Performance and safety assessment of materials used in the medical devices destinated for pressure ulcer management

Pressure ulcers are a significant health problem that affects a large population, especially the elderly and individuals with physical limitations. These injuries cause pain, are difficult to heal, and can be expensive to manage, leading to a negative impact on the quality of life of those affected. This scientific paper provides an overview of medical devices such as support surfaces, dressings, and topical agents for preventing and managing pressure ulcers. This review focuses on the importance of understanding the viscoelastic mechanical properties, water vapor transmission rate, and biocompatibility testing of medical devices, which can help define performance criteria needed to prevent and manage pressure ulcers effectively. The paper highlights the potential use of alginate, polyurethane, silicone, polyvinyl alcohol, and collagen as pressure relief and wound care solutions. Synthesizing this research can help medical device manufacturers make better decisions and improve the quality of care for patients with pressure ulcers.

Evolution of the Chronic Venous Leg Ulcer Microenvironment and Its Impact on Medical Devices and Wound Care Therapies

Studies have reported that the constituents of the wound microenvironment are likely to have critical roles in the degradation and fate of the polymeric matrix and the compounds dissolved in the wound dressing matrix. Thus, chronic wound assessment and the design of effective medical devices and drug products for wound care partly rely on an in-depth understanding of the wound microenvironment. The main aim of this review is to identify and discuss the different stages of chronic wound progression, focusing on the changes in the biochemical composition of the wound microenvironment, with particular attention given to venous leg ulcers (VLUs), as they are one of the most prevalent chronic wound aetiologies. The pathophysiology of venous ulcers is detailed, followed by a thorough review of what is known about the VLU microenvironment and its changes as a function of the evolution of the VLU. Simulating conditions for VLU are then discussed with the view of highlighting potentially relevant simulating media as a function of VLU evolution for a better assessment of biological safety, in particular medical devices intended to be in contact with these wounds.

Impact of lock solutions on the mechanical performance of polyurethane central venous catheters: A comparative study

The impact of ethanol locks on the mechanical performances of central venous catheters was compared to that of aqueous-based locks. Several mechanical tests were performed to evaluate catheter behavior: kinking radius measurements, burst pressure, and tensile tests. Different polyurethanes were studied to assess the impact of radio-opaque charge and polymer chemical composition on catheter behavior. The results were correlated to swelling measurements and calorimetric measurements. In particular, ethanol locks have a higher impact on long contact time than aqueous-based locks: stresses and strains at break were lower, and kinking radii were higher. However, for all catheters, the mechanical performances remain much higher than the normative requirements.

Surface properties and bacterial adhesion on polyurethane central catheters: Impact of ethanol lock solution

It was shown in the literature that ethanol locks have a positive effect on preventing catheter-related infections in patients with central venous catheters without causing any microbial resistance. However, ethanol is known to interact with polyurethanes. The consequences of this interaction on the catheter surface properties were studied as it can impact the biocompatibility of the material and the adhesion phenomena onto the surface. No physical and chemical degradation was put into evidence, but low molecular weight compounds such as additives were extracted from the catheter bulk or migrated and exudated onto its surface. Nevertheless, as far as bacterial adhesion is concerned, after the catheter was locked and the lock removed, the surface modifications promoted no adhesion.

Mechanical Performance and Cytotoxicity of an Alginate/Polyacrylamide Bipolymer Network Developed for Medical Applications

Several hydrogels could be used as scaffolds for tissue engineering and a model of extracellular matrices for biological studies. However, the scope of alginate in medical applications is often severely limited by its mechanical behavior. In the present study, the modification of the mechanical properties of the alginate scaffold is obtained by its combination with polyacrylamide in order to obtain a multifunctional biomaterial. The advantage of this double polymer network is due to an improvement in the mechanical strength with regard to the alginate alone, and in particular, its Young's modulus values. The morphological study of this network was carried out by scanning electron microscopy (SEM). The swelling properties were also studied over several time intervals. In addition to mechanical property requirements, these polymers must meet several biosafety parameters as part of an overall risk management strategy. Our preliminary study illustrates that the mechanical property of this synthetic scaffold depends on the ratio of the two polymers (alginate, polyacrylamide) which allows us to choose the appropriate ratio to mimic replaceable body tissue and be used in various biological and medical uses, including 3D cell culture, tissue engineering, and protection against local shocks.

