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Designing & Characterizing Matrix Diffusion Systems for Drug Release, Study notes of Medical Biochemistry

The design and functioning of matrix diffusion-controlled systems, where drugs are bound to polymeric carriers. Homogeneous and porous matrix systems, their release mechanisms, and performance testing methods such as ftir, sem, xrd, dsc, and in vitro release studies.

Typology: Study notes

2019/2020

Uploaded on 10/27/2022

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Design Matrix Diffusion-Controlled Systems
In a matrix diffusion-controlled system, the drug is bound to a polymeric
carrier in a dispersed form. For controlled release systems using non-
biodegradable polymeric materials as carriers, the solubility of the drug in the
system is the controlling factor for the release rate. For biodegradable
polymers, the release rate is controlled both by the solubility of the drug in
the system and by the rate of degradation of the polymeric carrier.
Matrix System Types
Homogeneous Matrix Systems
In a homogeneous matrix system, the drug is dissolved or dispersed in a
homogeneous matrix, primarily a polymer. Once the matrix system is
immersed in the dissolution medium, the drug present on the surface of the
matrix will dissolve in the dissolution medium. This will result in concentration
differences and the drug will diffuse from the inner to the outer layers of the
matrix. As a result, a depletion zone will form at the boundary of the matrix
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Design Matrix Diffusion-Controlled Systems

In a matrix diffusion-controlled system, the drug is bound to a polymeric carrier in a dispersed form. For controlled release systems using non- biodegradable polymeric materials as carriers, the solubility of the drug in the system is the controlling factor for the release rate. For biodegradable polymers, the release rate is controlled both by the solubility of the drug in the system and by the rate of degradation of the polymeric carrier.

Matrix System Types

Homogeneous Matrix Systems In a homogeneous matrix system, the drug is dissolved or dispersed in a homogeneous matrix, primarily a polymer. Once the matrix system is immersed in the dissolution medium, the drug present on the surface of the matrix will dissolve in the dissolution medium. This will result in concentration differences and the drug will diffuse from the inner to the outer layers of the matrix. As a result, a depletion zone will form at the boundary of the matrix

and will increase over time. The release rate will also decrease over time as the drug must diffuse over longer distances. Porous matrix systems Porous matrix systems are a variant of homogeneous matrix systems. In this case, the drug is dissolved in a porous polymer. Once the matrix system is immersed in the dissolution medium, the pores will be filled with the dissolution medium and the drug will be dissolved in the filled pores of the matrix. In addition to the solubility and diffusion coefficient of the drug in the release medium, the shape and volume of the pores in the matrix are also important. Performance Testing of Matrix Diffusion-Control System Before the tests are performed, the drug, polymer and other substances need to be made into polymer films, which are then subjected to a series of performance characterization tests.

  • FTIR spectroscopy, which is used to detect any physical and chemical interactions between the polymer and the drug.
  • SEM testing, which can be used to observe the surface morphology of the patch before and after drug release.
  • XRD testing, which is used to confirm the physicochemical properties of the drug in the polymer matrix of the transdermal patch.