Study On The Oral Self-Microemulsifying Drug Delivery System Of GBE50

Self-Microemulsifying Drug Delivery Systems (SMEDDS) compose of drug, oil phase, emulsifier and assist emulsifier, it is homogeneous, transparent solution.SMEDDS can spontaneously emulsifying to form microemulsion with particle size 10～100nm when mixing with water phase, ambient temperature and moderate mixing conditions.Its characteristics are small size, transparent microemulsion clarification, a large quantity of drug solubilization, formulation stability and drug exists in the small oil droplets, the rapid distribution of the entire gastrointestinal tract, reduced stimulation by drugs and the gastrointestinal wall in direct contact; drug at oil/water distribution between the two-phase, small droplets depend on the enormous surface area greatly improve the water insoluble drug dissolution, increased bioavailability of drugs at the same time to avoid water unstable drugs hydrolysis and drugs on the gastrointestinal tract adverse stimulus.SMEDDS prescription compose of the oil phase, emulsifier , assist emulsifier and drug and so on. The main indicators of quality assessment have microemulsion particle size, self-emulsifying rate, pseudo-ternary phase diagram, phase equilibrium, the polarity of microemulsion drops, microemulsion droplet charge, drug release rate in vitro, in vivo pharmacokinetics and bioavailability, etc. Preparation of SMEDDS mainly use microemulsion pseudo-ternary phase diagram to finish. Pseudo-ternary phase diagram of the preparation methods have add aqueous titration, add oil titration, add emulsifier titration and alternately add these components. Preparation of phase diagram, it is usually inspected at emulsifier and assist emulsifier at the different Km (Km is the ratio of emulsifier and the assist emulsifier) under the formation of microemulsions , emulsifier and assist emulsifier for the pseudo-ternary phase diagram of a vertex, oil phase and water phase for another two vertices, according to each component at the critical point when the percentage of the total percentage to determine the point in the phase diagram of the location of the critical point of each curve that is connected. The component must have at Km value of pseudo-ternary phase diagram, through the pseudo-ternary phase diagram to identify the biggest component microemulsifying regional.The active ingredients for SMEDDS are selected from the many fat-soluble or water insoluble drugs, SMEDDS can improve oral drug absorption, increase its bioavailability. Compared with the traditional method of bioavailability, the micro-emulsion drug delivery system has a more prominent advantages: (1) have a high solubilization capacity for the insoluble or fat-soluble drugs; (2) higher physical and chemical stability; (3) filling the hard capsule or soft capsule, preparation simple, easy to enlarge the production. Therefore, the topic select self-microemulsifying drug delivery system carrying GBE50 for research.GBE50 are from the Ginkgo biloba leaf extract, refined formed by the State Food and Drug Administration approved the production of second-class medicine and production approval of new drugs of Ginkgo biloba raw material, it is brown to yellow-brown powder; have a special aroma, bitter taste. It contains flavonoid glycosides, terpene lactones, such as chemical composition, total flavonoids of Ginkgo≥44%, flavone glycosides≥24%, free flavonoids≥20%; terpene lactones≥6%; ginkgolic acid≤5ppm.GBE50 compose of the main two ingredients: flavonoids and ginkgolide, there is a clear protective effect on pharmacological effects mainly in the blood system, cardiovascular, cerebrovascular and so on. GBE50 for the treatment of major clinical cardiovascular and cerebrovascular diseases such as coronary heart disease, angina, myocardial infarction, cerebral embolism, cerebral vasospasm.Ginkgolide of GBE50 is difficult to dissolve in water, flavonoid aglycone medium category of water-soluble is bad, the impact of ginkgolide and flavonoids dissolved absorption, oral absorption of ordinary formulations is bad, low bioavailability, and the ordinary formulations is bitter, effecting the clinical use and promotion. To overcome the shortcomings of existing GBE50 formulations to improve bioavailability and clinical effects, combined with self-microemulsifying drug delivery system, this thesis research GBE50-SMEDDS, because of SMEDDS characteristics, increasing the surface area, drug releasing quickly, can increase GBE50 absorption rate and bioavailability, played the role of quick and efficient.System study for GBE50-SMEDDS, the use of Equilibrium Solubility and Pseudo-ternary phase diagram of the components were screened. Finally selected Cremophor EL/propylene glycol/IPM as a self-microemulsifying basic formula, we prepared GBE50-SMEDDS and study their properties (appearance, self-microemulsifying time, particle size distribution) and in vitro release carried out a mission, eventually consisting of prescription GBE50 0.12g, Propanediol 0.3g, Cremophor EL0.5g, IPM 0.25g, Vit E 0.03g; GBE50-SMEDDS with water, O.IMHCI or 6.8PBS after contact under slight agitation is quickly form a stable microemulsion uniformity in 3 minutes, particle size is 20～50nm. Determination of in vitro dissolution after 45 minutes of dissolution SMEDDS capsule up to more than 80%, while only 40% powder capsules; Bulk-equilibrium reverse dialysis bag technique in reverse, GBE50-SMEDDS quick in vitro release, 15 minutes to achieve about 30%, 45 minutes to have 70%, 90 minutes after the balance, and finally reach 90%.Using TLC with silica gel thin aluminum plate , Ginkgolides A and B have been identified. Using RP-HPLC of self-microemulsifying composition of total flavonol glycoside contents, measuring method is simple, rapid, accurate and results are reliable, quercetin average recovery was 