STUDY OF THE PHASE BEHAVIOR OF THE GRAFT COPOLYMER POLY(ETHYLENEGLYCOL-CO-VINYLALCOHOL)

Recently, the graft copolymer of ethyleneglycol and vinylalcohol (PEV) has been found to be potentially useful in the formulation of solid dispersions of poorly soluble drugs. The polymer is hydrophilic, readily soluble in water, slightly surface-active and semi-crystalline. The purpose of the present study is to characterize the phase behavior of unprocessed PEV in order to fully exploit this polymer in the formulation of solid dispersions. In order to investigate the phase behavior of PEV, modulated differential scanning calorimetry (MDSC), High Performance (HPer) DSC and X-ray powder diffraction (XRPD) were used. At first, the conditions for MDSC were determined. Special attention was payed to the modulated heat flow and the Lissajous plots of the modulated heat flow versus modulated heating rate. Reproducible and accurate results in MDSC are based on the assumption that the sample is able to follow the heating/cooling regime imposed on it. An underlying heating rate of 2.5°C/min, an amplitude of 0.40°C and a period of 40s was selected out of 48 tested conditions. This condition ensures enough cycles (>6) of the modulated heat flow during step changes and transitions in the total heat flow. Also the Lissajous figure showed an adequate elliptic form without too much phase lag on it. Analysis of unprocessed PEV showed the presence of two glass transitions and two melting peaks, proving its semi-crystallinity. Investigation of PEG2000 and PVA(9500Da), the polymers that resemble the blocks in the co-polymer, showed that the first glass transition (Tg=-55°C) and first melting peak (Tm=15°C, ΔHm=ca.4J/g) correspond to those of PEG and the second glass transition (Tg=45°C) and second melting peak (Tm=212°C, ΔHm=ca.60J/g) correspond to those of PVA. XRPD analysis confirmed its semi-crystallinity and again PEV showed Bragg reflections comparable to those of PEG and PVA. The polymer remained semi-crystalline after hot-melt extrusion and spray-drying. Controlled cooling at rates up to 500°C/min could delay, but not avoid crystallization. Plastification of the amorphous domain of PEG or PVA was dependent on the type and concentration of plasticizer. The present results indicate the suitability of PEV from a material science perspective to be used as a carrier for solid dispersions.status: publishe

Upscaling of the hot-melt extrusion process: Comparison between laboratory scale and pilot scale production of solid dispersions with miconazole and Kollicoat IR

Since only limited amount of drug is available in early development stages, the extruder design has evolved towards smaller batch sizes, with a more simple design. An in dept study about the consequences of the differences in design is mandatory and little can be found in literature. Miconazole and Kollicoat IR were used as model drug and carrier for this study. Two series of solid dispersions were made with a laboratory scale (internal circulation-simple screw design) and a pilot scale extruder (continuous throughput-modular screw design). Efforts were made to match the operating parameters as close as possible (residence time, extrusion temperature and screw speed). The samples were analyzed with modulated DSC straight after production and after exact 24h and 15 days storage at -26 °C. The kinetic miscibility of the samples prepared with the laboratory scale extruder was slightly higher than the samples prepared with the pilot scale extruder. As the solid dispersions with high drug load were unstable over time, demixing occurred, slightly faster for the samples prepared with the laboratory scale extruder. After 15 days, the levels of molecular mixing were comparable, pointing to the predictive value of samples prepared on laboratory scale.status: publishe

Comparison Between Hot-Melt Extrusion and Spray-Drying for Manufacturing Solid Dispersions of the Graft Copolymer of Ethylene Glycol and Vinylalcohol

Purpose To investigate the effect of the manufacturing method (spray-drying or hot-melt extrusion) on the kinetic miscibility of miconazole and the graft copolymer poly(ethyleneglycol-gvinylalcohol). The effect of heat pre-treatment of solutions used for spray-drying and the use of spray-dried copolymer as excipient for hot-melt extrusion was investigated. Method The solid dispersions were prepared at different drug-polymer ratios and analyzed with modulated differential scanning calorimetry and X-ray powder diffraction. Results Miconazole either mixed with the PEG-fraction of the copolymer or crystallized in the same or a different polymorph as the starting material. The kinetic miscibility was higher for the solid dispersions obtained from solutions which were pre-heated compared to those spray-dried from solutions at ambient temperature. Hot-melt extrusion resulted in an even higher mixing capability. Here the use of the spray-dried copolymer did not show any benefit concerning the kinetic miscibility of the drug and copolymer, but it resulted in a remarkable decrease in the torque experienced by the extruder allowing extrusion at lower temperature and torque. Conclusion The manufacturing method has an influence on the mixing capacity and phase behavior of solid dispersions. Heat pre-treatment of the solutions before spray-drying can result in a higher kinetic miscibility. Amorphization of the copolymer by spray-drying before using it as an excipient for hot-melt extrusion can be a manufacturing benefit.status: publishe

Toll-like receptors : are they taking a toll on the heart in viral myocarditis?

