Comparison of self-microemulsifying drug delivery system versus solid dispersion technology used in the improvement of dissolution rate and bioavailability of vinpocetine.

The objective of this study is to compare the differences between self-microemulsifying drug delivery system (SMEDDS) and solid dispersion (SD) technology used to improve the dissolution rate and bioavailability of vinpocetine (VIP). The formulation of VIP-SMEDDS was composed of Labrafac, oleic acid, Cremophor EL, Transcutol P, and gum acacia which was used as solid absorbent. VIP-SD was prepared using poloxamer F68 as the carrier. In the solubility test, the solubility of VIP in SMEDDS was 17.3 times as much as that in SD. In the dissolution test, SMEDDS had shown better enhancement and stability in dissolving VIP than SD. When compared to VIP crude powder, the bioavailability of VIP in SMEDDS (VIP-SMEDDS) was 1.89-fold higher, and was less affected by food intake. However, the bioavailability of VIP in SD (VIP-SD) was bioequivalent to that of VIP crude powder. The tissue uptake of VIP-SMEDDS in Peyer's patches, intestine and liver after administration for 2 hours was more favorable than that of VIP-SD, which was 3.7 times higher in Peyer's patches, 2.2 times higher in intestine and 1.5 times higher in liver. In Caco-2 tests, the apparent permeability (P(app)) of VIP-SMEDDS was 2.65 times of that of VIP-SD. The width of the cell tight junctions of Caco-2 cell monolayer treated with VIP-SMEDDS were 9.6-fold wider, but there was no significant change after treatment with VIP-SD, when compared to the blank control. In conclusion, SMEDDS was more efficient than the traditional SD technology in increasing solubility, dissolution, intestinal permeability, lymphatic absorption and bioavailability of the insoluble drugs such as VIP, which is less affected by food intake.