Physicochemical Characterization and In Vitro Evaluation of Praziquantel-loaded Oleogels for Oral Drug Delivery

Oral delivery of poorly water-soluble drugs such as praziquantel (PZQ) is frequently limited by poor absorption and low bioavailability. Lipid-based carriers represent a promising strategy, as their matrices enhance solubility by incorporating hydrophobic molecules within a lipophilic environment. In this study, PZQ-loaded beeswax (BW) oleogels were formulated using palm oil (PO) or cottonseed oil (CSO) as lipid carriers, followed by physicochemical characterisation and in vitro studies. We hypothesised that differences in oil composition would influence the structure and physicochemical properties of BW oleogels, affecting drug release, in vitro digestion behaviour, and intestinal permeation. BW oleogels exhibited gelation at a critical concentration of 5% (w/w), resulting in a high oil-binding capacity of at least 98%. Microscopy and X-ray diffraction indicated concentration-dependent development of a dense, needle-like semi-crystalline network, while rheological analysis confirmed stable gel behaviour (G' > G″). For the first time, we demonstrate the application of a modified everted gut sac model, adapted to quantitatively investigate the intestinal interaction and permeation behaviour of PZQ-loaded oleogels. Simulated in vitro digestion revealed negligible release under salivary conditions and limited gastric release (< 16%), followed by a bioaccessible fraction of 52-57%. The BW oleogels exhibited reduced intestinal permeation relative to the free drug, indicating drug entrapment within the oleogel, while oleogel-intestinal tissue interaction remained below 7.8%. These findings highlight the potential of BW oleogels as oral carriers for hydrophobic compounds such as PZQ and suggest their applicability as modified-release delivery systems.