Fabrication,Characterization And In Vivo Evaluation Of Rutaecarpine Nanosuspensions

Nanosuspension is a sub-micron colloidal dispersion of pure drug particles in a liquid phase, which are stabilized by surfactants. It offers a best formulation for these poorly soluble drugs. Rutaecarpine (Rut) is a quinazolinocarboline alkaloid isolated from Evodia rutaecarpa. It has been reported that vasodilator response to Rut is related to activation of vanilloid receptor subtype 1 (VR1) and the resultant release of CGRP. Rut is classified as a Biopharmaceutics Classification System(BCS) Class-Ⅱcompound with a poor solubility in water as well as in organic media and a high permeability in Caco-2 cell-line model, resulting in poor absorption and low bioavailability upon oral administration. In this thesis, Rut nanosuspension was prepared and characterized. The influences of particle sizes and surfactants on the absorption of Rut were investigated.Fabrication:Microprecipitation was used to fabricate five Rut nanosuspensions with polyethylene glycol (PEG-400) and water as cosolvent. Rut was dissolved in PEG-400 and the resulting solution was then added to an aqueous surfactant solution (crystallization medium) to induce crystallization. A variety of experimental parameters including drug concentration, surfactant, PEG-400/water ratio, pulverization strength, pulverization time and temperature were studied. We demonstrated that surfactants had strongest effects on the particle sizes. SDC gave smallest particles. Lower solution temperature and stronger pulverization gave decreased drug particle sizes. To some extent, strong pulverization can result in increased solution temperature. The optimized preparation condition is:solutions are mixed in an ice bath and probe sonicator power is set at 240 w (10 mL). Three Rut nanosuspensions with an average particle size of-200nm using different crystallization mediums(1.0.5%SDC;2.0.5%SDC,0.25%Poloxamer188;3.0.5%SDC,0.25 %Poloxamer 188,0.25%Tween80) were prepared. Three Rut nanosuspensions with average particle sizes of-200nm,-600nm,-1000nm respectively using crystallization medium 3 was formulated under optimized conditions. Characterization:The Rut nanosuspensions were characterized by particle size distribution, Zeta-potential and morphology, and their solubility and dissolution properties. We also demonstrated that the dissolution rate could be enhanced by reducing drug particle size. The saturation solubility of three Rut nanosuspensions (200nm,600nm, 1000nm) were 120.88,16.26,14.56(μg·mL-1) and the zera-potential was higher than 30mv. TEM studies confirmed that the nanosuspension particle was acicular crystal and DSC studies revealed that the crystalline form of the drug was unstable. Rut nanosuspension particles are stable if stored at 25℃.In vivo evaluation:40 male SD rats were randomly divided into five groups (1:crystallization medium 3-1000nm; 2:crystallization medium 3-600nm; 3:crystallization medium 3-200nm; 4:crystallization medium2-200nm; 5:crystallization medium 1-200nm).Five formulations were administered to the five groups respectively at a 40 mg kg-1 dose level as i.g. Blood samples were collected from the retro-orbital sinus at different time points. The samples were added to treatedtubes which contain dried heparin and assayed by HPLC after appropriate processing. One-way analysis of variance(ANOVA) was used to test for significant difference in AUC, Cmax, group t-test was used for ka, Wilcoxon nonparametric test was used for Tmax.When comparing groups 1,2,3, formulation 3-200nm provided 4.2-fold and 7.7-fold enhancement in Cmax,4.3-fold and 9.4-fold enhancement in AUC0→∞relative to formulation 3-600nm and formulation 3-1000nm, respectively. The values Cmax and AUC0→∞for Rut (group 3) were significantly (p<0.01) larger than comparison (group 1 and group 2). As the same, the values Cmax and AUC0→∞of group 2 were significantly (p<0.01) larger than comparison group 1. However, there were no significant differences (P>0.05) in Cmax and AUC0→∞among groups 3,4,5. In addition, the Tmax and ka values of five groups were not remarkable differences (P>0.05). The results showed that diminishing the size of particles could increase the solubility and bioavailability of Rut; Alteration of surfactants had no remarkable effects on the absorption of Rut.By investigation on fabrication, characterization and relationship between absorption and particle size of drug, the thesis confirmed that diminished particle size could increase the saturation solubility and bioavailability of Rut. The total amount of absorption was increased by 9-fold when the particle size decreased from 1000 nm to 200 nm. There were no remarkable differences between the groups using drugs with same particle size. These results provided basic references of Rut for further research of dosage form, dose determination, pharmacokinetics and toxicology.