Construction Of Silybin Supersaturable Self-nanoemulsifying System And Discussion On Stability Mechanism In Vitro And In Vivo

Silybin(SLB)is a low-molecular-weight,high-lipid-soluble small molecule flavonoid component,in order to improve the bioavailability of SLB.Supersaturation is a commonly preparation method.Lipid-based drug delivery systems(LBFs)have been proven to be effective methods for improving poorly water-soluble and good lipid-soluble drug solubility.However,In recent years,a large number of research have shown that type IIIB and type IV LBFs have high drug loading capacity,and they will cause the loss of supersaturated solubilization after being dispersed in the gastrointestinal solution.Precipitation inhibitors(PPIs)can be added to stabilize or prolong the supersaturation state to increase the effectiveness of the formulation.This subject intends to prepare a supersaturable self-emulsifying drug delivery system(S-SNEDDS).A series of work has been done around the optimization of SLB-SSNEDDS preparation process and in vivo and in vitro evaluation,and the mechanism of PPIs maintaining stable supersaturation in biorelevant media.The research content of this article is mainly divided into the following 4 parts:1 Preparation and performance evaluation of silybin supersaturable self-emulsifying drug delivery systemTo develop and optimize SLB-SSNEDDS to increase the supersaturation of SLB in biorelevant media and extend the supersaturation time.Based on the solubility test,the emulsifying ability of the emulsifier,and the drawing of the pseudo-ternary phase diagram,the formulation composition of SLB-SNEDDS was optimized.The performance of various prescriptions was comprehensively evaluated by Analytic hierarchy process(AHP)to determine the optimal prescription ratio.Evaluate themaintenance of drug supersaturation and duration in biorelevant media to optimize the appropriate PPIs and dosages.The Optimal SNEDDS composition was Capryol 90:Cremophor RH: Transcutol HP(10: 67.5: 22.5)with a drug loading of 50.19 mg/g,supplemented by 2% HPMCAS MF(SLB-SSNEDDS-A)and 5% PVPK30(SLB-SSNEDDS-B).SLB-SSNEDDS was evaluated from performance indicators such as emulsification effect,emulsion size and surface morphology,in vitro drug release and in vitro supersaturation.After quality evaluation: The self-microemulsion formed by SLB-SSNEDDS-A / B is uniform and transparent,and the droplets are distributed in a spherical shape with uniform size.The emulsification time are(30.67 ± 4.16 s)and(25.42 ± 2.98s),and the average particle size are(11.67 ± 0.81 nm)and(13.11 ± 0.79nm),and the polydispersity indices are(0.15 ± 0.04)and(0.18 ± 0.03),respectively;the dissolution rates of the drugs in both biorelevant media increased significantly;after in vitro dilution,the supersaturation of SSNEDDS-A is stable at about 5.5 within2 h in Fa SSIF-V2 system,SSNEDDS-B can prolong the supersaturation stabilization time,and the supersaturation decreases after 60min;but in Fa SSGF system SLB-SSNEDDS-A / B can only prolong supersaturation relatively briefly.2 Research on the mechanism of polymers maintaining supersaturation stabilityIn order to better understand the phase change process of polymers in inhibiting drug supersaturation,the possible mechanism of polymer’s maintaining supersaturation in biorelevant media was explored.PVP K30,HPMC,Soluplus,and HPMCAS MF were used as model polymers,and SLB-SNEDDS was used as a supersaturation generation tool to study the effect of polymers on the phase transition of SLB.Furthermore,from the perspectives of thermodynamics and kinetics,the mechanism of polymer maintaining supersaturation stability is discussed.The results showed that Fa SSGF / Fa SSIF-V2 added polymers PVP K30,HPMC,Soluplus,and HPMCAS MF,and all showed different degrees of ability to maintain or prolong supersaturation.Thermodynamically,Soluplus(Fa SSGF)can increase the solubility of SLB and reduce the supersaturation.Kinetically,the polymers all showed varying degrees of SLB nucleation and crystal growth inhibition.Soluplus(Fa SSGF)andHPMCAS MF(Fa SSIF-V2)did not see the formation of crystal nuclei during the dispersion process within 2h;HPMCAS MF(Fa SSGF)and PVP K30(Fa SSIF-V2)significantly prolonged the nucleation time,which were 439 s,2306.68s;but HPMC and Soluplus have only weak nucleation inhibition.The four polymers have different degrees of inhibition on the growth rate of SLB crystal nuclei.Among them,PVPK30,HPMC and HPMCAS MF have the most obvious inhibition effect on crystal nuclei growth.SEM can further confirm that the addition of polymer can affect the crystal growth Habits.The crystallization kinetics of SLB was analyzed from solution viscosity and intermolecular interaction force.However,the viscosity values of the polymer solutions were almost the same;As for intermolecular interaction,only PVPK30(Fa SSIF-V2)and Soluplus(Fa SSIF-V2)showed that SLB might have some weak interaction.In summary,the viscosity of polymer solutions and intermolecular interactions do not explain the differences in the effects of the four polymers in different systems.Therefore,it can be further verified through related experiments whether polymer stabilization of the droplet morphology can be a possible mechanism.3 Caco-2 model to evaluate the effect of self-emulsifying preparation absorptionTo evaluate the effect of self-emulsifying preparations on cytotoxicity and osmotic absorption.The MTT method was used to determine the cytotoxic effects of Caco-2 at different prescription concentrations.A single layer model of Caco-2 cells was established to evaluate the membrane permeability and absorption enhancement of SLB-SNEDDS and SLB-SSNEDDS A/B in vitro.The results showed that the concentration of the preparation below 2mg/m L(including SLB100?g/m L)was no toxicity,PPIs had no significant effect on the cell viability rate.The transport results showed that compared with the non-formulation group,the Papp(AP→BL)in the self-microemulsion group had a significant increase,and 2%HPMCAS MF and5%PVPK30 had no affect on the SLB penetration process.4 In vivo pharmacokinetics of silybin and its self-emulsifying preparationTo investigate the pharmacokinetic behavior and bioavailability of SLB self-emulsifying preparations in rats.SLB suspension,SNEDDS and SSNEDDS-A /B(SLB:50mg/kg)were intragastrically administered to rats,and pharmacokinetic parameters in vivo were fitted according to the non-compartment model.The results showed that compared with the SLB suspension,the blood concentrations of the SLB SNEDDS and SSNEDDS-A/B groups were significantly increased,Cmax was 5.25 times,9.69 times,and 6.25 times,respectively;the average relative bioavailability was 578.45%,1139.44%,850.11%.Compared with SLB-SNEDDS,SLB-SSMEDDS-A/B Cmax was 1.85 times and 1.19 times,respectively;the average relative bioavailability was 197% and 146.97%,respectively.Therefore,the SNEDDS preparation can significantly improve the bioavailability of SLB;2% HPMCAS MF and 5% PVPK30 can better improve the gastrointestinal behavior of SLB-SNEDDS,enhance SLB absorption,and further improve SLB bioavailability.