrass line were able to prevent leaching of RDX through a 0.5-m root zone. These plants represent a promising plant biotechnology to sustainably remove RDX from training range soil, thus preventing contamination of groundwater.

Biotransformation of RDX and HMX by Anaerobic Granular Sludge with Enriched Sulfate and Nitrate

  RDX and HMX are widely used energetic materials and they are recognized as environmental contaminants at numerous locations. The present study investigated the biotransformation of RDX and HMX by anaerobic granular sludge under sulfate- and nitrate-enriched conditions. The results showed that RDX and HMX could be transformed by anaerobic granular sludge when nitrate was present. However, the biotransformation of RDX and HMX was negatively influenced, especially with high nitrate concentrations. Sulfate-enriched conditions were more favorable for the removal of ammunition compounds by anaerobic granular sludge than nitrate-enriched conditions. The removal of RDX and HMX under both nitrate- and sulfate-enriched conditions was facilitated by the use of glucose as additional substrate. This knowledge may help identify factors required for rapid removal of RDX and HMX in high-rate bioreactors. These results can also be applied to devise an appropriate and practical biological treatment strategy for explosive contaminated wastewater.

Use of Therapeutic Drug Monitoring, Electronic Health Record Data, and Pharmacokinetic Modeling to Determine the Therapeutic Index of Phenytoin and Lamotrigine

BACKGROUND

Defining a drug's therapeutic index (TI) is important for patient safety and regulating the development of generic drugs. For many drugs, the TI is unknown. A systematic approach was developed to characterize the TI of a drug using therapeutic drug monitoring and electronic health record (EHR) data with pharmacokinetic (PK) modeling. This approach was first tested on phenytoin, which has a known TI, and then applied to lamotrigine, which lacks a defined TI.

METHODS

Retrospective EHR data from patients in a tertiary hospital were used to develop phenytoin and lamotrigine population PK models and to identify adverse events (anemia, thrombocytopenia, and leukopenia) and efficacy outcomes (seizure-free). Phenytoin and lamotrigine concentrations were simulated for each day with an adverse event or seizure. Relationships between simulated concentrations and adverse events and efficacy outcomes were used to calculate the TI for phenytoin and lamotrigine.

RESULTS

For phenytoin, 93 patients with 270 total and 174 free concentrations were identified. A de novo 1-compartment PK model with Michaelis-Menten kinetics described the data well. Simulated average total and free concentrations of 10-15 and 1.0-1.5 mcg/mL were associated with both adverse events and efficacy in 50% of patients, resulting in a TI of 0.7-1.5. For lamotrigine, 45 patients with 53 concentrations were identified. A published 1-compartment model was adapted to characterize the PK data. No relationships between simulated lamotrigine concentrations and safety or efficacy endpoints were seen; therefore, the TI could not be calculated.

CONCLUSIONS

This approach correctly determined the TI of phenytoin but was unable to determine the TI of lamotrigine due to a limited sample size. The use of therapeutic drug monitoring and EHR data to aid in narrow TI drug classification is promising, but it requires an adequate sample size and accurate characterization of concentration-response relationships.

Assessment of the pharmacokinetic profile of novel s-triazine derivatives and their potential use in treatment of Alzheimer's disease

AIMS

The current treatment of Alzheimer's disease is purely symptomatic. Scientists are looking for new treatment options which could alter the course of the disease and improve the quality of life in patients with Alzheimer's disease. In this paper 14 novel s-triazine molecules have been evaluated for their lipophilicity. In addition docking study was carried out to evaluate acetylcholinesterase activity of these compounds.

MAIN METHODS

Lipophilicity was evaluated by RP HPTLC using 5 different mobile phases and obtained results were used in calculations of pharmacokinetic parameters - logBB, Ka and Pej. Multiple linear regression analysis was refined, taking account of molecular polarity (total polar surface area, TPSA) and molecular weight (Mw) descriptors. Appropriate QSAR models were developed. Docking studies were carried out using the Vina docking.

KEY FINDINGS

Five out of fourteen compounds evaluated [5-10] are selected as the most promising compounds with satisfactory pharmacokinetic properties and good docking scores.

SIGNIFICANCE

Compound 10 possesses the best combination of favourable pharmacokinetic characteristics (brain penetration, intestinal absorption) and capacity for acetylcholinesterase inhibition. Consequently this molecule should be further evaluated for potential therapeutic use in Alzheimer's disease.

The effects of co-medications on lamotrigine clearance in Japanese children with epilepsy

PURPOSE

Although it has been reported that some antiepileptic drugs have inducing or inhibiting effects on lamotrigine (LTG) clearance, whether they have the same effects in Asian epilepsy patients as in those in other countries has not been clarified, especially in children. The aim of this study was to determine the effects of co-medications on LTG clearance in Japanese children with epilepsy.

