Phosphorylated PEG-emulsifier: Powerful tool for development of zeta potential changing self-emulsifying drug delivery systems (SEDDS)

Aim: It was the aim of this study to synthesize a phosphorylated emulsifier possessing a PEG-linker for establishment of a potent zeta potential changing system in self-emulsifying drug delivery systems (SEDDS). Methods: N,N'-Bis(polyoxyethylene)oleylamine (POA) was phosphorylated utilizing pyrophosphoric acid. Successful synthesis of POA bisphosphate (POAP) was confirmed by NMR and HR CS MAS. After incorporation of 1% POAP into SEDDS (Kolliphor RH 40, Capmul PG-8, Labrafac Lipophile WL 1349, Labrafac PG; 30/20/20/30, v/v), according emulsions were incubated with intestinal alkaline phosphatase (IAP) and the zeta potential was measured. Additionally, the amount of released phosphate upon incubation with IAP or on Caco-2 cells was quantified by malachite green assay. Finally, cell viability studies on Caco-2 cells were performed and mucus permeation properties with and without IAP preincubation were assessed. Results: POAP was synthesized as brown viscous liquid with a yield of 36% and could be incorporated into SEDDS. By incubation with IAP a zeta potential shift from -15.1 to 6.5 mV was observed. A corresponding phosphate release in presence of isolated IAP as well as on Caco-2 cells was found. Assessment of the cytotoxic potential revealed no significant alteration in the safety profile of SEDDS by incorporation of POAP. Mucus permeation studies exposed a 2-fold higher permeation of fluorescein diacetate (FDA) having been embedded in SEDDS loaded with POAP in comparison to blank formulation and 3-fold higher permeability than for emulsions having been preincubated with phosphatase. Conclusion: The novel phosphorylated surfactant exhibiting a PEG-linker facilitated a potent zeta potential change of SEDDS.