大鼠血浆中眯达唑仑的LC-MS/MS测定

建立了LC-MS/MS法测定大鼠血浆中的咪达唑仑.血浆样品经碱化处理后再用乙醚提取.采用C18色谱柱,以乙腈-0.1%甲酸(60∶40)为流动相,三唑仑为内标,采用电喷雾电离源(ESI),选择性正离子多离子反应监测(MRM)m/z 326.0→291.0(咪达唑仑)和m/z 343.0→308.0(三唑仑).咪达唑仑在1～500 ng/ml浓度范围内线性关系良好.方法回收率大于95%,提取同收率大于76%,日内和日间RSD小于8%.     

单点采血反映口服CYP3A探针咪达唑仑的代谢清除率

目的:研究中国男性健康受试者口服咪达唑仑后其1＇-羟化代谢的药代动力学规律,并寻找适合的单个采血点血浆中1＇-羟化咪达唑仑/咪达唑仑的浓度比值来反映咪达唑仑的血浆清除率。方法:10名受试者禁食8小时后清晨空腹口服7.5mg咪达唑仑,利用非房室模型计算药代动力学参数。结果:咪达唑仑药代动力学参数C_(max)为(191±17)nmol/L,t_(max)为(1.01±0.14)h,t_(1/2)为(3.2±0.4)h,AUC_(0→∞)为(681±43)nmol·h·L~(-1),Cl_(oral)为(0.54±0.04)L/(h·kg),K_e为(0.2415±0.0021)h~(-1),K_α为(0.82±0.18)h~(-1)。1小时血浆中咪达唑仑与其代谢产物1＇-羟化咪达唑仑的比值与其清除率的相关性统计学上具有显著意义(r=0.7,P<0.05,n=10)。结论:可用口服咪达唑仑后1小时单个采血点的代谢产物1＇-羟化咪达唑仑与咪达唑仑浓度的比值来反映其血浆清除率,应用于CYP3A活性测定的人群试验。     

高效液相色谱法同时测定人血浆1'-羟基咪达唑仑与咪达唑仑含量

目的建立同时检测1’-羟基咪达唑仑和咪达唑仑血药浓度的高效液相色谱法。方法采用Zirchrom 反相柱(Kromasil C18， 250 mm×4.6 mm，5 μm)；柱温：40 ℃；流动相：醋酸铵水溶液-甲醇(35∶65，V/V)；流速：1.5 mL·min^-1，样品经碱化提取分离后，流动相溶解，在220 nm波长处检测，内标：地西泮溶液。结果1’-羟基咪达唑仑和咪达唑仑分别在0.005 ～0.100和0.01 ～0.20 μg·mL^-1范围内线性关系良好，最低检测浓度分别为0.002和0.003 μg·mL^-1。萃取回收率均＞95%，日内和日间RSD均＜5%。结论该方法专一性强、灵敏度高、简单可靠，可用于研究体内CYP3A4酶的活性。     

人细胞色素P450 3A活性测定

目的:建立测定人细胞色素P4503A酶活性的方法。方法:收集24h尿液,以HPLC法测定尿液中氢化可的松(HC)与6β-羟基氢化可的松(6β-OHC)的含量,以6β-OHC/HC来评估细胞色素P4503A酶的活性。结果:健康志愿者尿中6β-羟基氢化可的松和氢化可的松的比值为(8.5±3.0),肿瘤患者为(6.2±4.5)。结论:细胞色素P4503A酶的活性可以通过测定6β-OHC与HC的比值进行预测。     

