Double or Simple Emulsion Process to Encapsulate Hydrophilic Oxytocin Peptide in PLA-PEG Nanoparticles

Oral drug delivery using NPs is a current strategy for poorly absorbed molecules. It offers significant improvement in terms of bioavailability. However, the encapsulation of proteins and peptides in polymeric NPs is a challenge. Firstly, the present study focused on the double emulsion process in order to encapsulate the OXY peptide. Then the technique was challenged by a one-step simplified process, the simple emulsion.

In order to study the influence of formulation and process parameters, factorial experimental designs were carried on. The responses observed were the NP size (<200 nm in order to penetrate the intestinal mucus layer), the suspension stability (ZP < |30| mV) and the OXY loading.

It was thus found that the amount and the nature of surfactant, the ratio between the phases, the amount of PLA-PEG polymer and OXY, the presence of a viscosifying agent, and the duration of the sonication could significantly influence the responses. Finally, OXY-loaded NPs from both processes were obtained with NP size of 195 and 226 nm and OXY loading of 4 and 3.3% for double and simple emulsions, respectively.

The two processes appeared to be suitable for OXY encapsulation and comparable in term of NP size, peptide drug load and release obtained.