Development and In Vivo Evaluation of Ziyuglycoside I-Loaded Self-Microemulsifying Formulation for Activity of Increasing Leukocyte

Abstract

Ziyuglycoside I (ZgI), a major effective ingredient of Sanguisorba officinalis L, has shown good activity in increasing leukocyte of myelosuppression mice. However, oral ZgI therapy has been deterred by poor bioavailability because of its low aqueous solubility and permeability. Our study was to develop ZgI-loaded self-microemulsifying drug delivery system (SMEDDS) and evaluate its intestinal absorption, and pharmacokinetic and pharmacodynamic activity for increasing leukocyte. The formulation was designed and optimized by measuring the equilibrium solubility of ZgI in different vehicles and the pseudoternary phase diagram. Further, morphology, particle size, stability, in vitro release, in situ single-pass intestinal perfusion (SPIP), in vivo activity, and in vivo pharmacokinetic (PK) of ZgI-SMEDDS were charactered or studied. Optimized formulations for in vitro dissolution were Obleique CC497, Tween-20, and Transcutol HP with a proportion of 0.25/0.45/0.30 via D-optimal mixture design. Results showed that the solubility of ZgI was enhanced up to 23.93 mg/g and its average particle size was 207.92 ± 2.13 nm. The release of ZgI had been greatly improved by the SMEDDS. In SPIP, the intestinal absorption of SMEDDS was much better than plain ZgI. In PK, we found the oral bioavailability of ZgI-SMEDDS was 6.94-fold higher absolute bioavailability (21.94 ± 4.67) % than ZgI (3.16 ± 0.89) %. The most important was that the mice WBC of ZgI-SMEDDS group was significantly higher than that of the ZgI group. Our study suggested that SMEDDS could increase the solubility of ZgI, which was beneficial to improve oral bioavailability and enhance biological activity.

Keywords: SMEDDS; bioavailability; solubility; ziyuglycoside I.

Fig. 1

The chemical structure of ZgI

Fig. 2

Ternary phase diagram. a Oleic acid-Tween-20-Transcutol P. b Obleique CC497-Tween-20-Transcutol P. The colorized regions represent the microemulsion phase

Fig. 3

Drug loading 3D stereogram (a) and 2D contour map (b)

Fig. 4

Particle size 3D stereogram (a) and 2D contour map (b)

Fig. 5

The FTIR spectra of (a) SMEDDS, (b) ZgI, (c) physical mixture, (d) ZgI-SMEDDS

Fig. 6

The DSC thermograms of (a) SMEDDS, (b) ZgI, (c) physical mixture, (d) ZgI-SMEDDS

Fig. 7

Micromorphology of the ZgI-SMEDDS

Fig. 8

The cumulative drug release of the ZgI-SMEDDS and ZgI. Compared with the ZgI group, *P < 0.05

Fig. 9

Mean plasma concentration-time curves of ZgI after i.v of a single dose of 2 mg/kg of ZgI Tween-20 solution, oral administration of a single dose of 20 mg/kg of ZgI Tween-20 solution, and equivalent dose of oral ZgI-SMEDDS. Picture on the top right corner was the plasma concentration-time curves for 0-2 h duration (mean ± SEM, n = 6/group)