Pharmacokinetics,metabolism, excretion and plasma protein binding of 14C-levofloxacin after a single oral administration in the Rhesus monkey

Levofloxacin's metabolism, excretion, and in vitro plasma protein binding, together with its pharmacokinetics, were studied in the Rhesus monkey in support of an anthrax efficacy study in this species. Three males and three female Rhesus monkeys were dosed with a single oral dose of ¹⁴C-levofloxacin at 15?mg?kg^?1 (2?MBq?kg^?1). Following dose administration, blood samples were collected up to 48?h post-dose, and urine and faeces were quantitatively collected up to 168?h post-dose. Blood, plasma, urine, and faeces were analysed for total radioactivity. Metabolite profiling and identification was performed using radio-high-performance liquid chromatography (HPLC) and liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS). Additionally, the plasma protein binding of levofloxacin was determined in vitro by means of equilibrium dialysis. Peak plasma levels of total radioactivity and levofloxacin were rapidly reached after oral administration with a total radioactivity blood: plasma ratio close to unity. The elimination half-life of levofloxacin was estimated at about 2?h. Total radioactivity was mainly excreted in urine (about 57–86% of the dose) with faecal excretion accounting for only a minor fraction of the total amount of excreted radioactivity (about 7.4–14.7%). In the plasma, the majority of total radioactivity was accounted for by levofloxacin. In addition, two minor metabolites, i.e. levofloxacin n-oxide and presumably a glucuronide conjugate of levofloxacin, were detected. In the urine, five components were found, with levofloxacin being the major component. Minor metabolites included desmethyl levofloxacin, levofloxacin n-oxide, and a glucuronide conjugate of levofloxacin. In the faeces, the major analyte was a polar metabolite, tentatively identified as a levofloxacin glucuronide. The in vitro plasma protein binding was low (on average 11.2%) and independent of concentration (1.0–10.0?µg?ml^?1). No sex differences were noted in any of the investigations. The present data indicated that the metabolism and excretion pattern, and also the in vitro plasma protein binding of levofloxacin in the Rhesus monkey, were comparable with those previously reported in man, hereby supporting the use of this animal species in the efficacy evaluation of levofloxacin against inhalation anthrax. The shorter half-life of levofloxacin in the Rhesus monkey relative to man (2 versus 7?h) prompted the development of an alternative dosing strategy for use in the efficacy study.     

Pharmacokinetics,cerebrospinal fluid concentration,and safety of intravenous rifampin in pediatric patients undergoing shunt placements

Summary The objectives of this study were to characterize the pharmacokinetics and determine the cerebrospinal fluid concentrations and safety of intravenous rifampin in pediatric patients undergoing shunt placement. Nine patients (mean age 5.6 y) received a single dose of rifampin, 20 mg · kg⁻¹, administered intravenously 1 h prior to surgery. The peak serum concentrations ranged from 13.5–26.7 μg · ml⁻¹; cerebrospinal fluid concentrations ranged from 0.12–3.0 (mean: 1.4) μg · ml⁻¹. The mean total clearance, apparent distribution volume, and elimination half-life were 0.291 · kg⁻¹ · h⁻¹, 1.11 · kg⁻¹, and 2.8 h. The concentrations of rifampin achieved in the cerebrospinal fluid exceeded the minimum inhibitory concentrations by 100-to 1000-fold against Staphylococcus epidermidis. However, 5 of 9 patients developed cutaneous reactions during intravenous rifampin prophylactic therapy. Because of the high frequency of adverse effects and more than adequate rifampin concentrations achieved in the cerebrospinal fluid, rifampin doses lower than that used in this study may be evaluated in future studies. Supported by grants from the Children's Hospital Research Foundation, and Ohio State University office of Health Services     

The diffusion of pirprofen into the cerebrospinal fluid in man

Summary We have measured the concentrations of pirprofen at various times in plasma and cerebrospinal fluid (CSF) samples, drawn during diagnostic myelography from 28 patients affected by sciatica.After intramuscular injection of 400 mg plasma concentrations of pirprofen reached a peak in 60 min then fell slowly. In contrast, the CSF concentration rose until 12 h and then fell. Pirprofen rapidly crossed the blood-brain barrier and was detectable in CSF at 15–30 min after injection.These results support the suggested hypothesis of a central analgesic action of pirprofen along with the known peripheral one. A new sensitive HPLC method was developed for measuring the concentration of pirprofen in the CSF.     

