PVA/glutaraldehyde xerogels containing chitosan, PAA, PVP, and HPMC: swelling properties and drug-hydrogel interactions

The present work describes the development and characterization of poly(vinyl alcohol) (PVA)–glutaraldehyde-based composite xerogels that incorporate chitosan, poly(acrylic acid) (PAA), poly(vinylpyrrolidone) (PVP), and hydroxypropyl methylcellulose (HPMC), manufactured with solvent casting. The PVA–glutaraldehyde system crosslinked at 120 °C (F2) had the highest gel fraction (%GF) of 94.5 ± 1.2% of all the hydrogel formulations then chosen as the base formulation. Each additive polymer was then blended with F2 to obtain distinct xerogel composites. Both crosslinking temperature and polymer composition influenced xerogel characteristics in terms of swelling properties and drug-hydrogel interaction. The swelling analysis showed that F2-PVP performed a semi-interpenetrating polymer network (semi-IPN), while F2-Chi and F2-HPMC likely formed full-IPNs, however, with less mechanical stability. The effective crosslinking exhibited in all formulations indicated chemical interactions among PVA, glutaraldehyde, and each polymer, which was then confirmed by FTIR examination. Formula F2-PVP possesses a robust, sponge-like, and porous structure (as evidenced by SEM imaging) attributable to hydrogen bonding, even in the absence of covalent crosslinking. Furthermore, the F2-Chi, F2-PAA, and F2-HPMC xerogels demonstrated brittleness due to inadequate or irregular crosslinking mechanisms. A study on solute partition using five model drugs, amphotericin B (AmB), ketoconazole (KTZ), paracetamol (PCT), theophylline (TEO), and oxymetazoline HCl (OMZ), demonstrated the significance of electrostatic and polarity-based interactions. The F2-PAA formulation reported the strongest interaction with AmB and OMZ (cationic drugs), whereas lipophilic drugs have a robust interaction with F2-Chi, and hydrophilic drugs interact more significantly with F2 and F2-HPMC. These findings underscore the critical significance of polymer selection in the design of xerogel-based drug delivery systems and provide valuable insights for pharmaceutical and biomedical applications.