五味子甲素对大鼠咪达唑仑及其代谢物1′-羟基咪达唑仑药动学影响

目的:探讨五味子甲素(SchA)是否影响CYP3A底物-咪达唑仑在大鼠体内的代谢。方法:不同剂量的五味子甲素或酮康唑75mg/kg连续灌胃3d,采用单次十二指肠给药及腹股沟动脉插管,以CYP3A抑制剂(酮康唑)作为阳性对照,研究咪达唑仑在大鼠体内的代谢。高效液相色谱法(HPLC)测定血浆中咪达唑仑及其代谢物的浓度。结果:口服不同药物后咪达唑仑的主要药动学参数为:AUC(0-t)(mg.L-1.h)分别为:(1.08±0.29)(阴性对照)、(1.58±0.58)(SchA 8mg/kg)、(2.02±1.29)(SchA16mg/kg)、(2.22±1.25)(SchA 32mg/kg)、(3.34±2.25)(酮康唑75mg/kg);Cmax(mg/L)分别为:(1.6±0.6)(阴性对照)、(1.8±0.8)(SchA 8mg/kg)、(2.2±1.2)(SchA16mg/kg)、(2.2±0.7)(SchA 32mg/kg)、(2.9±1.1)(酮康唑75mg/kg)。1′-羟基咪达唑仑的主要药动学参数如下:AUC(0-t)(mg.L-1.h)分别为:(0.61±0.17)(阴性对照)、(0.40±0.15)(SchA 8mg/kg)、(0.39±0.20)(SchA16mg/kg)、(0.40±0.14)(SchA 32mg/kg)、(0.35±0.09)(酮康唑75mg/kg);Cmax(mg/L)分别为:(0.54±0.13)(阴性对照)、(0.42±0.15)(SchA 8mg/kg)、(0.39±0.16)(SchA 16 mg/kg)、(0.36±0.16)(SchA 32mg/kg)、(0.35±0.12)(酮康唑75mg/kg)。结论:结果表明,五味子甲素可以显著抑制咪达唑仑的代谢。     

HPLC法测定大鼠血浆中1’-羟基咪达唑仑及咪达唑仑的浓度

目的:建立大鼠血浆中咪达唑仑及其代谢产物1’-羟基咪达唑仑测定的高效液相色谱（HPLC）方法。方法:血浆样品以地西泮为内标,经碳酸盐缓冲液碱化后,由混合有机溶剂（正己烷:二氯甲烷=7:3,v/v）提取。采用Hypersil BDS C₁₈（250mm×4.6 mm,5μm）柱,以KH₂PO₄(0.02 mol·L^-1)缓冲液-乙腈-甲醇（38:20:42）为流动相,柱温40℃,流速1.0 ml·min^-1,于紫外230 nm处检测1’-羟基咪达唑仑及咪达唑仑浓度。结果:在该试验条件下,血浆中1’-羟基咪达唑仑的线性范围为8.32～832 ng·ml^-1,最低检测限为8.32 ng·ml^-1;咪达唑仑的线性范围为25～2 500 ng·ml^-1,最低检测限为25 ng·ml^-1。其日间和日内精密度均小于8%,提取回收率为84～90%。结论:本方法专属性强、灵敏度高、重复性好,适用于实验室评价药物间相互作用研究。     

机械通气患儿血浆中咪达唑仑及其代谢产物的测定

目的 建立测定人血浆中咪达唑仑及其代谢产物浓度的固相萃取和HPLC方法.方法 采用HPLC法分别测定29例ICU机械通气患儿给药24 h后血浆中咪达唑仑及其代谢产物浓度.色谱条件为：ZORBAX Eclipse XDB-C18色谱柱（4.6×250 mm,5 μm）;流动相为7.56 mmol/L硫酸铵溶液-乙腈,梯度洗脱,柱温25 ℃,流速1.0 ml/mmin,紫外检测波长254 nm.结果 4-羟基咪达唑仑、1＇-羟基咪达唑仑和咪达唑仑的保留时间分别为8.14、9.09和11.18 min.咪达唑仑及其羟基代谢产物的相对回收率98.88%～100.01%,RSD＜4%.29例患者血浆中咪达唑仑、1＇-羟基咪达唑仑和4-羟基咪达唑仑的平均浓度为0.68,0.28和0.08mg/L.结论 该方法适用于咪达唑仑及其代谢产物血药浓度的常规监测.     

