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The load and release characteristics on a strong cationic ion-exchange fiber: kinetics, thermodynamics, and influences.

Yuan J, Gao Y, Wang X, Liu H, Che X, Xu L, Yang Y, Wang Q, Wang Y, Li S - Drug Des Devel Ther (2014)

Bottom Line: The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion.Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences.The drug-fiber complexes exhibited sustained release.

View Article: PubMed Central - PubMed

Affiliation: School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, People's Republic of China.

ABSTRACT
Ion-exchange fibers were different from conventional ion-exchange resins in their non-cross-linked structure. The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion. Therefore, this work aimed to investigate the load and release characteristics of five model drugs with the strong cationic ion-exchange fiber ZB-1. Drugs were loaded using a batch process and released in United States Pharmacopoeia (USP) dissolution apparatus 2. Opposing exchange kinetics, suitable for the special structure of the fiber, were developed for describing the exchange process with the help of thermodynamics, which illustrated that the load was controlled by an ionic reaction. The molecular weight was the most important factor to influence the drug load and release rate. Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences. The drug-fiber complexes exhibited sustained release. Different kinds and concentrations of counter ions or different amounts of drug-fiber complexes in the release medium affected the release behavior, while the pH value was independent of it. The groundwork for in-depth exploration and further application of ion-exchange fibers has been laid.

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The distinction in structure between fiber (left) and resin (right).
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f1-dddt-8-945: The distinction in structure between fiber (left) and resin (right).

Mentions: Ion-exchange fibers, as a typical type of ion-exchange material, contain two components: a water insoluble structural component (framework) consisting of polymer chains, such as polyethylene, polypropylene, or viscose, and a functional component (exchange group) consisting of fixed negative (cationic exchanger) or positive (anionic exchanger) electric charges that are compensated by ions of the opposite charge, the so-called counter ions. The distinction between fibers and conventional resins is the non-cross-linked structure in the former.1,13,14 Unlike the exchange between drugs and resins that happens in the pores and channels of resin particles, the exchange between drugs and fibers is located on the surface of the nonporous framework (Figure 1), and the transport resistance is reduced significantly, meaning the exchange is inclined to be controlled by an ionic reaction process instead of a diffusion process. Thus, a much faster loading rate and larger loading amount are possible because of a lack of pores and channels. These characteristics facilitate the preparation of drug–fiber complexes and improve patient compliance by markedly reducing the dose of materials.


The load and release characteristics on a strong cationic ion-exchange fiber: kinetics, thermodynamics, and influences.

Yuan J, Gao Y, Wang X, Liu H, Che X, Xu L, Yang Y, Wang Q, Wang Y, Li S - Drug Des Devel Ther (2014)

The distinction in structure between fiber (left) and resin (right).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109635&req=5

f1-dddt-8-945: The distinction in structure between fiber (left) and resin (right).
Mentions: Ion-exchange fibers, as a typical type of ion-exchange material, contain two components: a water insoluble structural component (framework) consisting of polymer chains, such as polyethylene, polypropylene, or viscose, and a functional component (exchange group) consisting of fixed negative (cationic exchanger) or positive (anionic exchanger) electric charges that are compensated by ions of the opposite charge, the so-called counter ions. The distinction between fibers and conventional resins is the non-cross-linked structure in the former.1,13,14 Unlike the exchange between drugs and resins that happens in the pores and channels of resin particles, the exchange between drugs and fibers is located on the surface of the nonporous framework (Figure 1), and the transport resistance is reduced significantly, meaning the exchange is inclined to be controlled by an ionic reaction process instead of a diffusion process. Thus, a much faster loading rate and larger loading amount are possible because of a lack of pores and channels. These characteristics facilitate the preparation of drug–fiber complexes and improve patient compliance by markedly reducing the dose of materials.

Bottom Line: The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion.Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences.The drug-fiber complexes exhibited sustained release.

View Article: PubMed Central - PubMed

Affiliation: School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, People's Republic of China.

ABSTRACT
Ion-exchange fibers were different from conventional ion-exchange resins in their non-cross-linked structure. The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion. Therefore, this work aimed to investigate the load and release characteristics of five model drugs with the strong cationic ion-exchange fiber ZB-1. Drugs were loaded using a batch process and released in United States Pharmacopoeia (USP) dissolution apparatus 2. Opposing exchange kinetics, suitable for the special structure of the fiber, were developed for describing the exchange process with the help of thermodynamics, which illustrated that the load was controlled by an ionic reaction. The molecular weight was the most important factor to influence the drug load and release rate. Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences. The drug-fiber complexes exhibited sustained release. Different kinds and concentrations of counter ions or different amounts of drug-fiber complexes in the release medium affected the release behavior, while the pH value was independent of it. The groundwork for in-depth exploration and further application of ion-exchange fibers has been laid.

Show MeSH