Controlled delivery systems of cellulose matrix for oxytetracycline: In vitro dissolution (original) (raw)
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Kinetics of diffusion-mediated drug release enhanced by matrix degradation
Journal of Controlled Release, 1995
Modified diffusion equations with a time-dependent diffusion coefficient were derived to formulate the kinetics of drug release from a quickly degradable matrix. To compare the theoretical equations with experimental observation, microspheres containing aclarubicin hydrochloride (ACR) were prepared by the solvent evaporation method using DL-lactic acid (LA) oligomers with different weight-average molecular weights ranging from 1,900 to 9,600. ACR release profiles from the LA oligomer microspheres were apparently of quasi-zero order, showing no burst effect during the whole duration of release, unless the molecular weight of LA oligomers was as low as a few thousand. The early stage of drug release from the LA oligomer microspheres was well explained in terms of Fickian diffusion and the apparent initial diffusion coefficient could be determined as a function of the molecular weight of LA oligomer. The diffusion coefficient decreased with time as a result of degradation of the matrix. It was concluded that the newly derived equations were applicable for the drug release from the biodegradable matrix such as DL-LA oligomers.
2021
Controlled drug release is a promising pathway of biomedicine, meant to suppress side effects with the aim of increasing patient`s comfort. A route to achieve this goal represents the encapsulation of drugs into matrixes, capable to develop physical forces, which further can control the drugs release. To this purpose, mathematical modeling is an important tool, which offers the possibility to understand the drug release mechanisms and to further design new performant systems. In this paper, a theoretical model for drug release from an amphiphilic matrix is presented. This is achieved using a conservation multifractal law of probability density followed by validation of the model. Moreover, because nonsteroidal anti-inflammatory drugs (NSAIDs), such as diclofenac, are widely used in endometriosis as painkillers for dysmenorrhea management or Asherman syndrome for reducing the endometrial inflammation, some implications of our model for drug delivery systems applied in the field of gy...
In the present study, several combinations of different grades of hydroxy propyl methyl cellulose (HPMC) such as HPMC-K4M, HPMC-K15M, HPMC-K100M as hydrophilic polymers and hydrophobic polymer like ethyl cellulose(EC) are used to prepare the matrix tablets that resulted in desired and controlled drug release profile. Hydrophobic polymers provide several advantages including good stability at varying pH ranges and effectively retard the release of water soluble drug(s) along with hydrophilic polymers. Erythromycin ethylsuccinate is a model drug and having short half-life of 1.5 hours. Tablets containing 100 mg of drug were formulated by wet granulation. Pre-compression and post-compression parameters were evaluated for all the formulations, which are in the acceptable range. The dissolution data were fitted into zero-order, first-order, Higuchi and Korsemeyer–Peppas models to identify the pharmacokinetics and drug release mechanism. The optimized formulation (F5) prepared with EC: HPMC-K4M in the ratio 10 mg: 5 mg show 99.02% drug release in 24 hours, which is comparable with marketed sample. Kinetic results reveal that all formulations followed zero order. Hence, it can be concluded that the use of low viscous hydrophilic polymer can extend the release of drug up to 24 hours. Key Words: Controlled release, HPMC, Ethyl cellulose, Matrix tablets, Release Kinetics.
European Journal of Pharmaceutical Sciences, 1999
In the present work, the drug volume fraction profiles of a colored and very soluble drug, buflomedil pyridoxal phosphate, in the gel layer of initially glassy hydroxypropylmethyl cellulose matrices were studied, using image analysis of pictures of the matrices during swelling and release. The goal was to correlate the drug release kinetics with the dynamic behavior of the drug gradient in the gel layer. An inert (nonswellable) matrix, manufactured by substituting hydroxypropylmethyl cellulose with an inert polymer and containing the same amount of buflomedil pyridoxal phosphate, was prepared as well. The drug color gradient in the partially extracted region and the flux of this matrix were compared to the swellable matrix. The drug gradient in the dissolved drug gel layer of swellable matrices was observed. It was demonstrated that drug release kinetics does not only depend on drug diffusion and matrix erosion, but also on drug dissolution in the gel and on polymer relaxation.
