Self-Double-Emulsifying Drug Delivery System Enteric-Coated Capsules: A Novel Approach to Improve Oral Bioavailability and Anti-inflammatory Activity of Panax notoginseng Saponins

In this work, self-double-emulsifying drug delivery system enteric-coated capsules (PNS-SDE-ECC) were used to enhance the oral bioavailability and anti-inflammatory effects of Panax notoginseng saponins (PNS), which are rapidly biodegradable, poorly membrane permeable, and highly water-soluble compounds. The PNS-SDEDDS formulated by a modified two-step method spontaneously emulsified to W/O/W double emulsions in the outer aqueous solution, which significantly promoted the absorption of PNS in the intestinal tract. The release study revealed that PNS-SDE-ECC exhibited sustained release of PNS within 24 h and the stability study indicated that PNS-SDE-ECC were stable at room temperature for up to 3 months. Furthermore, compared to PNS gastric capsules, the relative bioavailability of NGR1, GRg1, GRe, GRb1, and GRd in PNS-SDE-ECC was increased by 4.83, 10.78, 9.25, 3.58, and 4.63 times, respectively. More importantly, PNS-SDE-ECC significantly reduced OXZ-induced inflammatory damage in the colon by regulating the expression of TNF-α, IL-4, IL-13, and MPO cytokines. Overall, the prepared PNS-SDE-ECC may serve as a viable vehicle for increasing the oral bioavailability of PNS and its anti-inflammatory action on ulcerative colitis. Graphical Abstract