Study on transdermal absorption of piperine in Erxiekang plaster Antidepressant-like effects of piperine and its neuroprotective mechinism Preparation of scutellarin-piperine co-amorphous complex and its in vitro release Study on in vitro percutaneous adsorption of Huayu Babu Sticking Plaster HPLC determination of four components in Tibetan medicine Dangzuo of different tibetan regions Studies of effective part group of piperine to regulating lipid Optimization and characterization of curcumin-piperine dual drug loaded self-microemulsifying drug delivery system by simplex lattice design