Objective: To prepare pH sensitive oral colon-specific drug delivery for Bruceae Fructus seed oil hard capsules. Method: Colon-specific drug delivery of Bruceae Fructus seed oil hard capsules were prepared by thin film coating method

with disintegration time as index

based on single factor tests

orthogonal design was adopted to optimize coating prescription

disintegration of hard capsules with different coating prescriptions under different pH conditions were investigated.HPLC was performed on determination of linoleic acid and oleic acid in Bruceae Fructus seed oil hard capsules with mobile phase of methanol-water(83: 17)

flow rate of 1.0 mL· min-1 and detection wavelength at 242 nm. Result: These prepared colon-specific drug delivery of Bruceae Fructus seed oil hard capsules below pH 6.8 were not collapse and only under pH 7.8 rapidly disintegrate

make this drug to achieve purpose of colon specific delivery;optimum coating formulations was as follows:acrylic resin Ⅲ 1.6 g

eudragit RL100 of 0.2 g

eudragit RS100 of 0.2 g

diethyl phthalate 1.5 mL

castor oil 1 mL

absolute ethyl alcohol 47.5 mL

acetone 47.5 mL

coating weight 3.8%.HPLC determination of separation degree of all kinds of fatty acids in Bruceae Fructus seed oil extract conformed to requirements

concentrations of linoleic acid and oleic acid were 116.37

288.26 mg· L-1

relative mass fractions were 2.91% and 7.21%

respectively. Conclusion: This optimized prescription can achieve positioning requirement of colon specific.This assaying method is reproducible and accurate with high sensitivity

which can be used for quality control of Bruceae Fructus seed oil controlled release capsules.