The Role of Stent Design and Polymers in Safety Outcomes – A Review

2012 ◽  
Vol 8 (1) ◽  
pp. 63
Author(s):  
Carlo Zivelonghi ◽  
Giulia Geremia ◽  
Michele Pighi ◽  
Flavio Ribichini ◽  
◽  
...  
Keyword(s):  
Clinical Performance ◽  
Drug Carrier ◽  
Chemical Properties ◽  
Vascular Wall ◽  
Radial Force ◽  
Vascular Trauma ◽  
Polymer Composition ◽  
Drug Eluting Stent ◽  
Stent Design ◽  
Drug Elution

Each component of a drug-eluting stent (DES) contributes to the safety of the device. Continuous efforts are being dedicated to the search of the optimal compromise between facility of use, safety and long-term efficacy. Shorter balloons reduce the vascular trauma beyond the stent struts; the metallic composition of the stent platform and the platform itself interact with the vascular wall in a long-lasting equilibrium between radial force, vessel patency and reparative cellular regrowth. The modality of drug elution is largely regulated by the chosen drug carrier, rather than by the chemical properties of the drug itself. Drug elution can be accomplished by permanent polymers that remain in the vessel wall forever, by biodegradable polymers that leave the naked metallic structure behind after their complete absorption, or even by direct release of the drug from stent reservoirs. The clinical performance of DESs has been exhaustively assessed in a large number of studies that have showed rapid and continuous improvements, from the first-generation DESs to the latest devices, based on substantial changes in stent design and polymer composition.

Amorphous and Crystalline Particulates: Challenges and Perspectives in Drug Delivery

2017 ◽  
Vol 23 (3) ◽  
pp. 350-361 ◽  
Author(s):  
Hisham Al-Obaidi ◽  
Mridul Majumder ◽  
Fiza Bari
Keyword(s):  
Crystal Engineering ◽  
Drug Carrier ◽  
Solid Dispersions ◽  
Chemical Properties ◽  
Pharmaceutical Product ◽  
Water Soluble ◽  
Amorphous Form ◽  
Physico Chemical ◽  
Water Soluble Drugs ◽  
Amorphous Drug

Crystalline and amorphous dispersions have been the focus of academic and industrial research due to their potential role in formulating poorly water-soluble drugs. This review looks at the progress made starting with crystalline carriers in the form of eutectics moving towards more complex crystalline mixtures. It also covers using glassy polymers to maintain the drug as amorphous exhibiting higher energy and entropy. However, the amorphous form tends to recrystallize on storage, which limits the benefits of this approach. Specific interactions between the drug and the polymer may retard this spontaneous conversion of the amorphous drug. Some studies have shown that it is possible to maintain the drug in the amorphous form for extended periods of time. For the drug and the polymer to form a stable mixture they have to be miscible on a molecular basis. Another form of solid dispersions is pharmaceutical co-crystals, for which research has focused on understanding the chemistry, crystal engineering and physico-chemical properties. USFDA has issued a guidance in April 2013 suggesting that the co-crystals as a pharmaceutical product may be a reality; but just not yet! While some of the research is still oriented towards application of these carriers, understanding the mechanism by which drug-carrier miscibility occurs is also covered. Within this context is the use of thermodynamic models such as Flory-Huggins model with some examples of studies used to predict miscibility.

Synthesis, Spectral, Bio Assay, Chromatographic - Studying of New Imidazole Reagents Via Three Components Reaction

2021 ◽  
Vol 19 (7) ◽  
pp. 115-122
Author(s):  
Mohammed Nawfal Abdul Maged Alkhafaji ◽  
Hutham Abd Ali Abd Al Hussain ◽  
Dr. Nagham Mahmood Aljamali
Keyword(s):  
Nervous System ◽  
Drug Targets ◽  
Biological Activities ◽  
Drug Carrier ◽  
Chemical Properties ◽  
Cancer Drug ◽  
Condensation Process ◽  
Chromatographic Study ◽  
The Central Nervous System ◽  
Physical And Chemical

Imidazoles are part of the theophylline Reagent, found in tea leaves and coffee beans, which stimulates the central nervous system. It is found in the anti-cancer drug mercaptopurine, which fights leukemia by interfering with DNA systems. A number of prepared imidazoles, including clotrimazole, are selective inhibitors of nitric oxide synthase, which makes them interesting drug targets in inflammation, respiratory diseases and tumors of the nervous system. Other biological activities of the drug carrier imidazole relate to deregulation of the intracellular fluxes of (Ca and K) ions. Novel imidazole –heterocyclic reagents were created via cyclization process then condensation process., followed by investigation of all created new reagents via a number of spectral performances (FT.IR, H.NMR)–spectrophotometric, other physical and chemical properties, and chromatographic study with microbial studying for all new created imidazole reagents.

