FORMULATION DEVELOPMENT OF DICLOFENAC SODIUM LOTION USING MIXED SOLVENCY CONCEPT AND IN VITRO EVALUATION

Abstract

The concept of mixed solvency is an emerging field which can serve as a new method for solubility enhancement and therefore deserves urgent attention of the scientific community to assess its efficiency and applicability. Mixed solvency concept suggests that each substance present on the earth whether solid, liquid or gas has solubilizing power. An objective of the present research was to develop an aqueous based diclofenac sodium lotion and to prove solubilizing power of solid substances. The described research is one typical example where safe concentrations of solid additives have been used to prepare aqueous based topical lotion (solution) of diclofenac sodium (a sparingly water soluble drug as per IP solubility descriptive term). Conventionally, diclofenac sodium is a drug of first choice as NSAID in the treatment of osteoarthritis, due to its less dose and lesser side effects as compared to other drugs. Diclofenac or its pharmaceutically acceptable salts and other NSAIDs produce their anti-inflammatory analgesic action through inhibition of prostaglandin synthesis. In the present research, blend of caffeine and niacinamide is used as solubilizer for solubility enhancement of diclofenac sodium. Approximate solubility of diclofenac sodium in DM water at room temperature was 1.2 % w/V. An aqueous blend containing two solid additives, namely niacinamide (5 % w/V) and caffeine (5 % w/V) was observed to have approximate solubility of diclofenac sodium 10 % w/V at room temperature. Therefore, a topical lotion of diclofenac could be developed. Diclofenac sodium, vitamin B3 (niacinamide), caffein, glycerin and sodium sulfite, were used for preparing topical formulation. Selection of solubilizers was done on the basis of solubility studies in various blends of solubilizers. Aqueous diclofenac lotion was formulated and in vitro evaluation was performed.