Encapsulation of florfenicol by in situ crystallization into novel alginate-Eudragit RS® blended matrix for pH modulated release

Florfenicol (FF) is a broad-spectrum antibiotic with the drawback of poor solubility in physiological media. Despite vehiculization of FF become an alternative, current devices usually showed low encapsulation efficiencies (EE) and uncontrolled fast release. In the present work, a novel drug delivery system based on alginate and Eudragit RS (R) (EuRS) for FF oral administration was developed. The strategy involved in situ crystallization of FF inside the matrix which allowed EE from 60 to 80%. Ionic gelation technique was used for pH-responsive beads preparation considering that alginate offers structural support for the hydrogel while hydrophobic EuRS delays the swelling of the system. Different formulations were analyzed by FTIR, DSC, XRD and SEM studies to demonstrate the presence of a blended polymeric matrix, the appearance of FF crystals and the role of EuRS in the FF release. A pH-dependent FF release was found when the drug and EuRS concentrations were modified. Approximately 40% and 20% of FF was released from alginate and alginate-EuRS beads at pH 7.4 in 1 h respectively, suggesting a modified release behavior. All formulations showed antimicrobial activity against Staphylococcus aureus and Escherichia coli. The blended formulation results a promising oral matrix adapted for the controlled release of FF along the intestine.