Biostability and biological performance of a PDMS-based polyurethane for controlled drug release (original) (raw)
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Polymers, Drug Release, and Drug-Eluting Stents
Journal of Interventional Cardiology, 2006
Implantable biomaterials mainly serve as physical support devices, carriers for bioactive molecules and guidance for tissue growth. For any application within or outside the cardiovascular area, biomaterials are subject to an extended set of requirements in order to establish safe application. These requirements mainly include acceptable biocompatibility and, if the material is to be degraded within the body, safe degradation characteristics. During degradation, biocompatible polymers are broken down into molecules that are metabolized and removed from the body via normal metabolic pathways. Major applications of these polymers include targeted drug delivery systems, resorbable sutures and orthopedic fixation devices. In the cardiovascular area they include biodegradable cardiovascular stents and drug-eluting stent (DES) coatings. This review focuses on general aspects of local drug delivery by implantable polymeric devices, with special emphasis on drug-eluting stents.
Viscoelastic Behavior of Drug-Loaded Polyurethane
Polymers
Drug-eluting stents are desirable platforms for local medicine delivery. However, the incorporation of drugs into polymers can influence the mechanical and physicochemical properties of said matrix, which is a topic that is still poorly understood. In fact, this is more noticeable since the apposition is most often accompanied by mechanical stresses on the polymer coating, which can induce therapeutic failure that can result in death. It is therefore necessary to better understand their behavior by examining their properties in conditions such as those in living beings. We studied polyurethane drug carriers made in-house. Diclofenac epolamine was chosen as a model hydrophilic medicine. We used thermal measurements (DMTA) and tensile tests. The aim was to establish the influence of the loading and release of the drug on the physicochemical properties of this polymer in the presence of a stagnant or circulating fluid medium, phosphate-buffered saline (PBS). For the two PU/drug loading...
Polyurethane membrane with porous surface for controlled drug release in drug eluting stent
Biomaterials research, 2014
Membrane covered drug eluting stents (DES) were prepared to prevent tumor ingrowth and to control drug release. Polyurethane (PU) is commonly used for DES coating material because of high tensile strength. The release of paclitaxel (PTX) may increase from porous PU membrane. Polyethylene glycol (PEG) was incorporated into PU membranes to form porous structure and control the release of hydrophobic anti-cancer drug such as PTX. The bare metal stents were coated with PEG incorporated PU and then, PEG was washed out to form porous structure. The crystallization of PTX was inhibited in porous PU membranes and the release of PTX from porous PU membranes was approximately 8.6% more extended over 19 days. The enhanced release of PTX from porous PU membranes may increase the patency for the DES covering materials.
Journal of Biomedical Materials Research Part A, 2008
Drug-eluting stents have proven superior to bare metal stents with lower restenosis rates. Local delivery of drugs from these stents is achieved in most cases with the help of biostable polymer coatings. However, since the polymer coating remains in the body well after all the drug is released, patients can potentially develop hypersensitivity to these polymers-leading to complications such as late-stent thrombosis. It is therefore important that the polymers are designed to be biocompatible and well tolerated by the body. The polymer coatings are also expected to be robust and provide good control over elution of the desired drug. This paper describes the devel-opment of a unique, proprietary polymer blend system, specially designed to meet these requirements. Mutually compatible, free-radical-initiated elastomeric polymers were designed to provide a robust coating and offer a steady, sustained release of the highly hydrophobic drug zotarolimus over an extended period. The polymer blend system is also well tolerated by the hydrophilic environment in vivo, as demonstrated through porcine studies.
Polyurethane-based drug delivery systems
International Journal of Pharmaceutics, 2013
Polyurethanes (PUs) are formed by a reaction between isocyanates and diols to yield polymers with urethane bonds (-NH-COO-) in their main chain. A great variety of building blocks is commercially available that allows the chemical and physical properties of PUs to be tailored to their target applications, particularly for the biomedical and pharmaceutical fields. This article reviews the synthesis and characterization of PUs and PU-copolymers, as well as their in vitro and in vivo biodegradability and biocompatibility. Particular emphasis is placed on the use of PUs for the controlled release of drugs and for the (targeted) delivery of biotherapeutics.
