Studies On Huperzine-A Sustained Release Hydrophilic Matrix Tablets

Huperzine A (Hup-A), one kind of alkaloid isolated from the Chinese herb named Huperzia serrata(Thunb)Trev,has a selective inhibition on acetylcholinestrase (AchE).Hup-A improves the memory of the patients with impaired memory or Alzheimer's diseases. Because its biological half-life is very short,the daily dose is often divided into two or three doses,that would result in plasma drug concentration fluctuating and side effects.The sustained-release preparation of Hup-A was developed,which may decrease the fluctuation of drug concentration and side-effects.This preparation might also be expected to improve compliance in patients.The UV spectrophotometry were studied to determinate the absorption of Hup-A from the intestine of the rats in situ .According to the literatures .high-performance liquid chromatography with UV detector was applied to detect the plasma concentrations in dogs.The minimum detection quantity was 2ng/ml,and the extraction recovery of Hup-A was 93.25%.The absorption situation and the intestinal wall permeation coefficients of Hup-A were measured by the rat intestinal recirculating method in situ.The absorption rate constants per 10cm were observed among duodenum,jejunum, ileum and colon, which were 0.0707h^-1,0.0976h^-1,0.102h^-1,0.1249h^-1, respective-ly.The study of the drug absorption effected by the different concentrations indicateed that the rat intestinal absorption of Hup-A was via passive transport mechanism.Hup-A sustained release tablet formulations contained hydroxypropyl methylcellulose(HPMC K4M)and EC(20cps)as gel-forming material,prepared with the wetting-granulation method . The drug realeasein was studied in pH6.8 phosphate buffer solution.The release process in virto was found to conform to the Higuchi equation .The formula and manufacturing techniques of the matrix...