Development and skin penetration pathway evaluation of microemulsions for enhancing the dermal delivery of celecoxib

This study aimed to develop a microemulsion using PEG-6 Caprylic/Capric Glycerides as a surfactant to enhance the dermal delivery of celecoxib. Confocal laser scanning microscopy (CLSM) using the colocalization technique was also used to investigate the skin penetration pathway of the microemulsion. The prepared microemulsion formulations were characterized in terms of size, surface charge, size distribution and type. The celecoxib-loaded microemulsion had particle sizes ranging from 48 to 214 nm with neutral charge and significantly increased the skin penetration of celecoxib. According to the CLSM study, the microemulsion might attach to any part of the skin before releasing the entrapped drug to penetrate the tissue. The transfollicular pathway might be the major skin penetration pathway for the microemulsion, whereas the intercellular and transcellular pathways are minor ones.