LC—MS直接沉淀法测定人体咪哒唑仑和1-羟咪哒唑仑及应用

目的：建立简便液质联用（LC—MS）直接沉淀法测定人体血浆咪哒唑仑及1-羟咪哒唑仑的浓度。方法：Waters XterraC18（150mm&#215;2．1mm，5μm）色谱柱，流动相为10mmol&#183;L^-1甲酸铵-乙腈（40：60，v／v），流速为0．2mL&#183;min^-1，进样体积为20μL，柱温为40℃，样品室温度为5℃。结果：咪哒唑仑线性范围为0．56～287ng&#183;mL^-1，1-羟咪哒唑仑线性范围为0．56～285ng&#183;mL^-1，咪哒唑仑和1-羟咪哒唑仑最低检测限低于0．14ng&#183;mL^-1和0．28ng&#183;mL^-1，方法灵敏、稳定，特异性高，已成功地应用到人体血浆咪哒唑仑及1-羟咪哒唑仑药代动力学研究。结论：该方法简便、准确，重复性好，可以准确地测定人体血浆咪哒唑仑及1-羟咪哒唑仑的浓度。     

细胞色素P450 3A 选择性探针药物的评价

理想的细胞色素P4 5 0 3A(CYP3A)探针药物有助于检测CYP3A活性 ,辅助临床合理用药。本文对CYP3A选择性探针药物进行比较和综合分析 ,评价各种CYP3A选择性探针药物的特点 ,阐明对临床合理用药的指导意义。在已筛选的CYP3A选择性探针药物中 ,咪哒唑仑是一较理想的探药。     

rCYP3A4孵育条件的优化及其中1’-羟基咪达唑仑含量测定

目的 建立rCYP3A4中1’-羟基咪达唑仑含量测定方法,并对rCYP3A4体外孵育条件进行优化. 方法 反相高效液相色谱法RP-HPLC测定rCYP3A4中1’-羟基咪达唑仑的浓度,用单因素实验法对其体外孵育条件进行优化,用线性Lineweaver-Burk 双倒数作图法研究rCYP3A4酶促动力学. 结果 1’-羟基咪达唑仑在18.20～1 820.00 ng&#8226;mL^-1内线性关系良好;体外优化的孵育条件为5 μmol&#8226;L^-1咪达唑仑、10 pmol rCYP3A4、孵育10 min;rCYP3A4酶促动力学参数Km为0.96 μmol&#8226;L^-1,Vmax为0.78 pmol&#8226;min^-1. 结论 RP-HPLC法操作简便、灵敏、快速,适用于rCYP3A4中1’-羟基咪达唑仑的浓度测定,rCYP3A4孵育条件优化及其酶促动力学研究为研究经 CYP3A4代谢的药物相互作用及其他物质对CYP3A4酶的影响提供理论依据.     

五酯胶囊对健康受试者咪哒唑仑及其代谢物1’-羟基咪哒唑仑药动学的影响

目的：研究健康受试者合用中药制剂五酯胶囊（wuzhi-capsule,WZ）前后CYP3A4探针药咪哒唑仑（Midazolam,MDZ）及其代谢物1’-羟基咪哒唑仑（1’hydmxymidazolam,1’-OH—MDZ）的动力学过程,以证实WZ是否影响MDZ的代谢过程,从而间接证明WZ对CYP3A4的影响。方法：研究分两期,12名健康男性志愿者在第-周期单剂量口服MDZ15mg后,开始连续服用WZ3粒,bid×7d,在第二周期依然单剂口服MDZ15mg,同时服用WZ3粒。每期口服MDZ后即按设计的时间采血,用LC／MS／MS法测定血浆MDZ及1’-OH。MDZ浓度,并分别计算药动学参数。结果：合用WZ前后MDZ的主要药动学参数：AUC0-24分别为（578-±227）和（1186±320）μg·L-1·h;t1／2分别]为（3．4±1．0）、（3．6±1．1）h;CL（s）分别为（31±17）、（14±6）L／h;tmax分别为（0．8±0．5）、（1．6±1．2）h;C-分别为（171±70）、（282±152）vg／L;V／F（C）分别为（149±98）、（67±24）L。合用WZ前后1’-OH．MDZ的主要药动学参数：AuG-24分别为（141±699）、（129±49）μg·L-1·h;t1/2分别为（5．6±3．3）、（5．0±2．1）h;CL（S）分别为（130±68）、（134±72）L／h;t-分别为（0．8±0．3）、（1．6±1．2）h;C-分别为（48±23）、（36±28）μg／L;V／F（C）分别为（918±499）、（935±544）L。结论：与使用WZ前相比,使用WZ后MDZ的AuC0—24和C-分别增加119．4％、85．6％,CL（s）降低52．1％,tmax延迟1倍。WZ能显著增加MDZ的血浓度和生物利用度。推测WZ可能是一种CYP3A4抑制剂或含有具有CYP3A4抑制作用的成分。     

