Study on Pharmacokinetics of Levofloxacin Polymorphs in Rats

Objective To study the pharmacokinetics difference of levofloxacin polymorphs in rats,evaluate the advantageous medical polymorph,and explore the effects of different polymorphs on clinical medicine. Methods Four crystal forms of levofloxacin were administered intragastrically to rats,and high performance liquid chromatography( HPLC) was used to measure the contents of levofloxacin in rat plasma. The pharmacokinetic parameters were calculated and compared Results After a single oral dose,the peak plasma concentration( Cmax) of crystal forms ofⅠ,Ⅱ,Ⅲ and Ⅳ of levofloxacin was 6. 984,9. 692,9.405,6. 424 mg·L- 1; the time to peak( tmax) was 0. 6,0. 9,1. 0,1. 0 h; the half-life( t1 /2) was 4. 207,2. 97,4. 857,1. 695 h;the area under the curve( AUC0→12 h) was 31. 478,42. 385,32. 406,31. 636 mg · h · L- 1. Conclusion There is no statistically significant difference in pharmacokinetic parameters. However,compared with other crystal forms,plasma concentration of crystal form II is higher and maintained longer. Therefore,crystal form II of levofloxacin is an advantageous polymorph for medicine.