Preparation and evaluation of O/W and W/O microemulsions containing diclofenac sodium
- Vol.83(1), Jan-Feb
- Mumbai Indian Journal of Pharmaceutical Science 2021
- 84-92p.
Microemulsions are widely used as potential drug delivery systems, especially through the dermal route as a means to avoid systemic side effects. Also, it is well known that the formation and characteristics of microemulsions depend on their composition. This study aimed to investigate the influence of various types and ratios of components which could dissolve diclofenac sodium on microemulsion formation in term of size of microemulsion regions through the construction of sixteen pseudoternary phase diagrams using the titration method. The data obtained were used to prepare oil-in-water and water-in-oil diclofenac sodium microemulsions. Two o/w and two w/o blank microemulsions were selected from the system providing the largest microemulsion region and these were subsequently incorporated with 1 % w/w diclofenac sodium. Afterward, their physicochemical and drug release properties were assessed. The largest microemulsion region was found in the system consisting of 2:1 Cremophor RH40:Span 80, ethylhexyl palmitate and 2:1 water:isopropanol. Characteristics of diclofenac sodium microemulsions were similar to those of their blank counterparts, with the exception of the drug-contained microemulsions having higher conductivity. Our findings indicated that compatibility of oil and surfactant structures was the crucial parameter for microemulsion formation. Furthermore, the present research not only expanded the phase behavior studies of microemulsions using different blends of Cremophor RH 40 and Span 80 as surfactant and cosurfactant mixtures, but also reported the application of ethylhexyl palmitate in microemulsion formulations. Incorporation of diclofenac sodium into four studied microemulsions did not affect microemulsion type. Location of the drug, drug mobility and interfacial film rigidity in microemulsions were found to influence the release characteristics of the loaded drug.