Development, Characterization and Evaluation of Parenteral Formulation of Diclofenac Sodium

Diclofenac sodium is a potent NSAID, classified under BCS class II category having a poor aqueous solubility. Recently, its injectable formulation got banned and withdrawn from the market due to its severe nephrotoxicity caused by the use of synthetic surfactant, i.e. Transcutol-P as solubilizer. Therefore, the present study was aimed to prepare Transcutol-P free injectable using Vitamin E TPGS as a biosurfactant which is in list of inactive ingredients by US-FDA. Various cost effective aqueous injectable formulations were prepared by mixed solvency method that were characterized and optimized for different in vitro quality control parameters. Further, ex vivo hemolytic study showed the increased safety (23.4 ± 1.6%) of optimized formulation as compared with its commercial counterpart (100 ± 4.2%) at 75 mg/ml. Furthermore, in vivo acute and sub-acute toxicity study demonstrated an increase in LD₅₀ to 123.75 ± 6.2 mg/kg to that of a commercial counterpart (109.96 ± 5.5 mg/kg). In addition, optimized formulation demonstrated better mean residence time and area under curve when compared with commercial test group, respectively. Moreover, optimized formulation was also evaluated for its therapeutic efficacy. The results obtained from acetic acid-induced writhing test in albino mice showed 78 ± 2.1% protection from writhes after 120 min, whereas the commercial formulation had only 48.3 ± 1.9% protection. Additionally, carrageenan-induced rat paw edema model also confirmed the better anti-inflammatory activity of optimized aqueous injectable formulation than its commercial counterpart. Thus, the developed aqueous injectable formulation of diclofenac is free from toxic Transcutol-P with enhanced safety and therapeutic efficacy.