Surface and mechanical properties of polyurethane central venous catheters after repeated contact with chemotherapy excipient solutions

This article investigates the impact of the interactions between polyurethane central venous catheters and solutions containing excipients used in cisplatin and paclitaxel formulations. Changes to the properties of catheters and the leaching of catheter additives into the infused solutions were studied while these solutions were infused cyclically for several months. Chemotherapy treatment was mimicked in vitro in compliance with hospital practices. The treatment cycle was repeated 10 times, using solutions containing only the excipients. After 10 treatment cycles, no physical or chemical degradation of the catheter was observed. Mechanical performances were stable, but surface modifications occurred, causing the surface to become more hydrophobic. A loss in polyurethane antioxidant amount was observed in part due to a leaching phenomenon.

Impact of mechanical stress on flexible tubing used for biomedical applications: Characterization of the damages and impact on the patient's health

Flexible tubing is a key part of a lot of medical devices used in hospital, but may be subjected to a lot of various mechanical stresses that can led to the failure or to complications for the patients. The nature and causes of these mechanical stresses were listed for peristaltic pump tubing, infusion set tubing and catheters. Their consequences in term of tubing damages and particular contamination were reported. The impact of the chemical nature of the tubing, of its size and also the impact of various parameters of the clinical acts were reviewed. Last the consequences for the patient's health were discussed.

Identification of the Major Degradation Pathways of Selumetinib

Selumetinib is administered orally in capsule form and is indicated for the treatment of neurofibromatosis. To facilitate dosage adjustments, liquid preparations, such as solutions or suspensions, are to be developed. This led, first, to determine the stability profile of soluble or dispersed selumetinib and, secondly, to look for ways to stabilize the active substance. The degradation kinetics of selumetinib as a function of stress conditions were determined and compared. The degradation products were detected and identified by LC-HRMSⁿ. In solution, selumetinib is sensitive to oxidation and degrades by photooxidation. In both cases, the side chain represented by the oxoamide group is concerned, leading to the formation of an amide derivative for the first case and an ester derivative for the second. The identification of such degradation mechanisms allowed us to study, in a targeted way, processes aiming at stabilizing the active molecule.

A versatile and straightforward process to turn plastics into antibacterial materials

Antibacterial activity without cell cytotoxicity is conferred to common plastic materials by dispersion of amphiphilic cationic methacrylate-based block copolymers (0.5–2 wt%), while maintaining the mechanical properties of the materials.

Investigating the static or dynamic flexural and compressive stresses on flexible tubing: Comparison of clamp and peristaltic pump impact on surface damages and particles leaching during infusion acts

This paper deals with the impact of the mechanical stresses on plasticized PVC infusion tubing. Stresses due to clamping were compared to those due to the use of a peristaltic pump. The degradation of the inner surface of plastic tubing due to a dynamic load with repeated flexion and compression was extensively studied in the case of peristaltic pump stress during extracorporeal (EC) acts. Even if clamping results in a less repeated stress, we show it can also lead to damages on the inner lumen of the tubing, especially in static conditions. As these degradations were responsible of particle shedding in the case of EC processes, a first evaluation of particular contamination was performed on the stressed infusion tubes.

Intrinsic stability of the antiviral drug umifenovir by stress testing and DFT studies

Umifenovir is an antiviral drug approved in China and Russia for the treatment of influenza. The available dosage form consists of capsules marketed under the brand name Arbidol®. Due to its broad spectrum, umifenovir may also be used in other viral contexts, alone or combined with other antiviral drugs. Although knowledge of umifenovir intrinsic stability may be useful for any potential development of other pharmaceutical forms for other routes of administration and for quality risk management, no data regarding this matter is available to date. In this study, the exploration of the molecule's behaviour under hydrolytic, oxidative and photolytic conditions was carried out experimentally and supported by density functional theory (DFT) studies. It comes out that umifenovir is sensitive to these stress conditions giving rise to 6 structurally characterized degradation products. The one-electron oxidation process produced on the sulphur atom is probably the main cause of umifenovir degradation with reference to the structures of the degradation products formed and the DFT data.

