大剂量甲氨蝶呤治疗小儿急性淋巴细胞白血病药动学

目的:研究10例急性淋巴细胞白血病患儿应用大剂量甲氨蝶呤(MTX)的体内药动学参数,探讨最佳解救时间,并对其不良反应进行分析.方法:使用统一的治疗方案,采用荧光偏振免疫(FPIA)方法,监测一定时间的MTX血药浓度.结果:MTX体内药动学药时曲线符合一房室模型,其Cmax为(60.3±14.3)μmol·L-1;Ke为(0.11±0.02)h-1;Vd为(655.2±411.8)L;CL为(15.2±8.5)L·h-1;t1/2(k)为(7.9±2.3)h;AUC0-10为(152.4±65.4)μmol·L-1·h;AUC0-∞为(157.2±73.7)μmol·L-1·h;MRT为(3.8±2.6)h.结论:开展小儿急性淋巴细胞白血病患儿使用大剂量甲氨蝶呤的体内药动学研究具有重要的临床意义.     

氯法拉滨注射液在白血病患者中的单剂量及多剂量临床药代动力学研究

目的:研究氯法拉滨注射液单剂量及多剂量静脉滴注的人体药动学过程.方法:4例白血病患者单剂量恒速静脉滴注氯法拉滨注射液52 mg·m-2·d-1,单剂量试验结束后进入多剂量给药试验,52 mg·m-2·d-1,连续给药5d.采用高效液相色谱串联质谱法测定血浆及尿液中氯法拉滨的浓度,并采用DAS药动学软件对试验数据进行处理,求算有关药动学参数.结果:4例受试者单剂量静脉滴注氯法拉滨注射液后,主要药动学参数分别为Cmax(414±205) μg/L,tmax(3.0±1.4)h,t1/2z(4.4±2.0) h,AUC0-t(2475±659) μg· h· L-1,AUC0-∞(2566±606)μg·h·L-1,CLz(21.2±5.1) L· h-1·m-2,Vz(142±97) L/m2,MRT(0-t)(6.3±2.2) h,Zeta(0.18±0.07) h-1,24 h平均尿液累积排泄率为(39.53±20.98)％.52 mg·m-2·d-1静脉滴注氯法拉滨注射液,连续给药5d,第5日达稳态,主要药动学参数为Cmax(581±126) μg/L,tmax(2.0±0.8) h,t1/2z(6.4±3.1)h,AUC0-t(2451±349) μg· h· L-1,AUC0-∞ (2603 ±409)μg·h·L-1,CLz(20·4±3.7)L·h-1·m-2,Vz(187±80) L/m,Zeta(0.13±0.05) h-1,MRT(0-t)(5.1±1.8) h,Css(102.14±14.53) μg/L,蓄积因子R(1.04±0.28),血药浓度波动度DF(576.26±226.89)％.结论:氯法拉滨注射液静脉滴注给药52 mg· m-2·d-1,连续给药5d,药物在体内无蓄积,安全性好.     

高效液相色谱法测定甲氨蝶呤对来氟米特在大鼠体内药动学的影响

目的:研究甲氨蝶呤对来氟米特在大鼠体内药动学的影响。方法:灌胃给予来氟米特以及灌胃给予甲氨蝶呤合并来氟米特,用HPLC法测定来氟米特代谢物A77 1726的药时曲线,使用DAS软件计算单独给药以及合并给药时来氟米特药动学参数。结果:口服来氟米特的血药经时过程符合一级吸收的二房室模型。单独给予来氟米特k10:4.368h-1,ka:0.501 h-1,k12:4.122 h-1,k21:0.241 h-1,AUC0-∞:12.638 mg.L-1 h-1,MRT0-∞:12.465 h,tmax:11 h,Cmax:1.422 mg.L-1;甲氨蝶呤合并来氟米特k10:0.219 1 h-1,ka:0.255 h-1,k12:0.156 h-1,k21:0.054 h-1,AUC0-∞:72.7 mg.L-1 h-1,MRT0-∞:24.139 h,tmax:4 h,Cmax:2.6 mg.L–1。结论:甲氨蝶呤能促进来氟米特的吸收,     

