Effect of Nanoparticle Surface on the HPLC Elution Profile of Liposomal Nanoparticles

Purpose

Nanoparticles have been used in diverse areas, and even broader applications are expected in the future. Since surface modification can influence the configuration and toxicity of nanoparticles, a rapid screening method is important to ensure nanoparticle quality.

Methods

We examined the effect of the nanoparticle surface morphology on the HPLC elution profile using two types of 100-nm liposomal nanoparticles (AmBisome^? and DOXIL^?).

Results

These 100-nm-sized nanoparticles eluted before the holdup time (about 4 min), even when a column packed with particles with a relatively large pore size (30 nm) was used. The elution time of the nanoparticles increased with pegylation of the nanoparticles and protein adsorption to the nanoparticles; however, the nanoparticles still eluted before the holdup time.

Conclusions

The results of this study indicate that HPLC is a suitable tool for rapid evaluation of the surface of liposomal nanoparticles.

     

Preparation,Physicochemical Characterization and Anti-fungal Evaluation of Nystatin-Loaded PLGA-Glucosamine Nanoparticles

Purpose

Nystatin loaded PLGA and PLGA-Glucosamine nanoparticles were formulated. PLGA were functionalized with Glucosamine (PLGA-GlcN) to enhance the adhesion of nanoparticles to Candida Albicans (C.albicans) cell walls.

Method

Quasi-emulsion solvent diffusion method was employed using PLGA and PLGA-GlcN with various drug–polymer ratios for the preparation of nanoparticles. The nanoparticles were evaluated for size, zeta potential, polydispersity index, drug crystallinity, loading efficiency and release properties. DSC, SEM, XRPD, ¹H-NMR, and FT-IR were performed to analyze the physicochemical properties of the nanoparticles. Antifungal activity of the nanoparticles was evaluated by determination of MICs against C.albicans.

Results

The spectra of ¹H-NMR and FT-IR analysis ensured GlcN functionalization on PLGA nanoparticles. SEM characterization confirmed that particles were in the nanosize range and the particle size for PLGA and PLGA-GlcN nanoparticles were in the range of 108.63?±?4.5 to 168.8?±?5.65 nm and 208.76?±?16.85 nm, respectively. DSC and XRPD analysis ensured reduction of the drug crystallinity in the nanoparticles. PLGA-GlcN nanoparticles exhibit higher antifungal activity than PLGA nanoparticles.

Conclusion

PLGA-GlcN nanoparticles showed more antifungal activity with appropriate physicochemical properties than pure Nystatin and PLGA nanoparticles.

     

Evaluation of Pharmacokinetics of Bioreducible Gene Delivery Vectors by Real-time PCR

Purpose

To investigate pharmacokinetics of reversibly stabilized DNA nanoparticles (rSDN) using a single-step lysis RT-PCR.

Methods

rSDN were prepared by coating bioreducible polycation/DNA polyplexes with multivalent N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers. Targeted polyplexes were formulated by linking cyclic RGD ligand (c(RGDyK)) to the HPMA surface layer of rSDN. The pharmacokinetic parameters in tumor-bearing mice were analyzed by PKAnalyst®.

Results

The pharmacokinetics of naked plasmid DNA, simple DNA polyplexes, rSDN, and RGD-targeted rSDN exhibited two-compartment model characteristics with area under the blood concentration–time curve (AUC) increasing from 1,102 ng?ml^?1?min^?1 for DNA to 3,501 ng?ml^?1?min^?1 for rSDN. Non-compartment model analysis revealed increase in mean retention time (MRT) from 4.5 min for naked DNA to 22.9 min for rSDN.

Conclusions

RT-PCR is a sensitive and convenient method suitable for analyzing pharmacokinetics and biodistribution of DNA polyplexes. Surface stabilization of DNA polyplexes can significantly extend their MRT and AUC compared to naked DNA. DNA degradation in rSDN in blood circulation, due to a combined effect of disulfide reduction and competitive reactions with charged molecules in the blood, contributes to DNA elimination.

