Study On Preparation And Evaluation Of Zedoary, Schizonepetae Volatile Oil Microcapsules

In order to overcome the disadvantages of low drug loading and large amount dose of inclusion complex of volatile oils prepared by traditionalβ-cyclodextrin technique, micro capsules of zedoary and schizonepetae volatile oil were prepared by the method of emulsion solvent diffusion to increase their drug loading and stability. EC was selected as coating material,Twain-80 and PEG-6000 were used as emulsifier. Single-factor method was applied to determine the important experimental factors. Orthogonal experiment design was applied to optimize preparation conditions, using encapsulation efficiency and drug loading as the evaluation index. The best conditions of preparing zedoary volatile oil microcapsules were as follows:the ratio of drug to EC and organic to aqueous were 1:3 and 1:7, respectively, the amount of emulsifying agent was 1%, the stir time was 2h. And the best preparation conditions of schizonepetae volatile oil microcapsules were as follows:the ratio of drug to EC and organic to aqueous were 1:2 and 1:5,respectively, the amount of emulsifying agent was 1%, the stir time was 2h. The average drug loading of volatile oil microcapsules prepared by the optimized conditions were 21.6%(zedoary volatile oil) and 29.99%(schizonepetae volatile oil), respectively.The chemical composition and surface morphology evaluation of the volatile oil microcapsules were characterized by TLC spotting, scanning electron microscopy, laser particle size distribution analyzer. The TLC results indicated that the chemical compounds in the oil of the microcapsules were almost the same as that in volatile oil. Therefore adding the capsule material in the volatile oil did not affect the chemical composition of oils. SEM results showed that the volatile oil microcapsules had good mobility and did not adhere to each other, meanwhile the surface was dotted with small holes that may help the drug to release. The diameter distribution of zedoary and schizonepetae oil microcapsules were 94μm-250μm and 45μm-220μm, respectively.The HPLC analysis methods of Germacrone in microcapsule of zedoary volatile oil and Pulegone in microcapsule of schizonepetae volatile oil were established, the stabilities of the two kinds of volatile oil microcapsules on the conditions of light, heat and moisture were studied by the HPLC method. Stability test results illustrated that the effect of temperature on the stability of the volatile oil microcapsules was higher than humidity and light. Thus, the oil microcapsules should be stored at room temperature,75% humidity and avoiding light.The volatile oil microcapsules which prepared by the emulsion solvent diffusion method had higher drug loading and good mobility characteristic, meanwhile the stability of volatile oil was increased. The technology process was simple and suitable for industrial production.