Pharmaceutics, 2020
Following the huge clinical success of drug-eluting vascular stents, there is a significant interest in the development of drug-eluting stents for other applications, such as the treatment of gastrointestinal (GI) cancers. Central to this process is understanding how particular drugs are released from stent coatings, which to a large extent is controlled by drug-polymer interactions. Therefore, in this study we investigated the release of docetaxel (DTX) from a selection of non-degradable polymer films. DTX-polymer films were prepared at various loadings (1, 5 and 10% w/w) using three commercially available polymers including poly(dimethylsiloxane) (PSi), poly (ethylene-co-vinyl acetate) (PEVA) and Chronosil polyurethane (PU). The formulations were characterised using different techniques such as photoacoustic Fourier-transform infrared (PA-FTIR) spectrophotometry, X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The effect of DTX on the mechanical properties of ...
Biomaterials, 2004
The long-term biostability of a novel thermoplastic polyurethane elastomer (Elast-Eon TM 2 80A) synthesized using poly(hexamethylene oxide) (PHMO) and poly(dimethylsiloxane) (PDMS) macrodiols has been studied using an in vivo ovine model. The material's biostability was compared with that of three commercially available control materials, Pellethane s 2363-80A, Pellethane s 2363-55D and Bionate s 55D, after subcutaneous implantation of strained compression moulded flat sheet dumbbells in sheep for periods ranging from 3 to 24 months. Scanning electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to assess changes in the surface chemical structure and morphology of the materials. Gel permeation chromatography, differential scanning calorimetry and tensile testing were used to examine changes in bulk characteristics of the materials.
An Insight into the Structural Diversity and Clinical Applicability of Polyurethanes in Biomedicine
Polymers
Due to their mechanical properties, ranging from flexible to hard materials, polyurethanes (PUs) have been widely used in many industrial and biomedical applications. PUs’ characteristics, along with their biocompatibility, make them successful biomaterials for short and medium-duration applications. The morphology of PUs includes two structural phases: hard and soft segments. Their high mechanical resistance featuresare determined by the hard segment, while the elastomeric behaviour is established by the soft segment. The most important biomedical applications of PUs include antibacterial surfaces and catheters, blood oxygenators, dialysis devices, stents, cardiac valves, vascular prostheses, bioadhesives/surgical dressings/pressure-sensitive adhesives, drug delivery systems, tissue engineering scaffolds and electrospinning, nerve generation, pacemaker lead insulation and coatings for breast implants. The diversity of polyurethane properties, due to the ease of bulk and surface mod...
Frontiers in bioengineering and biotechnology, 2015
We have recently reported the mechanical properties and hydrolytic degradation behavior of a series of NovoSorb™ biodegradable polyurethanes (PUs) prepared by varying the hard segment (HS) weight percentage from 60 to 100. In this study, the in vitro degradation behavior of these PUs with and without extracellular matrix (ECM) coating was investigated under accelerated hydrolytic degradation (phosphate buffer saline; PBS/70°C) conditions. The mass loss at different time intervals and the effect of aqueous degradation products on the viability and growth of human umbilical vein endothelial cells (HUVEC) were examined. The results showed that PUs with HS 80% and below completely disintegrated leaving no visual polymer residue at 18 weeks and the degradation medium turned acidic due to the accumulation of products from the soft segment (SS) degradation. As expected the PU with the lowest HS was the fastest to degrade. The accumulated degradation products, when tested undiluted, showed ...
Biomaterials, 1996
Two different commercial polymeric materials, a silicone and a polyurethane (PUR), were studied with regard to correlations between the chemical and physical compositions of the polymer surfaces and the biological response on implantation. Test specimens of the materials were manufactured according to standard procedures. The specimens were implanted in rats for 10 and 90 days. Before implantation the polymers were sterilized in three different ways, namely, beta irradiation, ethylene oxide sterilization and steam sterilization. The polymers were characterized before and after the implantation with respect to the chemical composition and the morphology of the surfaces. After implantation the biological response was evaluated by counting numbers of macrophages, giant cells, fibroblasts and other cells present at the surfaces. The thickness of the fibrous capsule surrounding the test specimens was measured at the thickest and thinnest parts.