Pharmacokinetics of vinpocetine and its metabolite, apovincaminic acid, in plasma and cerebrospinal fluid after intravenous infusion

The pharmacokinetics of vinpocetine (ethyl apovincaminate, Cavinton) and its metabolite, apovincaminic acid, was studied in patients with cerebrovascular disorders. Vinpocetine (1 mg/kg) was infused intravenously over 25 min. The elimination half-life of the parent drug in plasma was 4.7+/-2.13 h. Total clearance of vinpocetine was 0.79+/-0.1 1 h(-1) kg(-1). The presence of vinpocetine in cerebrospinal fluid shows that the drug is able to pass through the blood-brain barrier and reach the central nervous system which is a possible site of action. The maximum increase of cerebral blood flow (25%) was measured at 32 min after the start of the infusion.     

Rhesus monkey cerebrospinal fluid amine metabolite changes following treatment with the reversible monoamine oxidase type-A inhibitor cimoxatone

The effects of cimoxatone, a reversible inhibitor of monoamine oxidase type A (MAO-A), on the deaminated metabolites of norepinephrine, dopamine, and serotonin were examined in continuously collected rhesus monkey cerebrospinal fluid (CSF). Cimoxatone, 0.5–8 mg/kg given PO, produced dose-proportionate reductions of 24-h mean CSF 3-methoxy, 4-hydroxy phenylglycol (MHPG) concentrations of 21%–52%. Homovanillic acid (HVA) concentrations also decreased 27%–55%, while CSF 5-hydroxyindoleacetic acid (5-HIAA) decreases were somewhat smaller (7%–32% from baseline). All three metabolite concentrations reached a nadir approximately 6–10 h after drug administration, and required over 40 h to gradually return towards baseline following drug discontinuation. HVA concentration reductions in particular persisted during the entire 24-h period following treatment and were the slowest to return to baseline values. CSF concentrations of cimoxatone and its MAO-inhibiting O-demethyl metabolite showed a parallel time course peaking 6–10 h after treatment and persisting for up to 24 h in the case of cimoxatone and over 48 h for its metabolite. Single simultaneous time point determinations revealed 10-to 20-fold lower concentrations of cimoxatone and its metabolite in CSF compared to plasma 2 h after treatment. MAO-B activity in platelet-rich plasma was not inhibited by 8 mg/kg cimoxatone, indicating that this drug maintains MAO-A selectivity in vivo. As cimoxatone's preferential effects on catecholamine metabolites were similar to those previously observed with the irreversible MAO-A inhibiting antidepressant, clorgyline, our results are consistent with limited clinical trials data suggesting that cimoxatone may also prove to be an effective antidepressant.     

Effects of alcohol on cerebrospinal fluid norepinephrine in rhesus monkeys

Alcohol (1–3 g/kg) significantly increased the concentration of cerebrospinal fluid (CSF) norepinephrine (NE) in rhesus monkeys. This effect is consistent with the previously demonstrated activational and possible antidepressant effect of low doses of alcohol. The greatest increase was observed in subjects with low baseline levels of CSF NE. Individual differences in activation or euphoria could be related to differential increases in CSF NE following alcohol consumption.     