METHODS

A total of 342 routine serum concentration measurements of LTG in 102 Japanese epilepsy patients under 20years of age were reviewed. The dose-corrected concentration (DCC) of LTG was calculated as [concentration]/[dose/(body weight)], and the DCC of LTG was compared by co-medication. The difference in the DCC of LTG was compared between patients with and without valproic acid (VPA) and between those with and without drugs inducing glucuronic acid conjugation (phenytoin (PHT), carbamazepine (CBZ), and phenobarbital (PB)).

RESULTS

The DCC of LTG was significantly higher in patients on VPA and significantly lower in patients on drugs inducing glucuronic acid conjugation than in patients on LTG monotherapy. The DCC of LTG was significantly higher in patients on CBZ than in patients on PHT or PB. There was no correlation between the DCC of LTG and the concentration of VPA or metabolic inducers within the therapeutic range. Other antiepileptic drugs including clobazam, clonazepam, zonisamide, and levetiracetam had little effect on LTG concentration.

CONCLUSION

LTG concentration changes dramatically with concomitant antiepileptic drugs in Japanese children, as previously reported from other countries, and special attention is required. Although the dose of LTG should be adjusted when starting or discontinuing VPA or metabolic inducers, no adjustment is needed when changing the dose of VPA or metabolic inducers in the therapeutic range.

Multivariate approach to gill pathology in European sea bass after experimental exposure to cadmium and terbuthylazine

The combined use of guided quantitative expert analysis and of multivariate exploratory data analysis is reported as a robust, sensitive and sufficiently specific approach to study European sea bass gill secondary lamellar pathology after exposure to incremental doses of cadmium and terbuthylazine up to 48h. The following elementary pathological findings were considered: "epithelial lifting", "epithelial shrinkage", "epithelial swelling", "pillar cells coarctation", "pillar cells detachment", "channels fusion", "chloride cells swelling", and "chloride cells invasion". The relative spatial extension was determined according to exposure class and data were analyzed by means of canonical correspondence analysis (CCA), linear discriminant analysis (LDA) and canonical variates analysis (CVA). Histologically and ultrastructurally, cellular shrinkage/coarctation prevailed in cadmium exposed lamellae, whereas cellular swelling and epithelial lifting were predominant in terbuthylazine exposed lamellae compared to unexposed fish. Both CCA and CVA permit a good graphical data grouping according to exposure classes by means of the convex hull minimum polygons. This also reveals exposure dose and time gradients in CCA plot. Accordingly, epithelial swelling and epithelial shrinkage were comparatively associated to higher exposure time, whereas epithelial shrinkage and pillar cells coarctation were comparatively associated to higher exposure dose. LDA with only "epithelial shrinkage", "epithelial swelling" and "pillar cells coarctation" in the model classified correctly 87.5% of the cross-validated cases. A possible pathogenetic relationship between the discriminant elementary lesions and the toxic mode of action at the cellular level of both cadmium and terbuthylazine is also discussed.

NDELA and nickel modulation of triazine disposition in skin

Cutting fluids can become contaminated with metals (e.g., nickel, Ni) and nitrosamines (e.g., N-nitrosodiethanolamine, NDELA) and there is concern that these classes of contaminants can modulate dermal disposition and ultimately the toxicity of cutting fluid additives, such as irritant biocides (e.g., triazine). Biocides are added to these formulations to prevent bacterial degradation of commercial cutting fluids. The purpose of this study was to assess the dermal absorption and skin deposition of 14C-triazine when topically applied to porcine skin in an in vitro flow-through diffusion cell system as aqueous soluble oil (mineral oil, MO) or aqueous synthetic (polyethylene glycol, PEG) mixtures. 14C-Triazine mixtures were formulated with NDELA and/or Ni, or with a combination of three additional cutting fluid additives; namely, 5% linear alkylbenzene sulfonate (LAS), 5% triethanolamine (TEA) and 5% sulfurized ricinoleic acid. Neither Ni nor NDELA was absorbed during these 8-h studies. However, 14C-triazine absorption ranged from 2.72 to 3.29% dose in MO and 2.29-2.88% dose in PEG with significantly greater triazine absorption in MO than PEG when all additives and contaminates were present. The difference between these two diluents was most pronounced when NDELA and/or Ni were present in cutting fluids. These contaminants also enhanced triazine deposition on the skin surface and skin tissues especially with PEG-based mixtures. In essence, the dermal disposition of irritant biocides could be dependent on whether the worker is exposed to a soluble oil or synthetic fluid when these contaminants are present. Workers should therefore not only be concerned about dermatotoxicity of these contaminants, but also the modulated dermal disposition of cutting fluid additives when these contaminants are present in cutting fluid formulations.