Myocarditis is an inflammatory disease of the heart with viral infections being the most common aetiology. Its complex biology remains poorly understood and its clinical management is one of the most challenging in the field of cardiology. Toll-like receptors (TLRs), a family of evolutionarily conserved pattern recognition receptors, are increasingly known to be implicated in the pathophysiology of viral myocarditis. Their central role in innate and adaptive immune responses, and in the inflammatory reaction that ensues, indeed makes them prime candidates to profoundly affect every stage of the disease process. This review describes the pathogenesis and pathophysiology of viral myocarditis, and scrutinises the role of TLRs in every phase. We conclude with directions for future research in this field

Characterization of the copolymer poly(ethyleneglycol-g-vinylalcohol) as a potential carrier in the formulation of solid dispersions

In order to fully exploit the graft copolymer poly(ethyleneglycol-g-vinylalcohol) (EG/VA) in the formulation of solid dispersions, a characterization of its phase behavior before, during and after spray-drying and hot-melt extrusion is performed. Solid state characterization was performed using MDSC and XRPD. The effect of heating/cooling rate on the degree of crystallinity was studied using HPer DSC and ultra-fast chip calorimetry. EG/VA consists of two semi-crystalline fractions, one corresponding to the polyethyleneglycol (PEG) fraction (Tg = –57 °C, Tm = 15 °C) and one corresponding to the polyvinylalcohol (PVA) fraction (Tg = 45 °C, Tm = 212 °C). XRPD analysis confirmed its semi-crystallinity, and EG/VA showed Bragg reflections comparable to those of PVA. Spray-drying at a temperature lower than 170 °C resulted in amorphization of the PVA fraction, while after hot-melt extrusion at different temperatures, the crystallinity of this fraction increases. In both cases, the PEG fraction is not influenced. Plasticization of the amorphous domains of the PEG or PVA fraction of the copolymer was dependent on the type and concentration of plasticizer, suggesting that also other small organic molecules like drugs may not homogeneously mix with both amorphous domains. A controlled cooling rate of 3000 °C/s was necessary to make the copolymer completely amorphous.status: publishe

Toll-like receptors : are they taking a toll on the heart in viral myocarditis?

Myocarditis is an inflammatory disease of the heart with viral infections being the most common aetiology. Its complex biology remains poorly understood and its clinical management is one of the most challenging in the field of cardiology. Toll-like receptors (TLRs), a family of evolutionarily conserved pattern recognition receptors, are increasingly known to be implicated in the pathophysiology of viral myocarditis. Their central role in innate and adaptive immune responses, and in the inflammatory reaction that ensues, indeed makes them prime candidates to profoundly affect every stage of the disease process. This review describes the pathogenesis and pathophysiology of viral myocarditis, and scrutinises the role of TLRs in every phase. We conclude with directions for future research in this field

CSS 9453 Qualification des salles propres et monitoring des processus aseptiques dans les banques de matériel corporel humain, les structures intermédiaires et les établissements de production