Models for drug release of gentamicin in a polylactic acid matrix
Mathematics and Mechanics of Complex Systems, 2020
Recent experiments by Macha et al. (Front. Bioeng. Biotech. 7 (2019), art. id. 37) on the release of gentamicin embedded in a polylactic acid matrix film immersed in a body fluid solution have shown, first, a sudden burst phenomenon after several weeks and, second, a premature end to the release, such that a considerable amount of gentamicin is kept in the matrix. It is shown that such phenomena cannot be described adequately by assuming diffusion of the Fickian kind. In order to improve the modeling, extensions to Fickian diffusion are proposed as follows. The first one is of a phenomenological nature. A production term in the diffusion equation with intrinsic parameters is introduced, all of which can be interpreted intuitively and related to experimental data. The model allows one to capture the aforementioned departure from the timewise parabolic Fickian release characteristic eventually leading to complete release. Second, a micromodel is presented that provides a physical explanation for the proposed production: the drug is released from a carrier particle into the matrix, which eventually comes to an end due to the diminishing particle surface, and the drug adheres to a core due to surface tension. The material parameters of both models are determined by inverse analysis of experimental data. Communicated by Francesco dell'Isola. MSC2020: 60K50.
Drug release behaviour and mechanism from unmodified and in situ modified bacterial cellulose
Proceedings of the Indian National Science Academy, 2021
Bacterial cellulose (BC) is a suitable drug delivery carrier owing to the nanofibrous micro and mesoporous structure. One of the unique aspects is the tunability of BC microstructure by the addition of certain additives in the growth medium during the synthesis of cellulose by bacteria. In the present work, BC was in situ modified by adding Polyethylene glycol 2000 (PEG 2000). Effect of in situ modification on crystallinity, chemical composition, microstructure and morphology and, porosity was studied by XRD, FTIR, SEM and BET, followed by the effect on drug (Diclofenac sodium) loading and release kinetics. As a non-incorporating in situ modifier, PEG2000 increased the overall porosity, pore volume and decreased the specific surface area with no significant effect on crystallinity. In vitro, drug release studies revealed that a huge burst release for PEG modified BC as compared to pristine BC. The mechanism of release is further investigated by mathematical modelling. This work opens up avenues of exploring the wide possibility of tuning immediate and sustained drug release from bacterial cellulose for various release applications.
Controlled release of amoxicillin from bacterial cellulose membranes
Central European Journal of Chemistry, 2014
Bacterial cellulose (BC), a natural polymer with unique physical and mechanical properties, has several applications in the biomedical field, including drug loading and controlled drug delivery. For this study, a Box-Behnken experimental design was employed as a statistical tool to optimize the release of a model drug, amoxicillin, from BC membranes. Independent variables studied were the concentration of the drug (X1), the concentration of glycerol (X2) and the concentration of a permeation enhancer (X3). From the variables studied, drug concentration had the highest effect on drug release. Among the other independent variables, th linear and quadratic X2 terms, the linear X3 term and the interaction term X2X3 were found to affect the release of amoxicillin from bacterial cellulose membranes.
Controlled Release of Drugs FromHydrogel Based Matrices Systems: Experiments and Modeling
2012
Hydrogels are materials largely used in the formulation of pharmaceuticals since, in principle, they could produce a release system of zero-order kinetics, which is of great therapeutic interest. In this paper, a model was proposed for the description of the main transport phenomena involved in the drug release process from hydrogel matrices (water diffusion, polymer swelling, drug diffusion and polymer dissolution); the model predictions are successfully compared with a large set of experimental data, obtained working with matrices systems based on HPMC (Hydroxy Propyl Methyl Cellulose). The proposed model was found able to reproduce main features of the observed phenomena, it can thus be adopted for prediction of the performances of drug release systems from hydrogel matrices.