Guanidinylated Chitosan as a Multifunctional Enhancer for Improved Flurbiprofen Delivery

In this study, we investigated guanidinylated chitosan (GCS), a chemically modified derivative of unmodified low-molecular-weight chitosan (CS), as a multifunctional excipient to enhance the solubility and absorption of poorly water-soluble drugs. Flurbiprofen (FP) was selected as a model drug to compare the performance of kneaded dispersions GCS-based (FP-GCS) and CS-based (FP-CS). Both GCS and CS increased the solubility of FP in a concentration-dependent manner, with no significant differences between them. However, dissolution testing showed that FP-GCS kneaded dispersion significantly enhanced the dissolution rate of FP alone in water and simulated gastric fluid (pH 1.2), but not under simulated intestinal conditions (pH 6.8). In vivo pharmacokinetic studies in rats demonstrated that FP-GCS kneaded dispersion achieved the highest plasma concentration of FP, suggesting enhanced gastrointestinal permeability. Moreover, FP-GCS kneaded dispersion markedly reduced gastric ulceration in a rat ulcer model. These results indicate that GCS is an effective oral drug delivery excipient capable of improving both the bioavailability and gastrointestinal safety of FP.