Pharmacokinetics of midazolam in CYP3A4- and CYP3A5-genotyped subjects

Objective We investigated whether differences in pharmacokinetics of midazolam, a CYP3A probe, could be demonstrated between subjects with different CYP3A4 and CYP3A5 genotypes.Methods Plasma concentrations of midazolam, and of total (conjugated + unconjugated) 1OH-midazolam, and 4OH-midazolam were measured after the oral administration of 7.5 mg or of 75 µg of midazolam in 21 healthy subjects.Results CYP3A5*7, CYP3A4*1E, CYP3A4*2, CYP3A4*4, CYP3A4*5, CYP3A4*6, CYP3A4*8, CYP3A4*11, CYP3A4*12, CYP3A4*13, CYP3A4*17 and CYP3A4*18 alleles were not identified in the 21 subjects. CYP3A5*3, CYP3A5*6, CYP3A4*1B and CYP3A4*1F alleles were identified in 20, 1, 4 and 2 subjects, respectively. No statistically significant differences were observed for the AUC_inf values between the different genotypes after the 75-µg or the 7.5-mg dose.Conclusion Presently, CYP3A4 and CYP3A5 genotyping methods do not sufficiently reflect the inter-individual variability of CYP3A activity.     

Effect of an oral contraceptive preparation containing ethinylestradiol and gestodene on CYP3A4 activity as measured by midazolam 1'-hydroxylation

AIMS: To characterize the effect of an oral contraceptive (OC) containing ethinylestradiol and gestodene on the activity of CYP3A4 in vivo as measured by the 1'-hydroxylation of midazolam. METHODS: In this randomised, double-blind, cross-over trial nine healthy female subjects received either a combined OC (30 microg ethinylestradiol and 75 microg gestodene) or placebo once daily for 10 days. On day 10, a single 7.5 mg dose of midazolam was given orally. Plasma concentrations of midazolam and 1'-hydroxymidazolam were determined up to 24 h and the effects of midazolam were measured with three psychomotor tests up to 8 h. RESULTS: The combined OC increased the mean AUC of midazolam by 21% (95% CI 2% to 40%; P = 0.03) and decreased that of 1'-hydroxymidazolam by 25% (95% CI 10% to 41%; P = 0.01), compared with placebo. The metabolic ratio (AUC of 1'-hydroxymidazolam/AUC of midazolam) was 36% smaller (95% CI 19% to 53%; P = 0.01) in the OC phase than in the placebo phase. There were no significant differences in the Cmax, tmax, t(1/2) or effects of midazolam between the phases. CONCLUSIONS: A combined OC preparation caused a modest reduction in the activity of CYP3A4, as measured by the 1'-hydroxylation of midazolam, and slightly increased the AUC of oral midazolam. This study suggests that, at the doses used, ethinylestradiol and gestodene have a relatively small effect on CYP3A4 activity in vivo.     

Midazolam microdose to determine systemic and pre-systemic metabolic CYP3A activity in humans

Aim

We aimed to establish a method to assess systemic and pre-systemic cytochrome P450 (CYP) 3A activity using ineffective microgram doses of midazolam.

Methods

In an open, one sequence, crossover study, 16 healthy participants received intravenous and oral midazolam at microgram (0.001 mg intravenous and 0.003 mg oral) and regular milligram (1 mg intravenous and 3 mg oral) doses to assess the linearity of plasma and urine pharmacokinetics.