Plasma and cerebrospinal fluid concentrations of indomethacin in humans

Summary Plasma and cerebrospinal fluid (CSF) concentrations of indomethacin have been determined in 52 patients hospitalized for nerve-root compression pain. Samples of blood and CSF were collected at the same time in each subject, 0.5 to 12 h after a single intramuscular injection of 50 mg indomethacin. Analgesic effect was assessed by the absolute and percentage variation in Huskisson's visual analogue scale between dosing and sampling.According to its high lipid solubility, indomethacin rapidly crossed the blood-brain barrier, being detected in CSF 0.5 h after administration. After attainment of equilibrium within 2 h, the CSF level exceeded the free plasma level. Since the drug was extensively bound to serum albumin (99.7±0.1%), this phenomenon may represent a slight degree of binding of indomethacin in CSF.The analgesic activity was not related to either the plasma or CSF concentration of indomethacin.Supported by a grant from Merck-Sharp and Dohme Chibret France     

Plasma and cerebrospinal fluid pharmacokinetics of flurbiprofen in children

AIMS

This study was designed to characterize paediatric pharmacokinetics and central nervous system exposure of flurbiprofen.

METHODS

The pharmacokinetics of flurbiprofen were studied in 64 healthy children aged 3 months to 13 years, undergoing surgery with spinal anaesthesia. Children were administered preoperatively a single dose of flurbiprofen intravenously as prodrug (n = 27) or by mouth as syrup (n = 37). A single cerebrospinal fluid (CSF) sample (n = 60) was collected at the induction of anaesthesia, and plasma samples (n = 304) before, during and after the operation (up to 20 h after administration). A population pharmacokinetic model was built using the NONMEM software package.

RESULTS

Flurbiprofen concentrations in plasma were well described by a three compartment model. The apparent bioavailability of oral flurbiprofen syrup was 81%. The estimated clearance (CL) was 0.96 l h⁻¹ 70 kg⁻¹. Age did not affect the clearance after weight had been included as a covariate. The estimated volume of distribution at steady state (V_ss) was 8.1 l 70 kg⁻¹. Flurbiprofen permeated into the CSF, reaching concentrations that were seven-fold higher compared with unbound plasma concentrations.

CONCLUSIONS

Flurbiprofen pharmacokinetics can be described using only weight as a covariate in children above 6 months, while more research is needed in neonates and in younger infants.     

Diclofenac readily penetrates the cerebrospinal fluid in children

AIMS

The primary aim was to study the cerebrospinal fluid (CSF) penetration of intravenous diclofenac in children. The secondary aim was to evaluate the plasma diclofenac concentration at the onset of wound pain after inguinal surgery in children.

METHODS

A total of 31 children (24 boys) aged 3 months to 12 years received a single intravenous injection of diclofenac 1 mg kg⁻¹. Paired CSF and blood samples were obtained 5 min to 22 h (median 69 min) later. In children having inguinal surgery a second blood sample was obtained at the time that the children felt wound pain for the first time after surgery. Diclofenac concentrations in CSF, plasma and protein free plasma were measured by gas chromatography with mass spectrometric detection.

RESULTS

In the 28 CSF samples obtained at 5 min to 3 h 43 min after injection, diclofenac concentrations ranged between 0.5 and 4.7 μg l⁻¹. At 5.5 h the CSF concentration was 0.1 μg l⁻¹, and no diclofenac was detected in the two CSF samples obtained at 22 h. The median of plasma diclofenac concentration at the time when pain returned after inguinal surgery was 104 μg l⁻¹ (range 70–272 μg l⁻¹). No serious or unexpected adverse effects were reported.

CONCLUSIONS

Diclofenac penetrates the CSF rapidly, and a sufficient concentration to inhibit cyclooxygenase enzymes is sustained for up to 4 h.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Diclofenac, a nonselective nonsteroidal anti-inflammatory drug,, exerts analgesic action both in the peripheral tissues and in the central nervous system by inhibiting cyclooxygenase enzymes COX-1/2, but central nervous system penetration of diclofenac has not been evaluated in humans.