大鼠灌胃给予维血宁颗粒后虎杖苷血药浓度测定及药动学研究

目的:建立大鼠血浆中虎杖苷浓度的反相高效液相色谱(RP-HPLC)测定方法。方法:色谱柱为Diamonsil C18(200mm×4.6mm,5μm),流动相为乙腈-水(20∶80,V/V),流速为1.0mL·min-1,柱温为35℃,检测波长为303nm。大鼠ig维血宁颗粒后,测定不同时间血药浓度。采用DAS2.0药动学软件对血药浓度-时间数据进行拟合,计算相应药动学参数。结果:大鼠灌胃给予维血宁颗粒后,虎杖苷在大鼠体内药动学主要参数为:tmax=(0.403±0.063)h,Cmax=(1.715±0.097)mg·L-1,Ka=(6.894±3.275)h-1,t1/2α=(0.202±0.142)h,t1/2β=(2.484±1.624)h,CL/F=(32.229±22.027)L·h-1·kg-1,V1/F=(14.447±12.013)L·kg-1,AUC(0～t)=(1.511±0.550)mg·h·L-1,AUC(0～∞)=(1.955±0.765)mg·h·L-1。结论:虎杖苷在大鼠体内的药动学过程符合二室模型,进入体内分布迅速,代谢消除速度也较快。     

健康人单次口服不同剂量依地普仑片的药动学

目的研究中国健康志愿者单次口服不同剂量依地普仑草酸盐片的体内药动学特点.方法32例受试者单次空腹口服依地普仑草酸盐片,剂量分别为10(n=10),20(n=12),30mg(n=10).用HPLC荧光检测法测定血浆中的依地普仑浓度,用DAS统计软件进行数据处理,计算药动学参数.结果草酸依地普仑片药动学特点符合二房室模型,为线性药动学特点,单次口服依地普仑10,20和30mg的主要药动学参数是Cmax分别为(20.91±4.94),(40.28±10.13)和(57.66±10.51)μg·L-1;Tmax分别为(3.80±1.23),(4.18±0.98)和(4.00±1.49)h;t1/2分别为(34.08±26.58),(36.02±23.68)和(36.95±11.58)h;AUC0～1,分别为(846.8±466.7),(1437.5±535.5)和(2277.5±506.5)μg·h·L-1,AUC0～∞分别为(975.7±622.4),(1587.1±731.2)和(2496.6±707.4)μg·h·L-1.药动学参数的个体间差异较大,CV%最大值为77.99%.女性受试者和男性受试者的血浆清除率(CL/F)及单位剂量的AUC0～1和AUC0～∞值相似.结论中国健康受试者单次口服不同剂量草酸依地普仑的药动学参数具有线性药动学特点.     

重酒石酸长春瑞滨注射用乳剂及其市售注射液在肿瘤患者中的药动学比较

目的比较重酒石酸长春瑞滨注射用乳剂与市售注射液在肿瘤患者的药动学。方法在符合入选标准的肿瘤患者中,采用随机平行对照单次给药的方法进行药动学试验,给药剂量30 mg·m-2,采用LC-MS/MS法测定血浆样品中长春瑞滨的浓度,计算主要药动学参数并进行统计分析。结果重酒石酸长春瑞滨注射用乳剂和市售注射液在肿瘤患者中的主要药动学参数分别为:t1/2(16.78±5.24)和(20.03±24.72)h,CL(22.75±5.81)和(17.71±2.88)L·h-1·m-2,Vc(541.04±223.36)和(486.03±567.17)L·m-2,AUC0-t(1 297.09±308.73)和(1 629.31±309.41)μg·L-1·h,AUC0-∞(1 388.37±318.54)和(1 736.23±299.83)μg·L-1·h,ρmax(1 426.25±397.56)和(2 187.50±828.04)μg·L-1,tmax(0.22±0.04)和(0.29±0.18)h,MRT0-t(6.95±1.08)和(4.94±1.31)h;两制剂AUC0-t、t1/2、tmax、ρmax和Vc均无显著差异(P>0.05)。结论重酒石酸长春瑞滨注射用乳剂和市售注射液相比,在肿瘤患者中具有相似的药动学特征。     

