Fibers were spun from a mixture of dichloromethane (DCM) and dimethyl sulfoxide (DMSO) solution of poly(lactic acid)(PLA) containing various amounts of amoxicillin (Amox) as the active component. Composition changes during spinning, structure, solubility, and the location of the drug were considered during the evaluation of drug release and microbial activity. The results showed that the composition of the material changes during the preparation procedure. The solubility of the drug in the components and that of the components in each other is limited, which results in the formation of several phases and the precipitation of the drug. The technology used results in the partitioning of the drug; some is located inside, while the rest is among the fibers. The wetting of the fibers or disks by the water-based dissolution media is poor, the penetration of the liquid into and the diffusion of the active component out of the device takes considerable time. Drug release takes place in one, burst-like step, only Amox located among the fibers dissolve and diffuse into the surrounding medium. The slow second stage of release claimed in the literature is less probable because the size of the Amox molecule is considerably larger than the holes creating the free volume of the polymer. The prepared device has antimicrobial activity, inhibits the growth of the two bacterial strains studied. The time scale of activity is short and corresponds to that of the release experiments and the burst-like behavior of the device. The results clearly prove that physical-chemical factors play a determining role in the effect and efficiency of medical devices prepared from electrospun fibers containing an active component.
Keywords: PLA; amoxicillin; antimicrobial activity; composition; drug release; structure.