Structural changes in pH-responsive gelatin/hydroxypropyl methylcellulose phthalate blends aimed at drug-release systems

The present study aimed to investigate the thermal-and pH-dependent gelation behavior of gelatin/HPMCP blends using ultraviolet (UV) spectrophotometry, viscoelasticity, and dynamic light scattering (DLS). We found that the release of lisinopril from gelatin/HPMCP gels can be inhibited at low pH. UV spectrophotometric analysis showed that pH had a significant effect on the transparency of aqueous HPMCP systems and gelatin/ HPMCP gels. The viscoelastic patterns of gelatin/HPMCP at pH 4.6 considerably differed from those of gelatin/ HPMCP at pH 5.2 and 6.0. DLS measurements showed that HPMCP molecules in low concentrations underwent strong aggregation below pH 4.8. Such HPMCP aggregation induces a physical barrier in the matrix structures of the gelatin/HPMCP gels, which inhibits the drug release at pH 1.2. This hydrogel delivery system using polymer blends of gelatin/HPMCP can be used in oral gel formulations with pH-responsive properties.

Automated summary

The study investigated the thermal-and pH-dependent gelation behavior of gelatin/HPMCP blends using UV spectrophotometry, viscoelasticity, and DLS. Lisinopril release from the gels can be inhibited at low pH due to HPMCP aggregation. pH significantly affected the transparency of HPMCP systems and gelatin/HPMCP gels, with differences in viscoelastic patterns observed at different pH levels.