Development and Characterization of Tannic Acid‐Modified PVA‐κCarrageenan Gel for Sustained Release of Lidocaine

Abstract PVA‐κcarrageenan (κCar) gel is widely used in the pharmaceutical field for transdermal drug delivery, enhancing drug stability and bioavailability. This study aims to modify PVA‐κCar gel by introducing tannic acid. Lidocaine was used as a model drug for incorporation into the novel gel. The PVA‐κCar matrix was mixed with tannic acid prior to freeze– thaw cycle to create a gel composite. The physicochemical features of this gel were evaluated using FTIR, XRD, thermal analysis, and SEM. The presence of tannic acid has reduced the thermal stability of PVA‐κCar from 84 to around 70 °C. The gel content of tannic acid‐modified PVA‐κCar was 34.6% (A) and 52.1% (B). The addition of tannic acid substantially increased gel viscosity. Cytotoxicity analysis showed that tannic acid‐modified PVA‐κCar gel did not affect the viability of HCT colon cancer cells. The encapsulation efficiency of lidocaine in tannic acid‐modified PVA‐κCar was 13 ± 0.2% (A) and 12 ± 0.5% (B), while the drug loading was 0.96 ± 0.01 (A) and 0.91 ± 0.02 (B). In vitro release of lidocaine from the modified PVA‐κCar exhibited a sustained release mechanism in phosphate‐buffered saline solution. These findings indicate that the gel possesses advantageous characteristics as a drug carrier.