富马酸卢帕他定的人体药动学

目的:研究健康受试者单剂量和多剂量口服富马酸卢帕他定片的药动学.方法:采用HPLC-MS/MS法测定12名健康受试者单剂量和多剂量口服马酸卢帕他定片血浆药物浓度经时过程,运用DAS2.0程序计算主要的药动学参数.结果:血浆富马酸卢他定的线性范围为0.05～13μg·L-1,定量下限为0.05μg·L-1(S/N≥10).12名健康受试者单次空腹口服10mg富马酸卢帕他定片的主要药动学参数分别为:AUC0-24:(30.3±12.4)μg·L-1·h;AUC0-∞:(31.9±12.5)μg·L-1·h;V1/F:(619.0±202.5) L;CL/F:(368.5±166.4) L·h-1;MRT＜0-24:(5.0±0.6) h;MRT0-∞:(6.7±2.0) h;tmax: (1.0±0.4) h;Cmax:(8.3±2.7)μg·L-1;t1/2:(6.5±4.7)h.12名健康受试者连续7d服用10 mg富马酸卢帕他定片的主要药动学参数分别为 AUC0-24:(34.0±11.4)μg·L-1·h,AUC0-∞:(35.8±12.2)μg·L-1·h;C55_max:(9.4±3.2)μg·L-1;C55_max(0.35±0.14)μg·L-1;tmax: (0.92±0.31)h;V1/F:(702.9±289.2) L;CL/F: (321.3±145.8) L·h-1;MRT0-24:(5. 24±0. 34) h;MRT0-∞:(7.9±1.8)h;t1/2:(7.6±7.2)h.结论:单剂量组、多剂量组中男性和女性受试者药动学参数差异都无统计学意义,同时单剂量和多剂量之间差异也无统计学意义.     

LC-MS/MS法测定手术患者中罗哌卡因注射液的血浓度及药动学

目的评价国产甲磺酸罗哌卡因注射液在手术患者中的药动学特点。方法采用LC-MS/MS法测定血浆中罗哌卡因的浓度,并用非房室模型计算药动学参数。结果16例下腹部或下肢手术患者单剂量给予135mg甲磺酸罗哌卡因(含罗哌卡因100mg)或112.5mg盐酸罗哌卡因注射液(含罗哌卡因100mg)的主要药动学参数分别是:甲磺酸罗哌卡因组AUC0→t为(7904.14±3699.28)μg·h·L-1;AUC0→∞为(8300.40±3891.91)μg·h·L-1;ρmax为(1701.25±198.60)μg·L-1;tmax为(0.41±0.29)h;t1/2为(6.50±1.39)h;MRT0→t为(5.23±1.07)h;MRT0→∞为(6.59±1.29)h;Ke为(0.11±0.02)h-1;V/F为(135.23±65.45)L;CL/F为(13.78±4.45)L·h-1。盐酸罗哌卡因组AUC0→t为(9559.03±3890.03)μg·h·L-1;AUC0→∞为(9936.23±3974.98)μg·h·L-1;ρmax为(1483.75±318.21)μg·L-1;tmax为(2.12±2.57)h;t1/2为(5.12±1.12)h;MRT0→t为(5.97±0.65)h;MRT0→∞为(7.00±1.09)h;Ke为(0.14±0.03)h-1;V/F为(90.50±48.24)L;CL/F为(12.06±6.00)L·h-1。结论在下腹部或下肢手术患者受试者中,单剂量注射甲磺酸罗哌卡因注射液或盐酸罗哌卡因注射液15mL后的主要药动学参数均无差异,而且耐受性和安全性良好,无不良事件发生。     

