Cocktail法评价白香丹胶囊对大鼠体内CYP450酶活性的影响

目的：建立同时测定大鼠血浆中6种CYP450探针药物的方法,并采用Cocktail法研究白香丹胶囊对大鼠CYP450酶活性的影响。方法：选用茶碱(CYP1A2)、氯唑沙宗(CYP2E1)、甲苯磺丁脲(CYP2C6)、右美沙芬(CYP2D2)、奥美拉唑(CYP2D1)、咪达唑仑(CYP3A2)作为探针药物。大鼠随机分为对照组和给药组,给药组每天灌胃白香丹胶囊0.675 g?kg-1,对照组灌胃等量生理盐水,连续给药14天。第15天均灌胃给予6个探针药物,于不同时间点眼眶取血,采用LC-MS/MS法测定各探针药物浓度,计算药动学参数并进行组间t检验。结果：与对照组相比,给药组茶碱(P < 0.01)、氯唑沙宗(P < 0.01)、甲苯磺丁脲(P < 0.05)代谢显著加快,右美沙芬、奥美拉唑、咪达唑仑代谢无显著性差异。结论：白香丹胶囊对大鼠CYP1A2有中强诱导作用,对CYP2E1、CYP2C6有弱诱导作用。     

Cocktail探针药物法评价威麦宁胶囊对大鼠体内CYP450活性的影响

目的采用Cocktail探针药物法评价威麦宁胶囊对大鼠体内6种CYP450亚型酶活性的影响。方法分别选用甲苯磺丁脲、氯唑沙宗、茶碱、咪达唑仑、奥美拉唑和右美沙芬作为CYP2C6、CYP2E1、CYP1A2、CYP3A2、CYP2D1和CYP2D2的探针底物。大鼠每日灌胃威麦宁胶囊1.6 g·kg-1,采用LC-MS/MS测定给药前后大鼠体内6种混合探针的血药浓度,计算药动学参数。结果威麦宁胶囊连续给药2周后,与给药前相比,奥美拉唑ρmax、AUC0-t、tmax及AUC0-∞显著升高(P<0.05);咪达唑仑ρmax、AUC0-t和AUC0-∞显著升高(P<0.01或P<0.05);右美沙芬ρmax、AUC0-t升高(P<0.05);甲苯磺丁脲t1/2、AUC0-∞和tmax显著升高(P<0.01或P<0.05),而CL/F显著降低(P<0.01),ρmax、AUC0-t无显著改变(P>0.05);氯唑沙宗ρmax升高(P<0.05),CL/F降低(P<0.05),AUC0-t升高但无显著差异(P>0.05);茶碱ρmax、AUC0-t升高但无显著差异(P>0.05)。表明奥美拉唑、咪达唑仑和右美沙芬代谢明显减慢(均P<0.05),茶碱、甲苯磺丁脲、氯唑沙宗的代谢无显著差异;威麦宁胶囊对大鼠体内CYP2D1、CYP3A2、CYP2D2酶有抑制作用,对CYP1A2、CYP2C6、CYP2E1酶的活性无显著影响。结论当威麦宁胶囊与CYP2C19、CYP3A4、CYP2D6酶的底物药物合用时,需要调整给药剂量,避免因药物相互作用使体内血药浓度过高产生毒副作用。     

Cocktail探针药物法评价胃炎灵颗粒对大鼠体内CYP450活性的影响

目的研究胃炎灵颗粒对大鼠体内细胞色素P450酶活性的影响。方法分别以右美沙芬(CYP2D6)、咪达唑仑(CYP3A4)、奥美拉唑(CYP2C19)、茶碱(CYP1A2)、氯唑沙宗(CYP2E1)和甲苯磺丁脲(CYP2C9)作为探针底物,大鼠6只,每日灌胃胃炎灵颗粒4 g/kg,采用LC-MS/MS测定给药前后大鼠体内6种探针药物的血药浓度。结果胃炎灵颗粒连续给药10 d后,与给药前相比,大鼠体内的右美沙芬(P <0. 01)、甲苯磺丁脲(P <0. 01)代谢减慢,氯唑沙宗(P <0. 01)代谢加快,奥美拉唑、咪达唑仑、茶碱的代谢无显著差异。结论胃炎灵颗粒在大鼠体内对CYP2D6酶产生中强抑制作用,对CYP2C9酶产生弱抑制作用,对CYP2E1酶产生轻微诱导作用,对CYP3A4、CYP2C19和CYP1A2基本没有影响。     

