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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 release curves of drug-fiber complexes in pH 1.2 solution (A) and pH 6.8 buffer (B).Notes: The small pictures in the lower right showed the release curves of drug powder. Atenolol (■, solid), Tramadol (○, dash), Venlafaxine (▲, dot), Sinomenine (∇, dash dot), Diltiazem (★, dash dot dot).
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f7-dddt-8-945: The release curves of drug-fiber complexes in pH 1.2 solution (A) and pH 6.8 buffer (B).Notes: The small pictures in the lower right showed the release curves of drug powder. Atenolol (■, solid), Tramadol (○, dash), Venlafaxine (▲, dot), Sinomenine (∇, dash dot), Diltiazem (★, dash dot dot).

Mentions: The release profiles of each drug from the drug–fiber complexes in pH 1.2 HCl solution and pH 6.8 phosphate buffer are shown in Figure 7. The rate of drug release from the fiber was determined by extrapolating the time when 50% (t50%) and 80% (t80%) of the drug in the fiber was released into the dissolution medium (Table 5). Generally, the release rate decreased with increasing molecular weight. Atenolol was released very quickly from the fiber complexes, and the release rate was approximately the same as that of drug powder in pH 1.2 solution, and even faster than that of drug powder in pH 6.8 buffer. Atenolol-fiber complexes preformed an ability of rapid release. The reason for this is that the dissolving rate of atenolol powder is slow due to its strong surface hydrophobicity and comparatively low solubility; however, the highly dispersed state of the drug in the fiber accelerated the release. The other drug–fiber complexes exhibited sustained release, and the extent of this release increased as the molecular weight increased. Steric hindrance made it difficult for the extraction ions to approach the ionic bonds between the small ion-exchange groups and the much larger drug. Meantime, the release rate of tramadol was slower than that of atenolol, illustrating that the stronger affinity caused by higher charge density and ring structure between tramadol and the fiber made it harder to release. In oral administration, additional release control through another method, such as coating, is needed for ion-exchange resins.


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 release curves of drug-fiber complexes in pH 1.2 solution (A) and pH 6.8 buffer (B).Notes: The small pictures in the lower right showed the release curves of drug powder. Atenolol (■, solid), Tramadol (○, dash), Venlafaxine (▲, dot), Sinomenine (∇, dash dot), Diltiazem (★, dash dot dot).
© Copyright Policy
Related In: Results  -  Collection

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

f7-dddt-8-945: The release curves of drug-fiber complexes in pH 1.2 solution (A) and pH 6.8 buffer (B).Notes: The small pictures in the lower right showed the release curves of drug powder. Atenolol (■, solid), Tramadol (○, dash), Venlafaxine (▲, dot), Sinomenine (∇, dash dot), Diltiazem (★, dash dot dot).
Mentions: The release profiles of each drug from the drug–fiber complexes in pH 1.2 HCl solution and pH 6.8 phosphate buffer are shown in Figure 7. The rate of drug release from the fiber was determined by extrapolating the time when 50% (t50%) and 80% (t80%) of the drug in the fiber was released into the dissolution medium (Table 5). Generally, the release rate decreased with increasing molecular weight. Atenolol was released very quickly from the fiber complexes, and the release rate was approximately the same as that of drug powder in pH 1.2 solution, and even faster than that of drug powder in pH 6.8 buffer. Atenolol-fiber complexes preformed an ability of rapid release. The reason for this is that the dissolving rate of atenolol powder is slow due to its strong surface hydrophobicity and comparatively low solubility; however, the highly dispersed state of the drug in the fiber accelerated the release. The other drug–fiber complexes exhibited sustained release, and the extent of this release increased as the molecular weight increased. Steric hindrance made it difficult for the extraction ions to approach the ionic bonds between the small ion-exchange groups and the much larger drug. Meantime, the release rate of tramadol was slower than that of atenolol, illustrating that the stronger affinity caused by higher charge density and ring structure between tramadol and the fiber made it harder to release. In oral administration, additional release control through another method, such as coating, is needed for ion-exchange resins.

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