阿奇霉素分散片人体相对生物利用度及药动学

目的:研究受试制剂阿奇霉素分散片与参比制剂人体相对生物利用度及药动学.方法:20名健康受试者自身交叉单剂量口服阿奇霉素分散片受试制剂和参比制剂各500 mg,定时取血,用微生物法测定血药浓度.结果:受试制剂阿奇霉素分散片与参比制剂的血药浓度-时间曲线基本一致,符合一级吸收二房室模型.受试制剂与参比制剂的主要药动学参数分别为:消除半衰期t1/2β:(36.1±7.8)h,(39.9±10.3)h;Tmx:(2.4±0.5)h,(2.4±0.5)h;Cmax:(413.0±72.5)μg·L-1,(404.0±69.5)μg·L-1.药动学参数经配对t检验,P＞0.05,差异均无显著性.两种制剂的药时曲线下面积AUC0→t平均值分别为:受试制剂分散片(9 806±1 308)μg·L-1·h-1,参比制剂(9 949±1 395)μg·L-1·h-1;受试制剂分散片的相对生物利用度为:(99.0±9.0)%.结论:统计学结果表明,受试制剂阿奇霉素分散片与参比制剂生物等效.     

急性淋巴细胞白血病患儿中的甲氨蝶呤药动学

目的:建立一种快速、灵敏、专一的高效液相色谱法测定人体血浆中甲氨蝶呤(MTX)浓度的方法,并对15例经大剂量-甲氨蝶呤-四氢叶酸(HD-MTX-CF)化疗的急性淋巴细胞白血病(ALL)患儿进行动态血药浓度监测,提供临床HD-MTX-CF化疗及救援依据。方法:以岛津LC-10ATvp系列高效液相色谱仪进行监测,紫外检测波长302nm,0.3%磷酸-乙腈(85∶15)为流动相.血浆样品经三氯醋酸沉淀蛋白高速离心提取、富聚、定容后进样,以内标法进行色谱分析,将所测定的血药浓度以1.98μmol.L-1为界分别进行线性回归处理,所得血药浓度-时间数据经药动学程序(CPKDP)拟合,优化最佳药动学房室模型计算其药动学参数。结果:以对氨基苯甲酸为内标,MTX血药浓度分别在0.015 5~1.98μmol.L-1和1.98~254.04μmol.L-1范围内时,MTX同内标的峰面积比与浓度之间均呈良好的线性关系,r为0.994 4和0.999 7。MTX在ALL患儿体内的经时过程呈一房室模型,各个体间药动学参数存在一定的差异。结论:该方法灵敏,准确,抗干扰性好,适用于儿科临床血药浓度监测及其药动学研究。MTX在ALL患儿体内的经时过程呈一房室模型代谢。     

氨甲喋呤对映体对ECV304细胞抑制作用及其机制

目的探讨氨甲喋呤[(±)MTX]及其对映体[(+)MTX、(-)MTX]对ECV304细胞的生长抑制作用并探讨其机制。方法采用培养的ECV304细胞,应用MTT比色法分析其活性;用光学显微镜观察细胞的形态学变化;碘化丙啶(PI)单染流式细胞术检测细胞周期。结果在0.1～150μmol·L-1范围内,(+)MTX、(-)MTX和(±)MTX作用于ECV304细胞24、48、72h,均抑制细胞ECV304增殖,但抑制强度依次为(+)MTX>(±)MTX>(-)MTX,倒置显微镜观察不同浓度(±)MTX、(+)MTX和(-)MTX作用ECV304细胞不同时间后,出现细胞体积变小、核固缩等形态学改变。用10μmol·L-1的(+)MTX、(-)MTX和(±)MTX作用ECV304细胞48h后,PI单染流式细胞术检测ECV304细胞周期的影响,表明MTX消旋体及单一体干扰ECV304细胞DNA合成。结论(+)MTX和(-)MTX对ECV304细胞的抗增殖作用具有化学结构的立体选择性,(+)MTX的抗ECV304细胞增殖作用明显强于(-)MTX。     