Discovery and antiplatelet activity of a selective PI3Kβ inhibitor (MIPS-9922)

A series of amino-substituted triazines were developed and examined for PI3Kβ inhibition and anti-platelet function. Structural adaptations of a morpholine ring of the prototype pan-PI3K inhibitor ZSTK474 yielded PI3Kβ selective compounds, where the selectivity largely derives from an interaction with the non-conserved Asp862 residue, as shown by site directed mutagenesis. The most PI3Kβ selective inhibitor from the series was studied in detail through a series of in vitro and in vivo functional studies. MIPS-9922, 10 potently inhibited ADP-induced washed platelet aggregation. It also inhibited integrin αIIbβ3 activation and αIIbβ3 dependent platelet adhesion to immobilized vWF under high shear. It prevented arterial thrombus formation in the in vivo electrolytic mouse model of thrombosis without inducing prolonged bleeding or excess blood loss.

PBPK Model for Atrazine and Its Chlorotriazine Metabolites in Rat and Human

The previously-published physiologically based pharmacokinetic model for atrazine (ATZ), deisopropylatrazine (DIA), deethylatrazine (DEA), and diaminochlorotriazine (DACT), which collectively comprise the total chlorotriazines (TCT) as represented in this study, was modified to allow for scaling to humans. Changes included replacing the fixed dose-dependent oral uptake rates with a method that represented delayed absorption observed in rats administered ATZ as a bolus dose suspended in a methylcellulose vehicle. Rate constants for metabolism of ATZ to DIA and DEA, followed by metabolism of DIA and DEA to DACT were predicted using a compartmental model describing the metabolism of the chlorotriazines by rat and human hepatocytesin vitro Overall, the model successfully predicted both the 4-day plasma time-course data in rats administered ATZ by bolus dose (3, 10, and 50 mg/kg/day) or in the diet (30, 100, or 500 ppm). Simulated continuous daily exposure of a 55-kg adult female to ATZ at a dose of 1.0 µg/kg/day resulted in steady-state urinary concentrations of 0.6, 1.4, 2.5, and 6.0 µg/L for DEA, DIA, DACT, and TCT, respectively. The TCT (ATZ + DEA + DIA + DACT) human urinary biomonitoring equivalent concentration following continuous exposure to ATZ at the chronic point of departure (POD = 1.8 mg/kg/day) was 360.6 μg/L.

Variability in 24 hour excretion of cyanuric acid: implications for water exposure assessment

Cyanuric acid (CYA) excretion in urine has been used to estimate the volume of water ingested during swimming and other recreational activities in outdoor pools containing this chemical. These estimates of water ingestion are based on the assumption of 100% excretion within 24 hours, but the supporting evidence for this is scant. While adapting this methodology to investigate other water ingestion scenarios, we observed a high degree of variability in cyanuric acid excretion among experimental subjects, with over 25% of individuals excreting less than 80% of an ingested dose. Use of cyanuric acid to measure inadvertent water ingestion may be a valuable tool to generate data for health risk assessment of non-potable water sources, but our observations indicate that this technique carries an inherent degree of underestimation that should be taken into account when calculating water exposure.

First-in-human, open-label dose-escalation and dose-expansion study of the safety, pharmacokinetics, and antitumor effects of an oral ALK inhibitor ASP3026 in patients with advanced solid tumors

BACKGROUND

ASP3026 is a second-generation anaplastic lymphoma kinase (ALK) inhibitor that has potent in vitro activity against crizotinib-resistant ALK-positive tumors. This open-label, multicenter, first-in-human phase I study ( NCT01284192 ) assessed the safety, pharmacokinetic profile, and antitumor activity of ASP3026.

METHODS

Advanced solid tumor patients received oral ASP3026 in 3 + 3 dose-escalation cohorts at doses of 25-800 mg once daily in 28-day cycles. The endpoints were to identify the maximum tolerated dose (MTD), the recommended phase II dose (RP2D), and the pharmacokinetic profile of ASP3026. A phase Ib expansion cohort enrolled patients with metastatic, crizotinib-resistant ALK-positive solid tumors at the RP2D, and response was evaluated by RECIST 1.1.

RESULTS

The dose-escalation cohort enrolled 33 patients, including three crizotinib-resistant, ALK-positive patients, and the dose-expansion cohort enrolled another 13 crizotinib-resistant, ALK-positive non-small cell lung cancer (NSCLC) patients. ASP3026 demonstrated both linear pharmacokinetics and dose-proportional exposure for area under the plasma concentration-time curve and maximum concentration observed with a median terminal half-life of 35 h, supporting the daily dosing. Grade 3 rash and elevated transaminase concentrations were dose-limiting toxicities observed at 800 mg; hence, 525 mg daily was the MTD and RP2D. The most common treatment-related adverse events were nausea (38%), fatigue (35%), and vomiting (35 %). Among the 16 patients with crizotinib-resistant ALK-positive tumors (15 NSCLC, 1 neuroblastoma), eight patients achieved partial response (overall response rate 50%; 95% confidence interval 25-75%) and seven patients (44%) achieved stable disease.