     

Lomustine Nanoparticles Enable Both Bone Marrow Sparing and High Brain Drug Levels – A Strategy for Brain Cancer Treatments

Purpose

The blood brain barrier compromises glioblastoma chemotherapy. However high blood concentrations of lipophilic, alkylating drugs result in brain uptake, but cause myelosuppression. We hypothesised that nanoparticles could achieve therapeutic brain concentrations without dose-limiting myelosuppression.

Methods

Mice were dosed with either intravenous lomustine Molecular Envelope Technology (MET) nanoparticles (13 mg kg^?1) or ethanolic lomustine (6.5 mg kg^?1) and tissues analysed. Efficacy was assessed in an orthotopic U-87 MG glioblastoma model, following intravenous MET lomustine (daily 13 mg kg^?1) or ethanolic lomustine (daily 1.2 mg kg^?1 - the highest repeated dose possible). Myelosuppression and MET particle macrophage uptake were also investigated.

Results

The MET formulation resulted in modest brain targeting (brain/ bone AUC_0-4h ratios for MET and ethanolic lomustine?=?0.90 and 0.53 respectively and brain/ liver AUC_0-4h ratios for MET and ethanolic lomustine?=?0.24 and 0.15 respectively). The MET formulation significantly increased mice (U-87 MG tumours) survival times; with MET lomustine, ethanolic lomustine and untreated mean survival times of 33.2, 22.5 and 21.3 days respectively and there were no material treatment-related differences in blood and femoral cell counts. Macrophage uptake is slower for MET nanoparticles than for liposomes.

Conclusions

Particulate drug formulations improved brain tumour therapy without major bone marrow toxicity.

     

Assessment of the Protein–Protein Interactions in a Highly Concentrated Antibody Solution by Using Raman Spectroscopy

Purpose

To investigate the protein–protein interactions of a highly concentrated antibody solution that could cause oligomerization or aggregation and to develop a better understanding of the optimization of drug formulations.

Methods

In this study, we used Raman spectroscopy to investigate the structure and interactions of a highly concentrated antibody solution over a wide range of concentrations (10–200 mg/mL) with the aid of a multivariate analysis.

Results

Our analysis of the amide I band, I ₈₅₆ /I ₈₃₀ of Tyr, and the relative intensity at 1004 cm^?1 of the Phe and OH stretching region at around 3000 cm^?1 showed that across this wide range of concentrations, the secondary structure of the IgG molecules did not change; however, short-range attractive interactions around the Tyr and Phe residues occurred as the distance between the IgG molecules decreased with increasing concentration. Analysis of the OH stretching region at around 3000 cm^?1 showed that these short-range attractive interactions correlated with the amount of hydrated water around the IgG molecules.

Conclusions

Our data show that Raman spectroscopy can provide valuable information of the protein–protein interactions based on conformational approaches to support conventional colloidal approaches, especially for analyses of highly concentrated solutions.

     

<Emphasis Type="BoldItalic">In Vitro</Emphasis> Performance Testing of the Novel Medspray® Wet Aerosol Inhaler Based on the Principle of Rayleigh Break-up

Purpose

A new inhaler (Medspray®) for pulmonary drug delivery based on the principle of Rayleigh break-up has been tested with three different spray nozzles (1.5; 2.0 and 2.5 μm) using aqueous 0.1% (w/w) salbutamol and 0.9% (w/w) sodium chloride solutions.

Materials and methods

Particle size distributions in the aerosol were measured with the principles of time of flight (APS) and laser diffraction (LDA).

Results

The Medspray® inhaler exhibits a highly constant droplet size distribution in the aerosol during dose emission. Droplets on the basis of Rayleigh break-up theory are monodisperse, but due to some coalescence the aerosols from the Medspray® inhaler are slightly polydisperse. Mass median aerodynamic diameters at 60 l.min^?1 from APS are 1.42; 1.32 and 1.27 times the theoretical droplet diameters (TD’s) and median laser diffraction diameters are 1.29; 1.14 and 1.05 times TD for 1.5; 2.0 and 2.5 μm nozzles (TD: 2.84; 3.78 and 4.73 μm respectively).

