A bigel co-delivering highly hydrophilic and hydrophobic natural compounds for enhanced ulcerative colitis therapy

Bigel, formed by high-speed shearing of hydrogel and oleogel, is suited to deliver both lipophilic and hydrophilic active compounds. Patchouli oil and paeoniflorin, despite their potential in treating ulcerative colitis, face challenges due to patchouli oil's poor aqueous solubility and paeoniflorin's high solubility but low permeability. In this study, we developed an oral colon-targeted bigel system to co-deliver patchouli oil and paeoniflorin for treating ulcerative colitis. Patchouli oil served as both a therapeutic agent and an oil phase (excipient). The bigel system enhanced mechanical stability, prolonging retention at the colon and enabling effective colon-targeted drug delivery. Compared to oleogel, bigel significantly alleviated symptoms in DSS-induced colitis in mice, reduced inflammatory cytokine release, repaired intestinal mucosal damage, and regulated immune cell populations in the gut. The combination of patchouli oil and paeoniflorin in the bigel exerted a synergistic effect on ulcerative colitis treatment. This work underscores the efficacy of bigel in delivering a combination of hydrophilic and lipophilic drugs, offering a novel strategy for enhanced drug delivery in ulcerative colitis. It also provides a delivery platform technology for volatile oils.