Pharmacokinetic study of methotrexate following intra-articular injection of methotrexate loaded poly(L-lactic acid) microspheres in rabbits

The pharmacokinetics and tissue distribution of methotrexate (MTX) were investigated following intra-articular injection of either MTX solution or controlled release MTX loaded microspheres in healthy rabbit joints. MTX solution or MTX loaded microspheres (size 30-100 mum) (10 mg MTX) was injected into the right knee joint cavity of rabbits. Blood samples were taken at predetermined times from the jugular vein. Urine samples were also collected over time periods up to 24 h. The major organs and synovial tissues were removed for analysis 6 and 24 h post-injection (n = 4). MTX and 7-OH-MTX concentrations in the plasma and major organs were determined by HPLC. The MTX plasma area under the concentration-time curve (AUC) for rabbits injected with MTX solution was seven fold higher than that of the rabbits injected with MTX microspheres, while t(1/2) and mean residence time (MRT) were not significantly different between two treatment groups. Four fold more MTX was excreted in the urine from rabbits injected with MTX solution compared to those injected with MTX loaded microspheres 24 h following intra-articular injection. The concentration of MTX in the synovial tissues following intra-articular injection was significantly higher in the rabbits injected with microspheres than in the rabbits injected with MTX solution. MTX solution was rapidly cleared from the joint cavity while MTX encapsulated microspheres retained MTX in the joint cavity.     

Enhanced systemic availability of methotrexate in the presence of morin in rats

The present study aimed to investigate the effect of morin on the pharmacokinetics of methotrexate (MTX) in rats. Pharmacokinetic parameters of MTX were determined in rats following an intravenous administration of MTX (2 mg/kg) in the presence and absence of morin (25 mg/kg, p.o.). The cellular accumulation of MTX was also examined by using MDCK cells stably overexpressing hOAT1 or hOAT3. Compared with the control given MTX alone, pretreatment with morin 15 min prior to MTX administration significantly altered the pharmacokinetics of MTX in rats. Renal clearance and total clearance of MTX were reduced by 42% and 58%, respectively, in the presence of morin. Accordingly, the systemic exposure of MTX in the rats pretreated with morin was significantly higher than that from the control group. The mean residence time (MRT) and terminal plasma half-life of MTX were prolonged by 3.3- and 2.4-fold, respectively, by the concurrent use of morin. The cellular uptake of MTX (20 microM) was significantly reduced by the co-incubation with morin (100 microM) in MDCK-hOAT1 cells but not in MDCK-hOAT3 cells. Taken together, morin appeared to be effective in altering the pharmacokinetics of MTX in rats, likely by the inhibition of OAT1-mediated renal excretion.     

Effect of aspirin and sulindac on methotrexate clearance

The pharmacokinetics of low dose methotrexate (MTX) were evaluated in 12 rheumatoid arthritis patients in the presence and absence of steady-state levels of salicylic acid (ASA) and sulindac (SU). Using a Latin square design, patients were given MTX plus ASA (mean 3.4 g/day), MTX plus SU (mean 400 mg/day), or MTX alone. On a background of at least one year of regular MTX therapy, patients received 10 mg/m2 MTX iv (mean 17.8 mg) given after at least 2 weeks of treatment with each of the above regimens. Plasma concentrations of MTX and 7-hydroxymethotrexate (7-OH-MTX) were measured using HPLC. No differences in MTX clearance (Cl) were found comparing MTX alone, MTX + ASA, and MTX + SU. However, if one particular subject that had a very low clearance when receiving MTX alone was excluded, there was a statistically significant decrease in MTX clearance when either ASA or SUL were present. It is also noteworthy that ASA significantly increased the exposure of the subject to 7-OH-MTX and, to a lesser extent, so did sulindac. Since 7-OH-MTX has been shown to be an active metabolite when given for cytotoxic effects at higher doses and because it has been show to be nephrotoxic at doses a thousand-fold greater than used in rheumatoid arthritis, nonsteroidal anti-inflammatory drugs should be used cautiously with MTX until further large scale safety studies are conducted. The data indicate that if a clinically significant interaction were to occur, ASA is more likely than SU to interact with MTX.     

