Enrofloxacin

Polyvinyl alcohol (PVA) and polyvinyl alcohol-pectin (PVA-P) cryogels are potential devices for wound healing. These materials have advantages over commercial wound dressings such as: retaining an appropriate level of moisture around wound and gas permeability and antibacterial properties. In a previous work, PVA-P cryogels containingan antibiotic and an enzyme (enrofloxacin and keratinase respectively) have been developed with promising results. In the present work, an exhaustive chemical, morphological and physical characterization of these films was carried out in order to explain the effect of incorporation of pectin into PVA matrix. The results show that the presence of pectin in PVA cryogel increase the size of PVA nanodomains determined by XRD patterns indicating an interaction between both PVA and pectin polymers. PVA nanodomains and crystallinity degree changed when enrofloxacin and keratinase were immobilized into PVA-P cryogels determined by SAXS and DSC analysis. These results suggest a good incorporation of both drugs into the polymeric matrix. A model involving the complex formation between the enzyme and enrofloxacin allocated through and between PVA nanodomains is proposed and it correlates well with results obtained in previous work where enrofloxacin kinetic release was found retarded by the presence of keratinase in the cryogels.

A keratinase isolated from Paecilomyces lilacinus (LPS #876) was tested against proteins present in the skin but the high enzyme activity was detected on collagen. Keratinase was physically immobilized onto PVA–pectin cryogels and enzyme release was 20.8 ± 2.1%, 63.8 ± 0.2%, 41.5 ± 3.5% and 26.0 ± 3.5% in cryogels containing pectins with esterification degrees (DE) 33.0%, 55.0%, 62.7% and 71.7% respectively at 37 C after 3 h incubation. In presence of 0.75 M NaCl, the percentage of enzyme release changed to: 57.5 ± 1.5, 65.8 ± 3.8, 57.3 ± 0.2 and 34.0 ± 4.0 for the four pectins respectively.  In-vitro studies of enrofloxacin release from PVA–pectin cryogels at pH close to the human skin (pH = 5.5) showed 15.0% free antibiotic following first order kinetic at 37 C after 5 h incubation. However, in the presence of keratinase only 6.9% of enrofloxacin was released under the same experimental
conditions.