Polyglyceryl Oleate

Sahle F F, et al. European journal of pharmaceutics and biopharmaceutics, 2012, 82(1), 139-150.

Stable polyglycerol fatty acid ester surfactant (SAA)-based ceramide AP (CER [AP]) microemulsions (MEs) were formulated and characterized to enhance their solubility and penetration into the stratum corneum (SC). TCPL4 (polyglycerol-4-laurate), isopropyl palmitate (IPP), and water-1,2-pentanediol (PeG) were used as amphiphilic, oily, and hydrophilic components, respectively, and the effects of HPGMO4 (polyglycerol-4-oleate) as a cosurfactant (co-SAA) and linoleic acid (Lin A) as an oily component on the stability and properties of the microemulsions were investigated.
When polyglycerol-4-oleate was used as a co-SAA (TCPL4:HPGMO4, 1:1, m/m), the LC region completely disappeared and the two-phase region shrank significantly. Therefore, when increasing the proportion of Lin A in the oil phase, increasing the proportion of PeG in the hydrophilic phase, and using polyglycerol-4-oleate as a co-SAA, the ME region was greatly expanded and the stability of the ME was improved by shrinking the two phases and the liquid crystal region.
The DSC thermogram of TCPL4-based ME was obtained by titrating the SAA oil mixture [(TCPL4-HPGMO4 (1:1))-(IPP-Lin A (9:1)), 6.5:3.5, m/m)] with the hydrophilic phase (water-PeG, 1:1, v/v) (dilution line R = 65:35). It can be seen from the figure that the oil phase undergoes a phase transition at about +13.6 °C, while the hydrophilic phase undergoes a phase transition at 6.1 °C. With the increase of the encapsulation level, the components have moved to lower temperatures in the ME and further decreased.

Steinbach S C, et al. Die Pharmazie-An International Journal of Pharmaceutical Sciences, 2017, 72(8), 440-446.

In this work, two microemulsion (ME) formulations were prepared without or with 5% isosorbide (Polysorb P) to study the effect of isosorbide on the targeted delivery of ceramide (CER) to the stratum corneum (SC). Polyglycerol-4-oleate was the water soluble surfactant in both formulations. It concluded that both MEs are skin safe to administer to regulate the CER [NP] penetration of the skin.
Preparation of microemulsions
CER [NP] was insoluble in all the solvents so water and oil phases were prepared separately. For the MEs, weighed CER [NP] (0.3%) and [AP] (0.3%), the oil phase (C12-C15 alkyl benzoate, 10%) and the oil in water surfactant (polyglyceryl-4-laurate, 20%) in a glass vial and heated at 90 °C for 3 h. The mixture of 1,2-pentylene glycol and water (9:1, v/v, 50%) with the oil in water surfactant (polyglyceryl-4-oleate, 20%) was also heated in a drying oven for 15 min. Contents of both glass vials were mixed and heated further 15 min.
Additional to the basic ME a second formulation with 5 % isosorbide (Polysorb P) and 1,2-pentylene glycol/water mixture (9:1, v/v, 45%) was produced.