Lack of effects of polystyrene micro- and nanoplastics on activity and expression of human drug transporters.

Micro- and nanoplastics (MPs/NPs) constitute emerging and widely-distributed environmental contaminants to which humans are highly exposed. They possibly represent a threat for human health. In order to identify cellular/molecular targets for these plastic particles, we have analysed the effects of exposure to manufactured polystyrene (PS) MPs and NPs on in vitro activity and expression of human membrane drug transporters, known to interact with chemical pollutants. PS MPs and NPs, used at various concentrations (1, 10 or 100 µg/mL), failed to inhibit efflux activities of the ATP-binding cassette (ABC) transporters P-glycoprotein, MRPs and BCRP in ABC transporter-expressing cells. Furthermore, PS particles did not impair the transport of P-glycoprotein or BCRP substrates across intestinal Caco-2 cell monolayers. Uptake activities of solute carriers (SLCs) such as OCT1 and OCT2 (handling organic cations) or OATP1B1, OATP1B3, OATP2B1, OAT1 and OAT3 (handling organic anions) were additionally not altered by PS MPs/NPs in HEK-293 cells overexpressing these SLCs. mRNA expression of ABC transporters and of the SLCs OCT1 and OATP2B1 in Caco-2 cells and human hepatic HepaRG cells were finally not impaired by a 48-h exposure to MPs/NPs. Altogether, these data indicate that human drug transporters are unlikely to be direct and univocal targets for synthetic PS MPs/NPs.

PLGA-PEG-COOH nanoparticles are efficient systems for delivery of mefloquine to Echinococcus multilocularis metacestodes.

Alveolar echinococcosis (AE) is a severe disease caused by the infection with the larval stage of Echinococcus multilocularis, the metacestode. As there is no actual curative drug therapy, recommendations to manage AE patients are based on radical surgery and prophylactic administration of albendazole or mebendazole during 2 years to prevent relapses. There is an urgent need for new therapeutic strategies for the management of AE, as the drugs in use are only parasitostatic, and can induce toxicity. This study aimed at developing a drug delivery system for mefloquine, an antiparasitic compound which is highly active against E. multilocularis in vitro and in experimentally infected mice. We formulated mefloquine-loaded PLGA-PEG-COOH (poly-(lactic-co-glycolic acid)) nanoparticles that exhibit stable physical properties and mefloquine content. These nanoparticles crossed the outer acellular laminated layer of metacestodes in vitro and delivered their content to the inner germinal layer within less than 5 min. The in vitro anti-echinococcal activity of mefloquine was not altered during the formulation process. However, toxicity against hepatocytes was not reduced when compared to free mefloquine. Altogether, this study shows that mefloquine-loaded PLGA-PEG-COOH nanoparticles are promising candidates for drug delivery during AE treatment. However, strategies for direct parasite-specific targeting of these particles should be developed.

Maternal and Fetal Blood Pharmacokinetics and Organ Distribution of Atrazine, Propazine, Simazine, and Their Metabolites in Pregnant Rats After Chronic Oral Administration.

Environmental contamination by chlorotriazines has been evidenced in mother-child cohort suggesting more detailed risk assessment of these compounds in drinking water. Exposure of rodents to atrazine (ATZ) has been associated with alterations of endocrine and reproductive functions by disrupting neuroendocrine control at hypothalamus level. Perinatal exposure to low doses of ATZ has been associated with reproductive dysfunction, and to behavioral abnormalities in adult exposed during embryogenesis. The objectives of the current investigation were to (1) evaluate the influence of physicochemical properties of chlorotriazines on tissue distribution in pregnant rats and in fetuses and (2) gain a better understanding of fetal distribution of chlorotriazines in specific tissues, particularly in brain. Serial blood samples were obtained from pregnant rats after administration of ATZ, propazine (PRO), and simazine (SIM) via oral route at a dose of 10 mg/kg from day 15 to day 19. Maternal and fetal tissues were harvested at day 20, 24 h after the last dosing. The metabolic extraction ratio was estimated to 87% suggesting a significant first-pass effect explaining the low oral bioavailability. Blood exposure to parent compounds (ATZ, PRO, and SIM) was negligible (lower than 5%) compared with metabolite exposure. The main metabolite exposure involved diamino-s-chlorotriazine, ranging from 60% to 90% depending on the molecules administered. A correlation between tissue-to-blood ratio and physicochemical descriptors was observed for fat and mammary gland tissues but not for brain in adult rats. A more pronounced distribution in fetal brain was observed for ATZ and PRO, the 2 most lipophilic compounds.

PBPK model of methotrexate in cerebrospinal fluid ventricles using a combined microdialysis and MRI acquisition.