scholarly journals Synthesis and Appraisal of Natural Drug-Polymer-Based Matrices Relevant to the Application of Drug-Eluting Coronary Stent Coatings

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Bakhtawar Ghafoor ◽  
Murtaza Najabat Ali ◽  
Zainab Riaz
Keyword(s):  
Cardiovascular Diseases ◽  
Heart Diseases ◽  
Drug Carrier ◽  
Drug Eluting Stent ◽  
Burst Release ◽  
Coating Films ◽  
Degradable Polymer ◽  
Drug Eluting ◽  
Natural Drugs

Cardiovascular diseases are becoming a leading cause of death in the world, and attention is being paid to develop natural drug-based treatment to cure heart diseases. Curcumin, ginger, and magnolol are pharmaceutically active in many ways, having properties including anticoagulation, antiproliferation, anti-inflammatory, and antioxidant, and may be used to synthesis coatings for drug-eluting stents to treat cardiovascular diseases. In the present investigation, a degradable polymer with varying molecular weights was used as a drug carrier to control the degradation of polymer; three different natural drugs such as curcumin, magnolol, and ginger were used owing to their reported pharmacological properties. The results of in vitro measurements of all three natural drugs released from drug-loaded polymeric films showed an initial burst release followed by a sustained release for up to 38 days of measurement. On the other hand, different levels of hemocompatibility were observed by varying concentrations of natural drugs in human erythrocytes. As per the ASTM F756 standard, ginger having low concentration showed optimum hemocompatibility with regard to the drug-eluting stent application as compared with magnolol and curcumin concentrations, which showed suboptimal hemocompatibility and fall in the range of mild-to-severe blood toxicity category. The structure of the coating films was characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) with results suggesting that there was no chemical bonding between the polymer and drug. Thus, according to this study, it can be concluded that after more detailed in vitro testing such as hemocompatibility tests and platelet adhesion testing, ginger can be a better candidate as a drug-coating material for drug-eluting stent applications.

scholarly journals A Review Paper on Biomimetic Calcium Phosphate Coatings

2015 ◽  
Vol 9 (1) ◽  
pp. 56-64 ◽  
Author(s):  
X. Lin ◽  
K. de Groot ◽  
D. Wang ◽  
Q. Hu ◽  
D. Wismeijer ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Drug Carrier ◽  
Chemical Properties ◽  
Giant Cells ◽  
Clinical Applications ◽  
Bone Morphogenetic Protein 2 ◽  
Crystalline Lattice ◽  
Calcium Phosphate Coating ◽  
Phosphate Coatings ◽  
Calcium Phosphate Coatings

Biomimetic calcium phosphate coatings have been developed for bone regeneration and repair because of their biocompatibility, osteoconductivity, and easy preparation. They can be rendered osteoinductive by incorporating an osteogenic agent, such as bone morphogenetic protein 2 (BMP-2), into the crystalline lattice work in physiological situations. The biomimetic calcium phosphate coating enables a controlled, slow and local release of BMP-2 when it undergoes cell mediated coating degradation induced by multinuclear cells, such as osteoclasts and foreign body giant cells, which mimics a physiologically similar release mode, to achieve sustained ectopic or orthotopic bone formation. Therefore, biomimetic calcium phosphate coatings are considered to be a promising delivery vehicle for osteogenic agents. In this review, we present an overview of biomimetic calcium phosphate coatings including their preparation techniques, physico-chemical properties, potential as drug carrier, and their pre-clinical application both in ectopic and orthotopic animal models. We briefly review some features of hydroxyapatite coatings and their clinical applications to gain insight into the clinical applications of biomimetic calcium phosphate coatings in the near future.

Aliphatic polyester terpolymers for stent coating and drug elution: Effect of polymer composition on drug solubility and release

Drug Delivery ◽  
2009 ◽  
Vol 16 (6) ◽  
pp. 304-311 ◽  
Author(s):  
Delphine Chan-Seng ◽  
T. Ranganathan ◽  
Xiongfei Zhang ◽  
Yiwen Tang ◽  
Qing Lin ◽  
...  
Keyword(s):  
Polymer Composition ◽  
Drug Solubility ◽  
Aliphatic Polyester ◽  
Drug Elution ◽  
Stent Coating

scholarly journals TCT-478 Effect of different drug-eluting stent design on in-stent restenosis and stent thrombosis

2013 ◽  
Vol 62 (18) ◽  
pp. B146
Author(s):  
Oskar Angerås ◽  
Per Albertsson ◽  
Christian Dworeck ◽  
Inger Haraldsson ◽  
Dan Ioanes ◽  
...  
Keyword(s):  
Stent Thrombosis ◽  
Drug Eluting Stent ◽  
Stent Design ◽  
Stent Restenosis ◽  
Drug Eluting ◽  
In Stent Restenosis