Conclusions

The narrow particle size distribution in the aerosol from the Medspray® is highly reproducible for the range of flow rates from 30 to 60 l.min^?1. The mass median aerodynamic droplet diameter can be well controlled within the size range from 4 to 6 μm at 60 l.min^?1.

     

Population Pharmacokinetic Modeling to Describe the Total Plasma and Free Brain Levels of Fluconazole in Healthy and <Emphasis Type="BoldItalic">Cryptococcus neoformans</Emphasis> Infected Rats: How Does the Infection Impact the Drug’s Levels on Biophase?

Purpose

The present work aimed to evaluate the influence of experimental meningitis caused by C. neoformans on total plasma and free brain concentrations of fluconazole (FLC) in Wistar rats.

Method

The infection was induced by the administration of 100 μL of inoculum (1.10⁵ CFU) through the tail vein. Free drug in the brain was assessed by microdialisys (μD). Blood and μD samples were collected at pre-determined time points up to 12 h after intravenous administration of FLC (20 mg/kg) to healthy and infected rats. The concentration-time profiles were analyzed by non-compartmental and population pharmacokinetics approaches.

Results

A two-compartmental popPK model was able to simultaneously describe plasma and free drug concentrations in the brain for both groups investigated. Analysis of plasma and μD samples showed a better FLC distribution on the brain of infected than healthy animals (1.04?±?0.31 vs 0.69?±?0.14, respectively). The probability of target attainment was calculated by Monte Carlo simulations based on the developed popPK model for 125 mg/kg dose for rats and 400–2000 mg for humans.

Conclusions

FLC showed a limited use in monotherapy to the treatment of criptoccocosis in rats and humans to value of MIC >8 μg/mL.

     

Skin Absorption of Anions: Part One. Methodology for <Emphasis Type="Italic">In Vitro</Emphasis> Cutaneous Absorption Measurements

Purpose

Measurement of skin absorption of ions requires specific experimental protocols regarding the use of pig skin as a model, the viability of excised skin in water medium over 24 h, the presence of endogenous ions, and evaluation of the contributions of facilitated transport through ion channels and ion transporters.

Method

Absorption experiments of halide anions F^?, Cl^?, Br^? and I^? in excised skin were performed in Franz diffusion cells. Experiments were performed on human and porcine skin under various conditions so as to define and validate experimental protocols.

Results

The distributions of endogenous ions and the absorption kinetics of halide ions were similar in both porcine and human skin models. Fresh skin kept its viability over 24 h in salt-free water, allowing experiments following OECD guidelines. Permeation increased in the order F^? < Cl^? < Br^? < I^? for all receptor media and skin samples. Absorption was larger in fresh skin due to the transport through chloride channels or exchangers.

Conclusion

Skin absorption experiments of ions in Franz cells rely on working with fresh excised skin (human or porcine) and pure water as receptor fluid. Experiments with chloride blockers or frozen/thawed skin allow discriminating passive diffusion and facilitated transport.

     

Sustained Release from Ionic-Gradient Liposomes Significantly Decreases ETIDOCAINE Cytotoxicity

Purpose

Etidocaine (EDC) is a long lasting local anesthetic, which alleged toxicity has restricted its clinical use. Liposomes can prolong the analgesia time and reduce the toxicity of local anesthetics. Ionic gradient liposomes (IGL) have been proposed to increase the upload and prolong the drug release, from liposomes.

Methods

First, a HPLC method for EDC quantification was validated. Then, large unilamellar vesicles composed of hydrogenated soy phosphatidylcholine:cholesterol with 250 mM (NH₄)₂SO₄ - inside gradient - were prepared for the encapsulation of 0.5% EDC. Dynamic light scattering, nanotracking analysis, transmission electron microscopy and electron paramagnetic resonance were used to characterize: nanoparticles size, polydispersity, zeta potential, concentration, morphology and membrane fluidity. Release kinetics and in vitro cytotoxicity tests were also performed.

Results

IGL_EDC showed average diameters of 172.3?±?2.6 nm, low PDI (0.12?±?0.01), mean particle concentration of 6.3?±?0.5?×?10¹²/mL and negative zeta values (?10.2?±?0.4 mV); parameters that remain stable during storage at 4°C. The formulation, with 40% encapsulation efficiency, induced the sustained release of EDC (ca. 24 h), while reducing its toxicity to human fibroblasts.