99.25%, RSD 0.44%; kaempferol average recovery was 99.20%, RSD 0.43%; isorhamnetin average recovery was 99.31%, RSD 0.25%. The results show that, GBE50-SMEDDS containing ginkgolide A and B; total flavonol glycoside content is not less than 2.4%.Preliminary stability study, results showed that GBE50-SMEDDS has high stability while in a sealed packaging and storage under ambient temperature, the appearance of formulation, self-microemulsifying time, particle size and drug content determination was no significant change . Microemulsion with adding water is stable in 8h, thus ensuring GBE50 absorption in the gastrointestinal tract prior to the status of the microemulsion form of dissolved without precipitation to ensure that its oral bioavailability.GBE50-SMEDDS rat pharmacokinetics study, use morin as internal standard, quercetin, kaempferol and isorhamnetin as the reference substance, establish the ginkgo flavone analysis method of plasma samples. Plasma concentration-time curves and pharmacokinetic parameters showed that, Cmax of GBE50-SMEDDS increased 0.3 mg/Lthan the reference group, Tmax earlier 2.7 h, the elimination of rate decreases, the elimination half-life extend 7.4 h, the distribution rate increase , the distribution of half-life ahead 2.2h, AUC increased 13.8 mg.h/L, relative bioavailability is the reference of 152.47%, increased 52.47%. GBE50-SMEDDS new formulations has higher bioavailability than market existing agents Xinglin, providing an experimental basis for clinical efficacy improvement.The results of GBE50-SMEDDS acute toxicity in mice show that the maximum group have obvious toxicity, such as unresponsive, eyes dull, eyes have a discharge, or even death. Toxicity is caused by the agents in the oil phase materials, emulsifier and assist emulsifier.Half lethal dose LD50 = 0.33ml (0.36g)/10g, LD50 of 95% CI is 0.30～0.37ml (0.33～0.41g)/10g. GBE50-SMEDDS has acute toxic side effects of oral administration, LD50 is 1,800 times as the dose commonly used in normal adults (1.2g/60Kg). We can see, GBE50-SMEDDS although has toxic side effects, but it is safe while in clinical use according to instructions.The animal efficacy results of GBE50-SMEDDS show that in the acute blood stasis model rats hemorrheology experiment, compared with normal control group, blood stasis model group of the whole blood viscosity ratio (low-cut, medium-cut and high-cut values) and plasma viscosity are higher (P=0.000,0.000,0.000,0.014), showing that the model is successful. Compared with blood stasis model group, the positive control group can reduce whole blood viscosity (low-cut, medium-cut and high-cut values), (P=0.007, 0.01, 0.004); GBE50-SMEDDS high dose group can reduce the viscosity of whole blood (low-cut, medium-cut and high-cut values) and plasma viscosity (P=0.000, 0.000, 0.001,0.001); GBE50-SMEDDS medium dose group can reduce whole blood viscosity ( low-cut, medium-cut and high-cut values) and plasma viscosity (P=0.000, 0.001, 0.002,0.016); difference between the results of low-dose group were not significant, but have lower trend, showing GBE50-SMEDDS high, medium , low-dose group, have dose-effect relationship. The group differences in hematocnt results were not significant (due to pilot error and less sample size), but both the role of trends and dose-effect relationship, showed that an improvement in GBE50-SMEDDS acute blood stasis model and the role of hemorheology in rats and dose-dependent manner.GBE50-SMEDDS on isoproterenol-induced myocardial ischemia experiment, compared with normal control group, ischemic model group rats injected ISO myocardial ischemia soon after the change in electrocardiogram showed ST-segment elevation ( ST-30 and 35 min of P=0.001), indicating that it is a successful model. Compared with ischemic model group, the positive control group may be against ISO-induced myocardial ischemia in ECG changes, manifested as decreased ST segment (ST-30 and 35 min of P=0.038,0.007); GBE50-SMEDDS high-dose group could induced myocardial ischemia in ECG changes, manifested as decreased ST segment (ST-30 and 35 min of P=0.005,0.001); GBE50-SMEDDS medium dose group induce myocardial ischemia-induced changes in the electrocardiogram showed ST segment declined (ST-30 and 35 min of P=0.023,0.007); difference between the results of low-dose group were not significant, but has lower trend, showing GBE50-SMEDD high, medium and low-dose group, have dose-effect relationship. The results of T-wave in each group have no significant differences in statistical (due to pilot error and less sample size), but both have the role of trends and dose-effect relationship. GBE50-SMEDDS has an improvement in myocardial ischemia caused by changes in the role of ECG and has dose-dependent manner.Compared with normal control group, ischemic model group of CK, LDH and AST release increased (P=0.000), indicating that model is successful. Compared with ischemic model group, the positive control group could reduce CK, LDH and AST release (P=0.000,0.000,0.002); GBE50-SMEDDS high dose group reduced CK, LDH and AST release (P=0.000); GBE50-SMEDDS medium dose group were lower in CK, LDH and AST release (P=0.000); GBE50-SMEDDS low-dose group could reduce the CK, LDH release (P=0.005, 0.001); GBE50-SMEDDS high, medium and low-dose group, have dose-effect relationship. GBE50-SMEDDS improve myocardial ischemic injury in rats, and dose-dependent manner.Efficacy in animal experiments, GBE50-SMEDDS can improve the acute blood stasis model rats abnormality, and has a protective effect on isoproterenol-induced myocardial ischemia, and dose-dependent manner. Equivalent doses of GBE50-SMEDDS has a better effect than the control group existing market Xinglin granules , GBE50-SMEDDS efficiently improve the efficacy of GBE50, provide the basis of animal in order to improve the clinical efficacy of pharmacological experiments.