Results

Dose-normalized AUC and C_max were 37.1 ng ml⁻¹h [95% CI 35.5, 40.6] and 39.1 ng ml⁻¹ [95% CI 30.4, 50.2] for the microdose and 39.0 ng ml⁻¹h [95% CI 36.1, 42.1] and 37.1 ng ml⁻¹ [95% CI 26.9, 51.3] for the milligram dose. CL_met was 253 ml min⁻¹ [95% CI 201, 318] vs. 278 ml min⁻¹ [95% CI 248, 311] for intravenous doses and 1880 ml min⁻¹ [95% CI 1590, 2230] vs. 2050 ml min⁻¹ [95% CI 1720, 2450] for oral doses. Oral bioavailability of a midazolam microdose was 23.4% [95% CI 20.0, 27.3] vs. 20.9% [95% CI 17.1, 25.5] after the regular dose. Hepatic and gut extraction ratios for microgram doses were 0.44 [95% CI 0.39, 0.49] and 0.53 [95% CI 0.45, 0.63] and compared well with those for milligram doses (0.43 [95% CI 0.37, 0.49] and 0.61 [95% CI 0.53, 0.70]).

Conclusion

The pharmacokinetics of an intravenous midazolam microdose is linear to the applied regular doses and can be used to assess safely systemic CYP3A activity and, in combination with oral microdoses, pre-systemic CYP3A activity.     

Phenotyping CYP3A using midazolam in cancer and noncancer Asian patients

AIMS: To investigate CYP3A activity in cancer and noncancer Asian patients using midazolam and to reveal possible alternative traits for phenotyping CYP3A. METHODS: Intravenous midazolam 2.5 mg or 2.5-8 mg was administered to 27 cancer and 24 noncancer patients, respectively. Plasma was sampled at 0, 0.25, 0.5, 1, 1.5, 2, 3.5 and 5 h after intravenous ultrashort, 30 s infusion. Plasma midazolam and 1'-hydroxymidazolam concentrations were determined using GCMS. The disposition of midazolam and 1'-hydroxymidazolam in these patients was compared. Midazolam clearance was correlated with dose-normalized plasma midazolam concentrations (concentration/per dose). RESULTS: Clearance (CL) and steady state volume of distribution (Vss) of midazolam (mean +/- SD, 95% confidence level) in cancer (424 +/- 155, 61.3 ml min(-1); 1.21 +/- 0.46, 0.18 l kg(-1)) and noncancer (407 +/- 135, 57.1 ml min(-1); 1.15 +/- 0.33, 0.155 l kg(-1)) patients, respectively, were not different and comparable with published data. Clearance variability was 4-5 fold in both groups. Midazolam clearance correlated significantly with all plasma concentration/per dose at and after the 1-h time point, with a minimum correlation coefficient of r = 0.752, P < 0.001. CONCLUSIONS: CYP3A activities determined with different doses of midazolam in cancer and noncancer Asian patients showed variability of 4-5-fold and were not different between groups. One to two-fold plasma midazolam concentrations per dose may be feasible as a simple alternative phenotypic trait for hepatic CYP3A activity determination.     

Effect of danshen extract on the activity of CYP3A4 in healthy volunteers

AIMS

To assess the effect of danshen extract on CYP3A4 activity using midazolam as an in vivo probe.

METHODS

A sequential, open-label, two-period pharmacokinetic interaction study design was used to compare midazolam pharmacokinetic parameters before and after 14 days of administration of danshen tablets. Twelve healthy volunteers received a single oral dose (15 mg) of midazolam followed by danshen tablets (four tablets orally, three times a day) for 14 days. On the last day of the study they received four danshen tablets with a 15 mg midazolam tablet and plasma concentrations of midazolam and its corresponding metabolite 1–hydroxylmidazolam were measured prior to and after the administration of danshen tablets periodically for 12 h.

RESULTS

The 90% confidence intervals of C_max,t_1/2, CL/F and AUC(0,∞) of midazolam before and after administration of danshen tablets were (0.559, 0.849), (0.908, 1.142), (1.086, 1.688) and (0.592, 0.921), respectively; and those of C_max, t_1/2 and AUC(0,∞) of 1-hydroxylmidazolam after vs. before administration of danshen tablets were (0.633, 0.923), (0.801, 1.210) and (0.573, 0.980), respectively. Ratios of geometric LS means of C_max(1OHMid) : C_max(Mid) and AUC_max(1OHMid) : AUC_max(Mid) (after vs. before 14-day danshen) were 1.072 and 1.035, respectively.

CONCLUSIONS

Our findings suggest that multiple dose administration of danshen tablets may induce CYP3A4 in the gut. Accordingly, caution should be taken when danshen products are used in combination with therapeutic drugs metabolized by CYP3A.     