Conclusion

A novel formulation is proposed for etidocaine that promotes sustained release and reduces its cytotoxicity. IGL_EDC can come to be a tool to reintroduce etidocaine in clinical use.

     

SPECT-CT Comparison of Lung Deposition using a System combining a Vibrating-mesh Nebulizer with a Valved Holding Chamber and a Conventional Jet Nebulizer: a Randomized Cross-over Study

Purpose

To compare in vivo the total and regional pulmonary deposition of aerosol particles generated by a new system combining a vibrating-mesh nebulizer with a specific valved holding chamber and constant-output jet nebulizer connected to a corrugated tube.

Methods

Cross-over study comparing aerosol delivery to the lungs using two nebulizers in 6 healthy male subjects: a vibrating-mesh nebulizer combined with a valved holding chamber (Aerogen Ultra®, Aerogen Ltd., Galway, Ireland) and a jet nebulizer connected to a corrugated tube (Opti-Mist Plus Nebulizer®, ConvaTec, Bridgewater, NJ). Nebulizers were filled with diethylenetriaminepentaacetic acid labelled with technetium-99 m (^99mTc-DTPA, 2 mCi/4 mL). Pulmonary deposition of ^99mTc-DTPA was measured by single-photon emission computed tomography combined with a low dose CT-scan (SPECT-CT).

Results

Pulmonary aerosol deposition from SPECT-CT analysis was six times increased with the vibrating-mesh nebulizer as compared to the jet nebulizer (34.1?±?6.0% versus 5.2?±?1.1%, p?<?0.001). However, aerosol penetration expressed as the three-dimensional normalized ratio of the outer and the inner regions of the lungs was similar between both nebulizers.

Conclusions

This study demonstrated the high superiority of the new system combining a vibrating-mesh nebulizer with a valved holding chamber to deliver nebulized particles into the lungs as comparted to a constant-output jet nebulizer with a corrugated tube.

     

Gastric pH and Gastric Residence Time in Fasted and Fed Conscious Cynomolgus Monkeys Using the Bravo® pH System

Purpose

To measure fasted and fed gastric pH and gastric residence time (GRT) in Cynomolgus monkeys using Bravo® radiotelemetry capsules.

Methods

Continuous pH measurements were recorded with Bravo® capsules, which were either attached to the monkeys’ stomach or administered as free capsules. Meals (either slurry or standard), were administered at designated times with monkeys chair-restrained during slurry meal ingestion.

Results

From the attached capsule studies, the fasted gastric pH (～1.9–2.2) was consistent among monkeys. Under fasted conditions, pH spikes were infrequently observed (once every 7.9 min to 3.6 h) with peaks reaching pH 9.4 and having short durations (<1 min). After feeding, the gastric pH rose quickly and remained alkaline for approximately 4.5–7.5 h before returning to baseline. Although significantly different (p?

Conclusions

Fasted gastric pH was similar between monkeys and literature human values. After a meal, the monkey gastric pH was elevated for a longer duration than that in human. The monkey GRT appears longer than that observed in human under both fasted and fed conditions, although this is likely dependent on the Bravo® capsule size.

     

Electronic data capture using the Womac<Superscript>®</Superscript> NRS 3.1 Index (m-Womac<Superscript>®</Superscript>): a pilot study of repeated independent remote data capture in OA

Aim

A preliminary evaluation of mobile phone technology for repeated independent remote data capture using the mobile phone-based m-WOMAC^® NRS 3.1 Index.

Methods

Following orientation to the m-WOMAC^® Index, and initial completion in the office, patients took the phones home and independently completed the Index on four subsequent occasions over 12 days, sending their data each time to a server in USA.

Results

Three men and nine women with hip (n = 2) and knee (n = 10) OA successfully completed the m-WOMAC^® Index on each occasion. Average time to completing the Index at termination was 4.8 min. The majority of patients rated logging on/opening the application, completing the m-WOMAC^® Index on the phone, and sending data as very easy (10–11/12), and were very confident (11/12) in continuing to use the phone to report their symptoms.

