| Biapenem is a new carbapenem antibiotic, which possesses potent broad- spectrum antimicrobial activity because of their activity against Gram-positive and Gram-negative aerobic and anaerobic bacteria, and less bacterial resistance, compared with otherβ-lactam antibiotics.Biapenem could be used for a variety of infections caused by sensitive bacteria:septicemia pneumonia, lung abscess, refractory cystitis, pyelonephritis, peritonitis, gynecology annexitis, secondary infection caused by chronic respiratory diseases, and so on. Biapenem can be administrated alone because of its stability to human renal dehydrogenation peptidase-I (DHP-I). It also can be used for the treatment of bacterial meningitis, because of its ability of blood-brain barrier permeation and less potential of central nervous system toxicity for inducing seizures,ObjectiveTo develop a quick, sensitive, convenient HPLC method for determination of biapenem in human plasma and to study the disposition of biapenem in healthy chineses volunteers. And to provide evidence for dosing administration protocol of phase II clinical trial and clinical rational use of drug.MethodsThis study includes the following two parts: The first part was to choose the HPLC method with strong specificity, high sensitivity and high precision through optimizing the sample processing procedure and detecting methods. Procedure: The 200μL plasma sample was taked into a 1.5mL centrifuge tube then 20μL0.1 mg/mL internal standard was added in the plasma sample. The mixture was vortexed for 10 s , loaded by 100μL 7% ZnSO4 water-solution, vortexed for 3 min, and then centrifuged at 16,000×g for 5 min. 20μL aliquot of the supernatant was injected into the HPLC system for analysis.The second part was to study the pharmacokinetics of biapenem following asingle-administration and multiple-administration of biapenem in healthy volunteers. Thirty healthy volunteers were divided into three groups with five males and five females in each group (150mg for the low-dose group, 300mg for the middle-dose group, 600mg for the high-dose group). The drug was dilutioned by 0.9% sodium chloride injecta. Every subject was instilled with 100mLliquid for 1h. 4 ml blood was taked from side antibrachium for every person at the following time point:before administration 0h, and after administration 30 min,1.0 h,1.5 h, 2.0 h, 2.5 h ,4.0 h and 6.0 h.The blood samples were taken into the tube with heparin and then were centrifuged. Plasma was separated and stored at -20℃. The multiple dose experiment: once 300mg one person (the dilution method of physic liquor same as single dose ), twice a day,sustained 5 dayes, administer time was 1h(Take single dose administer as first day, only administer one time at fifth day). 4 ml blood was taked from side antibrachium for every person at the following time point:before administration at the second third fourth fifth day morning, 30 min, 1.0 h after administration begin and 30 min,1.0 h,1.5 h, 2.0 h, 2.5 h ,4.0 h, 6.0 h after the last administration. All plasma samples was determined by validated HPLC method and the pharmacokinetics parameter was calculated by DAS2.0 soft.ResultsFirst The biapenem plasma determination method was optimized. In this method, no endogenous substance interfered the determination; the liner range of standard curve from 0.2μg·mL-1 to 50μg·mL-1 with a good linear relationship; the lowest limit of quantification was 0.2μg·mL-1;the intra-precision and intra-precision RSD of three concentrations were less than 15.0% and the draw recovery rates were between 73 %-75 %. The developed HPLC method meeted the determination criterion requirement for biological samples.SecondThe 30 volunteers had been given different single dose injection biapenem. the Pharmacokinetics parameter are:Tmax were 0.93±0.12h,1.01±0.16h,and 1.00±0.00h,Cmax were 8.92±4.13mg·L-1,19.07±3.08mg·L-1, and 28.01±6.95 mg·L-1;t1/2 were 1.47±0.23h,0.98±0.26h, and 1.90±0.53h;AUC0-t were 11.24±3.09mg·h·L-1,22.15±3.96mg·h·L-1, and 35.58±4.65mg·h·L-1;AUC0-∞were 12.01±3.12mg·h·L-1,22.51±3.99mg·h·L-1, and 37.27±5.01mg·h·L-1;CL/F were 0.013±0.003L·h-1,0.007±0. 001L·h-1, and 0.016±0.002L·h-1。The 10 volunteers had been given multiple dose injection biapenem(300 mg once twice a day, continuous five days ) and the concentration of biapenem in the blood plasma had achieved the stable state at the second day. The average concentration of stable state was 0.68±0.11 mg·ml-1. The pharmacokinetics parameter was: t1/2 was 1.68±0.37 h, AUC0-t was 24.69±2.81 mg·h·L-1, Tmax was 1.00±0.00h and Cmax was 18.97±6.04 mg·L-1.Conculsion:First The determination method had been developed and the precision, accurauy, selectivity, repeatability are good for determination of biapenem in human plasma.The calibration curves were over the range of 0.2 -50μg·mL-1 in plasma and the correlation coefficient was >0.999, the average retain time of biapenem was about 3.95min, and the lowest limit of quantification was 0.2μg·mL-1. The intra- and inter-run relative standard deviations obtained from three validation runs were all less than5%. The method recoveries and extraction recoveries were more than75%. All the parameter showed that the method is applicable to the pharmacokinetics study of biapenem in human.Second The results showed that pharmacokinetics of biapenem had coincidence with two compartment model. The pharmacokinetics parameter were as fellowed : t1/2 of three groups were (1.15±0.17), (1.06±0.28) and (1.05±0.06)h, repectively. There was no significant difference and it present first order elimination rate constant. The Cmax were (8.92±0.41),(19.07±3.08),and (35.60±6.95)mg·L-1 and AUC0-t were (11.17±3.01),(22.14±3.97),and (45.26±3.85)mg·L-1·h,the Cmax and AUC0-t had a liner relation with the dosage over the range of 150-600 mg, regression equations were Cmax=0.0587X-0.655(R2=0.9972) and AUC0-t h=0.0759X-0.39 (R2=0.9998). The t1/2,Cmax,AUC0-t of multiple administer were (1.21±0.13)h, (22.14±3.97) mg·L-1·h, and 18.96±6.03)mg·L-1·h, there was no significant difference, compare with single-dose pharmacokinetic parameters. It was indicated that biapenem don't accumulation in human body at the multipe dose of 300 mg (twice per day).Third No adverse reaction event was observed in the study. It was indicated that biapenem was safe for human at doses of 150-600 mg. |
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