WHAT THIS STUDY ADDS

• Diclofenac penetrates the cerebrospinal fluid rapidly, and after a single intravenous dose of 1 mg kg⁻¹, sufficient concentrations to inhibit COX-1/2 are sustained for up to 4 h.

     

Penetration of praziquantel into cerebrospinal fluid and cysticerci in human cysticercosis

Summary Two patients with cysticercosis received praziquantel (PZQ) 75 mg/kg/day orally together with 30 mg prednisone daily for 3 weeks. The first patient presented with grand-mal seizures, a pyramidal tract syndrome and subcutaneous cysticerci, and the other had internal hydrocephalus necessitating drainage. Serial plasma samples were taken after the first dose of PZQ. Lumbar CSF was obtained from the first patient and ventricular CSF from the second. Subcutaneous cysticerci were removed from the first patient. PZQ in the specimens was assayed by GLC.For distribution between plasma and CSF a rate constant of 4.9 h^–1 for free PZQ, corresponding to a t_1/2 of 8 min or less for the non-protein bound fraction was calculated for Patient 1. In the second patient the distribution was so rapid that the rate constant could not be calculated. The difference in distribution rate might have been due to use of different sampling times or to a time lag in the entry of PZQ between the ventricles and the lumbar sac.The rate constant for distribution of the drug between plasma and parasites was 1.4 h^–1, corresponding to a t_1/2 of 30 min or less. Thus PZQ penetrates rapidly into the CSF. It enters the parasite more slowly, although still more rapidly than the plasma half-life of PZQ (1–1 1/2 h).     

Enantioselective distribution of albendazole metabolites in cerebrospinal fluid of patients with neurocysticercosis

AIMS: Albendazole (ABZ) is effective in the treatment of neurocysticercosis. ABZ undergoes extensive metabolism to (+) and (-)-albendazole sulphoxide (ASOX), which are further metabolized to albendazole sulphone (ASON). We have investigated the distribution of (+)-ASOX (-)-ASOX, and ASON in cerebrospinal fluid (CSF) of patients with neurocysticercosis. METHODS: Twelve patients with a diagnosis of active brain parenchymal neurocysticercosis treated with albendazole for 8 days (15 mg kg(-1) day(-1)) were investigated. On day 8, serial blood samples were collected during the dose interval (0-12 h) and one CSF sample was taken from each patient by lumbar puncture at different time points up to 12 h after the last albendazole dose. Albendazole metabolites were determined in CSF and plasma samples by h.p.l.c. using a Chiralpak AD column and fluorescence detection. Population curves for CSF albendazole metabolite concentration vs time were constructed. RESULTS: The mean plasma/CSF ratios were 2.6 (95% CI: 1.9, 3.3) for (+)-ASOX and 2.7 (95% CI: 1.8, 3.7) for (-)-ASOX, with the two-tailed P value of 0.9873 being non-significant. These data indicate that the transport of ASOX through the blood-brain barrier is not enantioselective, but rather depends on passive diffusion. The present results suggest the accumulation of the (+)-ASOX metabolite in the CSF of patients with neurocysticercosis. The CSF AUC(+)/AUC(-) ratio was 3.4 for patients receiving albendazole every 12 h. The elimination half-life of both ASOX enantiomers in CSF was 2.5 h. ASOX was the predominant metabolite in the CSF compared with ASON; the CSF AUC(ASOX)/AUC(ASON) ratio was approximately 20 and the elimination half-life of ASON in CSF was 2.6 h. CONCLUSIONS: We have demonstrated accumulation of the (+)-ASOX metabolite in CSF, which was about three times greater than the (-) antipode. ASOX concentrations were approximately 20 times higher than those observed for the ASON metabolite.     

A phase II trial of piroxantrone in adenocarcinoma of the pancreas

Summary Thirty-five evaluable patients with advanced adenocarcinoma of the pancreas were treated with piroxantrone at a dose of 150 mg/m² intravenously every 21 days. No objective responses were observed (95% confidence interval 0% –10%). Toxicities of grade 3 were primarily hematologic and were seen in 28 patients. Piroxantrone is inactive in pancreatic cancer and no further investigation of this agent in this tumor is recommended.     