Conclusions

These data support the feasibility of repeated independent remote data capture using the m-WOMAC^® NRS3.1 Index.

     

Fabrication of 3-O-sn-Phosphatidyl-L-serine Anchored PLGA Nanoparticle Bearing Amphotericin B for Macrophage Targeting

Purpose

To fabricate, characterize and evaluate 3-O-sn-Phosphatidyl-L-serine (PhoS) anchored PLGA nanoparticles for macrophage targeted therapeutic intervention of VL.

Materials and Methods

PLGA-AmpB NPs were prepared by well-established nanoprecipitation method and decorated with Phos by thin film hydration method. Physico-chemical characterization of the formulation was done by Zetasizer nano ZS and atomic force microscopy.

Results

The optimized formulation (particle size, 157.3?±?4.64 nm; zeta potential, ? 42.51?±?2.11 mV; encapsulation efficiency, ～98%) showed initial rapid release up to 8 h followed by sustained release until 72 h. PhoS generated ‘eat-me’ signal driven augmented macrophage uptake, significant increase in in-vitro (with ～82% parasite inhibition) and in-vivo antileishmanial activity with preferential accumulation in macrophage rich organs liver and spleen were found. Excellent hemo-compatibility justified safety profile of developed formulation in comparison to commercial formulations.

Conclusion

The developed PhoS-PLGA-AmpB NPs have improved efficacy, and necessary stability which promisingly put itself as a better alternative to available commercial formulations for optimized treatment of VL.

     

Production of Inhalation Phage Powders Using Spray Freeze Drying and Spray Drying Techniques for Treatment of Respiratory Infections

Purpose

The potential of aerosol phage therapy for treating lung infections has been demonstrated in animal models and clinical studies. This work compared the performance of two dry powder formation techniques, spray freeze drying (SFD) and spray drying (SD), in producing inhalable phage powders.

Method

A Pseudomonas podoviridae phage, PEV2, was incorporated into multi-component formulation systems consisting of trehalose, mannitol and L-leucine (F1?=?60:20:20 and F2?=?40:40:20). The phage titer loss after the SFD and SD processes and in vitro aerosol performance of the produced powders were assessed.

Results

A significant titer loss (~2 log) was noted for droplet generation using an ultrasonic nozzle employed in the SFD method, but the conventional two-fluid nozzle used in the SD method was less destructive for the phage (~0.75 log loss). The phage were more vulnerable during the evaporative drying process (~0.75 log further loss) compared with the freeze drying step, which caused negligible phage loss. In vitro aerosol performance showed that the SFD powders (~80% phage recovery) provided better phage protection than the SD powders (~20% phage recovery) during the aerosolization process. Despite this, higher total lung doses were obtained for the SD formulations (SD-F1?=?13.1?±?1.7?×?10⁴ pfu and SD-F2?=?11.0?±?1.4?×?10⁴ pfu) than from their counterpart SFD formulations (SFD-F1?=?8.3?±?1.8?×?10⁴ pfu and SFD-F2?=?2.1?±?0.3?×?10⁴ pfu).

Conclusion

Overall, the SD method caused less phage reduction during the powder formation process and the resulted powders achieved better aerosol performance for PEV2.

     

AM2389, a high-affinity,in vivo potent CB<Subscript>1</Subscript>-receptor-selective cannabinergic ligand as evidenced by drug discrimination in rats and hypothermia testing in mice

Rationale

The endocannabinoid signaling system (ECS) has been targeted for developing novel therapeutics since ECS dysfunction has been implicated in various pathologies. Current focus is on chemical modifications of the hexahydrocannabinol (HHC) nabilone (Cesamet^®).

Objective

To characterize the novel, high-affinity cannabinoid receptor 1 (CB₁R) HHC-ligand AM2389 [9β-hydroxy-3-(1-hexyl-cyclobut-1-yl)-hexahydrocannabinol in two rodent pre-clinical assays.

