Pickering emulsions stabilized with biodegradable nanoparticles for the co-encapsulation of two active pharmaceutical ingredients.

Innovative Pickering emulsions co-encapsulating two active pharmaceutical ingredients (API) were formulated for a topical use. An immunosuppressive agent, either cyclosporine A (CysA) or tacrolimus (TAC), was encapsulated at high drug loading in biodegradable and biocompatible poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NP). These NP stabilized the oil droplets (Miglyol) containing an anti-inflammatory drug, calcitriol (CAL). The influence of the API on the physico-chemical properties of these emulsions were studied. Emulsions formulated with or without API had a similar macroscopic and microscopic structure, as well as interfacial properties, and they exhibited a good stability for at least 55 days. The emulsions did not alter the viability of human keratinocytes (HaCaT cell line) after 2 and 5 days of exposure to NP concentrations equivalent to efficient API dosages. Thus, these new Pickering emulsions appear as a promising multidrug delivery system for the treatment of chronical inflammatory skin diseases.