Objective: To optimize extracting technology of Rehmanniae Radix in Shiduqing capsules and compared its pharmacodynamic action before and after being processed. Method: HPLC was employed to determine the content of catalpol with mobile phase of acetonitrile-0.1% phosphoric acid (1:99) and detection wavelength at 210 nm.With extracting amount of catalpol as index

orthogonal test was adopted to optimize extraction technology by taking liquid-solid ratio

grinding degree and extracting time as factors.With physiological saline as blank control and dexamethasone as a positive control

pharmacodynamic action of Rehmanniae Radix before and after being processed was compared by anti-inflammatory and analgesic test. Result: Optimum extracting technology was as following:shattered into 5 mm small pieces and extracted twice with 20 times the amount of water for 1.5 hours per time.Before and after being cut

inhibition rates for xylene-induced auricle swelling in mice of high-dose(16 g·kg-1) groups were 33.72% and 48.34%

while low-dose groups were 43.13% and 64.31%

respectively. Conclusion: This optimized extracting technology is stable and feasible

which provides a reference for industrial production of Shiduqing capsules.