Post hoc study to investigate the potential causes of poor quality of cardiovascular medicines collected in sub-Saharan countries

OBJECTIVES

The incidence of cardiovascular diseases is increasing and there is a growing need to provide access to quality cardio drugs in Africa. In the SEVEN study, we analysed 1530 cardiovascular drug samples randomly collected from 10 African countries. By that time, of the seven drugs products analysed, only those containing amlodipine and captopril had very low assay values with active substance contents that could be less than 75% of those expected. In this article we investigate complementary aspects of the amlodipine and captopril samples so to explain the previously observed low assays for these two drugs.

DESIGN

Post hoc analysis of the captopril and amlodipine drugs samples and their packages collected in the context of the SEVEN study.

SETTING

10 countries were concerned: Benin, Burkina Faso, Congo, Democratic Republic of the Congo, Guinea, Côte d'Ivoire, Mauritania, Niger, Senegal and Togo.

PARTICIPANTS

Local scientists and hospital practitioners collected the drug samples in the 10 African countries.

OUTCOME MEASURES

The drug amount and the relative amounts of drug impurities, as well as the main compounds of the drugs packaging, were analysed.

RESULTS

Identification of the blister packaging of the samples led to separate both amlodipine and captopril drug samples in two groups. Mann Whitney's bilateral test showed a significant difference (p<0.0001) between the median value of the captopril dosage when tablets are packaged in blisters providing higher protection to humidity (n=105) as opposed to the tablets packaged in blisters providing lower humidity protection (n=130).

CONCLUSION

Based on these results, particular attention should be paid to the materials and types of packaging used in order to minimise the lack of control over the exposures and drug circuits present in these different countries.

Electrospun Poly(ε-caprolactone) Fiber Scaffolds Functionalized by the Covalent Grafting of a Bioactive Polymer: Surface Characterization and Influence on in Vitro Biological Response

The purpose of this study is to present the poly(caprolactone) (PCL) functionalization by the covalent grafting of poly(sodium styrene sulfonate) on electrospun scaffolds using the "grafting from" technique and evaluate the effect of the coating and surface wettability on the biological response. The "grafting from" technique required energy (thermal or UV) to induce the decomposition of the PCL (hydro)peroxides and generate radicals able to initiate the polymerization of NaSS. In addition, UV irradiation was used to initiate the radical polymerization of NaSS directly from the surface (UV direct "grafting from"). The interest of these two techniques is their easiness, the reduction of the number of process steps, and its applicability to the industry. The selected parameters allow controlling the grafting rate (i.e., degree of functionalization). The aim of the study was to compare two covalent grafting in terms of surface functionalization and hydrophilicity and their effect on the in vitro biological responses of fibroblasts. The achieved results showed the influence of the sulfonate functional groups on the cell response. In addition, outcomes highlighted that the UV direct "grafting from" method allows to moderate the amount of sulfonate groups and the surface hydrophilicity presents a considerable interest for covalently immobilizing bioactive polymers onto electrospun scaffolds designed for tissue engineering applications using efficient post-electrospinning chemical modification.

Effects of electron beam sterilization on polyethylene terephthalate: Physico-chemical modifications and formation of non-volatile organic extractables

Our investigations hereby involve the effects of ionizing radiation as a sterilization method, and especially electron beams, on a medical grade Polyethylene Terephthalate (PET). Ionizing radiations are known to induce free radicals formation in the polymer that will then either degrade or crosslink, depending on its chemical nature, ionizing type and irradiation atmosphere (Charlesby, 1967; Dole, 1972 and Dole, 1973). The evaluation of packaging material modifications under radiation sterilization is of great interest and the objective of our paper is to focus on both PET volume modifications and extractable analyses after electron beam sterilization. As regards the polymeric matrix and after sterilization, we did not observe by means of spectral analyses, any single chemical modification whatsoever, whereas by thermal techniques we evidenced polymer chain scissions. As for the non-volatile organic extractables, we further substantiate the presence of numerous compounds, namely oligomers and trimers especially, along with benzoic and terephthalic acids in particular. With respect to pharmaceutical stakes however, we claim herein that the 25kGy sterilization dose used, triggers oligomers and extractables formation, a result which is promising for further risk analysis.