CONCLUSIONS

ASP3026 was well tolerated and had therapeutic activity in patients with crizotinib-resistant ALK-positive advanced tumors.

TRIAL REGISTRATION

ClinTrials.gov: NCT01284192.

Human Metabolite Lamotrigine-N(2)-glucuronide Is the Principal Source of Lamotrigine-Derived Compounds in Wastewater Treatment Plants and Surface Water

Wastewater and surface water samples, extracted with four solid-phase extraction cartridges of different chemistries, were suspect-screened for the anticonvulsant lamotrigine (LMG), its metabolites, and related compounds. LMG, three human metabolites, and a LMG synthetic impurity (OXO-LMG) were detected. Preliminary results showed significantly higher concentrations of OXO-LMG in wastewater effluent, suggesting its formation in the wastewater treatment plants (WWTPs). However, biodegradation experiments with activated sludge demonstrated that LMG is resistant to degradation and that its human metabolite lamotrigine-N(2)-glucuronide (LMG-N2-G) is the actual source of OXO-LMG in WWTPs. In batch reactors, LMG-N2-G was transformed, following pseudo-first-order kinetics to OXO-LMG and LMG, but kinetic experiments suggested an incomplete mass balance. A fragment ion search applied to batch-reactor and environmental samples revealed another transformation product (TP), formed by LMG-N2-G oxidation, which was identified by high-resolution mass spectrometry. Accounting for all TPs detected, a total mass balance at two concentration levels in batch reactors was closed at 86% and 102%, respectively. In three WWTPs, the total mass balance of LMG-N2-G ranged from 71 to 102%. Finally, LMG-N2-G and its TPs were detected in surface water samples with median concentration ranges of 23-139 ng L(-1). The results of this study suggest that glucuronides of pharmaceuticals might also be sources of yet undiscovered, but environmentally relevant, transformation products.

Cardiac factors affecting the success of vardenafil in erectile dysfunction

BACKGROUND/AIM

To evaluate the predictability of vardenafil success in patients with erectile dysfunction (ED) by using cardiological tests.

MATERIALS AND METHODS

Patients diagnosed with ED who did not benefit from lifestyle changes (n = 68) were evaluated with an abridged 5-item version of the International Index of Erectile Function (IIEF-5). The pretreatment and posttreatment IIEF-5 scores were compared with pretreatment data obtained from cardiological examinations.

RESULTS

When pretreatment scores were compared with test parameters, mitral flow E/A ratio and tissue Doppler imaging (TDI) E'/ A', exercise test duration, exercise capacity in MET, and percentage of maximum heart rate were found to be statistically significant. Furthermore, there was a significant negative correlation between mitral flow E/A ratio, TDI E'/A', exercise test duration, exercise capacity in MET, and the difference in post- and pretreatment IIEF-5 scores.

CONCLUSION

As a diastolic function indicator, TDI E'/A' positively correlates with pretreatment IIEF-5 scores and negatively correlates with the beneficial effect of vardenafil treatment. As a result, the cardiological status of the patient correlates with individual IIEF-5 scores, and it seems to be useful in predicting vardenafil success.

6-Hydroxy-1,2,4-triazine-3,5(2H,4H)-dione Derivatives as Novel D-Amino Acid Oxidase Inhibitors

A series of 2-substituted 6-hydroxy-1,2,4-triazine-3,5(2H,4H)-dione derivatives were synthesized as inhibitors of D-amino acid oxidase (DAAO). Many compounds in this series were found to be potent DAAO inhibitors, with IC50 values in the double-digit nanomolar range. The 6-hydroxy-1,2,4-triazine-3,5(2H,4H)-dione pharmacophore appears metabolically resistant to O-glucuronidation unlike other structurally related DAAO inhibitors. Among them, 6-hydroxy-2-(naphthalen-1-ylmethyl)-1,2,4-triazine-3,5(2H,4H)-dione 11h was found to be selective over a number of targets and orally available in mice. Furthermore, oral coadministration of D-serine with 11h enhanced the plasma levels of D-serine in mice compared to the oral administration of D-serine alone, demonstrating its ability to serve as a pharmacoenhancer of D-serine.

