Studies On Huperzine A Microemulsion Temperature/pH-sensitive In Situ Gel For Nasal Delievery

Huperzine A(Huperzine A, Hup A) is an alkaloid extracted from endemic plant Melaleuca tower(Huperzia serrata) by Chinese scholars,for the treatment of AD and BSF in clinical practice. There is a drawback is that the liver metabolism and microbial degradation exists, resulting in low oral bioavailability after oral administration and impacting the therapeutic effect of patients. The drug can be achieved rapidly through the nasal mucosa environment absorption by means of microemulsion with a strongly fat-soluble, small particle size and low viscosity. Due to microemulsion of low viscosity and the mucociliary clearance, it could lower drug concentration in vivo and reduce drug distribution in the brain after administration. In situ gel drug delivery system increase the contact time between the drug and the nasal mucosa increases for the purpose of improving the absorption of drug. On the basis of the existing laboratories,Huperzine A microemulsion as a model drug, was prepared with a hydrophilic gel matrix polymer material into Huperzine A microemulsion temperature / pH-sensitive in situ gel.OBJECTIVE: To study the formulation and technology of Huperzine A microemulsion temperature / pH in situ gel and build a stable nasal drug delivery system.METHODS: By establishing the method of Huperzine A content and in vitro release for the determination of drugs before prescribing research, and we investigated the physical stability in the simulated nasal fluids at the same time. Under non-physiological conditions(temperature:29~34?, pH:6.0 ~ 7.0), the prescription formulation can exist in a flow state like solution. It can be converted into semi-solid gel under simulated environmental conditions of the nasal cavity(Temperature:29~34?,pH: 6.0 ~ 7.0). Referring to Chinese Pharmacopoeia 2015 version of the relevant provisions, the pH and clarity of Huperzine A microemulsion gel as well as the inreaction between the drug and the matrix material should be checked for the pharmaceutical formulations. Pathological observation of nasal mucosa, which was applied to evaluate the safety of the site after administration.As a control rat itself, the microdialysis experiment was conducted by UHPLC/MS /MS determination of blood and brain tissue concentration after Huperzine A microemulsion temperature / pH-sensitive in situ gel was administered by nose. The pharmacokinetic parameters of Huperzine A microemulsion, Huperzine A microemulsion temperature-sensitive in situ gel and huperzine A solution were compared in study, respectively.RESULTS:(1) The poloxamer F127 and F68 were selected as temperature-sensitive matrix materias and chitosan CS as a pH-sensitive matrix material. The optimal formulation is 20.41% F127(w/v),1.58% F68(w/v),0.65% CS(w/v), and( 0.02%benzalkonium bromide) consisting of Huperzine A microemulsion(9.09%(v/v)screened by single factor and Central composite response surface design.(2) The release of Huperzine A was investigated by diffusion cell method and gel dissolusion behavior by free film dissolution. Both are based on first order kinetic and the cumulative drug release rate and cumulative dissolution of the gel had a good linear relationship in vitro. Studies between temperature-sensitive and temperature /pH-sensitive found that the gel dissolution is the effect of temperature and temperature /pH-sensitive in situ gel in vitro release, while the drug can diffuse from the temperature/ pH-sensitive system in situ gel formation.(3) Huperzine A microemulsion temperature / pH-sensitive in situ gel after administration did not cause damage to the nasal mucosa columnar structure, although it can be observed isolated epithelial cells. At the same time there is no occurrence of necrosis of epithelial cells, so it can be used as a safer pharmaceutical formulation used in nasal administration.(4) The vivo bioavailability of Huperzine A microemulsion temperature / pH-sensitive in situ gel in the distribution of brain regions was was better than Huperzine A intravenous injection group and has a similar DIT. The absolute bioavailability of Huperzine A microemulsion temperature / pH in situ gel was 122.6% and 120.4% for blood and brain ? Huperzine A microemulsion temperature-sensitive in situ gel as115.1% and 108.5%, and absolute bioavailability of microemulsion as 97.6% and 96.4%,It showed that Huperzine A microemulsion temperature / pH-sensitive in situ gel for nasal administration can prolong the metabolism of drug, avoid the burst of drug and improve the bioavailability in vivo.CONCLUSION: Huperzine A microemulsion temperature / pH-sensitive nasal in situ gel can significantly improve the bioavailability in vivo after nasal administration. And it has similar DIT proving the existence of rhinocerebral path to improve the bioavailability of the drug compared with intravenous administration.