Phospholipid-surfactant vesicles based hydrogels for the topical administration of diclofenac diethylamine

Skin and mucosa represent commonly employed routes for the administration of several drugs with favorable physical-chemical properties (i.d molecular weight ≤500 Da; partition coefficient ~1 for skin). Penetration, permeation and, finally, absorption of topically applied drugs can be challenging since mucosa and, even more, the skin, act as natural barriers [1]. In the last decades, several strategies have been developed to promote drug absorption across mucosa and skin barriers, including lipid vesicular systems. These systems include liposomes, niosomes, ethosomes, and elastic and deformable vesicles, also known as transferosomes [2]. Particularly, transferosomes, which are formed by phospholipids and a non-ionic surfactant, acting as an “edge activator”, are able to squeeze among the layers of the skin and release the drug more deeply, thereby promoting absorption and a more effective local (and eventually systemic) pharmacological effect [3]. The aim of the study was to prepare and characterize mixed vesicles formed by phospholipids and the non-ionic surfactant polyglyceryl-3metylglucose distearate to improve the delivery across the skin and mucosa of the anti-inflammatory drug diclofenac diethylamine.