SEDDS: A game changing approach for the oral administration of hydrophilic macromolecular drugs

Since the development of self-emulsifying drug delivery systems (SEDDS) in 1980's, they attract the attention of researchers in order to confront the challenge of poor water-solubility of orally given drugs. Within recent years, SEDDS were also discovered for oral administration of hydrophilic macromolecular drugs such as peptides, proteins, polysaccharides and pDNA. Due to hydrophobic ion pairing (HIP) with oppositely charged lipophilic auxiliary agents the resulting complexes can be incorporated in the lipophilic phase of SEDDS. Depending on the solubility of the complex in the SEDDS pre-concentrate and in the release medium drug release can be adjusted on purpose by choosing more or less lipophilic auxiliary agents in appropriate quantities for HIP. Within the oily droplets formed in the GI-tract drugs are protected towards degradation by proteases and nucleases and thiol-disulfide exchange reactions with dietary proteins. The oily droplets can be made mucoadhesive or highly mucus permeating depending on their target site. Furthermore, even their cellular uptake properties can be tuned by adjusting their zeta potential or decorating them with cell penetrating peptides. The potential of SEDDS for oral administration of hydrophilic macromolecular drugs could meanwhile be demonstrated via various in vivo studies showing a bioavailability at least in the single digit percentage range. Owing to these properties advanced SEDDS turned out to be a game changing approach for the oral administration of hydrophilic macromolecular drugs.