| Florfenicol is an antibiotic of chloramphenicol, it has F and CH3SO2- to substitute with-OH and -NO2 of chloramphenicol. Therefore, Florfenicol shows better antibacterial effect than chloramphenicol and doesn't cause anaemia of regeneration barriers. However, the water solublility of florfenicol is very low and this has an impact on its bioavailability. There are currently organic solvent, inclusion, solid dispersion and other methods to increase its solubility, but can not achieve the desired effect. Therefore, to make water-soluble florfenicol prodrug by chemical methods shows a good prospect and will be the trend of such studies.Florfenicol molecule has a p-hydroxyl group, in the presence of alkaline catalyst, could be esterified with carboxylic acid or anhydride. The best synthesis process of Fl-S was chosed by single factor and orthogonal test.The results showed that:4 dimethylaminopyridine (DMAP) as catalyst and acetone as the solvent, florfenicol: Succinic Anhydride:DMAP=1:1.2:1.2 (molar ratio), temperature:60℃, reaction time:8h conditions can make the highest synthesis rate of Fl-S. Use of bicarbonate sodium solution and hydrochloric acid can achieve the effect of purification and crystallizeation of Fl-S. Fl-SNa obtaining excellent characteristics can be prepared by freeze-drying.In this study, the high purity of Fl-S was determined by the melting point apparatus and high performance liquid chromatography (HPLC) analysis. Retention time of florfenicol and Fl-S was 7.850min and 12.175min, respectively. UV absorption spectra showd that the modification of florfenicol may be phenyl, hydroxyl, chlorine group atom andcarbonyl; infrared absorption spectra showed that florfenicol and its modification had a similar structure, but the modification possessed carboxylic acid carbonyl and ester carbonyl; Fl-S can be hydrolyzed to florfenicol by strong alkaline hydrolysis. In summary, the successful synthesis of Fl-S could be confirmed. Results of water solubility and partition coefficient florfelicol and Fl-SNa at 25℃: solubility of florfelicol was 0.135±0.002g/100mL, Fl-S-Na was 54.524±0.12g/100mL, solubility of Fl-SNa was greatly increased. Lipid-water partition coefficient of florfenicol was 2.38, Fl-S-Na was 0.16. Hemolysis experiments of Fl-SNa showed that there was no hemolysis when the concentration of Fl-SNa was achieved 10mg/mL. It was proved that their potential application in water-soluble injection or injection powder preparation for intramuscular or intravenous injection in animals. Factor experiments of high temperature (60℃), high humidity (90%±5%,75±5%) and strong light (4500lx±500lx) of Fl-SNa powder showed that Fl-SNa was greatly influenced by humidity, its weight was improved 25.6% after 5d under the conditions of 75% humidity.The Fl-SNa solution and conventional florfenicol injection were administrated on health rabbits by intramuscular injection. Using florfenicol as a reference, their pharmaco-kinetic differences were compared. Plasma drug concentration was determined by HPLC, limit of detection of plasma concentrationwas O.lug/mL. Pharmacokinetic parameters were analyzed by DAS2.0 pharmacokinetic program. The data was analyzed by SPSS (17.0). The results showed that data of A, B group was in line with a two-compartment model (weight=1/CC), The main pharmacokinetic parameters and the fitting equation as follows: A group:Ka was (1.483±0.031) 1/h, T1/2αwas (0.576±0.044) h, T1/2βwas (2.501±0.203) h, AUC (0-∞) was (28.851±0.494) mg/L* h, Cmax was (8.863±0.254) mg/L, Tmax was (1±0.000) h, the fitting equation:C=73.69e-1.208t+5.592e-0.278t-79.282e-1.483t. B Group:Ka was (0.703±0.084) 1/h, T1/2αwas (1.324±0.295) h, T1/2βwas (1.475±0.168) h, AUC (0-∞) was (39.187±0.413) mg/L* h, Cmax was (7.363±0.085) mg/L, Tmax was (2±0.000) h, the fitting equation:C=126.57e-0.539t+12.417e-0.474t-138.987e-0.703t。In summary, According to the principle of prodrug, this issue made succinic anhydride and hydroxyl of florfenicol to form ester, to synthesize its prodrug of florfenicol Succinate (Fl-S), Fl-S then reacted with alkaline salts to form the water-soluble florfenicol succinate sodium (Fl-SNa). Preliminary studies of characterization and pharmacokinetics in rabbits of Florfenicol and Fl-SNa were carried out. The method is simple, the yield is high, the reaction required less, and it is suitable for industrial production. |
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