血液系统恶性肿瘤患儿甲氨蝶呤清除延迟危险因素的回顾性分析（英文）

甲氨蝶呤延迟清除是接受大剂量甲氨蝶呤化疗患者的一个临床特别关注点。本文旨在回顾性分析与血液系统恶性肿瘤患儿甲氨蝶呤浓度和延迟清除相关的因素。根据甲氨蝶呤治疗后24或42小时血清甲氨蝶呤浓度,将甲氨蝶呤化疗周期分为正常清除组或延迟清除组。通过χ²检验、Fisher’s精确检验、Mann-Whitney检验或Spearman’s相关性检验评价与甲氨蝶呤浓度和延迟清除相关的临床特征。采用广义估计方程校正同一名患者多个化疗周期的聚集效应和混淆因素。本研究共纳入43例患儿138个化疗周期进行评价。剂量、白细胞、血红蛋白和血尿素氮与24小时甲氨蝶呤血清浓度显著相关(P <0.05)。未发现基线特征与42小时甲氨蝶呤血清浓度之间的显著相关性。在34个化疗周期(24.6%)中观察到甲氨蝶呤延迟清除,剂量、白细胞、血红蛋白、血尿素氮和并发感染是甲氨蝶呤延迟清除的显著危险因素(P <0.05)。本研究发现了与甲氨蝶呤浓度和消除相关的数个风险因素,可用于识别甲氨蝶呤清除延迟高风险的患者,但研究结果有待在进一步的大规模研究中证实。     

来氟米特和甲氨蝶呤联合治疗类风湿关节炎(英文)

目的 :观察小剂量来氟米特和甲氨蝶呤联合应用治疗类风湿关节炎的疗效和安全性。方法 :64例类风湿关节炎病人随机分入 2组 ,各 32例。 2组病人于治疗前 1wk停用非甾体类抗炎镇痛药。试验开始时来氟米特 +甲氨蝶呤组 (Lef +MTX)给予来氟米特 2 0mg ,po ,qd +甲氨蝶呤 (MTX) 7.5mg po ,qw ,服 4wk后来氟米特 10mg ,po ,qd +MTX 7.5mg ,po ,qw ;MTX组服甲氨蝶呤 15mg ,po ,qw ,2组均以 2 4wk为一个疗程。治疗前、治疗后wk 12 ,2 4均做体检及实验室检查 ;治疗前后摄双手正位片。结果 :Lef +MTX组显效 88%( 2 8/32例 ) ,MTX组 38%( 12 /32例 )。Lef +MTX组不良反应 4例占 12 %,主要为皮疹、恶心 ;MTX组 14例占 4 3%,主要为恶心、呕吐、口腔溃疡、脱发、ALT升高、心悸、月经不调等。结论 :来氟米特与甲氨蝶呤联合治疗起效快、疗效佳、不良反应率低。     

两种慢作用抗风湿药联合治疗类风湿关节炎临床观察

目的　观察两种慢作用抗风湿药联合治疗类风湿关节炎 (RA)的疗效及安全性。方法　 50例活动期RA患者随机分为两组 ,每组 2 5例 ,第 1组服用甲氨蝶呤 (MTX) 1 0mg/周 +雷公藤多甙 2 0mg ,每日 3次 ;第 2组服用MTX 1 0mg/周 +柳氮磺吡啶 (SASP) 1 0g ,每日 2次 ,观察 3个月。 结果　MTX +雷公藤多甙组在 6、1 2周的有效率分别为 84% ,92 % ,不良反应发生率为 36 % ,MTX +SASP组为 56 % ,88% ,不良反应发生率为 2 8%。结论　MTX +雷公藤多甙组及MTX +SASP组治疗RA的疗效相似 ,均优于单独应用MTX ,副作用无明显增加     

Intracellular disposition of methotrexate in acute lymphoblastic leukemia in children

