Design and optimization of polyherbal gels for topical drug delivery by central composite statistical design

The current aims to design and develop the optimized gel formulation containing the extracts of three leaf drugs Tamarindus indica, Nyctanthus arborstris, Memecylon malabaricum employing Carbopol 940 and HPMC as a gelling agent. The polyherbal gel formulations were optimized for desired viscosity and spreadability using central composite design by selecting the concentration of Carbopol 940 and HPMC as independent variables. A central composite design with two factors at three levels of different concentration of Carbopol 940 and HPMC K4M(1-1.5% and 1-2%), respectively, were used. Viscosity and spreadability were chosen as dependent variables. The pH and drug content were also determined for the prepared formulations. The in vitro drug release of optimized formulation through dialysis membrane was conducted for 8hrs using Franz diffusion cell apparatus to find out the amount of release of phenolic content during the period of study. Polyherbal gel formulation with Carbopol 940 and HPMC (1:1 w/w) was found to be the optimized formulation with desired viscosity and high spreadability of 3620cps and 18.61g cm/sec respectively, with required skin pH of and drug content of 97.05%. Invitrorelease of phenolic content was found to be more than 88.02±1.5% after 8hrs. Optimized poly herbal hydrogel formulation with high polyphenolic content is suitable for topical application. Further, this formulation has the potential to be used topically for disorders that require antioxidant therapy.