| Total glucosides of paeony (TGP), which is used to treat rheumatoid arthritis(RA), is presented by numbers of pharmacies, whose main component is Paeoniflorin (Pae), and both drugs have a good anti-inflammatory and immunomodulatory effect. But the effect of TGP is very slow, according to the reference that when Pae was given by intragastric (ig)administration to the rats alone, the bioavailability of Pae is only 0.3%, so as the main component of TGP, the poor absorption of Pae may be one of the reasons which result in the slow effect. Microemulsion (ME) is a new vehicle for drugs, and it can increase the stability of drugs, increase the bioavailability and delay the release of drugs. Our experiment studies the therapeutic effect of Pae ME preparation on rats with adjuvant arthritis (AA), and then studies the absorption kinetics of Pae ME preparation in intestine and pharmacokinetics (PK) in vivo based on pharmacodynamics experiments.Whether alterting pharmacokinetics characteristic of drugs can have an influence on therapeutic effect or not? And all the above provides the experiment evidence for developing the new preparation of Pae ME.Objective:1. Study and compare the therapeutic effect on AA rats among Pae ME preparation, Pae liquor and TGP solution, meanwhile, study whether therapeutic effect of Pae ME preparation is superior to other two drugs or not?2. Compare Pae ME preparation with Pae liquor in absorption in intestines, and study whether the absorption in intestines of Pae ME preparation is superior to Pae liquor or not?3. Establish the high performance liquid chromatograph (HPLC) method for analyzing the concentration of Pae in biological sample, the aim of this study is to study the PK parameters of Pae in AA rats after ig administration Pae ME preparation, and compare the PK parameters between Pae ME preparation and Pae liquor at a dosing of 100mg·kg-1.Methods:1. Establish AA rat model and study therapeutic effect on AA rats by paw swelling, polyarthritis index, arthritis tenderness, thymus index, spleens index and patho-morphology of synovial membrane tissue.2. Establish the HPLC assay by Hypersil C18 column (4.6mm×250mm, 5μm)with methanol-water (32:68, V:V) at a flowing speed of 0.8ml·min-1, wavelength of UV was 230nm, and 30μl sample was injected into the C18 column after filtering through 0.45μm microporous membrane, meanwhile the temperature of column was 30℃. Detect and compare Pae concentration in intestine perfusate of different time between Pae liquor and Pae ME preparation, and then calculated correlated absorption kinetics parameters.3. Establish the HPLC assay by Hypersil C18 column (4.6mm×250mm, 5μm) with acetonitrile-water-glacial acetic acid (18:82:0.4, V:V:V) at a flowing speed of 0.7ml·min-1 with a detection wavelength of UV 230nm, and 30μl of sample was injected into the C18 column where the temperature was 30℃. The plasma sample was extracted with acetoacetate, blown by Nitrogen gas, and dissolved in methanol for HPLC analysis. Detect concentration of drug in plasma at different time after ig administration of Pae ME preparation and Pae liquor in AA rats. The plasma concentration-time curve, determination of compartment model and the pharmacokinetic parameters were then calculated with DAS ver 2.0 practical PK program.Results: 1. Three groups of Pae ME preparation(25, 50, 100mg·kg-1)inhibited obviously the secondary paw swelling, down-regulated polyarthritis index, ameliorated arthritis tenderness response in AA rats; groups of Pae ME preparation(50, 100mg·kg-1)conspicuously suppressed the abnormal thymus index and spleens index; the group of Pae ME preparation (100mg·kg-1) significantly reduced the infiltration of inflammatory cells, inhibited synovialis'and blood vessel's proliferation; compared to the groups of Pae liquor and TGP, the therapeutic effect of Pae ME preparation's (50,100mg·kg-1) on AA rats was better.2. When the concentration raised from 2.0 to 20.0μg·ml-1, the uptake of Pae increased linearly, and the absorption rate(Ka) almost kept at the same level, besides, the uptake and absorption rate of Pae ME preparation was higher than Pae liquor; as the concentration of perfusate was 20.0μg·ml-1, different segments of intestine had different Ka and uptake, such as Ka and the uptake of colon were evidently higher than duodenum, jejunum, ileum, the Ka were(0.501±0.031), (0.086±0.003), (0.108±0.017), (0.114±0.006)h-1 respectively.3. The mean plasma concentrations of Pae after ig Pae ME preparation with multidoses in AA rats (25mg·kg-1, 50mg·kg-1, 100mg·kg-1) could be fitted to a two-compartment model ,the main PK parameters of Pae in AA rats were as follows: T1/2α(h)were 1.358±0.872, 1.575±0.454, 1.482±0.472; T1/2β(h)were 12.005±3.137, 11.319±2.688, 11.550±3.666; CL/F(L·h-1·kg-1)were 3.619±0.753, 6.258±1.498, 8.551±0.841; V1/F(L·kg-1)were 25.712±5.790, 58.594±25.319, 51.657±29.631; Tmax(h)were 2.500±0.000, 2.700±0.274, 3.200±0.447; Cmax(μg·L-1)were 572.115±33.722, 752.829±83.140, 1707.165±337.110; AUC0-t(μg·h·L-1)were 5479.465±883.216, 6590.466±1524.686, 9544.072±984.886; AUC0-∞(μg·h·L-1)were 7145.370±1440.355, 8496.499±2689.046, 11840.405±1158.676; MRT0-t(h)were 8.842±0.360, 8.833±0.696, 8.095±0.803;3. Compared with PK parameters of Pae liquor group(100mg·kg-1)in AA rats, Cmax,AUC0-t,AUC0-∞of ME preparation group significantly increased, MRT0-∞ of ME preparation group significantly prolonged, and V1/F,CL/F of ME preparation group significantly decreased.Conclusion: 1.Compared with groups of Pae liquor and TGP, Pae ME preparation's(50, 100mg·kg-1)therapeutic effect on AA rats is better.2.The absorption of Pae ME preparation is a first-order process with the passive diffusion mechanism; the Pae ME preparation's absorption is better than its liquor in intestine; compared by uptake and ka among different segments in intestine, the absorption of Pae ME preparation is higher in ileum and colon.3.The administration of Pae by carrier ME significantly increases the bioavailability; prolongs the mean residence time; decreases the clearance of Pae. |
PDF Full Text Request