Imatinib: Major photocatalytic degradation pathways in aqueous media and the relative toxicity of its transformation products

Imatinib (IMA) is a highly potent tyrosine kinase inhibitor used as first-line anti-cancer drug in the treatment of chronic myeloid leukemia. Due to its universal mechanism of action, IMA also has endocrine and mutagenic disrupting effects in vivo and in vitro, which raises the question of its environmental impact. However, to date, very little information is available on its environmental fate and the potential role of its transformation products (TPs) on aquatic organisms. Given the IMA resistance to hydrolysis and direct photolysis according to the literature, we sought to generate TPs through oxidative and radical conditions using the AOPs pathway. Thus, the reactivity of the cytotoxic drug IMA in water in the presence of OH and h+ was investigated for the first time in the present work. In this regard, a non-targeted screening approach was applied in order to reveal its potential TPs. The tentative structural elucidation of the detected TPs was performed by LC-HRMSⁿ. The proposed approach allowed detecting a total of twelve TPs, among which eleven are being described for the first time in this work. Although the structures of these TPs could not be positively confirmed due to lack of standards, their chemical formulas and product ions can be added to databases, which will allow their screening in future monitoring studies. Using the quantitative structure-activity relationship (QSAR) approach and rule-based software, we have shown that the detected TPs possess, like their parent molecule, comparable acute toxicity as well as mutagenic and estrogenic potential. In addition to the in silico studies, we also found that the samples obtained at different exposure times to oxidative conditions, including those where IMA is no longer detected, retained toxicity in vitro. Such results suggest further studies are needed to increase our knowledge of the impact of imatinib on the environment.

Impact of simulated biological aging on physicochemical and biocompatibility properties of cyclic olefin copolymers

We study the effect of simulated biological aging on the properties of cyclic olefin copolymers and particularly their biocompatibility. Already reported as biocompatible polymers according to ISO/EN 10993 guidelines, COC are good candidates for medical devices. The influence of two major additives (antioxidants and lubricants) was investigated and comparison with non-aging COC was done. Four in vitro simulated biological conditions were tested: 2 extreme pH (1 and 9) to simulate digestive tract environment; THP-1-derived macrophages contact and pro-oxidant medium with hypochlorite solution simulating the oxidative attack during the foreign body reaction. After one month of incubation with the different media at 37 °C, surface topography was studied by atomic force microscopy (AFM) and IR spectroscopy. Extracts of incubated media were also analysed in chromatography to investigate potential degradation products. Cytotoxicity (MTT and LDH) of the materials was evaluated using cell culture methods with L929 fibroblasts. Oxidative stress (ROS and SOD analysis) and two inflammatory biomarkers (Il-6 and TNF-α secretion) were explored on THP-1-derived macrophages in direct contact with aged COC. Surface topography of COC was modified by aging conditions with an influence of antioxidant presence and under some conditions. HPLC analysis realized on freeze-dried solutions issued from the different incubations showed the presence of traces of low molecular weight compounds issued from polyphenolic antioxidant and from COC degradation. GC-MS analysis carried out directly on the different incubated COC, showed no detectable leachable molecules. No cytotoxicity has been observed with the different aged COC. However, results show that the pH environment had an influence on the cytotoxicity tests with a protecting effect of antioxidant presence; and pro-oxidant incubating conditions decreased cellular viability on COC. pH 1 and pH 9 conditions also induced an increase of ROS production which was partially reduced for COC containing an antioxidant or a lubricant. Il-6 production was globally more important for aged COC compared with basal condition and particularly for oxidative simulated environment. Those results indicate that physiological factors like pH or oxidant conditions have an impact on surface topography and on COC interaction with the biological environment but without compromising their biocompatibility. Antioxidant or lubricant presence could modulate these variations pointing out the necessity of a thoroughly investigation for biocompatibility assessment of COC as a component of implantable devices. COCs show a good biocompatibility even after accelerated aging under extreme biological conditions.