Influence of valproic acid concentration and polymorphism of UGT1A4*3, UGT2B7 -161C > T and UGT2B7*2 on serum concentration of lamotrigine in Chinese epileptic children

PURPOSE

To investigate the impact of valproic acid (VPA) and genetic polymorphism of the major metabolizing enzyme (UGT1A4, UGT2B7) of lamotrigine (LTG) and VPA on LTG concentration in Chinese epileptic children.

METHODS

Three single nucleotide polymorphisms (UGT1A4*3, UGT2B7 -161C > T and UGT2B7*2) were analyzed by polymerase chain reaction-restriction fragment length polymorphism or direct DNA sequencing. The concentrations of LTG and VPA were measured by high-performance liquid chromatography (HPLC) and fluorescence polarization immunoassay, respectively. The adjusted concentration of LTG was defined as the concentration-to-dose-ratio (CDRLTG). Data analysis was performed using IBM SPSS Statistics 21.0.

RESULTS

A total of 56 patients treated with LTG as monotherapy and 158 patients treated with LTG plus VPA were included in this study. In the polytherapy group, LTG concentration showed a good linear relationship with gender, age, daily LTG dose, VPA concentration, and UGT1A4*3 polymorphism, but had no relationship with the polymorphism of UGT2B7 -161C > T or UGT2B7*2. Moreover, LTG concentration and CDRLTG for the UGT1A4*3 were higher compared to UGT1A4*1 (LTG: 7.24 ± 3.51 vs 5.26 ± 3.27 μg/mL, p = 0.001; CDRLTG: 2.75 ± 1.02 vs 2.14 ± 0.96 μg/mL per mg/kg, p < 0.001, respectively). In the monotherapy group, there was no statistical difference between UGT1A4*3 and UGT1A4*1 in LTG concentration or CDRLTG. The patients in the polytherapy group were divided into two subgroups according to VPA concentration (lower/higher: 10-50/50-125 μg/mL). CDRLTG values of the patients carrying the UGT1A4*3 genotype were higher compared to UGT1A4*1*1 (2.86 ± 1.03 vs 2.22 ± 0.94 μg/mL per mg/kg, p = 0.001) only when the VPA concentration was higher.

CONCLUSIONS

UGT1A4*3 polymorphism had an effect on LTG concentration only with VPA co-administration, and the effect was remarkable when VPA concentration was higher.

Synthesis, 18F-Radiolabelling and Biological Characterization of Novel Fluoroalkylated Triazine Derivatives for in Vivo Imaging of Phosphodiesterase 2A in Brain via Positron Emission Tomography

Phosphodiesterase 2A (PDE2A) is highly and specifically expressed in particular brain regions that are affected by neurological disorders and in certain tumors. Development of a specific PDE2A radioligand would enable molecular imaging of the PDE2A protein via positron emission tomography (PET). Herein we report on the syntheses of three novel fluoroalkylated triazine derivatives (TA2–4) and on the evaluation of their effect on the enzymatic activity of human PDE2A. The most potent PDE2A inhibitors were ¹⁸F-radiolabelled ([¹⁸F]TA3 and [¹⁸F]TA4) and investigated regarding their potential as PET radioligands for imaging of PDE2A in mouse brain. In vitro autoradiography on rat brain displayed region-specific distribution of [¹⁸F]TA3 and [¹⁸F]TA4, which is consistent with the expression pattern of PDE2A protein. Metabolism studies of both [¹⁸F]TA3 and [¹⁸F]TA4 in mice showed a significant accumulation of two major radiometabolites of each radioligand in brain as investigated by micellar radio-chromatography. Small-animal PET/MR studies in mice using [¹⁸F]TA3 revealed a constantly increasing uptake of activity in the non-target region cerebellum, which may be caused by the accumulation of brain penetrating radiometabolites. Hence, [¹⁸F]TA3 and [¹⁸F]TA4 are exclusively suitable for in vitro investigation of PDE2A. Nevertheless, further structural modification of these promising radioligands might result in metabolically stable derivatives.

Bioaccumulation kinetics of the conventional energetics TNT and RDX relative to insensitive munitions constituents DNAN and NTO in Rana pipiens tadpoles

The manufacturing of explosives and their loading, assembling, and packing into munitions for use in testing on training sites or battlefields has resulted in contamination of terrestrial and aquatic sites that may pose risk to populations of sensitive species. The bioaccumulative potential of the conventional explosives 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and of the insensitive munitions (i.e., less shock sensitive) compound 2,4-dinitroanisole (DNAN) were assessed using the Northern leopard frog, Rana pipiens. Trinitrotoluene entering the organism was readily biotransformed to aminodinitrotoluenes, whereas no transformation products were measured for RDX or DNAN. Uptake clearance rates were relatively slow and similar among compounds (1.32-2.19 L kg(-1) h(-1) ). Upon transfer to uncontaminated water, elimination rate was very fast, resulting in the prediction of fast time to approach steady state (5 h or less) and short elimination half-lives (1.2 h or less). A preliminary bioconcentration factor of 0.25 L kg(-1) was determined for the insensitive munitions compound 3-nitro-1,2,4-trizole-5-one (NTO) indicating negligible bioaccumulative potential. Because of the rapid elimination rate for explosives, tadpoles inhabiting contaminated areas are expected to experience harmful effects only if under constant exposure conditions given that body burdens can rapidly depurate preventing tissue concentrations from persisting at levels that may cause detrimental biological effects.

