Pharmacokinetics Of Sitafloxacin Granules In Healthy Chinese Subjects

Purpose:Sitafloxacin is a quinolone antibacterial drug,with broad antimicrobial spectrum and strong antibacterial activity.It has a broad antibacterial spectrum of aerobic or anaerobic gram positive or gram negative bacteria and non shaped bacteria,and especially displays stronger antibacterial activities than other quinolone antibacterial drugs against those as pneumococcal(including penicillin resistance and macrocyclic lactone antibiotic resistant pneumococca)、enterococci genera、Pseudomonas aeruginosa bacteria and coliform(containing quinolone resistant Escherichia coli).Sitafloxacin has dual inhibitory effects on bacterial DNA gyrase and topoisomerase IV and its inhibitory effect is stronger than other quinolones.It is reported that against Streptococcus pneumoniae the dual inhibitory activity were 17 and 4 times of levofloxacin,120 and 1.5 times of ciprofloxacin,14 and 2.5 times of moxifloxacin,respectively.Sitafloxacin was first used clinically in the form of tablets and granules in Japan in 2008,orally administered from 25 mg to 200 mg.It was primarily for symptoms of respiratory tract and urinary tract infectious diseases.10 clinical trials and 13 in vitro studies conducted in Japan have shown the safety of treatment with sitafloxacin.Then we wondered whether sitafloxacin could be applied well in China.Therefore,based on the sitafloxacin granules(having completed the preclinical studies and obtained SFDA drug clinical trial document)developed by a domestic company,we investigated the pharmacokinetic characteristics of sitafloxacin granules in healthy Chinese subjects,prodiving information for further clinical evaluation as an orally fluoroquinolone antibacterialMethods and Results:This study consists of three parts.(I)To establish and validate the method for determining concentrations of sitafloxacin in human plasma and urine samples.For plasma and urine samples,methanol was used as the precipitant.Chromatographic separation was carried on a Poroshell 120 SB-C18 column(2.1 mm×50 mm,2.7μm)with a mobile phase consisting of 38%of methanol and 62%of 0.1%formic acid.The flow rate of the mobile phase was 0.5 mL/min.Moxifloxacin hydrochloride was used as the internal standard(IS).The MRM transitions of m/z 410.1→392.0 and 402.2→384.1 were used to quantify sitafloxacin and IS,respectively.Method validation results:There was no interference in plasma and urine samples.The calibration curves for determination the concentration of sitafloxacin in plasma and urine showed good linearity over the range of 10.00～4000 ng/mL and 0.250～200 μg/mL,respectively.The lower limit of quantification were 10.00 ng/mL and 0.250 μg/mL,respectively.The recoveries in plasma and urine samples were 97.4%～100.6%and 94.0%～98.2%,respectively.In the plasma,the intra-batch accuracy was 90.1%～97.5%,while intra-batch precision was 1.9%～4.4%,and inter-batch accuracy was 95%-97.7%,while inter-batch precision was 2.4%-6%In the urine,the intra-batch accuracy was 100.8%～102.9%,while intra-batch precision was 0.5%～3.2%,and inter-batch accuracy was 99.8%～102%,while inter-batch precision was 1%～4.8%.Analytes were stable during the study.(Ⅱ)The pharmacokinetics study following a single oral administration of sitafloxacin granules(50,100,200 mg)in healthy subjects.It’s a phase Ⅰ,single center,open-label,randomized study which consists of three dose groups.The 50 mg dose group is designed as two period crossover study with five days’ wash-out period and then the two groups of subjects were reversed to go on the fasting and postprandial study investigating the diet impact.10 subjects each dose group,half male and half female,were enrolled in the Clinical Trial Unit of the First Affiliated Hospital of Nanjing Medical University complying with GCP and the declaration of Helsinki.The pharmacokinetic characteristics following the oral administration of sitafloxacin granules were studied,and the safety of the drug was observed.Plasma samples were collected before and after administration within 36 h,while in 50 mg dose group,the urine samples were also collected before and after dosing within 60 h.The concentration of sitafloxacin in plasma and urine samples were determined by using the validated LC-MS/MS method mentioned in part Ⅰ.We used Das 2.1.1 and Excel 2007 software to calculate noncompartmental pharmacokinetic