Study On Castor Oil-Cyclodextrins Inclusion Complexes And Pickering Emulsions

The castor oil is still taken orally as a traditional laxative and hard for patients to be accepted because of its strong excitant smell and unpleasant taste.The development of suitable dosage forms is a key to improve the patient compliance and efficacy of castor oil.The inclusion complexes formed with cyclodextrins were frequently used to cover up bad smell,increase the aqueous solubility and stability of drug molecules.This thesis adopts the cyclodextrins as the main component to prepare castor oil inclusion complexes and Pickering emulsion.The main contents are as follows:The castor oil inclusion complexes were prepared by grinding the saturated aqueous solution ofβ-cyclodextrin with castor oil.The preparation process of inclusion complexes was optimized and samples were characterized by powder X-ray diffraction and infrared spectroscopy.The results showed that the castor oil inclusion complexes can be successfully obtained when the weight ratio of castor oil andβ-cyclodextrin was1:1 and 2:1 confirmed by powder X-ray diffraction and infrared spectroscopy results.N-hexane ultrasonic heating cycles and gas chromatography were used to determine the content of castor oil and ricinoleic acid in the preparation.The results showed that the extraction yield of castor oil was 94.96-99.69%,percentage markup amount of castor oil was 91.70-103.6%,which confirmed that the method was suitable for the determination of the castor oil content.Under the gas chromatographic conditions established,blank solvent and accessories didn’t interfere with the determination of ricinoleic acid methyl ester and the recovery of ricinoleic acid methyl ester was 96.13 to 101.57%,RSD<2%,which showed that the method is suitable for the determination of ricinoleic acid methyl ester in the preparation.The results of ricinoleic acid content in 3 batches were in line with the“Chinese pharmacopoeia”rules for castor oil.High-speed shear dispersion method was used to prepare castor oil Pickering emulsions and the factors affecting the formation and stability of the emulsion were investigated.The appearance,sedimentation characteristics and particle size of the emulsion were chosen as evaluation index to investigate the influence of type and concentration of cyclodextrins,pH of continuous phase,preparation methods,preparation temperature,dispersing time and dispersion speed on emulsion preparation.The results showed that high-speed shear dispersion method has higher rates of emulsion compared with grinding.Castor oil emulsions can be prepared withα-cyclodextrin andβ-cyclodextrin,and emulsion droplet size decrease with cyclodextrins concentration increase in the continuous phase.The best emulsions can be prepared with neutral continuous phase at room temperature.Dispersing time has no significant effect on emulsion preparation.The emulsion droplet size was decrease with the increase in dispersion speed.To study the formation mechanism of castor oil Pickering emulsion.The castor oil/α-cyclodextrin microparticles,which stabilized the emulsions,were characterized by the measurement of interfacial tension and the contact angleθ_ow,powder X-ray diffraction,scanning electron microscope,differential interference microscope,cryo-scanning electron microscopy.The physical stability of emulsions with differentα-cyclodextrin content in the continuous aqueous phase was investigated by determination of the droplet size and sedimentation rate.As a result,it was indicated that the amphiphilic supramolecule of castor oil andα-cyclodextrin indeed formed and absorbed at the oil/water interface,and then forming three-dimensional network structure to stabilize emulsion.The averageθ_ow for the castor oil/α-cyclodextrin microparticles was below 90^o,which tended to stabilize O/W emulsion.When the content ofα-cyclodextrin in the continuous phase was increased there were more microparticles formed at the oil/water interface and in the continuous aqueous phase and thus the physical stability of emulsion was better.Conscious animal ink method was used to study efficacy of castor oil inclusion complexes and Pickering emulsion.The results showed that the onset time of castor oil inclusion complexes was longer than castor oil but the efficacy of castor oil inclusion complexes is equivalent with castor oil,the onset time and efficacy of castor oil Pickering emulsion were same as castor oil.In conclusion,castor oil inclusion complexes and Pickering emulsions could be prepared with cyclodextrins as main accessory,meanwhile castor oil inclusion complexes and Pickering emulsions have the efficacy of diarrhea,which provides new drug delivery dosage form for castor oil oral formulations.