Synthesis Of Florfenicol Sodium Succinate And Research On Its Pharmacological Effect

Based on prodrug strategy,florfenicol sodium succinate(F-S-Na)had been synthesized successfully in our laboratory,which is water-solube prodrug of florfenicol by esterification with succinic anhydride.Then,the antibacterial activity and acute toxicity of F-S-Na were researched.The p-hydroxy of florfenicol could be esterified with acid anhydride in the presence of catalyst. The high purity of F-S was determined by melting point test and high performance liquid chromatography analysis.The modification of florfenicol may has benzene ring,hydroxyl,chlorine group atom and carbonyl,analyzed by ultraviolet absorption spectrum.Through analyzed by infrared absorption spectrum,florfenicol and its modification have a similar structure,but the modification posses ester-carbonyl and carboxy-carbonyl.The binds among atoms were determined by ¹H-NMR, ¹³C-NMR and MS.To combine together these methods,the molecular structure of F-S could be identified.In clinical praeparatum,the water-solubility of 300mg/mL or more are often desired,and F-S-Na was found to have excellent solubility in water,over 500mg/mL.The hydrolytic circumstance of F-S-Na was investigated by HPLC method under different conditions.Florfenicol and F-S-Na have the same ultraviolet absorption maximum at 224 nm.This method shows good seperating degree of florfenicol and F-S-Na when phosphonic acid was added in the eluent.The retention time of florfenicol and F-S-Na were 10.3min and 13.9min,respectively.The F-S-Na was stored in water 60d at room temperature,the relative transformation. efficiency(the peak area of florfenicol/the sum of florfenicol and F-S-Na)was only 0.706%,the result suggested that the ester bond breaking in F-S-Na could not be accelerated swimmingly by water.At 37℃,the relative transformation efficiency was below 3%when the F-S-Na was stored in new-born calf serum after 4 hours,only 3.844%after 72 hours.F-S-Na was studied on rat following single intramuscular administration at a dose of 100.0mg/kg(florfenicol was 76.2mg/kg equivalently),F-S-Na was transformed into florfenicol in blood plasma fleetly after injection.The peak time of florfenicol in blood plasma was 1 hour after administration,and the peak concentration was.25.05μg/mL,the relative transformation efficiency was 77.71%.The concentration of florfenicol in blood plasma was more than 6μg/mL in 4 hours, after administration,F-S-Na was converted to florfenicol efficiently and in substantial amounts,it is shown that the compound can be used to treat or prevent bacterial infections well.After 8 hours,the plasma concentration of florfenicol was low and abiding.These hydrolyze experiment indicated that the stability of F-S-Na in vitro is good,the F-S-Na could be hydrolyzed sufficiently rapidly and in sufficient amounts to provide florfenicol in a concentration in rat which was catalyzed by some enzymes.These tests demonstrated that the water-soluble prodrug of floffenicol was prepared successfully.Micro-dilution method was used in the antibacterial experiment.Florfenicol inhibited the growth of Bacillus coli,staphylococcus aureus,Bacillus subtilis,Bacillus typhi,Salmonella,Bacillus aeruginosus,Bacillus proteus and Gaffkya tetragena,and the MIC was 0.5,4,2,1,2,2,1 and 2μg/mL,respectively.The MIC of F-S-Na was 64,256,128,128,256,256,128 and 128μg/mL, respectively.The antibacterial activity of the modification decreased significantly,it is shown that the active group of florfenicol was defiladed successfully,which is consistent with prodrug strategy.The LD₅₀of F-S-Na injection in mice by intramuscular injection was found to be over 5000mg/kg,the result indicated that the toxicity of this compound was very low.