Pancreatic cancer stem cell proliferation is strongly inhibited by diethyldithiocarbamate-copper complex loaded into hyaluronic acid decorated liposomes

BACKGROUND

Pancreatic cancer stem cells (CSCs) are responsible for resistance to standard therapy, metastatic potential, and disease relapse following treatments. The current therapy for pancreatic ductal adenocarcinoma (PDAC) preferentially targets the more differentiated cancer cell population, leaving CSCs as a cell source for tumor mass formation and recurrence. For this reason, there is an urgent need to improve current therapies and develop novel CSC-targeted therapeutic approaches.

METHODS

Hyaluronic acid (HA) decorated liposomes, containing diethyldithiocarbamate‑copper (Cu(DDC)₂), able to target the specific CSC marker CD44 receptor were prepared by ion gradient technique and fully characterized. Their antiproliferative effect was evaluated on pancreatic CSCs derived from PDAC cell lines or patients. To clarify the mechanism of action of Cu(DDC)₂ liposomes, ROS level neutralization assay in the presence of N-acetyl-L-cysteine was performed.

RESULTS

Liposomes showed high encapsulation efficiency and Cryo-TEM analysis revealed the presence of Cu(DDC)₂ crystals in the aqueous core of liposomes. In vitro test on pancreatic CSCs derived from PDAC cell lines or patients showed high ROS mediated anticancer activity of HA decorated liposomes. The sphere formation capability of CSCs obtained from patients was drastically reduced by liposomal formulations containing Cu(DDC)₂.

CONCLUSIONS

The obtained results show that the encapsulation of Cu(DDC)₂ complex in HA decorated liposomes strongly increases its anti-proliferative activity on pancreatic CSCs.

GENERAL SIGNIFICANCE

This paper describes for the first time the use of HA decorated liposomes containing Cu(DDC)₂ against pancreatic CSCs and opens the way to the development of nanomedicine based CSC-targeted therapeutic approaches.

Pemetrexed degradation by photocatalytic process: Kinetics, identification of transformation products and estimation of toxicity

This study employed a UV-A/visible/TiO₂ system to investigate the degradation of pemetrexed, an antifolate agent used in chemotherapy. The laboratory-scale method employed a photostability chamber that could be used to study multiple samples. Reversed-phase HPLC coupled with high-resolution ESI-LTQ-Orbitrap mass spectrometry was used to determine the transformation products (TPs) of PEME. Based on the identified TPs and existing chemical knowledge, the mechanism of degradation of the target compound was proposed. Concentrations were monitored as a function of time, and the degradation kinetics were compared. The structures of seven TPs, four of which have not been described to date, were proposed. Most of the TPs stemmed from OH radical additions to the dihydropyrrole moiety and oxidative decarboxylation of the glutamate residue. Based on the elucidated structures, a computational toxicity assessment was performed, showing that the TPs with higher log D values than the parent compound are more toxic than the PEME itself. To support these findings, the toxicities of irradiated samples on Vibrio fischeri were monitored over time. The experimental results corresponded well with the results of previous computational studies.

Biocompatibility of polymer-based biomaterials and medical devices – regulations,in vitroscreening and risk-management

Biomaterials play an increasing role in modern health care systems.

Permeability of expander breast implants: In vitro and in vivo analyses

INTRODUCTION

The biocompatibility of the polysiloxane breast implant has been studied moderately. The aging of these implants due to lipid penetration and the release of polymerization impurities, such as Platine or octamethylcyclotetrasiloxane (named D4), has already been documented. Since these studies, manufacturing procedures have been improved; thus, the security of breast implants has also improved. Although polymerization and the choice of monomer influence the shell properties, few studies have compared these together in breast implants. Our study compares the permeability and mechanical resistance of 3 breast expander shells after in vivo and in vitro aging.

