Preparation, Characterization, Properties Of Emamectin Benzoate Solid Dispersions And Study On Its Wettable Powder

Solid dispersions,as an intermediate of pharmaceutical processing,has been widely used in medicine field,and used for increase the solubility or dissolution rate of insoluble drugs,which can be made of enteric drugs in order to achieve targeted drug release.In this study,solid dispersion technology was applied for pesticide formulation processing.The solvent-grinding method was used for emamectin benzoate to produce solid dispersion which water-soluble carrier-polyvinyl pyrrolidone K30(PVP K30)and water-insoluble material-polyacrylic resin III(PRIII)served as carrier,respectively.The drug loading and encapsulation efficiency of solid dispersion was detected using high performance liquid chromatography(HPLC),and the value was as a standard for screening conditions to improve the processing of machining process.Moreover,characteristics of emamectin benzoate solid dispersion were analyzed by method of UV scanning(UV),infrared scanning method(IR),differential scanning calorimetry(DSC),X-ray powder diffraction(XRD),and scanning electron microscope method(SEM).On this basis,the solid dispersion was processed into 5%wettable powder,and the diamondback moth,Plutella xylostella(Linnaeus),was used for indoor toxicity test using leaf-dipping method.(1)Emamectin benzoate-PVP K30 solid dispersions and its wettable powdersIn this study,solid dispersions was prepared by grinding emamectin-PVP K30 mixing with some solvent,and the drug loading and encapsulation efficiency,which was measured by HPLC,was as an standard for screening optimum craft of preparation of solid dispersions.The results showed that,the feed ratio of emamectin benzoate and PVP K30 should be controlled at the range of1:1 to 1:50,and preferred solvent is methanol with 600r/min,60min.By characterizing analysis for this solid dispersions,PVP K30 as a carrier played a role in emamecting benzoate embedded rather than just physical mixing,and hydrogen or new chemical bonds were formed between emamectin benzoate and the carrier by using infrared spectroscopy scanning method.Moreover,using method of differential scanning calorimetry,we found that emamectin benzoate and the carrier were not only simply physical mixing,but forming a new chemical bonds.The results of X-ray powder diffraction showed that the strucrure of emamectin benzoate was transferred from crystal into non-crystalline by solid dispersion technique,existing with molecular or amorphous state,and the effect of crystal converted was strengthened with increasing of carrier amount.The microstructure of the solid dispersion was identified by using electron microscope scanning,and the irregular shape of the solid dispersion was observed.By characterizing analyzed for this solid dispersions,PVP K30 as a carrier played a role in emamecting benzoate embedded,hydrogen or new chemical bonds was formed in intermolecular,and the structure of emamectin benzoate was transferred into amorphous or molecular from crystal form.By comparing the solubility of the original drug,different feed ratio of solid dispersions and a physical mixture of original drug and carrier,we found that,when the feed ratio of solid dispersion is 1:10,the solubilization ratio is highest with almost 37.5 times.UV photolysis experiments showed that UV photolysis rate of emamectin benzoate-PVP K30 solid dispersion was significantly reduced comparing with original drugs,and represented that the solid dispersion we prepared had a property of resistance to photolysis.Moreover,the emamectin-PVP K30 solid dispersion was processed into wettable powders,and we found that,the processed wettable powder can improve the insecticidal activity of emamectin benzoate by toxicity determination.(2)Emamectin benzoate-PRIII solid dispersions and its wettable powdersIn this experiment,delivery material-polyacrylate resinIII(PRIII)as carrier,sustained-release solid dispersion of emamectin benzoate-PRIII was prepared,and drug loading and encapsulation efficiency,which was measured by HPLC,was as an standard for screening optimum craft of preparation of solid dispersions.The results showed that,the feed ratio of emamectin benzoate and PRIII should be controlled at the range of 1:4 to 1:50,and the preferred solvent was methanol.Calculated the yield for selecting a processed container,porcelain mortar was the best.The characteristic of emamectin benzoate-PRIII solid dispersions was carried out by using UV spectra,infrared spectra and differential scanning calorimetry curves,found that carrier PRIII also have embedded effect of emamectin benzoate original drug,and the embedding degree increase along with content of the carrier.The experiment of X-ray powder diffraction revealed that the structure of mamectin benzoate-PRIII solid dispersion converted crystal to non-crystal such as amorphous or molecular state.Due to diffraction peaks from crystal still have when the feed ratio of solid dispersion was 1:1,while the peaks eaks disappeared when the feed ratio of was the range of 1:4 to 1:50,we suggested that the feed ratio of solid dispersion should be controlled in the range of 1:4 to 1:50.Scanning electron microscope pictures indicated that there were pore structure of emamectin benzoate-PRIII solid dispersion,and speculated that the release of emamectin benzoate original drug will be slown down by the presence of pore structure.The studies on UV photolysis experiments of emamectin benzoate-PRIII solid dispersion revealed that the release of processed solid dispersion was retarded effectively.Processing emamectin benzoate-PRIII solid dispersion into wettable powders,and then compared these wettable powders with other commercially emamectin benzoate emulsifiable concentrate,we found that,the wettable powder,which was prepared in this experiment,can extend the persistent period of emamectin benzoate.