Study on Kinetics and Biocompatibility Evaluation of Multiple Polymer Layer with Biochemical Material Properties in Drug-Eluting Stent

2013 ◽  
Vol 644 ◽  
pp. 183-188
Author(s):  
Sergey Pavlinich ◽  
Xi Wei Liu ◽  
Hong Zhao ◽  
Zhen Li ◽  
Li Li
Keyword(s):  
Release Kinetics ◽  
Drug Carrier ◽  
Comparative Method ◽  
Single Layer ◽  
Drug Eluting Stent ◽  
Multiple Layer ◽  
Drug Eluting ◽  
Poly Ethylene ◽  
Surface Morphologies ◽  
Spraying Method

The Paclitaxel-eluting stents (PTX) with three-layered polymer coating were studied in this work. The PLGA (polylactic acid-co-glycolic acid) with 15 percent PEG (poly ethylene glycol) concentration in blend have been applied for preparing multiple layer drug carrier and fabricated on the surface of 316L stainless steel stents by ultrasonic atomization spraying method. The Paclitaxel was explored in doses: (~255μg) for single layer coated PTX (30 wt%), and (~275μg) for multiple layer coated PTX in accordance. Pre- and post-expansion surface morphologies of multiple layer stent were examined by scanning electron microscopy (SEM). The Paclitaxel release kinetics was studied by comparative method of release profiles of single layer PTX with 3-layered polymer coated PTX. The biocompatibility by hemolysis ratio and dynamic clotting time with platelet adhesion measurements also was investigated.

scholarly journals In Vitro Degradation Behaviours of PDO Monofilament and Its Intravascular Stents with Braided Structure

2016 ◽  
Vol 16 (2) ◽  
pp. 80-89 ◽  
Author(s):  
Cong-er Wang ◽  
Pei-hua Zhang
Keyword(s):  
Mechanical Properties ◽  
Vascular Wall ◽  
Radial Force ◽  
Temporary Increase ◽  
Crystalline Region ◽  
Bending Rigidity ◽  
Intravascular Stents ◽  
Braided Structure ◽  
Intravascular Stent

Abstract Biodegradable intravascular stent has attracted more and more focus in recent years as an effective solution for angiostenosis. Ideal stents were expected to exhibit sufficient radial force to support the vascular wall, while suitable flexibility for the angioplasty. After vascular remodeling, stents should be degraded into small molecular and be eliminated from human body, causing no potential risk. In this paper, poly-p-dioxanone (PDO) monofilament was braided into net structure with four different braiding density, two of which exhibited sufficient radial force larger than 30 kPa, and three of which showed the bending rigidity within 11.7–88.1 N•mm2. The degradation behaviors of monofilaments and stents have been observed for 16 weeks. The findings obtained indicate that degradation first occurred in morphology region, which induced temporary increase of crystallinity, monofilament bending rigidity and stent mechanical properties. During this period, monofilament tends to be hard and brittle and lost its tensile properties. Then the crystalline region was degraded and stent mechanical properties decreased. All the results reveal that the PDO intravascular stents with braided structure were able to afford at least 10 weeks of sufficient support to the vascular wall.

scholarly journals A viewpoint on material and design considerations for oesophageal stents with extended lifetime

2022 ◽  
Author(s):  
Caitlin E. Jackson ◽  
Liam S. J. Johnson ◽  
Dominic A. Williams ◽  
Hans-Ulrich Laasch ◽  
Derek W. Edwards ◽  
...  
Keyword(s):  
Patient Survival ◽  
Drug Eluting Stent ◽  
Material Surface ◽  
Device Performance ◽  
Stent Design ◽  
Novel Treatments ◽  
Construction Methods ◽  
Drug Eluting

AbstractOesophageal stents are meshed tubular implants designed to maintain patency of the oesophageal lumen and attenuate the symptoms of oesophageal cancer. Oesophageal cancers account for one in twenty cancer diagnoses and can lead to dysphasia, malnutrition and the diminishment of patient quality of life (QOL). Self-expanding oesophageal stents are the most common approach to attenuate these symptoms. Recent advances in oncological therapy have enabled patient survival beyond the lifetime of current devices. This introduces new complications for palliation, driving the need for innovation in stent design. This review identifies the factors responsible for stent failure. It explores the challenges of enhancing the longevity of stent therapies and outlines solutions to improving clinical outcomes. Discussions focus on the role of stent materials, construction methods, and coatings upon device performance. We found three key stent enhancement strategies currently used; material surface treatments, anti-migratory modifications, and biodegradable skeletons. Furthermore, radioactive and drug eluting stent designs were identified as emerging novel treatments. In conclusion, the review offers an overview of remaining key challenges in oesophageal stent design and potential solutions. It is clear that further research is needed to improve the clinical outcome of stents and patient QOL.

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