Optimization of Diclofenac Sodium Gel by Using Calendula Oil as Sorption Promotor

  Diclofenac sodium (DFS) is a Non-Steroidal Anti-Inflammatory drug, used in the treatment of inflammation and degenerative disorder of the musculoskeletal system. The present study is based on the preparation of DFS topical gel for the purpose of obtaining optimized gel which will give better results considering the formulation and patient compliance. For the preparation of topical gel carbopol polymer and different excipients are used for final preparation. The calendula oil is used as penetration enhancer in this final formulation in different concentration. These formulations with and without calendula oil were compared with marketed preparation with respect to its permeation, pH, viscosity, spreadability, extrudability. Permeation experiments were performed on excised rat skin (675/02/C/CPCSEA or GNCP/IAEC/2011-2012/Pharmaceutics-2). On the basis of in–vitro drug diffusion study and other properties of gel, we have concluded that calendula oil is best penetration enhancer for DFS gel. The solubility of DFS in the solvent system containing 1%calendula oil also checked and it was similar to that without enhancer. These results suggest that the enhancing effect of calendula oil is independent on the solubility of drug in the solvent system and were dependent on the concentration of calendula oil.