慢性不可预见性温和应激模型大鼠的肝脏药物代谢酶活性变化研究

采用鸡尾酒(cocktail)探针药物法研究慢性不可预见性温和应激(chronic unpredictable mild stress,CUMS)造成的抑郁状态对大鼠体内6种CYP450亚酶活性的影响。根据Katz法建立CUMS大鼠抑郁模型;分别选用甲苯磺丁脲、氯唑沙宗、茶碱、咪达唑仑、奥美拉唑及右美沙芬作为大鼠CYP2C6、CYP2E1、CYP1A2、CYP3A2、CYP2D1、CYP2D2的探针底物,采用液质联用法(LC-MS/MS)测定对照组与模型组大鼠体内6种混合探针的血药浓度,计算药动学参数。结果表明,茶碱和氯唑沙宗代谢显著加快(P<0.01),甲苯磺丁脲、右美沙芬、奥美拉唑、咪达唑仑的代谢无显著差异。结果说明,慢性不可预见性温和应激造成的抑郁状态对CYP1A2有强诱导、对CYP2E1有中强诱导作用。     

毛冬青胶囊对大鼠体内细胞色素P450 代谢活性的影响*

目的：采用Cocktail探针药物法研究毛冬青胶囊对大鼠CYP1A2、CYP3A2、CYP2C6、CYP2D1、CYP2D2和CYP2E1体内代谢活性的影响。方法：分别以茶碱、咪达唑仑、甲苯磺丁脲、奥美拉唑、右美沙芬和氯唑沙宗作为探针底物,将大鼠随机分为3组：空白对照组、毛冬青的低剂量组和高剂量组。低、高剂量组每日分别灌胃给予毛冬青胶囊1.8、3.6 g·kg-1,空白对照组每日给予与低剂量组等体积的生理盐水,各组均为1次/天,连续14 d。各组分别于第15天给予Cocktail探针药物,于给药前、后不同时间点取血,用LC-MS/MS检测各探针药物的血药浓度,计算药代动力学参数。结果：茶碱低剂量组cmax、AUC0-t有极显著差异（P≤0.01）;甲苯磺丁脲高剂量组和氯唑沙宗低剂量组AUC0-t有显著差异（P≤0.05）;其他无统计学差异。结论：毛冬青胶囊对大鼠体内CYP2C6和CYP1A2有强诱导作用,对CYP2E1有中强诱导作用,其他亚型基本无影响。     

HPLC 法同时测定大鼠血浆中 CYP450酶探针药物氯唑沙宗、甲苯磺丁脲和咪达唑仑浓度

目的：建立同时测定大鼠血浆中细胞色素 P450（CYP450）酶探针药物氯唑沙宗、甲苯磺丁脲和咪达唑仑浓度的高效液相色谱法。方法色谱柱采用 Diamonsil C18（250 mm ×4．6 mm,5μm）,流动相为甲醇与磷酸二氢铵缓冲液（61∶39,V ／V）,流速1 mL·min －1,检测波长230 nm,带宽4 nm,柱温35℃,以地西泮为内标,同时检测氯唑沙宗、甲苯磺丁脲和咪达唑仑的大鼠血浆药物浓度。结果氯唑沙宗、甲苯磺丁脲和咪达唑仑均在0．1～50 mg·L －1（r ＝0．9995）的范围内线性关系良好;低、中、高3个浓度下,3种探针药物精密度试验中相对标准偏差为4．78％～9．78％,回收率为92．71％～109．79％。结论该方法操作简便,灵敏度高,重现性好,符合生物样品分析要求,适用于同时测定3种 CYP450酶亚型探针药物氯唑沙宗、甲苯磺丁脲和咪达唑仑的大鼠血浆药物浓度,可为 CYP450酶活性测定提供分析方法学参考。     