RESULTS

In vitro, all tested shells quickly sorbed linear molecules, such as fatty acids, and released siloxane impurities. The penetration of a molecule with steric hindrance, such as cholesterol, is slower. Allergan shells have the highest rates of molecule sorption and siloxane release. In vivo, after implantation, Allergan shells lost their initial mechanical properties over time. This observation was not found for mentor shells. For all brands, many biological molecules penetrate the shells, among which cholesterol and fatty acids are always present.

DISCUSSION

The aging of polysiloxane shells depends on the sorption of many biological molecules and the release of siloxane impurities. The siloxanes are impurities and / or degradation products that are due to aging. Moreover, according to our results, the shells act as matrices that separate molecules according to their chemical and physical properties.

CONCLUSION

Not all polysiloxane expander shells have the same properties during aging. The manufacturing procedures and the choice of siloxane monomers are the two most probative factors that explain the observed differences.

Biocompatibility assessment of cyclic olefin copolymers: Impact of two additives on cytotoxicity, oxidative stress, inflammatory reactions, and hemocompatibility

This work reports the biocompatibility evaluation of cyclic olefin copolymers (COC) as candidates for implantable medical devices. The focus was to establish the influence of two major additives (antioxidant and lubricant) on the overall biocompatibility. The cytotoxicity was evaluated according to ISO 10993-5 guidelines using L929 fibroblasts, HUVEC, and THP-1-derived macrophages. Oxidative stress (ROS, GSH/GSSG, and SOD analysis) and pro-inflammatory cytokines (Il-6 and TNF-α secretion) were quantified using THP-1 cells in direct contact with films. Hemocompatibility was assessed through haemolysis testing, dynamic blood coagulation, platelet adhesion, and activation (membranous P-selectin expression). Results show that the different types of COC have successfully passed the in vitro biocompatibility tests. The presence of antioxidant induces however a slight decrease in ROS production in correlation with a high SOD activity and a modification in blood coagulation profile probably linked to antioxidant recrystallization phenomenon on the surface of COC. The lubricant presence reduced haemolysis, fibrinogen adhesion, and platelet activation. Surface nanotopography of COC highlights different types of needles and globules according to the present additive. Those primary results indicate that COC are promising biomaterial. However, additives influenced some biological parameters pointing out the necessity of a global approach of risk analysis for biocompatibility evaluation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3333-3349, 2017.

Characterization of the surface physico-chemistry of plasticized PVC used in blood bag and infusion tubing

Commercial infusion tubing and blood storage devices (tubing, blood and platelets bags) made of plasticized PVC were analyzed by spectroscopic, chromatographic and microscopic techniques in order to identify and quantify the additives added to the polymer (lubricants, thermal stabilizers, plasticizers) and to put into evidence their blooming onto the surface of the devices. For all the samples, deposits were observed on the surface but with different kinds of morphologies. Ethylene bis amide lubricant and metallic stearate stabilizers were implicated in the formation of these layers. In contact with aqueous media, these insoluble deposits were damaged, suggesting a possible particulate contamination of the infused solutions.

Exploring complex transitions between polymorphs on a small scale by coupling AFM, FTIR and DSC: the case of Irganox 1076® antioxidant

Thanks to adhesion force mapping by AFM, solid/solid transitions are distinguished from melting/recrystallization processes occurring in the same temperature range.

RP-HPLC detection and dosage method for acrylic monomers and degradation products released from implanted medical devices

Acrylic copolymers are useful in medical therapeutics. As in dental implants or intraocular lenses, acrylics are present in many medical devices or drug adjuvants. Industrial using of acrylics is still important in painting or textile manufacturing. Scientific research background has proved that acrylic suffer for depolymerized and cross-linking mechanisms under heating and photo-oxidative conditions. Those aging processes could lead to release of unreacted monomers and degradation products. We developed a new RP-HPLC method with good resolution, recovery, linearity, detection and quantification limits that is efficient for acrylic monomers quantification in in vitro and in vivo saline solution matrices. This method allows the detection of copolymer and medical devices degradation products too. Both the limit of quantification and the limit of detection for monomers and degradation products are above cytotoxic concentrations for human epithelial cells. Those biological results confirm the interest of the method for dosage of unreacted acrylics after polymerization and for the research of degradation products in body fluids as aqueous humor.