黄芩苷及三七总皂苷配伍脑脊液药代动力学研究

目的建立大鼠脑脊液中黄芩苷的HPLC-MS/MS测定方法,研究黄芩苷及配伍三七总皂苷的大鼠脑脊液药代动力学变化。方法大鼠尾静脉注射黄芩苷和黄芩苷-三七总皂苷配伍溶液,采集脑脊液样品,利用LC-MS/MS测定脑脊液中黄芩苷的含量。色谱柱为Agilent Eclipse XDB-C18(4.6 mm×150 mm,5μm),流动相为乙腈:1 mmol·L-1乙酸铵(含0.1%甲酸):0.1%氨水梯度洗脱;质谱检测离子为m/z 445/269(黄芩苷[M-1]-),m/z 237/194(卡马西平[M+1]+)。结果在5～200μg·L-1范围内,黄芩苷与内标卡马西平的峰面积比值与浓度的线性关系良好,回收率为87.15%～92.73%。黄芩苷在单独给药组和三七总皂苷配伍组的药代动力学参数分别为:Cmax为(189.67±20.13)、(237.00±51.86)μg·L-1,AUC0-t为(6612.96±1023.65)、(5466.63±267.06)μg·min·L-1,AUC0-∞为(6930.43±1060.41)、(5682.13±412.79)μg·min·L-1,T12为(108.84±45.67)、(102.54±38.37)min,CL为(15.39±2.60)、(18.32±0.88)L·min-1·kg-1。结论建立的HPLC-MS/MS测定方法能够准确灵敏地测定脑脊液中的黄芩苷。黄芩苷能够透过血脑屏障进入大鼠脑脊液,合用三七总皂苷后黄芩苷的药代动力学参数无明显变化,说明三七总皂苷对黄芩苷的脑脊液代谢没有明显影响。     

Temporary reversal of serum to cerebrospinal fluid glycerol concentration gradient after intravenous infusion of glycerol

Summary Glycerol 50 g infused i. v. over 2 to 6 h is widely used to treat cerebral oedema in patients with acute stroke. Its transit through the blood-cerebrospinal fluid barrier in subjects with uninflamed meninges has now been examined. In 7 patients with an external ventriculostomy for occlusive hydrocephalus, each of whom was given 500 ml of a 10% solution IV over 4 h, serum and CSF were repeatedly sampled during and after the infusion and glycerol was measured enzymatically.The highest serum glycerol level of 191–923 mg/l was observed at the end of the infusion. The maximum CSF glycerol of 18.7–110.8 mg/l was attained 0–1 h after the end of the infusion. Elimination both from serum and CSF approximated a single-exponential decay; the elimination half-life from serum was 0.29–0.56 h compared to 1.03–3.68 h from CSF. In six of the seven cases there was a temporary reversal of the serum/CSF concentration gradient during glycerol elimination. The ratios of the AUCs of CSF and serum, which describe the overall penetration of glycerol into CSF, ranged from 0.09–0.31.In conclusion, the serum level of glycerol produced by giving 50 g IV glycerol over 4 h may not be sufficiently high reliably dehydrate to brain tissue in many patients, and the slow elimination of glycerol from the CSF may be related to the so-called rebound phenomenon.     

