Study On The Pharmacokinetics Of Cycloserine In Humans

Background Tuberculosis?TB?is a chronic infectious disease caused by mycobacterium tuberculosis infection.Mycobacterium tuberculosis can invade the body organs,mainly the lungs.About 250,000 people died of TB every year in China,which is twice more than the sum of all kinds of infectious disease deaths.Cycloserine is suitable for TB caused by sensitive bacteria,active tuberculosis?including renal tuberculosis?of insufficient initial treatment?streptomycin,isoniazid,rifampicin and ethambutol?.Cycloserine can effectively inhibit mycobacterium tuberculosis,but anti-tuberculosis effect is relatively weaker than isoniazid,streptomycin and other first-line anti-tuberculosis drugs.Cycloserine has no drug resistance,and it is effective on drug-resistant TB.The mechanism of action is inhibition of cell wall synthesis of mycobacterium tuberculosis.In recent years,due to the frequent resistance of mycobacterium tuberculosis bacterium,cycloserine is received more and more attention and widely used.At present,the domestic reports of study on cycloserine is few,pharmacokinetic reports is more rare.ObjectiveA rapid,sensitive and selective high performance liquid chromatography-tandem mass spectrometry?HPLC/MS/MS?method was to be developed for determination of cycloserine in human plasma.And then the method should be applied in a pharmacokinetic study of cycloserine capsule in healthy Chinese volunteers.We observed pharmacokinetic characteristics in human blood with a single oral medicine and repeat treatment,which provide the basis for clinical application and declaration.Method Niacin was used as internal standard?IS?.After a simple protein precipitation using methanol as the precitation solvent,analytes and IS were separated on a ZORBAX SB-Aq?4.6×250mm,5?m?column via isocratic elution using methanol:water?consisting 5mM ammonium formate and 0.05%formic acid??85:15,v/v?as the mobile phase.The flow rate was0.8 mL/min?40%imported mass spectrometry?.The inject volume was 2?L and a chromatographic total run time of 3.5 min was achieved.Mass spectrometry detection was conducted through electrospray ionization in positive ion multiple reaction monitoring mod using the transitions of m/z 102.8?75.0?DP:16V,CE:13V,CXP:12V?and m/z 124.2?80.1?DP:53V,CE:14V,CXP:5V?for cycloserine and niacin,respectively.Three single doses of cycloserine 250mg?500mg and 1000mg were administered twice daily according to an open randomized three way crossover design for single dose pharmacokinetic study.A single dose of cycloserine 250mg was administered 13 times?twice daily?for multiple dosing pharmacokinetic study.Results The liner calibration curves for cycloserine was obtained in the concentration range of 0.4995-99.900?g/mL in plasma,and the lower limit of 0.4995?g/mL quantification was The intraday and interday relative standard deviation?RSD?for cycloserine over the entire concentrations across validation runs were all less than 6.14%.The main pharmacokinetic parameter of oral cycloserine 250mg?500mg and 1000mg as below:the values of Cmax were13.81±2.31?22.89±5.47?52.79±12.76?g/mL,Tmax were 0.70±0.55?1.03±1.02?0.90±0.99h,AUC0-?were 190.13±58.45,386.54±153.78,829.43±292.25?g·h/mL.The main pharmacokinetic parameter of oral cycloserine?250mg?13 times as below:the values of Cmax was 26.91±9.68?g/mL,Tmax was 1.19±0.84 h,AUC0-?was 485.39±288.55?g·h/mL.Conclusion This study developed fast,selective,and sensitive HPLC-MS/MS methods for the determination of cycloserine in human plasma.The former has been successfully applied in a pharmacokinetic study of cycloserine capsule.Cmax and AUCs showed a dose dependent.The average of cycloserine clear half-life?t1/2 z?in plasma was 14.19?3.60²6.19?h,was nothing to do with dosage.There was no difference between the main pharmacokinetic parameters?AUC0-t,AUC0-?,Tmax,Cmax and CLz?and the sexes.But MRT0-t,MRT0-?,t1/2z and Vz were statistically significant difference between male and female.After oral cycloserine capsule for 13 times,every time 250 mg,the main pharmacokinetic parameters had no statistical significance with a single dose?P<0.05?.t_1/2z,MRT_0-?were significant difference between male and female,female were lower than male subjects.The body accumulation index was 2.28±0.65.