Study On The Lipid Nanopaticles Loaded With Tetrandrine

Tetrandrine(TET)is the major active constituent of Stephania tetrandra S.Moore,it has been already applied clinically to treat rheumatism,arthralgia,neuralgia,lung cancer and silicosis and etc.When TET is administered per oral,tetrandrine was difficult to dissolve in water,resulted to low bioavailability.When TET is intravenous administered,because of the widely pharmacological effects,it has safety problem.Lipid nanoparticles loaded with tetrandrine was made to reduce adverse effect and toxity for intravenous administration,and improve bioavailability for oral administration.HPLC methods were developed for the determination of TET in vitro.The mobile phase consisted of potassium dihydrogen phosphate/methanol/acetonitrile/triethanolamine(50/25/25/0.75,v/v/v/v),and the pH was adjusted to 5.0.Preformulation study showed the solubility and n-octyl alcohol/water partition coefficient of TET were affected by pH.TGA experiments showed that TET was stable under condition of preparing the lipid nanoparticles.In this study,tetrandrine solid lipid nanoparticles(TET-SLNs)were prepared using a melt-emulsification and ultrasonication method.The stirring time,stirring speed,ultrasonic time and intensity were investigated.Different solid lipids were screened by the solubility of TET and the stability of the SLN made of these lipids.The screened lipids were stearic acid,glyceryl monostearate and Precirol ATO 5.Central Composite Design was used to optimize the ratios and amount of the main emulsifying agents including lecithin and Poloxamer 188,effects of the emulsifying agents on properties of SLN such as particle size distribution,entrapment efficiency and drug loading investigated.The optimal composition of the TET-SLN formulation was as followed:TET(0.15 g),stearic acid(0.2 g),glyceryl monostearate(0.2 g),Precirol ATO 5(0.6 g),lecithin(0.75 g),Poloxamer 188(0.75 g),sodium deoxycholate(0.1 g)and water(25 ml).The particles of TET-SLN were spheric under transmission electron microscopy.The mean diameters,zeta potential and entrapment efficiency of SLN were 134 ± 18 nm,-53.8 ± 15.7 mv and 89.01%± 1.61%.Long-term stability testing demonstrated that the SLNs had the propensity to gelatinize,the SLNs should be lyophilized to prevent gelatinization.The cryoprotectants were chosen as 10%sucrose solution.DSC and XRD showed that the crystal form of the lipid was changed in SLN,and TET was in an amorphous state in SLN.Tetrandrine nanostructured lipid carriers(TET-NLCs)were also prepared using a melt-emulsification and ultrasonication method.Different types and ratios of solid lipids and liquid lipids were screened by the solubility of TET and the stability of the NLC made of these lipids.The screened lipids were glyceryl monostearate,and oleic acid,and liquid lipids can increase entrapment efficiency.Central Composite Design was used to optimize the ratios and amount of the emulsifying agents including lecithin and Tween 80,the properties of NLC including particle size distribution,entrapment efficiency and drug loading were investigated as the effects of the emulsifying agents.The optimal composition of the TET-SLN formulation was as follows:TET(0.15 g),glyceryl monostearate(0.7 g),oleic acid(0.3 g),lecithin(0.6 g),Tween(0.8 g),sodium deoxycholate(0.05 g)and water(25 ml).The particles of TET-NLC were spheric under transmission electron microscopy.The mean diameters,zeta potential and entrapment efficiency of SLN were 136 ± 18 nm,-45.3 ± 13.2 mv and 86.48%± 1.13%.The in vitro release of TET-NLC was faster than SLN.Compared with SLN,TET-NLC was stable,stability testing demonstrated that the NLCs had no propensity to gelatinize.The cryoprotectant was 10%maltose solution.DSC and XRD showed that the crystal form fo the lipid was changed in NLC,the liquid lipid made the crystal form out of order,and TET was in an amorphous state in TET-NLC.A HPLC method was established to determine the blood and tissue samples of rats.Oral and intravenous pharmacokines behaviors of TET lipid nanoparticles were investigated.The mean AUC0-? of SLN and NLC were 1.44 fold and 1.58 fold higher than TET suspension.Oral administration showed that compared with TET suspension,TET-SLN and TET-NLC can improve the bioavailability.Intravenous administration showed that the plasma concentration of SLN was higher than that of TET solution,the mean AUC0-? of SLN was 2.14 fold and 1.58 fold higher than TET solution.CL was decreased,MRT and t1/2 were prolonged.The biodistribution study of mice showed that compared with TET solution,TET-NLC pocessed higher concentrations in lung,spleen,liver(reticuloendothelial system organ),and decrease the concentrations in heart and kidney.The concentrations of TET in the heart and kidney were 24.08 ± 9.84 and 26.81 ± 9.33?g/g for TET-SLNs,while the corresponding values were 87.84 ? 20.36 and 83.30± 16.92 ?g/g for the TET solution at 2 min.The decrease of concentrations in heart and kidney may reduce adverse effect and toxity.In this research,tetrandrine solid lipid nanoparticles and tetrandrine nanostructured lipid carriers were prepared for intravenous administration,and oral administration.Reliable scientific basis was provided for the new dosage form development of tetrandrine.