parameters,and used SPSS 11.5 software to study the relation between the dosage and parameters Cmax and AUC to see if it was linear.Impacts of gender and diet factors on pharmacokinetic characteristics were also investigated.All dose groups were evaluated the safety after oral dosing.Results of this part showed that the noncompartmental pharmacokinetic parameters in dose groups of 50 mg(fasting)、50 mg(postprandial)、100 mg(fasting)and 200 mg(fasting)were(760.3 ± 127.7)ng/mL、(366.1±37.6)ng/mL、(1428 ± 224)ng/mL、(2830±623)ng/mL of Cmax,(0.50 ± 0.15)h、(2.58± 0.76)h、(0.55±0.22)h、(0.85±0.29)h of Tmax,(4.37 ± 1.13)h、(4.83 ± 1.59)h、(4.76 ± 1.53)h、(5.74±0.75)h of t1/2,(5.97 ± 1.19)h、(7.53 ± 1.53)h、(6.19± 1.35)h、(6.86 ± 0.76)h of MRT0-∞,(3377 ± 827)ng·h/mL、(3024 ± 672)ng·h/mL、(6820 ± 1254)ng·h/mL,(15439+2951)ng·h/mL of AUC0-∞,respectively.C1/F were(15.44 ± 2.98)L/h,(17.12 ± 3.00)L/h,(15.10 ± 2.70)L/h and(13.36 ±2.35)L/h.Vd/F were(94.3 ± 13.6)L,(115.2 ± 27.3)L,(100.4 ± 23.4)L and(112.2± 30.7)L.The amount of accumulative excretion of sitafloxacin in urine under fasting and postprandial conditions were(35.01±3.18)mg and(32.95±5.34)mg respectively.The rate of accumulative excretion of sitafloxacin in urine under fasting and postprandial conditions were(70.0±6.4)%and(65.9±10.7%)respectively.In preliminary pharmacokinetic study of the relationship between dose and parameters,it could be concluded that oral administration of 50 to 200 mg sitafloxacin granules’Cmax and AUC0-∞ in the human body had linear pharmacokinetics.30 subjects were well tolerated and no adverse reactions about those such as allergy,gastrointestinal tract,central nervous system and cardiac toxicity were found.The results of ECG and hearing tests were normal.No adverse events and serious adverse events occurred.(Ⅲ)The pharmacokinetics study following a multiple oral administration of sitafloxacin granules(100 mg)in healthy subjects.In the second part of the study,the single 100 mg dose was followed by 100 mg daily for 5 days from day 3.The pharmacokinetics were studied,and the safety of the drug was observed.The plasma samples were collected before and after dosing within 36 h on day 7,while on day 5 and 6 the samples were also collected before dosing.The concentrations of plasma were determined by using the validated LC-MS/MS method in part I.Das 2.1.1 and Excel 2007 software were used to calculate noncompartmental pharmacokinetic parameters,and SPSS 11.5 software was used to calculate the influence of multiple dosing on the pharmacokinetic parameters.Evaluation of safety after oral administration of drugs was carried on.Steady-state plasma concentration was reached after administered continuously for 3 days.The average concentration was(39.03 ± 20.49)ng/ml,the DF of steady-state plasma concentration was(4.364 ±1.078),indicating that concentrations of multiple dose of 100 mg fluctuates.On day 7,the pharmacokinetic parameters were as follows:Cmax(1200±309)ng/ml,Cav(268.3± 47.7)ng/ml,Tmax(0.67±0.32)h,t1/2(5.35 ± 1.68)h,AUCSS(6440 ± 1144)ng·h/mL,AUC0-∞(6795 ± 1449)ng·h/mL.10 subjects were well tolerated and at 120 h after dosing,most of laboratory tests results such as blood,urine,stool,APTT were in the normal range.Hearing examination and ECG examination were within normal range.No adverse reactions such as allergy,gastrointestinal tract,central nervous system and cardiac toxicity were found.No adverse events and serious adverse events occurred.Conclusion:Method validation results showed that the established LC-MS/MS method could be used to determine drug concentration of sitafloxacin in human plasma and urine samples,thus the method could be used for pharmacokinetic study of sitafloxacin in the human subjects.The clinical trial study showed that the oral absorption of the drug was rapid,the half-life was long,and the distribution of the tissue was wide.Study on the relationship between the parameters of pharmacokinetics and dose in the range 50～200 mg showed the characteristics were linear pharmacokinetics.Multiple oral test showed that the 5-day multiple dosing of the drug did not accumulate.The impact of diet on pharmacokinetics was not significant that the peak concentration decreased and the time to peak concentration prolonged.Gender had little influence on the pharmacokinetic characteristics.The subjects were well tolerated,and it was safe within the dose range of the trial.