Phototransformation patterns of the antiplatelet drug tirofiban in aqueous solution, relevant to drug delivery and storage

Tirofiban in aqueous solution mostly photodegrades through photosensitized oxidation reactions and the photoproducts formed are not structurally alerting for genotoxicity.

Density functional theory and liquid chromatography-multistage mass spectrometry to characterize raltitrexed photo-degradation mechanisms

The structure of raltitrexed photoproducts was elucidated by LC-ESI-HR-MSⁿ. Photodegradation pathways are proposed, using DFT approach to support assumptions. Ralitrexed photodegrades as per photosensitization mechanisms.

Studying DEHP migration in plasticized PVC used for blood bags by coupling Raman confocal microscopy to UV spectroscopy

Plasticized PVC is widely used to make medical devices such as tubing, perfusion bags and blood bags. By using confocal Raman microscopy on a PVC sheet plasticized with around 40% of di-(2-ethylhexyl)phthalate (DEHP), we propose a simple and sensitive approach to studying and understanding the diffusion of plasticizers from polymers into the surrounding media. Moreover, we sought to correlate our findings to standard measurements conducted by UV spectroscopy. This study showed differences in the concentration gradient observed due to the diffusion of the plasticizer inside a PVC sheet. We can thus follow the critical DEHP ratios that can impact the diffusion process. Water and ethanol were chosen as storage media: in ethanol, the lowest concentration of DEHP was observed at the surface resulting in the formation of a less plasticized layer near the interface; unlike ethanol, PVC sheets stored in water showed a greater concentration of DEHP on the film surface as an exudation of DEHP onto the surface.

Impact of the nature and concentration of plasticizers on the ability of PVC to sorb drug

The sorption of a drug by an infusion set may dramatically reduce the drug delivery efficiency. In this paper, we investigated how the drug sorption, in static conditions, is affected by the plasticizer's nature and ratio in the case of plasticized PVC, one of the most common material for infusion set tubing. Within the study, the drug concentration in diazepam solutions was studied after contact with PVC films containing different amounts of DEHP, DEHT, TOTM and DINCH® plasticizers. Moreover the partition coefficients between material and water were calculated. The drug sorption levels were equivalent for the different plasticizers and there was a plasticizer ratio for which the drug uptake was enhanced. As a consequence, the amount of sorbed drug might not be only linked to the amount of plasticizer in the film and to the solubility of the drug in the plasticizer alone: it must probably depend on specific interactions between plasticizer and PVC.

A comprehensive study of apixaban's degradation pathways under stress conditions using liquid chromatography coupled to multistage mass spectrometry

The main degradation pathways of apixaban, a novel anticoagulant drug acting as factor Xa inhibitor, has been established based on the degradation products identification using liquid chromatography coupled to multistage high resolution mass spectrometry.

Identification of dabigatran etexilate major degradation pathways by liquid chromatography coupled to multi stage high-resolution mass spectrometry

The major degradation mechanisms of dabigatran etexilate were deduced in the context of stress testing. Under hydrolytic stress conditions, O-dealkylation may occur along with formation of benzimidic acid derivatives.

A multiscale approach to assess the complex surface of polyurethane catheters and the effects of a new plasma decontamination treatment on the surface properties

Polyurethane catheters made of Pellethane 2363-80AE® were treated with a low temperature plasma developed for the decontamination of reusable polymer devices in hospitals. We investigated the modifications of the polymer surface by studying the topographic modifications, the chemical modifications, and their consequences on the wettability and bacterial adhesion. This study showed that plasma treatment modified the topography and grafted oxygen and nitrogen species onto the surface, resulting in an increase in the surface polarity. This effect could be correlated to the number of nitrogen atoms interacting with the surface. Moreover, this study demonstrated the significance of multiscale heterogeneities, and the complexity of industrial medical devices made from polymers. Their surface can be heterogeneous, and they contain additives that can migrate and change the surface composition.