Spray drying of double emulsions containing PLGA/PVA yielded nanoparticles of similar size as precipitation by direct solvent displacement (Fig. 1). The addition of different matrix excipients to the emulsions before drying did not influence the resulting nanoparticle size. Only P-407 seemed to decrease the resulting nanoparticle size. P-407 is a surface-active block copolymer suitable for the stabilization of PLGA double emulsions and suspensions alone, resulting in particles of a smaller hydrodynamic diameter when using the same manufacturing method and parameters (9). A possible explanation is that P-407 may replace PVA, to a certain extent, at the liquid/liquid interface before drying or at the particle/liquid interface after drying and reconstitution.
Fig. 1 Resulting nanoparticle sizes after spray drying of PLGA/PVA double emulsions with and without the addition of different matrix excipients. Spray-dried powders were reconstituted in purified water, then aggregates were removed by filtration, and particle size distribution was measured by dynamic light scattering. Nanoparticles precipitated by solvent displacement without spray drying served as the control. Measurements were done in triplicate, RSD < 0.5%