Study On The Formulation Process And Oral Bioavailability Of Luteolin

Luteolin is a kind of natural flavonoids,which is widely found in all kinds of plants.It is cheap and easy to get,and has a wide range of pharmacological effects.It can be used for anti-inflammatory,anti-allergy,neuroprotection,anti-cancer,anti cardiovascular disease and depression.However,due to its poor water solubility and low bioavailability,its clinical application is limited.Nanocrystals technology is a new dosage form which can improve the oral bioavailability by reducing the drug particle size and changing some physical properties of the drug.It has the advantages of wide applicability,large drug loading and easy production.In order to improve the solubility and oral bioavailability of luteolin,nanocrystals technology was used to prepare luteolin.The specific content mainly includes the following four parts:1.Study on the relationship between dose and pharmacokinetics of LuteolinIn this paper,nanocrystals technology is used to reduce the particle size of drugs,increase the solubility of drugs,and improve the oral bioavailability of drugs.The results showed that C_maxand AUC increased with the increase of oral dose in the range of 10-80 mg/kg,but when the dose was 120 mg/kg,there was no significant difference between C_maxand 80 mg/kg,but AUC was still increasing.It is speculated that C_maxcan reach the saturation concentration in vivo due to the restriction of enzyme or carrier at 120 mg/kg dose,which indicates that LUT can improve the solubility and bioavailability of LUT in vivo by increasing the oral dosage of LUT at10-120 mg/kg,and nanocrystals technology is suitable for the study of LUT.2.Study on the preparation of luteolin nanocrystalsThe high-pressure homogenization method was used to prepare nanocrystals.After the drug was sheared by the high shear homogenization emulsification and dispersion machine,the single factor investigation was carried out under the condition of other factors unchanged.The effects of different homogenization pressure,homogenization times,drug concentration,homogenization temperature and different excipients on LNC particle size and PDI were investigated respectively.The results show that the optimal preparation process of LUT is to shear 5 mg/m L LUT at 13000rpm for 10 min with a high-pressure homogenizer,and homogenize it at 20 bar,50 bar twice,200 bar,500 bar five times and 800 bar ten times with a high-pressure homogenizer at a controlled temperature of 50℃.Excipients had no significant effect on the particle size and PDI of LNC.Due to the limited methods of improving bioavailability of nanocrystals technology,LUT were modified by SDS,TPGS respectively to prepare SLNC,TLNC,STLNC solution.The ratio of LUT to SDS=2:1,LUT to SDS=5:1,and the nanocrystals was solidified by freeze-drying technology.3.Study on the physical and chemical properties of nanocrystalsThe maximum absorption wavelength of LUT was 350 nm by UV spectraphotometer,and the in vitro methodology of LUT was established by HPLC.The results show that the method has good specificity,linear range,precision,stability,recovery,detection limit,quantitative limit and repeatability,all of which meet the requirements of methodology,indicating that the methodology is suitable for the determination of LUT in vitro.LNC,SLNC and TLNC were characterized by Malvern nanoparticle size,zeta potential,SEM,TEM,FT-IR,TG and XRD.The results show that the average particle size and PDI of LNC,SLNC and TLNC are401.30±9.22 nm,432.60±8.06 nm,439.90±7.57 nm and 0.271±0.038,0.257±0.017,0.252±0.019 respectively;the zeta potential is approximately 0;SEM and TEM show that the average particle size of LUT is about 400 nm,the morphology of LNC and SLNC are rod-shaped,TLNC is diamond shaped;FT-IR shows that the functional groups of nanocrystals have not changed,TG shows that the nanocrystals have thermal stability,but the nanocrystals containing SDS are more sensitive to temperature,and the nanocrystals have no chemical change in the homogenization process;XRD results show that the crystal form of the nanocrystalline tends to be amorphous,but SDS and TPGS do not change the crystal form of LUT.In addition,the solubility of LUT can be significantly improved by nanocrystals technology,and LUT nanocrystals solution with good physical and chemical stability.4.Pharmacokinetic study of nanocrystalsHPLC was used to study the in vivo methodology,baicalein was used as the internal standard.The results of methodological investigation showed that the method had good specificity,linearity,detection limit,quantitative limit.The results of intra-day precision and inter-day precision met the requirements.The recovery and stability of luteolin were good,indicating that the method was suitable for the determination of LUT in vivo.LUT was intravenous administration at 2 mg/kg,oral administration at20 mg/kg,the results showed that the absolute bioavailability of LUT,LNC,SLNC and TLNC are 4.57%,9.04%,16.11%and 9.36%respectively,compared with that of intravenous injection.The relative bioavailability of LNC,SLNC and TLNC were197.70%,352.65%and 205.41%of LUT respectively.Nanocrystals technology can significantly improve the bioavailability of LUT,the modification of SDS and TPGS can further improve the bioavailability of LNC.