Synthesis Of Ibuprofen-eugenol Ester Prodrug And Study On Its Microemulsion Drug Delivery System

Depressing the upper gastrointestinal (GI) of NSAID and formulating poorly water-soluble drug into microemulsion delivery system were considered as two focuses in this study. Base on these two considerations, Ibuprofen eugenol ester (IEE) was synthesized. Meanwhile the physical-chemical properties, in vitro and in vivo's stability, transport mechanism and metabolism way of IEE were also investigated. IEE can be applied to mciroemulsion formulation for oral and intravenous administration. The pharmacokinetics, distribution and pharmacodynamics of the formulation were also examined in order to explore the possibility of increasing the curative effect, and decreasing the GI side effect by structure transform and formulation design.IEE [propionicacid.2-[4-(2-methylpropyl) phenyl], 2-methoxy-4-(2- propenyl) phenyl ester] was synthesized by acyl chloride method using ibuprofen and eugenol as the raw materials. The method was simple and reproducible. It can be applicable to mass production. The structure of IEE was confirmed by MS, UV, IR, ¹H-NMR spectrum, respectively. And the melting point is 41.2±0.5℃.During the physical and chemical properties studies, the solubility of the drug in different pH was determined. The solubility of IEE in water was very low (2.98μg/ml), and was not effected by pH. It belongs to poorly water-soluble lipophilic drug. However, it is easily soluble in various solvent and oil (>200mg/kg). The CLogP was 6.45. IEE shows its well stability by the results of the experiments in different temperature, humidity, and light studies. The kinetics of ester hydrolysis was studied in aqueous buffer solutions. It was stable at a wide pH range 1.10-9.96. Over this range, IEE hydrolyzed fast with pH increased.The Caco-2 cell model was utilized to examine the mechanism of IEE transport across the intestinal membrane. With the exposure to PMSF, an inhibitor of serine protease/mammalian esterase, the apparent permeability coefficients of IEE from AP-to-BL (14.46×10^-6cm/s) and BL-to-AP (15.04×10^-6cm/s) were found to be statistically indifferent (P>0.05). Therefore, IEE transported across Caco-2 cell monolayer vis an passive mechanism. The effect of BSA, PMSF, concentration, inhibitors, and temperature on the transport was investigated. It was founded that the BSA didn't affect transport of IEE in different sacs. Without the exposure to PMSF, IEE can be hydrolysis into ibuprofen before or during transport. The transport of IEE was actually due to the combine result of IEE and ibuprofen. Under various concentrations, the different P_app of IEE, ibuprofen and saturate degree of esterase for hydrolysis caused the differents of P_app. The permeability coefficient was not affected when verapamil and indomethin were added, illustrating the drug was not transported via efflux mechanism. The P_app of IEE was affected by temperature significantly because of the different active of esterase under various temperatures. It can be concluded that the transport of IEE depends on the esterase participation. Therefore, the absorption oflEE was shown well.IEE and its seven metabolites were first identified in rat urine and plasma with LC/MSn method, which included one phaseâ… metabolite and six phaseâ…¡metabolites. It found that the metabolites substrates included IEE and ibuprofen, which illustrated that IEE had undergone expand metabolite. No IEE but ibuprofen was found in plasma sample after 1 h iv or oral administration. It demonstrates that the IEE can be hydrolysis to ibuprofen in vivo. However, no eugenol was found both in plasma and urine sample. According to the experimental results in this study, it can be deemed that the IEE was hydrolyzed to form eugenol and ibuprofen, followed by conjugation with glucuronic acid, which forms the major metabolic pathway of IEE in rats. LC/MSⁿ study brought the foundation for pharmacokinetic analysis of IEE-ME.A novel microemulsion, which administrated for oral and intravenous route, was prepared to facilitate the absorption, decrease GI side effect, and increase the bioavilability. For the mieroemulsions, Miglyol 812 was chosen as oil phase, SbPC and HS-15^R as surfactants (S), PEG400 and ethanol (7:3) as cosurfactant (CoS) and the double-distilled water as water phase. Pseudo-ternary phase diagrams were constructed to obtain the concentration range of each component for the microemulsion formation. The effects of various ratio of SbPC to HS-15 and different weight ratios of surfactant to cosurfactant (S/CoS) on the droplet size were investigated, as well as viscosity and stability of microemulsion. The constitute of stable blank ME with more oil and little surfactant was confirmed. The effect of drug on the ME was also examined. When the drug content was below 40ï¼…in oils (Miglyol 812), drug-loading of ME can obtained 100ï¼…with less droplet size. When the drug content was above 40ï¼…, the drug loading declined and the drug precipitation was founded. The droplet size and droplet distribution increased. The consist of optimize formulation was IEE/Miglyol 812/SbPC/HS-15/PEG 400/Ethanol/Water (6.4/9.6/6/6/8.4/3.6/60g).The in vivo pharrnacokinetic behavior of IEE was studied utilizing HPLC method. Using the oral and intravenous route, the absolute bioavailability and pharmaeokinetic study of IEE microemulsion in rats were performed. The pharmacokinetic parameters were studied according to non-compartment model. The distribution study after intravenous administration indicated that the drug concentration in liver and spleen, RES-rich tissues after the dose of IEE-ME were significantly lower. However, the drug concentrations were higher in heart, lung and brain than those after the dose of ibuprofen solution. The prolongation of the MRT and the delay of removal of IEE-ME from circulation indicated that the formulation has sustained effect.Acute toxicity results suggested that the LD₅₀ of IEE-ME for oral and intravenous formulation were 714.7 and 197.2 mg/kg, respectively. The pharmaceutical safety test results indicated that hymolysis, simulation and pyrogen, none of these negative effects was found. The analgesic activity of IEE-ME was the same as the ibuprofen in mice utilizing hot plate method and acetic acid-induced analgesic method after the same dosage of oral and intravenous administration in pharmcodynamics test. Inhibitory effect of IEE-ME was significant by using intraplantar injection of carrageenan in rat and dimethylbenzene induced ear swelling in mice, respectively. The results of ulcerogenic activity indicated that the IEE-ME can significantly decrease(P＜0.05)the GI irritation after oral administration. It was the same as the control group.