Effect of single and repeat doses of casopitant on the pharmacokinetics of CYP450 3A4 substrates midazolam and nifedipine

AIM

To evaluate the impact of single and repeated doses casopitant on the pharmacokinetics of single dose midazolam and nifedipine (CYP3A substrates) in healthy subjects. The effect on debrisoquine metabolism (CYP2D6 substrate) was also assessed.

METHODS

Three open-label studies were conducted in healthy subjects. In the first study subjects received single dose 50 or 100 mg oral casopitant, single dose 5 mg oral midazolam and single dose 10 mg oral debrisoquine. In the other two studies subjects received repeated doses of 10 mg (study 2), 30, or 120 mg oral casopitant and single doses of 5 mg oral midazolam (study 2) and single doses of 10 mg oral nifedipine (study 3). Plasma concentration–time data were analyzed using standard non-compartmental methods. The effect of casopitant on all probes was assessed using geometric means ratios and corresponding 90% confidence intervals (CIs).

RESULTS

The AUC(0,∞) of midazolam was increased 1.44-fold (90% CI 1.35, 1.54) and 1.52-fold (90% CI 1.41, 1.65) after co-administration with a single dose of 50 or 100 mg casopitant, respectively. Debrisoquine metabolism was unchanged. After 3 days of casopitant administration, midazolam AUC(0,∞) was increased 1.45- (90% CI 1.32, 1.59), 2.02- (90% CI 1.75, 2.32), and 2.67-fold (90% CI 2.18, 3.27) after co-administration with 10, 30 or 120 mg casopitant, respectively. After 14 days of casopitant administration, midazolam AUC(0,∞) was increased 1.51- (90% CI 1.40, 1.63) to 3.49-fold (90% CI 2.98, 4.08). After 3 days of casopitant administration, nifedipine AUC(0,∞) was increased 1.56- (90% CI 1.37, 1.78) and 1.77-fold (90% CI 1.54, 2.04) after co-administration with 30 or 120 mg casopitant, respectively. Similar increases in nifedipine exposure were observed after 14 days of casopitant administration.

CONCLUSIONS

Casopitant is a dose- and duration-dependent weak to moderate inhibitor of CYP3A.     

The distribution and gender difference of CYP3A activity in Chinese subjects

AIMS: To investigate the distribution of CYP3A activity in the Chinese population, and to test for gender-related differences in CYP3A activity. METHODS: Using midazolam as a probe drug, CYP3A activity in 202 Chinese healthy subjects (104 men) was measured by plasma 1'-hydroxymidazolam:midazolam (1'-OH-MDZ:MDZ) ratio at 1 h after oral administration of 7.5 mg midazolam. The different phases of the menstrual cycle including preovulatory, ovulatory and luteal phases of 66 women phenotyped with midazolam were recorded. The concentrations of 1'-OH-MDZ and MDZ in plasma were measured by HPLC RESULTS: A 13-fold variation of CYP3A activity (log1'-OH-MDZ:MDZ: range -0.949-0.203) was shown. The CYP3A activity was normally distributed as indicated by the frequency distribution histogram, the probit plot and the Kolmogorov-Smirnov test (P > 0.05). The CYP3A activity of women was higher than that of men (median: -0.36 vs -0.43, P < 0.05; 95% CI for difference: -0.127, -0.012). There was a significant difference in CYP3A activity between the three phases of the menstrual cycle. The activity was highest in the preovulatory phase and decreased sequentially in the ovulatory and luteal phases (P < 0.05). CONCLUSIONS: A normal distribution of CYP3A activity was observed in the Chinese population. The CYP3A activity is higher in female subjects than in males. CYP3A activity differed across the phases of the menstrual cycle.     