[Experimental comparative pharmacokinetics of levofloxacin, triazavirin, and related conjugate]

A comparative study of the pharmacokinetics of levofloxacin and triazavirine as well as 2-methylthio-6-nitro-1,2,4-triazolo[5,1-ñ]-1,2,4-triazine-7(4Í)-ide (3S)-(-)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methylpiperazin-1-yl)-7-oxo-7H-pyrido[1,2,3-d,e]-1,4-benzoxazine-6-carboxylic acid (conjugate 2) obtained by conjugation of triazavirine and levofloxacin, representing a new class of pharmacological agents, was carried out in experiments on rats. It is established that conjugate 2 in comparison to individual levofloxacin and triazavirine has a higher relative bioavailability and lower rate of elimination, which can lead to improved effectiveness of therapy at reduced dose and frequency of drug administration.

Tissue deposition and residue depletion in rainbow trout following continuous voluntary feeding with various levels of melamine or a blend of melamine and cyanuric acid

This study determined the deposition and depletion in rainbow trout after continuous administration of melamine (MEL) alone or a blend of MEL and cyanuric acid (CYA). The plasma, muscles, kidneys, liver and gills were sampled at 0, 3, 7, 13, 21, 28 and 42d. After the final sampling at 42d, fish from the MEL0.05, MEL20 and MCA groups were fed the control diet (MEL0) for the depletion test. Co-administration with cyanuric acid accelerated the deposition time to the Css for melamine; during the withdrawal phrase, the melamine and CYA concentrations in the tissues decreased exponentially. Compared to the t(½) for single oral administration, the t(½) for melamine and cyanuric acid after 42d continuous feeding was prolonged. The presence of trace CYA in the plasma and kidneys of trout was detected in the MEL20 group, indicating that MEL can convert into CYA in rainbow trout.

Pharmacokinetics and toxicity predictors of new s-triazines, herbicide candidates, in correlation with chromatogrpahic retention constants

Herbicides, which are ubiquitously present in soil and food, have been proven to cause human health hazard effects, hence development of new herbicide-active compounds is recommended. In this paper, nine 2,4-bis(cycloalkyl)-6-chloro-s-triazines were considered as herbicide candidates and their pharmacokinetics and toxicity were reviewed on the basis of in silico descriptors. Both, pharmacokinetic and toxicity predictors were presented as functions of their lipophilicity, quantified with retention constants that were obtained by liquid chromatography. None of the candidates investigated has functional groups for genotoxicity hazards and endocrine disruptions; they have acceptable toxicity and favorable pharmacokinetic properties based on computer-aided analyses. Two candidates have been selected as lead compounds for further research.

Identification of in vitro metabolites of a new anticoccidial drug nitromezuril using HepG2 cells, rat S9 and primary hepatocytes by liquid chromatography/tandem mass spectrometry

RATIONALE

Nitromezuril is a novel triazine compound possessing remarkable anticoccidial activity that could have possible future use in the prevention of coccidiosis; however, its metabolic characteristics have still not been revealed.

METHODS

In the present study, the in vitro metabolism of nitromezuril in HepG2 cells, rat S9 and primary hepatocytes was investigated using high-performance liquid chromatography with electrospray ionization tandem mass spectrometry. The structures of metabolites and their product ions were easily and reliably characterized based on the accurate MS(2) spectra and known structure of nitromezuril.

RESULTS

As expected, three metabolites (M1-M3) were detected in a HepG2 cells system, one metabolite was respectively detected and identified as M1 in rat S9 and M2 in rat primary hepatocytes. M1 and M2 were confirmed respectively based on comparing their retention times, full scan, product ion scan with available authentic standards and M3 was tentatively identified as hydroxyl compound of M2.

CONCLUSIONS

Pathways of nitromezuril were reported for the first time and no obvious species difference was shown. The proposed metabolic pathways of nitromezuril can be expected to play a key role in pharmacodynamics and food safety evaluations.

