Preparation And Pharmacokinetics Of Oleanolic Acid Solid Dispersion

Oleanolic acid?OLA?is a triterpenoid organic compound,which is usually distributed in the form of free acid or aglycon in various plants in nature.It has liver-protecting enzymes,anti-inflammatory,immune regulation lowering blood sugar and blood pressure,anti-arrhythmia,inhibition of platelet aggregation and anti-polyoxidation,anti-tumor,anti-HIV virus and other pharmacological effects.According to the biopharmaceutics classification system?BCS?,it belongs to class IV and has low permeability and solubility,which limits its clinical application and development.In order to improve the dissolution of OLA and increase its absorption,this study applied solid dispersion technology to polyvinylpyrrolidone?PVP?and polyvinylcaprolactam-polyvinyl acetate-polyethylene glycol graft copolymer?Soluplus?was used as a carrier to prepare a solid dispersion of composite carrier by solvent evaporation method and microwave quenching method.The cumulative dissolution was used as an evaluation index to investigate the different preparation methods,the ratio between the two carriers,the ratio of drug to the carrier,and finally determined the optimal preparation process and related quality evaluation;the pharmacokinetics of the solid dispersion of OLA with composite carrier was studied by intragastric administration of rats,and the differences in the pharmacokinetic parameters of the OLA composite carrier and the single carrier solid dispersion were compared.Objective:An analytical method for determining the oleanolic acid content and the dissolution of OLA solid dispersion was established.The solid dispersion was prepared by solvent evaporation method and microwave quenching method,and the best preparation process and prescription were screened,and the related quality evaluation was carried out.A method for the determination of OLA in rat plasma by ultra-high performance liquid chromatography-mass spectrometry?UPLC-MS/MS?was established.The pharmacokinetics of the solid dispersion of oleanolic acid was studied.Methods:1 The content and dissolution of OLA solid dispersion were determined by high performance liquid chromatography?HPLC?,and the methodological investigation was carried out.The dissolution medium,sampling time,dosage mode and rotation speed were investigated,and the dissolution conditions of the solid dispersion were screened out under the conditions.2 The solid dispersion of OLA composite carrier was prepared by solvent evaporation method and microwave quenching method.The cumulative dissolution was used as the index to investigate the ratio of drug-carrier and the ratio between the carriers by single factor experiment.On this basis,orthogonal experiments were used to optimize the formulation process and finally determine the optimal preparation process.3 Analysis of pure OLA,physical mixtures and solid dispersions by various physical and chemical means such as X-ray diffraction?X-RD?,electron microscopy?SEM?,infrared spectroscopy?IR?and differential scanning calorimetry?DSC?.At the same time,the oil-water partition coefficient and stability of pure OLA and solid dispersions were determined.4 UPLC-MS/MS was established to determine the oleanolic acid content in rat plasma,and the methodological investigation was carried out.Rats were selected as test subjects,and OLA and solid dispersions were respectively administered by intragastric administration.The body?single carrier solid dispersion and composite carrier solid dispersion?was studied for its pharmacokinetic characteristics in rats,and the pharmacokinetic parameters were calculated.Results:1 The content was determined by HPLC method,wherein the detection wavelength was 215 nm,the linear range of oleanolic acid was 2²00?g/mL,and the standard curve Y=6.1745X-2.7218?r=0.9998?.The precision RSD was 0.21%,the average sample recovery was 99.47%,and its RSD was 0.21%,less than 2%,indicating good stability.The cumulative dissolution of the solid dispersion was determined by HPLC.The regression equation was Y=6.032X-0.927?r=0.9999?,and the relationship was good in the linear range of 2²00?g/mL.The dissolution conditions were as follows:0.3%dodecyl group Sodium sulfate?SDS?as the dissolution medium,the method was paddle method,the temperature of the dissolution medium was?37±0.5??,the rotation speed was 100 r/min,and the method of administration was not capsule filling,and the sampling time was 120 min.2 The single factor test investigated the two preparation methods,the drug-carrier ratio and the ratio between the carriers.The results showed that