Membrane-assisted production of S1P loaded SLNs for the treatment of acne vulgaris

The incorporation of the sparingly soluble drug sphingosine-1-phosphate (S1P) into solid lipid nanoparticle (SLN) formulations using a ceramic membrane-assisted emulsification technique was investigated. SLNs have been used as an alternative to emulsions and liposomes in cosmetic and pharmaceutical preparations for the last two decades. They were prepared by replacing the liquid lipid part of the emulsions with a lipid part, which is solid at room temperature and/or at body temperature. The influence of a number of parameters on the particle size and size distribution of formulation and on the lipid flux were issued here. The chosen experiment parameters were: Lipid concentration varied from 5 to 20% w/w at various trans-membrane pressures (4–6 bar) and at aqueous phase cross-flow velocities varied from 2 to 12.5 m/s. A mono-channel ceramic membrane with a pore size of 0.2 µm and a 0.4 µm 19-channel membrane were used. It was shown that the investigated membrane system allows the preparation of SLNs with a mean particle size between 0.2 and 1 µm. The advantages of using a membrane-supported process are excellent scaling-up abilities and the control of the particle size through an appropriate selection of process parameters such as aqueous phase cross-flow velocity, lipid phase pressure and membrane properties.