Drug-loaded fibers

The kinetics of release of the drug is controlled by the semicrystaUine nature of the polymer as well as by the morphology of the polymer/drug composite. Three basic morphological models for dmg-loaded polymers (or polymer particles), first proposed by Kissel et al. (1993) apply to drug-loaded nanofibers as well (Verreck et al. 2003a)  

Drug dissolved in the polymer matrix at the molecular level. 

Drug distributed in the polymer matrix as crystalline or amorphous particles. 

Drug enclosed in the polymer matrix yielding a core of the drug encapsulated by a polymer layer (similar to a reservoir device). 

Widi nanofiber devices the third morphology is obtained by coaxial spinning of core-shell nanofibers rather than firom phase separation. The three morphologies are illustrated in Fig. 7.1. 

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Two basic types of drug-loaded fibers have been reported. 

Yu, D.G., Shen, X.X., Zhang, S.F., Zhu, L.M., Branford, W.C., 2009. Applications of polarization microscope in detemtining the physical status of API in the wet spinning drug-loaded fibers, in ICBBE, The 2nd International Conference. Bioinformatics Biomedical Engineering, 1375—1378. lEE, New York. 

However, currently the more popular process for preparing drug-loaded fibers is co-blending, in which the active ingredients and filament-forming materials are blended together to prepare the spinning liquids which are... 

The selection of suitable polymers with the desired characteristics for the manufacture of drug-loaded fibers is of vital importance. In order to... 

DDS matrix DDS and reservoir DDS. Correspondingly, there are two basic types of drug-loaded fibers fibers in which the drug is dissolved or dispersed throughout the polymer matrix, giving a monohthic system, and reservoir or depot fibers. The latter is mainly dependent on the whether the fibers structure can offer the desired release profiles. The former has no special inner structure, and, of the two, is the more commonly mentioned in the academic hterature. Release profiles are mainly dependent on the physico-chemical properties of the polymer and the high surface area of the fibers. 

As far as interface reactions are concerned, the drug-loaded fibers will present no problems as long as the chosen polymers are considered to be safe, although the incorporation of drugs may have some effect on the properties of the base materials. One possibility would be the occurrence of surface modifications, which could be disadvantageous in respect of interface reactions. 

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