audience: researcher, professional, student, popularizationConformément à l’Arrêté Royal (AR) du 28 septembre 2009 fixant les normes de qualité et de sécurité pour le don, le prélèvement, l’obtention, le contrôle, le traitement, le stockage et la distribution de matériel corporel humain (AR, 2009), les banques de matériel corporel humain (MCH), les structures intermédiaires et les établissements de production doivent disposer d’installations adaptées – salles propres – pour le traitement du MCH. Avant la mise en service ou à la suite de travaux, le bon fonctionnement des salles propres doit être démontré grâce à l’exécution de tests de classification et de qualification. Afin de limiter autant que possible le risque de contamination microbiologique, notamment de contamination croisée, pendant la production des MCH, des processus aseptiques doivent être mis en œuvre en fonction du type de MCH et de l’application chez l’être humain. L’efficacité de ces processus aseptiques doit être surveillée entre autre par l’évaluation des particules et du nombre d’unités formant colonies (UFC) constaté dans l’air, sur les surfaces, les consommables, les appareils, les vêtements et/ou les empreintes digitales. Les différents contrôles sont établis sur base de l’analyse de risques. L’avis CSS 8699 relatif aux recommandations en matière de validation et de contrôle de l’environnement au sein des banques de MCH, les structures intermédiaires et les établissements de production date de 2012. À la suite de l’obtention de nouvelles informations, de l’apparition de nouvelles technologies et de l’évolution des exigences, ainsi que la révision de la norme internationale pour la classification et le contrôle des salles propres (NBN EN ISO 14644-1 en 2), le Conseil Supérieur de la Santé (CSS) a décidé de revoir l’avis CSS 8699. Dans le cadre de l’évaluation de l’avis CSS 8699, les problèmes suivants ont été identifiés et ont été pris en compte dans le présent avis : L’avis CSS 8699 se limitait à la classification et au contrôle de l’environnement et n’apportait aucun conseil concernant le contrôle des processus de production aseptiques : o Le matériel source (MCH) est limité et il existe une grande variabilité intrinsèque entre les matériels sources ; o Pour certains types de MCH, le matériel source est contaminé avant ou lors du prélèvement ; o La production des MCH s’effectue souvent à petite échelle ; o Il existe une grande diversité des processus de production aseptiques au sein de différents types de banques de MCH ; o Les processus de production aseptiques comportent souvent de nombreuses opérations manuelles ; o Tous les processus de prélèvement et de production ne peuvent pas être effectués de manière aseptique. Harmonisation avec les concepts de gestion des risques ; La terminologie utilisée dans l’avis CSS 8699 n’était pas toujours univoque ; Une nouvelle version des normes internationales NBN EN ISO14644-1 et 2 a été publiée en 2016 et enrichie de nouvelles informations et techniques dans le cadre de la classification et du contrôle des salles propres à l’aide de compteurs de particules.En 2014, 8,5 % de toutes les réactions indésirables graves recensées en Europe à la suite de la transplantation de MCH étaient imputables à des infections, principalement des contaminations avec des bactéries et des champignons. La prévention des infections consécutives à la transplantation de MCH est un important défi que doivent relever les banques de MCH, les structures intermédiaires et les établissements de production. Il convient sur ce plan de tenir compte de 4 risques majeurs de contamination : Le risque de contamination du MCH durant le prélèvement (type d’environnement où le prélèvement est effectué, durée d’exposition du MCH à l’environnement direct, pathologie sous-jacente chez le donneur, etc.) ; Le risque de contamination du MCH durant le traitement (classe de propreté de la salle blanche où le traitement est effectué, durée d’exposition du MCH à l’environnement direct, nombre de manipulations critiques exécutées, type de traitement, etc.) ; Le risque de contamination croisée avec un autre MCH (efficacité de la procédure de nettoyage et de désinfection appliquée, type de MCH, donneurs infectieux, instruments ou consommables contaminés, etc.) ; Le risque d’infections post-opératoires durant la transplantation ou l’administration du MCH chez le patient (statut immunitaire du patient, forme d’administration, site d’administration, etc.). Conformément aux législations européenne et belge, les banques de MCH, les structures intermédiaires et les établissements de production doivent disposer d’infrastructures adaptées – « salles propres » – pour maîtriser les risques de contamination durant le traitement du MCH. Le CSS recommande de déterminer la qualité de l’air appropriée de ces salles propres à l’aide d’une analyse des risques documentée prenant en compte l’ensemble des risques potentiels de contamination par l’environnement direct et le processus de production et répondant au moins à la classe de propreté minimale telle que définie dans l’AR de 2009. Afin d’assurer la qualification des salles propres, il convient d’élaborer un plan directeur de validation déterminant les tests de qualification à réaliser ou à répéter, les moments où ceux-ci doivent être réalisés ou répétés, ainsi que l’état de fonctionnement dans lequel ils doivent être réalisés ou répétés. Par ailleurs, le CSS préconise la mise sur pied d’un programme de monitoring permettant de déceler les évolutions des tendances de la contamination microbiologique au cours du processus de production aseptique et d’adopter les mesures correctrices en temps opportun. Le programme de monitoring doit identifier, contrôler et suivre les points critiques du processus de production aseptique, identifiés sur la base d’une analyse des risques documentée. Les valeurs d’alertes et de seuils doivent être spécifiées par salle propre contrôlée, par état de fonctionnement et par processus aseptique

Monitoring Blood-Brain Barrier Integrity Following Amyloid-β Immunotherapy Using Gadolinium-Enhanced MRI in a PDAPP Mouse Model.

BACKGROUND: Amyloid-related imaging abnormalities (ARIA) have been reported with some anti-amyloid-β (Aβ) immunotherapy trials. They are detected with magnetic resonance imaging (MRI) and thought to represent transient accumulation of fluid/edema (ARIA-E) or microhemorrhages (ARIA-H). Although the clinical significance and pathophysiology are unknown, it has been proposed that anti-Aβimmunotherapy may affect blood-brain barrier (BBB) integrity. OBJECTIVE: To examine vascular integrity in aged (12-16 months) PDAPP and wild type mice (WT), we performed a series of longitudinal in vivo MRI studies. METHODS: Mice were treated on a weekly basis using anti-Aβimmunotherapy (3D6) and follow up was done longitudinally from 1-12 weeks after treatment. BBB-integrity was assessed using both visual assessment of T1-weighted scans and repeated T1 mapping in combination with gadolinium (Gd-DOTA). RESULTS: A subset of 3D6 treated PDAPP mice displayed numerous BBB disruptions, whereas WT and saline-treated PDAPP mice showed intact BBB integrity under the conditions tested. In addition, the contrast induced decrease in T1 value was observed in the meningeal and midline area. BBB disruption events occurred early during treatment (between 1 and 5 weeks), were transient, and resolved quickly. Finally, BBB-leakages associated with microhemorrhages were confirmed by Perls'Prussian blue histopathological analysis. CONCLUSION: Our preclinical findings support the hypothesis that 3D6 leads to transient leakage from amyloid-positive vessels. The current study has provided valuable insights on the time course of vascular alterations during immunization treatment and supports further research in relation to the nature of ARIA and the utility of in vivo repeated T1 MRI as a translational tool