We established a RP-HPLC method for the analysis of silymarin in microemulsion. Silymarin was separated using a ODS C18 column and monitored at the wavelength 288 nm. The mobile phase consisting of methanol-water-acetic acid （42：58：0.5, v/v/v） was pumped at a flow rate of 1.0 mL/min. The linear range of calibration curve was 10-1000 μg/mL. The average recovery was 99.0%-100.7% for silybin isomers. The RSD values of inter-day and intra-day assays were lower than 1.6% for silybin isomers. The method is simple, rapid, reproducible and precise for the quantitative determination of silymarin in microemulsion.
The sinomenine hydrochloride （SH） patch, a topical drug delivery system, was prepared and characterized. The in vitro release was studied according to the paddle-over-disk method in the appendix of Chinese Pharmacopeia （appendix XD, 2005）. Stability of SH patch was evaluated at accelerated testing conditions （40 ℃, 75% RH）. Pharmacological and pharmacokinetics study were also performed. It was found that the release of SH from patches depended on pH value of the release medium. There were no significant differences between SH patches stored for 6 mon and those stored for 0 mon in the drug content, initial adhesion, lasting stickiness, peeling strength and in vitro release. SH patches exhibited better anti-inflammatory activity as well as analgesic efficacy. More importantly, primary pharmacokinetic parameters of SH patch, such as Cmax and AUC, were much lower than those of SH solution dosed orally. In conclusion, the patch might be a promising delivery system for SH, which bypassed the gastrointestinal tract and was a convenient, efficacious, safe and non-invasive delivery method.