Materials and methods

CB₁R mediation of AM2389-induced hypothermia in mice was evaluated with AM251, a CB₁R-selective antagonist/inverse agonist. Additionally, two groups of rats discriminated the full cannabinergic aminoalkylindole AM5983 (0.18 and 0.56 mg/kg) from vehicle 20 min post-injection in a two-choice operant conditioning task motivated by 0.1% saccharin/water. Generalization/substitution tests were conducted with AM2389, AM5983, and Δ⁹-tetrahydrocannabinol (Δ⁹-THC).

Results

Δ⁹-THC (30 mg/kg)-induced hypothermia exhibited a faster onset and shorter duration of action compared with AM2389 (0.1 and 0.3 mg/kg). AM251 (3 and 10 mg/kg) attenuated/blocked hypothermia induced by 0.3 mg/kg AM2389. In drug discrimination, the order of potency was AM2389?>?AM5983?>?Δ⁹-THC with ED₅₀ values of 0.0025, 0.0571, and 0.2635 mg/kg, respectively, in the low-dose condition. The corresponding ED₅₀ values in the high-dose condition were 0.0069, 0.1246, and 0.8438 mg/kg, respectively. Onset of the effects of AM2389 was slow with a protracted time-course; the functional, perceptual in vivo half-life was approximately 17 h.

Conclusions

This potent cannabinergic HHC exhibited a slow onset of action with a protracted time-course. The AM2389 chemotype appears well suited for further drug development, and AM2389 currently is used to probe behavioral consequences of sustained ECS activation.

     

PEG-Benzaldehyde-Hydrazone-Lipid Based PEG-Sheddable pH-Sensitive Liposomes: Abilities for Endosomal Escape and Long Circulation

Purpose

To fabricate an acid-cleavable PEG polymer for the development of PEG-cleavable pH-sensitive liposomes (CL-pPSL), and to investigate their ability for endosomal escape and long circulation.

Methods

PEG-benzaldehyde-hydrazone-cholesteryl hemisuccinate (PEG_B-Hz-CHEMS) containing hydrazone and ester bonds was synthesised and used to fabricate a dual pH-sensitive CL-pPSL. Non-cleavable PEGylated pH-sensitive liposome (pPSL) was used as a reference and gemcitabine as a model drug. The cell uptake and endosomal escape were investigated in pancreatic cancer Mia PaCa-2 cells and pharmacokinetics were studied in rats.

Results

The CL-pPSL showed accelerated drug release at endosomal pH 5.0 compared to pPSL. Compared to pPSL, CL-pPSL released their fluorescent payload to cytosol more efficiently and showed a 1.4-fold increase in intracellular gemcitabine concentration and higher cytotoxicity. In rats, injection of gemcitabine loaded CL-pPSL resulted in a slightly smaller V_d (149?±?27 ml/kg; 170?±?30 ml/kg) and shorter terminal T_1/2 (5.4?±?0.3 h; 5.8?±?0.6 h) (both p?>?0.05) but a significantly lower AUC (p?<?0.01), than pPSL, due to the lower PEGylation degree (1.7 mol%) which means a ‘mushroom’ configuration of PEG. A five-time increase in the dose with CL-pPSL resulted in a 11-fold increase in AUC and a longer T_1/2 (8.2?±?0.5 h).

Conclusion

The PEG-detachment from the CL-pPSL enhanced endosome escape efficiency compared with pPSL, without significantly compromising their stealth abilities.

     

Skin Absorption of Anions: Part Two. Skin Absorption of Halide Ions

Purpose

The purpose of the study was to sort skin penetration of anions with respect to their properties and to assess their mechanisms of penetration.

Methods

Aqueous solutions of halides at two concentrations were prepared and quantitative penetration studies were carried out for 24 h using Franz diffusion cells. The iodide permeation was also measured after blocking of anion channels and transporters to investigate the role of this specific transport.

Results

Absorption of halide ions into skin revealed large differences of transport between these anions according to the Hofmeister series. Increasing steady-state fluxes and lag times in the order F^? < Cl^? < Br^? < I^? were observed in permeation experiments. The steady-state fluxes were proportional to the concentration for each halide ion. Longer lag times for iodide or bromide ions were explained by the ability of such sticky chaotropic anions to interact with apolar lipids especially in the stratum corneum. Inhibiting ion exchangers and channels decreased the flux of iodide ions by 75%, showing the high contribution of the facilitated transport over the passive pathway.