Methotrexate (MTX) is a key agent for the treatment of acute lymphoblastic leukemia in children and the benefit of high-dose MTX is well established as it significantly increases cure rates and improves patients' prognosis. However, the determinants of MTX therapeutic effect are not clearly identified, although intracellular polyglutamation is essential. MTX, the monoglutamate form (MTXG?) inhibits the dihydrofolate reductase (DHFR) implicated in the folate cycle. MTXG? is metabolized to active methotrexate polyglutamates (MTXPG) with sequential gamma-linkage of 2 to 6 glutamyl residues by the folylpolyglutamate synthetase (FPGS). Long chain MTXPG have higher affinity than MTX for the enzymes involved in de novo purine synthesis such as 5-aminoimidazole-4-carboxamide ribonucleotide transformylase (ATIC) and thymidilate synthase (TS), which results in a reinforcement of MTX inhibition. Thus, intracellular formation of MTXPG enhances the cytotoxic and antileukemic effect of MTX. Different pharmacogenetic polymorphisms contribute to interindividual variability in MTX response to treatment. In addition, pharmacokinetic interactions with 6-mercaptopurine (6-MP), frequently co-administered, have been reported. And factors affecting intracellular MTX disposition and 6-MP/MTX interactions, including pharmacogenetic polymorphisms affecting MTX disposition are reviewed.     

Methotrexate loaded poly(L-lactic acid) microspheres for intra-articular delivery of methotrexate to the joint

A controlled release delivery system that localizes methotrexate (MTX) in the synovial joint is needed to treat inflammation in rheumatoid arthritis (RA). The purpose of this work was to develop and characterize MTX loaded poly(l-lactic acid) (PLLA) microspheres and evaluate in vivo tolerability and MTX plasma concentrations following intra-articular injection into healthy rabbits. MTX loaded PLLA (2 kg/mole) microspheres were prepared using the solvent evaporation method and characterized in terms of size, molecular weight, thermal properties, and release rates into phosphate buffered saline (PBS) (pH 7.4) at 37 degrees C. Biocompatibility was evaluated by observing the swelling of the joints of the rabbits and histological analysis following the injection of the microspheres. MTX concentrations in the plasma and urine samples of rabbits were evaluated by high-performance liquid chromatography (HPLC). MTX loaded microspheres showed a rapid burst phase followed by a slow release phase. MTX loaded and control microspheres were biocompatible and plasma concentrations of MTX were tenfold higher in rabbits injected intra-articularly with free MTX than MTX microspheres. MTX microspheres may retain the drug in the joint by reducing clearance from the joint into the blood.     

The effect of vindesine on methotrexate hydroxylation in the rat

The effect of vindesine (VDS) on methotrexate (MTX) disposition was studied in bile-drained rats administered VDS prior to [3H]MTX, and in isolated rat hepatocytes and rat liver homogenate concomitantly incubated with MTX and VDS at 37 degrees. In vivo, 7-hydroxylation was reduced by 0.65 mg/kg VDS. In VDS-treated animals, biliary recovery of the MTX dose (50 mg/kg) as 7-hydroxymethotrexate (7-OH-MTX) (1.75 +/- 0.2%, mean +/- SEM) was significantly reduced compared to controls (2.83 +/- 0.57%). In vitro, hydroxylation of MTX (10-200 microM) in hepatocytes was reduced by 14.3 and 66.4% (means) at 12.5 and 100 microM VDS, respectively. With increasing VDS concentrations up to 100 microM, a reduction in intracellular MTX accumulation could account for the decreased MTX hydroxylation. Experiments in a cell free system gave no evidence of inhibition of 7-OH-MTX formation by VDS. In vitro MTX transport studies demonstrated that VDS inhibited the hepatocellular influx of MTX, as (1) the accumulation of MTX corresponded inversely to increasing VDS concentrations and (2) the MTX efflux was not increased by VDS. The apparent Ki for VDS inhibition of MTX influx was 57 microM. We suggest that VDS, by reducing the 7-OH-MTX formation in liver cells, may have implications for combination chemotherapy regimens which include MTX.