Pharmacokinetic approaches to drug distribution in the cerebrospinal fluid based on ventricular administration in beagle dogs

Two mathematical approaches are described to approximate the distribution of compounds (e.g., drugs) in the cerebrospinal fluid (CSF) downstream of or distal to both the ventricular injection site and the cisterna magna sampling site. The first approach uses a graphic representation and is, in essence, model independent;the second approach considers the geometry and physiology of CSF distribution and clearance. In all studies, radiolabeled inulin was used as an internal standard since it is not metabolized and is eliminated from the CSF primarily by bulk flow. Temporal comparison of the study compound to radiolabeled inulin in the cisternal CSF allowed testing of these models in beagle dogs. One use of this data is in the estimation of the drug exposure integral for antineoplastic drugs administered in the CSF to treat leptomeningeal neoplasia.Abbreviations CSF cerebrospinal fluid - ICSF intracerebrospinal fluid - DFMO -difluoromethylornithine - MGBG methylglyoxal bis(guanylhydrazone) - ACNU 3-[(4-amino-2-methyl-5-pyrimidinyl)-ethyl]-1-(2-chloroethyl)-1-nitrosourea This work was supported in part by HEW grants CA-30571 and CA-13525.     

HPLC法测定脑脊液中去甲万古霉素的浓度

目的 :建立HPLC法测定人脑脊液中去甲万古霉素浓度。方法 :采用ODS hypersilC1 8柱 ,甲醇 0 0 5mol/L KH2PO4(1 6∶84,pH =5 0 )为流动相 ,检测波长 2 80nm ,以替硝唑为内标对去甲万古霉素进行定量测定。结果 :脑脊液中去甲万古霉素在 1～ 6 0mg/ml范围内浓度与峰面积具良好线性 (r =0 9993) ,平均回收率为 98 70 %± 2 6 5 % ,日内及日间RSD分别为 1 73%～ 1 95 %和 3 6 2～ 6 78%。     

Serotonin in cisternal cerebrospinal fluid of rhesus monkeys: basal levels and effects of sertraline administration

RATIONALE: Studies of rodents suggest that extracellular fluid and cerebrospinal fluid (CSF) serotonin (5-HT) concentrations provide a better index of released 5-HT than the frequently obtained measure of CSF 5-hydroxyindoleacetic acid (5-HIAA). The measurement of cisternal CSF 5-HT levels in the monkey might offer a method of assessing the effects of agents and actions on central 5-HT functioning in primate brain. OBJECTIVE: To address methodological issues related to the determination of monkey cisternal CSF 5-HT and to examine the effects of a selective serotonin reuptake inhibitor (SSRI) on the measure. METHODS: Monkey CSF was obtained by cisternal puncture and 5-HT levels determined by high performance liquid chromatography, after screening for blood contamination. RESULTS: When blood contamination was minimized, a mean (+/-SD) basal concentration of cisternal CSF 5-HT 87+/-36 pg/ml (n=13) was observed. Good longitudinal stability (variances of 16 and 20%) of CSF 5-HT was demonstrated in two monkeys sampled over a 3-month period. A two-fold increase in CSF 5-HT was seen in seven animals treated with the SSRI sertraline (20 mg/kg PO, mean treatment period of 12 days): pre- and post-drug 5-HT concentrations were 85+/-39 and 162+/-53 pg/ml (P=0.0007); in contrast, levels of 5-HIAA decreased from 40.0+/-5.7 to 20.4+/-2.2 ng/ml (P=0.0001). CONCLUSIONS: The measurement of monkey cisternal CSF 5-HT appears to provide a useful index of central 5-HT release. Initial results tend to support a role for increased extracellular 5-HT in the mechanism of action of chronically administered SSRIs.     

大鼠血浆和脑脊液中甲氨蝶呤浓度测定及其应用

目的　建立测定大鼠血浆和脑脊液中甲氨蝶呤(MTX)浓度的HPLC法,为脑内靶向制剂及其在动物体内药动学研究提供方法学。方法　采用高效液相色谱-紫外检测法,用C18键合硅胶柱,流动相为甲醇- 0 . 0 5mol·L-1醋酸铵缓冲液(2 3∶77,pH =6 ) ,检测波长313nm。血浆样品沉淀蛋白后取上清液进样,脑脊液样品离心后直接进样。本法应用于MTX纳米粒给药后大鼠血浆、脑脊液中药物浓度测定。结果　该法专属性好,最低检测浓度为16 μg·L-1,血浆和脑脊液样品检测线性、精密度、回收率等指标均符合生物样品分析标准,在应用中取得良好效果。结论　本法可用于测定大鼠血浆和脑脊液中MTX的浓度。     