The objective of the study was to evaluate the distribution of methotrexate (MTX) in cerebrospinal fluid (CSF) lateral ventricles and in cisterna magna after 3rd intraventricular CSF administration in a rabbit model. MTX or gadolinium chelate (Gd-DOTA) was administered in the 3rd ventricle with a local microdialysis to study the pharmacokinetics at the site of administration and with a simultaneous magnetic resonance imaging (MRI) acquisition in the 3rd ventricle, the lateral ventricles and in the cisterna magna. A specific CSF Physiologically Based Pharmacokinetic (PBPK) model was then extrapolated for MTX from Gd-DOTA data. The relative contribution of elimination and distribution processes to the overall disposition of MTX and Gd-DOTA in the 3rd ventricle was similar (i.e., around 60% for CLE and 40% for CLI) suggesting that Gd-DOTA was a suitable surrogate marker for MTX disposition in ventricular CSF. The PBPK predictions for MTX both in CSF of the 3rd ventricle and in plasma were in accordance with the in vivo results. The present study showed that the combination of local CSF microdialysis with MRI acquisition of the brain ventricles and a PBPK model could be a useful methodology to estimate the drug diffusion within CSF ventricles after direct brain CSF administration. Such a methodology would be of interest to clinicians for a rationale determination and optimization of drug dosing parameters in the treatment of leptomeningeal metastases.

Preparation and characterization of spironolactone-loaded nano-emulsions for extemporaneous applications.

In neonates as well as in adults having swallowing difficulty, oral medication is given through a nasogastric tube making liquid formulations preferable. In this study, we present the high potential of nanometric emulsions formulated by spontaneous surfactant diffusion, as extemporaneous formulations of hydrophobic drug. Spironolactone used as hydrophobic drug model, was incorporated in oil before formulation at a concentration of 13.5mg/g oil. Then, all formulations were evaluated from pharmacotechnical and clinical standpoints, for their use in hospital or community pharmacy. The strength of this new liquid formulation lies on the simplicity, efficiency and reproducibility of their low energy process as on clinical aspects: high dose uniformity, facility to be administered through in nasogastric tube without any retention and a stability of 2 months at least compatible for an extemporaneous use. Moreover, this emulsion presented spironolactone content of 3.75 mg/ml among the most concentrated formulations published.

Ex vivo and in vivo diffusion of ropivacaine through spinal meninges: influence of absorption enhancers.

Following epidural administration, cerebrospinal fluid bioavailability of local anesthetics is low, one major limiting factor being diffusion across the arachnoid mater barrier. The aim of this study was to evaluate the influence of absorption enhancers on the meningeal permeability of epidurally administered ropivacaine. Five enhancers known for their ability to increase drug permeability via transcellular and/or paracellular pathways, i.e. palmitoyl carnitine, ethylenediaminetetraacetic acid, sodium caprate, dodecylphosphocholine and pentylglycerol, were tested ex vivo on fresh specimen of meninges removed from cervical to lumbar level of rabbit spine following laminectomy and placed in diffusion chambers. Among them, sodium caprate lead to the best permeability improvement for both marker and drug (440% and 112% for mannitol and ropivacaine, respectively) and was therefore selected for in vivo study in a sheep model using microdialysis technique to evaluate epidural and intrathecal ropivacaine concentrations following epidural administration. Resulting dialysate and plasma concentrations were used to calculate pharmacokinetic parameters. Following sodium caprate pre-treatment, ropivacaine intrathecal maximal concentration (Cmax) was 1.6 times higher (78 ± 16 µg ml(-1) vs 129 ± 26 µg ml(-1), p<0.05) but the influence of the absorption enhancer was only effective the first 30 min following ropivacaine injection, as seen with the significantly increase of intrathecal AUC(0-30 min) (1629 ± 437 µg min ml(-1) vs 2477 ± 559 µg min ml(-1), p<0.05) resulting in a bioavailable fraction 130% higher 30 min after ropivavaine administration. Co-administration of local anesthetics with sodium caprate seems to allow a transient and reversible improvement of transmeningeal passage into intrathecal space.

Specific and non-specific phagocytosis of ligand-grafted PLGA microspheres by macrophages.

We evaluated the influence of ligand grafting on the rate and intensity of uptake of poly(d,l-lactide-co-glycolide) microparticles by alveolar macrophages. Microspheres with a mean diameter of 2.5 microm were obtained by spray drying. Three ligands (WGA, an RGD containing peptide and mannose-PEG(3)-NH(2)) and a cationic molecule (PLL) were covalently grafted on the particle surface using the carbodiimide method. Their grafting efficiency was quantified, and WGA grafting was characterized by confocal laser scanning microscopy (CLSM) and by atomic force microscopy (AFM). The uptake by macrophages of surface-modified microspheres was quantified by CLSM. This work showed that the uptake of negatively charged ligand-grafted microspheres (-26 to -51 mV) was increased up to two to four times according to the ligand compared to ungrafted microspheres (-81 mV) and displayed saturation as opposed to the cationic PLL-grafted microspheres. Moreover, a specific receptor-mediated phagocytosis mechanism was suggested based on free ligand, cytochalasin D and +4 degrees C incubation that decreased the microparticle uptake. Furthermore, this work clearly showed that the relative contribution of specific and non-specific processes to the overall uptake varied greatly according to the ligands, and was dependent on the particle-to-cell ratio. In conclusion, this work showed that ligand grafting can enhance the uptake of microparticles, with a variable relative contribution of specific and non-specific uptake mechanism.