the solid dispersion of OLA composite carrier prepared by solvent evaporation method had a mass ratio of drug to carrier of 1:7,when the mass ratio of the PVP k30 and Soluplus was 1:2,the cumulative dissolution at 120 min was87%,which was significantly higher than the cumulative dissolution of pure OLA and physical mixture.While the sample prepared by microwave quenching method at the same ratio had a cumulative dissolution of only 47%.The orthogonal design was used to optimize the formulation process,in which the ratio of drug to load,the ratio between carriers and the temperature of spinning were the influencing factors.Based on the comprehensive score of the dissolution rate?P?of 120 min and the time(t_1/2)used for dissolution,the comprehensive evaluation score was calculated to determine the optimal preparation process.The optimum preparation process was as follows:the drug loading ratio was 1:7,the carrier ratio was 1:2,and the rotary distillation temperature was 40?.The optimization was consistent with the results of the solid dispersion prepared by examining the relevant factors by a single factor.3 The OLA solid dispersion was a yellow-white powder with uniformity and no agglomeration.X-RD results showed that the OLA showed multiple diffraction peaks in the range of 6o²0oindicating that the drug has crystallinity,while the OLA solid dispersion lacked characteristic peaks in the diffraction pattern,indicating that the drug substance was the amorphous form was dispersed in the carrier.The SEM results indicated that the OLA existed in the form of fine needle crystals.PVP k30 and Soluplus existed in spherical or spheroidal shape.The microscopic characteristics of the solid dispersion were significantly different from those of the above structure,and no needle crystals were found.The IR results showed that the OLA had strong peaks at 1700 cm^-1and 3450 cm^-1,respectively,which were stretching vibrations of C=O and-OH.The absorption peak intensity of the OLA solid dispersion at 3450 cm^-1 was significantly decreased,indicating that there may be hydrogen bonding interaction between the pure OLA and the two carriers in the solid dispersion;The DSC results indicate that the OLA,PVP k30 had a melting peak at 314?and 127?,respectively,while Soluplus had characteristic melting point peak at about 320?.There is no drug peak in the thermal analysis of the solid dispersion,and only the carrier peak is present.In summary,it was speculated that the pure OLA was uniformly dispersed in the two carriers in an amorphous state.4 By determining the oil-water partition coefficient of the OLA and the solid dispersion,the following conclusions were drawn:Compared with the pure drug,the Papp value of the solid dispersion was significantly reduced,indicating that the water solubility of the drug was significantly enhanced after the OLA was made into a solid dispersion,which promoted the in vivo absorption and distribution of OLA.5 The preliminary stability study found that the appearance and cumulative dissolution of the OLA solid dispersion sample powder changed under high temperature?60??,while the sample content changed little;Under the conditions of high humidity?RH 90%±5%?and strong light?4500 Lx±500 Lx?,the appearance and content of the solid dispersion of OLA varied greatly,indicating that its stability was susceptible to humidity and light intensity.6 The content of oleanolic acid in rat plasma was determined by UPLC-MS/MS.The linear range of OLA in plasma samples was 1¹200ng/mL.The standard curve equation was:Y=337.98453X+12190.30630?r=0.99706?,the minimum quantitation limit was 1 ng/mL;The accuracy of QC samples was 100.1¹01.4%,the accuracy of RSD was<3.97%;the matrix effects of OLA and internal standard glycyrrhetinic acid were93.4⁹9.5%,108.3%,respectively;extraction recovery was>85%and the RSD values of all samples meet the requirements of biological samples.After administration,the concentration of OLA in plasma was determined.The results showed that the peak time of the three groups was different,the C_maxax of the solid dispersion group was 7¹1 times of the pure OLA group,and the C_max of the composite carrier solid dispersion group was significantly higher than that of the pure OLA group and the single carrier group.It can improved its bioavailability.Conclusion:The composite carrier OLA solid dispersion prepared by solvent evaporation method can significantly improve the dissolution of OLA.The pharmacokinetic results showed that the composite carrier OLA preparation prepared by solid dispersion technology can significantly improve its bioavailability.