Vardenafil dihydrochloride

Vardenafil (VAR) is synthetic, highly selective, and potent inhibitor of phosphodiesterase-5 which competitively inhibits cyclic guanosine monophosphate (cGMP) hydrolysis and thus increases cGMP levels. It is clinically approved for treatment of erectile dysfunction in men, including diabetic and postprostatectomy patients. Several methods of VAR synthesis are included in this review. UV spectroscopy of VAR showed a λmax of approximately 270nm, and IR spectroscopy principal peaks were observed at 3420 (NH), 1724 (CO), 1600 (CC, and CN), 1491 (CHCH) cm(-1). Characteristic carbonyl (CO) carbon was observed in nuclear magnetic resonance spectroscopy at 162.44ppm. The molecular mass was observed at m/z=488.9 (molecular weight=488.2) and the fragmentation pattern was studied using ion trap mass spectrometry. In addition, different analytical methods for determination of vardenafil are also described in this profile. Pharmacokinetic properties of VAR have great impact on efficacy. VAR is rapidly absorbed and slowly metabolized, with an absolute bioavailability of 15%. It is extensively metabolized by CYP3A4 into several metabolites, the most pharmacologically active of which is N-desethyl VAR (M1). The elimination half-life of VAR and M1 is about 4-5h. VAR is primarily excreted as metabolites in the feces and to a small extent in urine. VAR is generally well tolerated, with a favorable safety profile and few transient side effects, including headache, flushing, dyspepsia, and rhinitis.

Nephrotoxic potential and toxicokinetics of melamine combined with cyanuric acid in rats

To investigate the nephrotoxic potential of melamine (MEL) and cyanuric acid (CA) in male Sprague-Dawley rats, 7-d repeated-dose studies were performed. The experimental groups of MEL100 and CA100 were orally administered with MEL and CA at 100 mg/kg/d for 7 d, respectively. In groups dosed with MEL-CA mixtures, melamine and cyanuric acid (1:1) were simultaneously administered at 4, 20, or 100 mg/kg/d for 7 d (i.e., MEL-CA4, MEL-CA20, or MEL-CA100, respectively). Body weights were not markedly affected in MEL100, CA100, and MEL-CA4 groups, but significantly reduced in MEL-CA 20 and 100 rats. Most parameters determined in sera and tissues were not markedly altered in MEL100, CA100, and MEL-CA4-treated rodents. However, BUN, creatinine, total protein, and kidney weights were significantly increased in MEL-CA20- and MEL-CA100-treated animals. Renal histopathologic findings also revealed signs of toxicity, including tubular dilatation, crystal deposition, granulomatous tubulo-interstitial inflammation, and tubular necrosis with regeneration. Data suggested that the combination of MEL and CA might be responsible for observed nephrotoxicity that was not seen following individual exposure to either MEL or CA alone. Subsequently, the concentrations of MEL and CA were determined in serum, urine, and kidney tissues by using liquid chromatography-mass spectrometry. Toxicokinetic studies indicated that MEL or CA alone might be eliminated almost completely within 24 h after dosing showing no accumulation in kidney. However, the combined MEL-CA dose produced marked accumulation of chemicals in blood and kidneys. These results suggested that combined MEL and CA might produce renal toxicity due to significant chemical accumulation in kidney accompanied by low excretion.

[Clinical efficacy and pharmacokinetics of lamotrigine for childhood-onset intractable epilepsy]

OBJECTIVE

We investigated the clinical efficacy and pharmacokinetics of lamotrigine (LTG) as an add-on therapy in childhood-onset intractable epilepsy.

METHODS

We reviewed the charts of 28 outpatients who had received LTG as an add-on therapy. The data collected included epilepsy type, seizure frequency, concomitant anti-epileptic drugs, dosage of LTG and LTG serum levels. Furthermore, we reviewed the relationship between the LTG serum levels (microg/ml) and dosage of LTG (mg/kg/day), as well as the relationship between the LTG serum levels (microg/ml) and clinical efficacy in the following 2 groups:the valproate sodium (VPA) combination group and the non-VPA combination group.

RESULTS

A reduction of 50% or more in seizure frequency was observed in 10 patients. In addition, there was a high correlation between the LTG serum levels and the dosage of LTG in each group. In the VPA combination group, the average of LTG serum levels in patients with adequate therapeutic response (50% reduction in seizure frequency) was higher than that in patients without adequate therapeutic response. In the non-VPA combination group, the average LTG serum level in adequate response patients was lower than that in patients without adequate therapeutic response. However, the epilepsy types of adequate response patients differed in the two groups.

CONCLUSIONS

The LTG serum level is predictable based on the dosage of LTG. It was judged that the effective blood concentration of LTG differed when used with VPA, although factors other than the combined use of VPA should have been taken into consideration also.

