Construction Of Triptolide Nanoemulsion Gels And Its Transdermal Delivery Mechanisms

Triptolide is the main active ingredient of tripterygium wilfordii,used extensively as an antirheumatoid,anti-eczema,immunosuppressive,nephrotic syndrome and malignant tumouragent in traditional Chinese medicine.The pharmacological effects of TPL are attributed to its anti-inflammatory,analgesic,anti-tumor and immune-regulating properties.However,the oral intake of TPL exists in a high-toxicity region,and the digestive system and urogenital system have adverse reaction rates of 35.8%and 22.8%,respectively,severely limiting its clinical application.Transdermal drug delivery is an important approach to effectively reduce these adverse reactions.However,its composition is complicated by poor water solubility and difficult entry through the skin,which affects the extent of its curative effect.Therefore,using the nano-preparation technology to research the triptolide nano-transdermal drug delivery system is great significance for clinical.In this study,the transdermal carriers of triptolide was prepared,the triptolide nanoemulsions and triptolide nanoemulsion gels were prepared.The in vitro transdermal characteristics of the carriers were characterized.The transdermal behavior was studied by Franz diffusion cells,skin microdialysis,etc.The mouse ear chronic dermatitis eczema model was established and its pharmacodynamics was investigated.Electron microscopy,spectroscopic analysis and fluorescence microscopy were used to investigate the structural changes of the skin to elucidate the mechanism of penetration and the in vivo transport properties.The first part of the subject selected O/W nanoemulsions,nanoemulsion gels for its transdermal delivery carrier,preparation and characterization the triptolide nanoemulsion,triptolide nanoemulsion gels to study them in vitro release and transdermal properties.Nanoemulsion gels can make the drug stable release;maintain effective plasma concentration in long time.Compared to TPL gels,the transdermal cumulative permeation of TPL-nanoemulsions and TPL-nanoemulsion gels was significantly increased.The second part of this project adopts the simultaneous microdialysis technique of skin and blood to establish LC/MS detection method of triptolide.LC/MS detection method is used to detect the plasma concentration samples in vivo to study the pharmacokinetic of triptolide.The in vivo microdialysis showed the AUC_0–∞,C_maxax and MRT for TPL-NPs is bigger than the TPL-gels.The third part of the subject was pharmacodynamics research of triptolide nanoemulsion gels.The mice were sensitized with 7%2,4-dinitro-chloropropiophenone solution of DNCB acetone and repeatedly treated with 0.3%2,4-dinitrochlorobenzene solution to establish a model of dermatitis/eczema.We measure the thickness of the mouse ears and evaluate the ear-swelling rate and the degree of inflammation.The ELISA method was used to measure the cytokine concentration of IFN-γ,IL-4 and IL-8in the animal serum.The high and moderate dosages of the TPL-nanoemulsion gels can significantly improve the symptoms of dermatitis/eczema inflammation and edema erythematic in mice ears and can reduce the expression of IFN-γand IL-4.Moreover,the TPL-nanoemulsion gels cause less gastrointestinal damage than that of the Tripterygium wilfordii oral tablet does.The fourth part of the subject prepared triptolide nanoemulsions and triptolide nanoemulsion gels.The integrity of the nanoemulsions and nanoemulsion gels during transdermal delivery and its effects on the surface of skin were also investigated.The penetration mechanisms of nanoemulsions and nanoemulsion gels were investigated by differential scanning calorimetry（DSC）and Fourier transform infrared spectroscopy（FTIR）.The transport characteristics of fluorescence-labelled nanoemulsions were probed using fluorescence microscope.TPL-nanocarriers reduce the barrier function of the stratum corneum through the hydration of stratum corneum and the changes of lipids and keratins in stratum corneum,thereby promoting the percutaneous penetration of drugs.The skin transport properties study showed that coumarin-6 first entered the stratum corneum and then spread to the active epidermis.In addition,most of the fluorescence remained in the hair follicle after laser irradiation,revealing that drug mainly passed through the skin appending organs to percutaneous absorption.The experimental results in this study indicate that the nanoemulsions and nanoemulsion gels are beneficial to the transdermal absorption of triptolide.The pharmacokinetics curve of nanoemulsion gels is more gradual,which helps to reduce the drug accumulation in specific organs,improved the safety.The triptolide nanoemulsion gels have good effects of anti-dermatitis and eczema,and the damage to the gastrointestinal tract is lower than the oral administration.The penetration mechanism of nanocarrier is due to the hydration of the stratum corneum,better skin closure characteristics and fluidity.The drugs are mainly absorbed through skin appendages such as hair follicles to percutaneous absorption.The nanoemulsion gels show a higher permeability,can increase drug retention in the skin.This will provide a new carrier for triptolide,which is of great significance for better clinical efficacy.This study can clarify the mechanism of transdermal permeation of nanocarriers and development new transdermal formulation has the important significance of theoretical and practical.In the mean while,this study can provide a new technology and method for the basic research of transdermal drug delivery,and enrich the research content of external treatment of traditional Chinese medicine.