Hepsulfam distribution in blood,plasma and cerebrospinal fluid of baboons

Summary The alkylating agent Hepsulfam (Sulfamic acid 1,7-heptanediyl ester, NSC 329680) was developed as a more hydrophilic analog of busulfan. The objective of this study was to determine partitioning of hepsulfam between blood, plasma, and cerebrospinal fluid (CSF) in two female baboons following intravenous administration. Hepsulfam was administered at 11 mg/kg, and blood and CSF levels were determined by gas chromatography with electron capture detection. Blood levels were fairly constant btween animals (17–25 and 20–23 μg/ml) for six hours after administration, following peak levels of 43 and 33 μg/ml, respectively, for the two animals. Peak plasma levels of 35 and 36 μg/ml were achieved, and initial plasma half-lives in babbons were similar to those seen in other species, with at_1/2 α of 1 h. The plasma terminal half life of 0.2 h, estimated from limited sampling times, was shorter in baboons than in mice, dogs, or humans. Baboon CSF levels decreased from 1.7 to 0.3 μg/ml during 6h post infusion, and peak concentrations in CSF lagged behind plasma levels. CSF/plasma ratios ranged from 0.33 to 0.62 in one animal, whereas ratios of 0.2–0.25 were maintained in the other animal during the same period. Results from this study indicate hepsulfam will enter the CSF following intravenous administration, and the CSF/plasma ratios are lower than those obtained following oral busulfan administration.     

美罗培南在化脓性脑膜炎新生儿血浆和脑脊液中药动学和药效学的关联研究

目的 探讨美罗培南在化脓性脑膜炎的新生患儿血浆和脑脊液中的药动学和药效学的关联。方法 试验招募2016年5月—2021年5月在扬州大学附属医院诊断为化脓性脑膜炎的58例新生儿患者,均获得血浆样品,其中17人获得脑脊液样品。出生后2～4周的新生儿以及4～6周的婴幼儿使用8 h的剂量间隔,美罗培南使用剂量为40 mg·kg^-1,输注时间超过30 min。使用带有DIGITAL FORTRAN编译器的NONMEM软件包分析数据。超高效液相色谱联用串联质谱（UHPLC-MS/MS）测定血浆和脑脊液中的美罗培南浓度。使用最终模型估计值的蒙特卡罗模拟（n＝1 000）用于生成不同给药方案的游离血药浓度水平维持在目标菌群的最低抑菌浓度（MIC）之上的时间（fT＞MIC）占1个给药间隔的百分比（% fT＞MIC）和最小抑菌浓度（MIC）值：1、2、4、8 mg·L^-1。结果 美罗培南在血浆中的峰浓度（C_max）、曲线下面积（AUC）、清除率（CL）、表观分布容积（V_d）高于脑脊液中的各项数据,差异有统计学意义（P＜0.05）;血浆中的半衰期（t_1/2）低于脑脊液,差异有统计学意义（P＜0.05）。用蒙特卡罗模拟10 000例患者目标获得概率,随着MIC值增加,血浆目标获得概率降低;血浆中40%最低抑菌浓度（MIC）的时间百分比（40% TMIC）、60% TMIC、80% TMIC、100% TMIC目标获得概率逐渐降低。随着MIC值增加,脑脊液目标获得概率降低;脑脊液中40% TMIC、60% TMIC、80% TMIC、100% TMIC目标获得概率逐渐降低。结论 模拟试验表明,当MIC为2 μg·mL^-1时,美罗培南在血浆中的目标获得概率可以达标,其在脑脊液中的目标获得概率不能达标,治疗时需要增加美罗培南的剂量或缩短给药间隔,以达到治疗目标。