天然冰片对大鼠细胞色素P450四种亚型活性的影响

目的：用Cocktail探针药物法研究天然冰片对大鼠细胞色素P450四种亚型CYP1A2、CYP2C6/11、CYP2E1和CYP3A活性的影响。方法：将大鼠随机分为2组,给药组灌胃给予天然冰片-0.8%CMC-Na混悬液,剂量90mg/kg,对照组灌胃给予不含药物的0.8%CMC-Na溶液,每天1次,连续7d。于第8天,两组大鼠均尾静脉注射混合探针药物溶液（茶碱10mg/kg、甲苯磺丁脲2.5mg/kg、氯唑沙宗10mg/kg、氨苯砜5mg/kg）,眼内眦静脉采血,超高效液相色谱法检测各探针药物的血药浓度,采用WinNonlin 5.0.1计算药代动力学参数。结果：与对照组相比,天然冰片组中甲苯磺丁脲的t1/2、AUC0-t、AUC0-∞和MRT0-∞明显减小,两组之间的差异具有统计学意义（P〈0.05）;而两组之间茶碱、氯唑沙宗和氨苯砜的药代动力学参数则没有明显差异。结论：天然冰片对大鼠CYP2C6/11的活性具有诱导作用,对CYP1A2、CYP2E1和CYP3A活性无显著影响。     

评价HPPH对细胞色素P450酶体外代谢活性的影响

目的:评价HPPH在体外对大鼠及人肝微粒CYP450酶的6种亚型酶活性的影响,预测使用HPPH可能出现的药物相互作用。方法:将注射用HPPH与CYP450酶的6种亚型的特异性探针底物非那西汀(CYP1A2)、甲苯磺丁脲(CYP2C9)、S-美芬妥因(CYP2C19)、右美沙芬(CYP2D6)、氯唑沙宗(CYP2E1)、咪达唑仑(CYP3A4)和睾酮(CYP3A4)与大鼠及人肝微粒进行孵育反应,采用HPLC-MS/MS法测定对应的7种代谢产物(对乙酰氨基酚、羟基甲苯磺丁脲、4-羟基美芬妥因、O-去甲基右美沙芬、6-羟基氯唑沙宗、1′-羟基咪达唑仑、6β-羟基睾酮)的浓度。结果:在本实验条件下,HPPH浓度为1.00~50.00μmol·L-1时,未发现其对大鼠的CYP1A2、CYP2C9、CYP2D6、CYP2E1、CYP3A4产生抑制作用。在本实验条件下,HPPH浓度为0.50~10.00μmol·L-1时,未发现其对人CYP1A2产生抑制作用;但对人CYP2C9、CYP2C19、CYP2D6、CYP2E1均存在抑制作用;对人CYP3A4,对底物咪达唑仑存在抑制作用,对底物睾酮未发现抑制作用。结论:HPPH对CYP450酶的抑制作用存在种属差异,在人体内HPPH与CYP450酶作用有待体内实验进一步证明。     

别嘌呤醇对大鼠CYP450酶活性的影响

目的用Cocktail探针药物法研究别嘌呤醇对大鼠细胞色素P450（CYP450）同工酶的影响。方法将SD大鼠随机分为2组。别嘌呤醇组为实验组,生理盐水组为对照组,采用高效液相色谱-质谱联用技术测定连续给药14d后大鼠血浆中相应探针药物的浓度及其药动学参数。结果别嘌呤醇体内给药14d后,大鼠体内非那西丁的AUC（0-∞）（P〈0．01）、clnax（P〈0．05）和t1／2（P〈0．05）显著大于对照组,CL显著低于对照组（P〈0．01）;而甲苯磺丁脲、奥美拉唑和右美沙芬探针药物的药动学参数均无显著变化。结论别嘌呤醇抑制大鼠CYP1A2酶,对CYP2C9、CYP2C19和CYP2D6酶的影响不显著。     

甲基原薯蓣皂苷对人肝微粒体中7种CYP450酶活性的影响

目的研究甲基原薯蓣皂苷对CYP450酶的7种亚型酶活性的影响。方法将MPD和CYP450酶7种亚型的特异性探针底物咖啡因(CYP1A2)、右美沙芬(CYP2D6)、甲苯磺丁脲(CYP2C9)、s-美芬妥因(CYP2C19)、氯唑沙宗(CYP2E1)、香豆素(CYP2A6)及咪达唑仑(CYP3A4)与人肝微粒体进行孵化反应,采用HPLC和LC-MS/MS法测定对应的7种代谢产物(1,7-二甲基黄嘌呤、去甲右美沙芬、4-羟基甲苯磺丁脲、4-羟基美芬妥因、6-羟基氯唑沙宗、7-羟基香豆素和1-羟基咪达唑仑)的浓度,通过与对照组比较,确定MPD对以上7种酶活性的影响。结果MPD在1~10μmol.L-1时对7种酶均无明显抑制作用,在100μmol.L-1时对CYP2D6有抑制趋势,但对其他6种酶无抑制作用,均无统计学意义(P>0.05)。结论MPD在与以上6种酶(CYP1A2、CYP2E1、CYP2C19、CYP3A4、CYP2C9和CYP2A6)代谢的药物联合用药时,发生药物相互作用的可能性较小。     

