Preparation And Quality Evaluation Of Tanshinone â…¡A Microemulsion

Tanshinoneâ…¡A has superactive pharmacological actions on cardia and cerebralvessels, high pharmacological activity of anti-leukaemia and anti-tumor. However,the poor solubility and short half-time of elimination of Tanshinoneâ…¡A greatlylimited its clinical application. Microemulsion as a potential carrier for injectabledrug with good application perspectives, can improve the solubility of drugs,lengthen the drug's acting time in vivo due to its slow release from microemulsion,and reduce pain caused by injection due to its low viscosity. We selectedmicroemulsion as drug carrier and tanshinone IIA as the model drug to preparetanshinoneâ…¡A microemulsion. We investigated the characters of tanshinoneâ…¡Acorrelated. Then by the pseudo-ternary phase diagrams, we investigated theformulation and formula technology of microemulsion, screening the formula ofblank microemulsion with low content of surfactants, good solubilization and stablequality, and prepared tanshinone It A microemulsion. The quality of tanshinoneâ…¡Amicroemulsion was assessed by transmission electron microscope, laser nano-sizeranalyzer, Zeta potential meter, HPLC and so on. This work aimed to supply valuabletrials for the preparation of injectable microemulsion for Chinese medicinalingredients with poor solubility.Through the investigation of the solubility of tanshinoneâ…¡A, we found its poorsolubility in water/oil. Tanshinoneâ…¡A was not stable under the intensive light andhigh temperature after the investigation of the effects on the stability trials, and concluded that it should be stored away from light. We established an accurate assaymethod of tanshinoneâ…¡A, which settled the foundation for blank microemulsionformula screening and quality evaluation of tanshinoneâ…¡A microemulsion.We chose the soybean phospholipids, polyoxyethylene hydrogenated castor oiltween-80, F68 as suffactants, ethanol, iso-propyl alcohol, propylene glycolpolyethylene glycol 400 and glycerine as co-surfactants, ethyl oleate, glyceryltrioleate, caprylic acid/caprin acid tri-glyceroester and injectable soybean oil as oilphase. On the basis of the pseud-triangular phase diagrams obtained from titrationmethod, the effects on the area of microemulsion and the solubilization amounts ofoil of various elements (surfactants, co-surfactants and oils) were investigated tosearch rational microemulsion formula. We found that the area of microemulsion andthe solubilization amounts of oil was small with various surfactants single used. Thesystem composed of Cremophor EL/ethanol/Ethyl Oleate/water showed the besteffect. After further research we found that the area of microemulsion and thesolubilization amounts of oil was better than single surfactant, by using combinatedsurfactants with different hydrophilicity and lipophilicity. And we received the besteffect from the combination of Cremophor EL and lecithin. Using the combination ofCremophor EL and lecithin as mixed surfactants, the effects of Rs (the ratio ofCremophor EL and lecithin), Km (the mass ratio of surfactant/co-surfactant),temperature and the drug, on the area of microemulsion were further investigated.We preliminarily fixed the alternative Km (3:1:2 and 3:1:4) for further research ofthe formula. On the basis of the research of phase diagram, physico-chemicalproperty such as appearance, particle diameter and distribution, weight of drugloaded and stability were investigated to optimize the fomula. Finally we ascertainedthe blank microemulsion formula, the optimized one was the system of CremophorEL/lecithin/ethanol/Ethyl Oleate/water (2:1:2:5). Single factor test was used toinvestigate the effects of preparation technology such as dispersion method,temperature, agitating time and velocity, on the weight of drug loaded ofmicroemulsion. The preparation condition was chose that, the drug was added after the blank microemulsion prepared, and agitated for 6 hours at the rate of 200 r·min^-1at 25℃. We preapared tanshinoneâ…¡A microemulsion with the optimizedmicroemulsion formula under the condition screened.The quality of tanshinoneâ…¡A microemulsion was assessed. Tanshinoneâ…¡Amicroemulsion was uniform and transparent fluid with light orange, its viscosity was6.5 mm³Â·s^-1, with the conductivity 65.9μs·cm^-1. We found that tanshinoneâ…¡Amicroemulsion were almostly in sphaeroid form and its distribution was uniformthrough the transmission electron microscope. The particle diameter and itsdistribution of tanshinoneâ…¡A microemusion were determined by laser grainsizeanalyzer of Nano-Zetasize 3000HS, its mean diameter was 22.6 nm, with Zetapotential -2.7 mV. We established an accurate method for the determination oftanshinoneâ…¡A in the microemulsion. Tanshinoneâ…¡A was determined byRP-HPLC, the line rang was 2.164～138.5μg·ml^-1, (r=0.9999, n=6). Its averagerecovery rate was 98.75% and the RSD 1.45%. The method was convenient, rapid,accurate and suitable for assay of Tanâ…¡A in the preparation, and the loaded drug was748.4μg.ml^-1. Physical appearance, particle size, distribution and contents oftanshinoneâ…¡A were used as indexes to evaluate the stability of tanshinoneâ…¡AME. After storage for 3 months against the light at 4℃, its physical appearance,particle size with distribution and contents of tanshinoneâ…¡A changed little. Butunder room temperature, the appearance had changed into light color with thecontent declined lightly. The result showed that its stability was quite good.Crernophor EL/lecithin microemulsion were obtained through our research with lowcontents of surfactants and good stability, which significantly improved the solubility oftanshinoneâ…¡A, exceeding 100 times than solved in water. We achieved the primaldestination of the investigation, and supply valuable trials for the preparation ofinjectable microemulsion for Chinese medicinal ingredients with poor solubility.