CYP3A5~*3和CYP3A4~*18B基因多态性对肾移植患者环孢素药代动力学的影响

目的回顾性研究肾脏移植后1mon,CYP3A5*3和CYP3A4*18B基因多态性对CsA药代动力学参数的影响。方法采用PCR-RFLP方法分析了63名肾脏移植患者CYP3A5*3和CYP3A4*18B基因型;荧光偏正免疫法用于检测肾移植患者静脉全血中的CsA浓度。结果在63名肾移植患者中,CYP3A5*3和CYP3A4*18B突变等位基因发生频率分别为0.770(95CI:0.767～0.773),0.235(95CI:0.235～0.241),而且这些等位基因表现出完全连锁不平衡。在移植术后1mon内,携带CYP3A4*1/*1野生型纯合子患者的C0以及剂量校正谷血浓度(C0/D)均明显高于携带CYP3A4*1/*18B杂合子或CYP3A4*18B/*18B突变型纯合子患者(P<0.05,Mann-WhitneyUtest);CYP3A5*1/*1基因型组的给药剂量明显高于CYP3A5*1/*3或CYP3A5*3/*3基因型组(P=0.004<0.01,Kruakal-Wallistest);CYP34*18B和CYP3A5*3联合考虑,对于CYP3A5表达组,同样发现C0、C0/D在CYP3A4*1/*1组C0以及C0/D均明显高于CYP3A4*1/*18B或CYP3A4*18B/*18B组(P<0.05,Mann-WhitneyUtest);而其他药动学参数在CYP3A5*3及CYP3A4*18B各组间相比差异则没有统计学意义。结论CYP3A5*3和(或)CYP3A4*18B基因多态性对肾移植后1monCsA药代动力学有一定影响,移植前CYP3A5*3基因型的分析仍需进一步研究。     

Pharmacokinetics of intravenous and oral midazolam in plasma and saliva in humans: usefulness of saliva as matrix for CYP3A phenotyping

AIMS

To compare midazolam kinetics between plasma and saliva and to find out whether saliva is suitable for CYP3A phenotyping.

METHODS

This was a two way cross-over study in eight subjects treated with 2 mg midazolam IV or 7.5 mg orally under basal conditions and after CYP3A induction with rifampicin.

RESULTS

Under basal conditions and IV administration, midazolam and 1′-hydroxymidazolam (plasma, saliva), 4-hydroxymidazolam and 1′-hydroxymidazolam-glucuronide (plasma) were detectable. After rifampicin, the AUC of midazolam [mean differences plasma 53.7 (95% CI 4.6, 102.9) and saliva 0.83 (95% CI 0.52, 1.14) ng ml⁻¹ h] and 1′-hydroxymidazolam [mean difference plasma 11.8 (95% CI 7.9, 15.7) ng ml⁻¹ h] had decreased significantly. There was a significant correlation between the midazolam concentrations in plasma and saliva (basal conditions: r = 0.864, P < 0.0001; after rifampicin: r = 0.842, P < 0.0001). After oral administration and basal conditions, midazolam, 1′-hydroxymidazolam and 4-hydroxymidazolam were detectable in plasma and saliva. After treatment with rifampicin, the AUC of midazolam [mean difference plasma 104.5 (95% CI 74.1, 134.9) ng ml⁻¹ h] and 1′-hydroxymidazolam [mean differences plasma 51.9 (95% CI 34.8, 69.1) and saliva 2.3 (95% CI 1.9, 2.7) ng ml⁻¹ h] had decreased significantly. The parameters separating best between basal conditions and post-rifampicin were: (1′-hydroxymidazolam + 1′-hydroxymidazolam-glucuronide)/midazolam at 20–30 min (plasma) and the AUC of midazolam (saliva) after IV, and the AUC of midazolam (plasma) and of 1′-hydroxymidazolam (plasma and saliva) after oral administration.

CONCLUSIONS

Saliva appears to be a suitable matrix for non-invasive CYP3A phenotyping using midazolam as a probe drug, but sensitive analytical methods are required.

WHAT IS ALREADY KNOWN ABOUT THE SUBJECT

• Midazolam is a frequently used probe drug for CYP3A phenotyping in plasma. Midazolam and its hydroxy-metabolites can be detected in saliva.

WHAT THIS STUDY ADDS

• The concentrations of midazolam and its hydroxy-metabolites are much lower in saliva than in plasma, but the midazolam concentrations in both matrices show a significant linear correlation.
• Saliva appears to be a suitable matrix for CYP3A phenotyping with midazolam, but very sensitive methods are required due to the low concentrations of midazolam and its hydroxy-metabolites.