Transformation of biocides irgarol and terbutryn in the biological wastewater treatment

The biocides irgarol and terbutryn enter the wastewater treatment plant (WWTP) via combined sewer systems after leaching from coatings and paints of materials. In this study, the biotransformation of irgarol and terbutryn was examined in aerobic batch experiments with activated sludge taken from the nitrification zone of a conventional WWTP, since currently there is no information about the fate of irgarol and terbutryn in biological wastewater treatment. Both, irgarol and terbutryn were transformed into one main transformation product (TP) following pseudo first-order kinetics. The TPs were tentatively identified by high-resolution mass spectrometry (HR-MS) to be irgarol sulfoxide and terbutryn sulfoxide. The final confirmation of the proposed chemical structures of the TPs was achieved by a comparison of mass spectra and nuclear magnetic resonance (NMR) spectra with those of authentic reference standards (e.g., synthesized). An analytical method for the sensitive quantification of irgarol, terbutryn and their TPs in environmental samples was developed based on solid phase extraction (SPE) and LC tandem MS detection. Irgarol sulfoxide and terbutryn sulfoxide were detected in the effluents (average concentrations up to 22 ng L(-1) and 65 ng L(-1)) of all four investigated WWTPs as well as in streams and small rivers (up to 14 ng L(-1) and 34 ng L(-1)). Luminescent bacteria inhibition test with Vibrio fischeri exhibited that the TPs irgarol sulfoxide and terbutryn sulfoxide feature a similar bacterial toxicity than the parent compounds.

Comparative studies and modeling structures of two new isomers containing binuclear PdII complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPTZ)

The synthesis and comparative studies of two new binuclear PdII isomer complexes derived from TPTZ, [2,4,6-tri-(2-pyridyl)-1,3,5-triazine], have been synthesized and characterized. Their structures have been investigated by elemental analyses, spectral (IR, UV-vis, mass and 1H-NMR) and thermal measurements. Electronic and magnetic studies suggest a distorted square-planar around the two PdII ions. The HOMO, LUMO and DFT parameters on the atoms have been calculated to confirm the geometry of the ligand and their complexes. Kinetic parameters were determined using Coats-Redfern and Horowitz-Metzger methods. Also, the geometry of the two isomers is confirmed using DFT method from DMOL3 calculations. Moreover, the two PdII complexes have different specific optical rotation where the red PdII complex has dextrorotatory (+5.68) while the yellow PdII complex has levorotatory (-9.37). The results of biological activity for the two PdII complexes promised to be effective in tumor treatment.

The impact of age on lamotrigine and oxcarbazepine kinetics: a historical cohort study

Age as well as estrogen levels may have an impact on the pharmacokinetics of lamotrigine (LTG) and monohydroxycarbazepine (MHD), the active metabolite of oxcarbazepine (OXC). To assess the effects of age and menopause, we evaluated retrospectively a therapeutic drug-monitoring database. Samples from 507 women and 302 men taking LTG and 464 women and 319 men taking OXC were used to develop a population pharmacokinetic model. Data were analyzed using NONMEM software and were compared with a population pharmacokinetic model based on samples of 1705 women and 1771 men taking carbamazepine (CBZ). Age was a significant factor contributing to pharmacokinetic variability in individuals using LTG, OXC, and CBZ with increasing clearance as a function of bioavailability (Cl/F) over age 18, a maximum Cl/F at 33years (CBZ) and 36 years (LTG and OXC), and a gradual decrease of Cl/F towards older age. We found no effect of perimenopausal age range on LTG and MHD clearance.

Comparative toxicokinetics of organic micropollutants in freshwater crustaceans

Exposure and depuration experiments for Gammarus pulex and Daphnia magna were conducted to quantitatively analyze biotransformation products (BTPs) of organic micropollutants (tramadol, irgarol, and terbutryn). Quantification for BTPs without available standards was performed using an estimation method based on physicochemical properties. Time-series of internal concentrations of micropollutants and BTPs were used to estimate the toxicokinetic rates describing uptake, elimination, and biotransformation processes. Bioaccumulation factors (BAF) for the parents and retention potential factors (RPF), representing the ratio of the internal amount of BTPs to the parent at steady state, were calculated. Nonlinear correlation of excretion rates with hydrophobicity indicates that BTPs with lower hydrophobicity are not always excreted faster than the parent compound. For irgarol, G.pulex showed comparable elimination, but greater uptake and BAF/RPF values than D.magna. Further, G. pulex had a whole set of secondary transformations that D. magna lacked. Tramadol was transformed more and faster than irgarol and there were large differences in toxicokinetic rates for the structurally similar compounds irgarol and terbutryn. Thus, predictability of toxicokinetics across species and compounds needs to consider biotransformation and may be more challenging than previously thought because we found large differences in closely related species and similar chemical structures.