Self-emulsifying drug delivery systems containing sulfate-based surfactants: Are they responsive to alkaline phosphatase?

This study aimed to develop self-emulsifying drug delivery systems (SEDDS) containing sulfate-based surfactants, namely, sodium dodecyl sulfate (SDS), sodium octyl sulfate (SOS) and sodium cetearyl sulfate (SCS), and to evaluate intestinal alkaline phosphatase (IAP)-triggered sulfate release from these SEDDS. Results showed a time-dependent release of para-nitrophenol from para-nitrophenyl phosphate (p-NPP) and para-nitrophenyl sulfate (p-NPS) when incubated with isolated IAP indicating that the enzyme can also cleave sulfate groups. Moreover, sulfate release from p-NPS and sulfate-based surfactants was observed. SEDDS containing sulfate-based surfactants exhibited a narrow droplet size distribution and polydispersity index (PDI). A droplet size of 35.31 +/- 0.41 nm to 41.15 +/- 0.98 nm, PDI of 0.17 +/- 0.02 to 0.26 +/- 0.02 and zeta potential of 9.59 +/- 0.85 mV to -18.53 +/- 2.75 mV were recorded. Droplet size and PDI showed a minor increase upon contact with isolated IAP. Incubation with isolated IAP caused a rapid sulfate release from sulfate-based surfactantcontaining SEDDS (SDS-SEDDS, SOS-SEDDS and SCS-SEDDS). Furthermore, resulting SEDDS exhibited a nontoxic profile. According to these results, SEDDS containing sulfate-based surfactants can be considered as valid alternative to IAP-responsive drug delivery systems containing phosphorylated auxiliary agents.