Development of a new approach to investigating the drug transfer from colloidal carrier systems applying lipid nanosuspension-containing alginate microbeads as acceptor

As a new approach to analyzing the release behavior of lipophilic drugs from colloidal carriers, solid trimyristin nanoparticles were incorporated into differently sized (34–1363 μm) calcium alginate hydrogel microbeads to serve as acceptor in release studies. The microbeads were prepared by electrostatic droplet generation or by a spraying method. Trimyristin nanoemulsion samples loaded with the fluorescent drug model Nile red were mixed with the nanoparticle-containing microbeads to perform transfer studies. As a result of a rather large diffusion barrier a slow transfer (24–57 min) was observed using large acceptor beads (∼330–1360 μm). In contrast, Nile red transferred quickly (∼1.4 min) into smaller microbeads (<50 μm). This new experimental approach applying nanoparticle-containing hydrogel particles with a size below 50 μm as acceptor systems is a promising technique to investigate the release of lipophilic substances from lipid nanoparticles under close to realistic conditions. However, there is still room for technical improvement, e.g., with regard to the water loss from microbeads that was observed during sampling by centrifugation and filtration (required to separate the small sized alginate particles) which is expected to have had some effect on the dye content determined during these experiments.

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