Conclusion

Ions transport had contributions coming from passive diffusion through the skin layers and transport mediated by ion channels and binding to ion transporters.

     

Modern Intermittent Haemodialysis (IHD) is an Effective Method of Removing Salicylate in Chronic Topical Salicylate Toxicity

Introduction

There are limited data on modern intermittent hemodialysis (IHD) efficacy on salicylate elimination from topical poisoning.

Case report

A 54-year-old male sought treatment for dyspnea but was then diagnosed with salicylate toxicity from topical application of Dencorub Extra Strength Heat Gel® for 1 week. Each tube contained 100 g with 26 % methylsalicylate (26 g). Laboratory workup was remarkable for an elevated anion gap of 30 and salicylate concentration of 78.7 mg/dL [5.7 mmol/L (N?<?0.4 mmol/L)]. Treatment with urinary alkalinization was followed by hemodialysis for 5 h. Extraction ratios were 0.44 with clearance rates of 78.5 mL/min. Salicylate concentrations fell rapidly following initiation of hemodialysis with no rebound observed.

Discussion

Modern high flux IHD is an effective method of removing salicylates in the treatment of chronic topical poisoning.

     

Investigation Into the Effects of Tenilsetam on Markers of Neuroinflammation in GFAP-IL6 Mice

Purpose

To test the short- and long-term effects of Tenilsetam on chronic neuroinflammation in the GFAP-IL6 mouse.

Methods

From 3 months of age, GFAP-IL6 mice were divided into 2 groups and fed with Tenilsetam enriched food pellets or control food pellets, respectively, for either 5 or 15 months. Total numbers of Iba-1⁺ microglia, TSPO⁺ cells were determined using an unbiased stereological method. Levels of methylglyoxal and TNF-α in the cerebellar homogenate were tested using HPLC and ELISA, respectively.

Results

Tenilsetam decreased the total number of Iba-1⁺ microglia in both the cerebellum and the hippocampus of GFAP-IL6 mice at 8 months and in the cerebellum at 18 months. In the cerebellum, it decreased the density of microglia in GFAP-IL6 mice to a similar level after 5 and 15 months’ feeding. Tenilsetam prevented the volume loss of the cerebellum at 8 months. It also significantly decreased TNF-α in the cerebellum of GFAP-IL6 mice to a similar level of WT mice after 15 months of feeding.

Conclusion

Tenilsetam has anti-inflammatory effects evidenced by the decreased number of microglia in both the cerebellum and hippocampus, and decreased TNF-α levels in the GFAP-IL6 Tenilsetam fed animals.

     

Population Pharmacokinetic Modeling of Etoposide Free Concentrations in Solid Tumor

Purpose

This study aimed to determine free etoposide (ETO) concentrations in two regions of Walker-256 (W256) solid tumor using microdialysis and to establish a population pharmacokinetic (popPK) model to describe simultaneously free tumor and total plasma concentrations.

Methods

W256 tumor-bearing Wistar rats received ETO 10 or 20 mg/kg i.v. bolus. Free ETO concentrations were sampled from central and peripheral regions of the tumor via CMA/20 probes for up to 7 h, whereas blood samples were collected via carotid artery cannulation. Total plasma and free tumor concentration-time profiles were analyzed by non-compartmental approach using WinNonlin® v. 5.3. PopPK modeling was conducted using MONOLIX v.4.3.3.

Results

ETO penetration was higher in the periphery (61?±?15% and 61?±?29%) than in tumor center (34?±?6% and 28?±?11%) following 10 and 20 mg/kg doses, respectively (ANOVA, α?=?0.05). A 4-compartment model fitted ETO concentration-time profiles in all sampling compartments.

Conclusions

The popPK model allowed the simultaneous fitting of plasma and tumor concentrations and a better understanding of ETO distribution in solid tumors. ETO plasma concentrations are not a good surrogate for tumoral exposure, emphasizing the importance of knowing intratumoral concentrations to predict drug response.