scholarly journals Drug Release Analysis and Optimization for Drug-Eluting Stents

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Hongxia Li ◽  
Yihao Zhang ◽  
Bao Zhu ◽  
Jinying Wu ◽  
Xicheng Wang
Keyword(s):  
Drug Release ◽  
Surrogate Model ◽  
Expected Improvement ◽  
Drug Eluting Stents ◽  
Optimization Approach ◽  
Optimized Design ◽  
Kriging Surrogate Model ◽  
Adaptive Optimization ◽  
Release Analysis ◽  
Drug Eluting

The drug release analysis and optimization for drug-eluting stents in the arterial wall are studied, which involves mechanics, fluid dynamics, and mass transfer processes and design optimization. The Finite Element Method (FEM) is used to analyze the process of drug release in the vessels for drug-eluting stents (DES). Kriging surrogate model is used to build an approximate function relationship between the drug distribution and the coating parameters, replacing the expensive FEM reanalysis of drug release for DES in the optimization process. The diffusion coefficients and the coating thickness are selected as design variables. An adaptive optimization approach based on kriging surrogate model is proposed to optimize the lifetime of the drug in artery wall. The adaptive process is implemented by an infilling sampling criterion named Expected Improvement (EI), which is used to balance local and global search and tends to find the global optimal design. The effect of coating diffusivity and thickness on the drug release process for a typical DES is analyzed by means of FEM. An implementation of the optimization method for the drug release is then discussed. The results demonstrate that the optimized design can efficiently improve the efficacy of drug deposition and penetration into the arterial walls.

Examination of drug release and distribution from drug-eluting stents with a vessel-simulating flow-through cell

2011 ◽  
Vol 78 (1) ◽  
pp. 36-48 ◽  
Author(s):  
Anne Seidlitz ◽  
Stefan Nagel ◽  
Beatrice Semmling ◽  
Niels Grabow ◽  
Heiner Martin ◽  
...  
Keyword(s):  
Drug Release ◽  
Drug Eluting Stents ◽  
Drug Eluting ◽  
Flow Through

scholarly journals Assessment of a mathematical model considering the effect of flow rate on in-vitro drug-release from PLGA films

2021 ◽  
Vol 321 ◽  
pp. 04011
Author(s):  
Navideh Abbasnezhad ◽  
Farid Bakir ◽  
Stéphane Champmartin ◽  
Mohammadali Shirinbayan
Keyword(s):  
Mathematical Model ◽  
Drug Release ◽  
Flow Rate ◽  
Drug Carrier ◽  
Diclofenac Sodium ◽  
Drug Eluting Stents ◽  
In Vitro Drug Release ◽  
Drug Eluting ◽  
Release Profiles

Drug-eluting stents implanted in blood vessels are subject to various dynamics of blood flow. In this study, we present the evaluation of a mathematical model considering the effect of flow rate, to simulate the kinetic profiles of drug release (Diclofenac Sodium (DS)) from in-vitro from PLGA films. This model solves a set of non-linear equation for modeling simultaneously the burst, diffusion, swelling and erosion involved in the mechanisms of liberation. The release parameters depending on the flow rate are determined using the corresponding mathematical equations. For the evaluation of the proposed model, test data obtained in our laboratory are used. To quantify DS release from drug-carrier PLGA films, we used the flow-through cell apparatus in a closed-loop. Four flow rate values are applied. For each value, the model-substance liberation kinetics showed an increase in drug released with the flow rate. The simulated release profiles show good agreement with the experimental results. Therefore, the use of this model could provide a practical tool to assess in-vitro drug release profiles from polymer matrices under continuous flow rate constraint, and could help improve the design of drug eluting stents.

Sustained drug release using cobalt oxide nanowires for the preparation of polymer-free drug-eluting stents

2018 ◽  
Vol 33 (3) ◽  
pp. 352-362 ◽  
Author(s):  
Tarek M Bedair ◽  
Il Jae Min ◽  
Wooram Park ◽  
Yoon Ki Joung ◽  
Dong Keun Han
Keyword(s):  
Drug Release ◽  
Cobalt Oxide ◽  
Drug Eluting Stents ◽  
Therapeutic Drug ◽  
Burst Release ◽  
Release Behavior ◽  
Cobalt Chromium ◽  
Oxide Nanowires ◽  
Drug Eluting

Polymer-based drug-eluting stents (DESs) represented attractive application for the treatment of cardiovascular diseases; however, polymer coating has caused serious adverse responses to tissues such as chronic inflammation due to acidic by-products. Therefore, polymer-free DESs have recently emerged as promising candidates for the treatment; however, burst release of drug(s) from the surface limited its applications. In this study, we focused on delivery of therapeutic drug from polymer-free (or -less) DESs through surface modification using cobalt oxide nanowires (Co3O4 NWs) to improve and control the drug release. The results demonstrated that Co3O4 NWs could be simply fabricated on cobalt–chromium substrate by ammonia-evaporation-induced method. The Co3O4 NWs were uniformly arrayed with diameters of 50–100 nm and lengths of 10 µm. It was found that Co3O4 NWs were comparatively stable without any delamination or change of the morphology under in vitro long-term stability using circulating system. Sirolimus was used as a model drug for studying in vitro release behavior under physiological conditions. The sirolimus release behavior from flat cobalt–chromium showed an initial burst (over 90%) after one day. On the other hand, Co3O4 NWs presented a sustained sirolimus release rate for up to seven days. Similarly, the polymer-less specimens on Co3O4 NWs substrates sustained sirolimus release for a longer-period of time when compared to flat Co–Cr substrates. In summary, the current approach of using Co3O4 NWs-based substrates might have a great potential to sustain drug release for drug-eluting implants and medical devices including stents.

scholarly journals Design Optimization of a VX Gasket Structure for a Subsea Connector Based on the Kriging Surrogate Model-NSGA-II Algorithm Considering the Load Randomness

Algorithms ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 42 ◽  
Author(s):  
Wei Zeng ◽  
Tao Ren ◽  
Lijun Yu ◽  
Jingjing Huang
Keyword(s):  
Surrogate Model ◽  
Training Sample ◽  
Christmas Tree ◽  
Optimization Approach ◽  
Fe Model ◽  
Kriging Surrogate Model ◽  
Fe Method ◽  
Nsga Ii ◽  
Simulation Accuracy ◽  
Sealing Performance

The VX gasket is an important part of the wellhead connector for a subsea Christmas tree. Optimization of the gasket’s structure can improve the connector’s sealing performance. In this paper, we develop an optimization approach for the VX gasket structure, taking into consideration working load randomness, based on the Kriging surrogate model-NSGA-II algorithm. To guarantee the simulation accuracy, a random finite element (R-FE) model of the connector’s sealing structure was constructed to calculate the gasket’s sealing performance under random working load conditions. The working load’s randomness was simulated using the Gaussian distribution function. To improve the calculation efficiency of the sealing performance for individuals within the initial populations, Kriging surrogate models were constructed. These models accelerated the optimization speed, where the training sample was obtained using an experimental method design and the constructed R-FE model. The effectiveness of the presented approach was verified in the context of a subsea Christmas tree wellhead connector, which matched the 20'' casing head. The results indicated that the proposed method is effective for VX gasket structure optimization in subsea connectors, and that efficiency was significantly enhanced compared to the traditional FE method.

A computational model for drug release in coronary drug eluting stents

2006 ◽  
Vol 39 ◽  
pp. S292
Author(s):  
P. Zunino ◽  
M. Prosi ◽  
F. Gervaso ◽  
S. Minisini ◽  
L. Formaggia
Keyword(s):  
Drug Release ◽  
Computational Model ◽  
Drug Eluting Stents ◽  
Drug Eluting

Integrated HPC OGV and Pre-Diffuser Design Optimization Using Kriging Surrogate Model

2013 ◽  
Author(s):  
Hongtao Wang ◽  
Weiliang Xie ◽  
Meining Chen
Keyword(s):  
Design Optimization ◽  
Boundary Layers ◽  
Surrogate Model ◽  
High Performance ◽  
Guide Vane ◽  
Thickness Distribution ◽  
Adverse Pressure Gradient ◽  
Optimization Process ◽  
Expected Improvement ◽  
Kriging Surrogate Model

The integration of high compressor outlet guide vane (OGV) and combustor pre-diffuser requires some radial turning to be performed within the OGV passage. However, the enhanced loading of OGV leads to the increase in adverse pressure gradient within the OGV passage. Consequently, both the end-wall and blade boundary layers are thickened which could lead to boundary layers separation. In this work, an adaptive global optimization process is applied for the OGV/pre-diffuser system, which combines design of experiment (DOE), Kriging surrogate model and micro genetic algorithm. The meridional flow passage of OGV/pre-diffuser system is parameterized using Bezier curves with the combination of mean line and thickness distribution. In order to prevent the OGV corner separation, the bowed design is applied to the OGV to help delay flow separation. A composite curve combined with two straight lines and a conic Bezier curve is used to represent the OGV stacking line along circumference so that the bowed blades could be parameterized. Aerodynamic performance evaluations of the compressor are performed using a three dimensional Reynolds-averaged Navier-stokes computational fluid dynamics solver — NUMECA. In the optimization process, expected improvement sample criteria is adopted for balancing the exploration and exploitation with Kriging surrogate model. Reasonably high performance is confirmed by comparing the baseline and optimal designs. This study gives some insights into design optimization of an integrated OGV/Pre-diffuser for axial compressor.

Sign in / Sign up

Export Citation Format

Share Document