稳心颗粒对大鼠细胞色素P450酶的影响

目的 用cocktail探针药物法评价稳心颗粒对大鼠体内CYP1A2,CYP2C9,CYP2C19,CYP2D6,CYP2E1和CYP3A4亚型酶活性的影响. 方法 雄性Wistar大鼠随机分为稳心颗粒高、低剂量组和空白对照组. 稳心颗粒高、低剂量组灌胃给予稳心颗粒,空白对照组灌胃给予0.9%氯化钠溶液,连续7 d. 第8天腹腔注射探针药物咖啡因、甲苯磺丁脲、奥美拉唑、美托洛尔、氯唑沙宗和氨苯砜. 尾静脉取血,用高效液相色谱法检测血样,比较药动学参数变化. 结果高、低剂量稳心颗粒分别使咖啡因的AUC_(0-∞)增加1.635倍和 1.435倍,分别使氨苯砜的AUC_(0-∞)增加1.816倍和1.324倍. 高剂量稳心颗粒使奥美拉唑和氯唑沙宗的AUC_(0-∞)增加2.748倍和1.696倍. 结论 高剂量稳心颗粒对CYP2C19和CYP2E1活性有弱抑制作用,稳心颗粒对CYP1A2和CYP3A4的活性有弱抑制作用.     

振源胶囊对细胞色素P_(450)酶CYP1A2、CYP3A4、CYP2E1的影响

目的:研究振源胶囊对细胞色素P450酶CYP1A2、CYP3A4、CYP2E1的影响。方法:用Cocktail探针药物法,将Wistar大鼠随机分组,灌胃给予振源胶囊溶液,以生理盐水组为空白对照,诱导10d,于股动脉插管,注射给予3种探针药物咖啡因、氨苯砜、氯唑沙宗,通过高效液相色谱法检测各探针药物的代谢率来评价各组CYP1A2、CYP3A4、CYP2E1亚型酶的活性;药动学计算采用DAS2.0软件完成。结果:给予振源胶囊的大鼠,咖啡因代谢加快,半衰期缩短;氨苯砜代谢减慢,半衰期延长;氯唑沙宗半衰期与空白对照组比较无显著差异(P>0.05)。结论:振源胶囊对大鼠CYP1A2有诱导作用,对CYP3A4有抑制作用,对CYP2E1的作用不明显。     

丹参-红花药对配伍前后对大鼠肝药酶亚型CYP1A2、CYP2E1和CYP3A4活性的影响

目的 研究丹参、红花药对配伍前后对大鼠肝药酶亚型CYP1A2、CYP2E1和CYP3A4活性的影响。方法 分别选用咖啡因、氯唑沙宗和咪达唑仑作为CYP1A2、CYP2E1和CYP3A4的探针药物。将大鼠随机分为4组,即空白对照组、丹参（1.2 g生药/kg）组、红花（0.4 g生药/kg）组、丹参（1.2 g生药/kg）+红花（0.4 g生药/kg）组,按上述剂量ig给药7 d。于末次给药后30 min,尾iv探针药物咖啡因、氯唑沙宗和咪达唑仑溶液,在不同的时间点取血进行检测;以甲硝唑为内标,采用HPLC法检测探针药物咖啡因、氯唑沙宗和咪达唑仑的量,评价各药物组对大鼠CYP3A4、CYP2E1和CYP1A2活性的影响。结果 与空白对照组比较,丹参组咖啡因、氯唑沙宗和咪达唑仑的清除率（CL）有所增强,曲线下面积（AUC）减少,其半衰期（t_1/2）有减少趋势,但差异均不显著;红花组咖啡因和氯唑沙宗的CL有所降低,但差异不显著,咪达唑仑的CL显著降低（P<0.01）,氯唑沙宗的AUC增加,但差异不显著,咖啡因和咪达唑仑的AUC明显增加（P<0.05、0.01）;丹参+红花组咖啡因和氯唑沙宗的CL明显降低（P<0.05）,曲线下面积（AUC）明显增加（P<0.05）,其t_1/2有延长趋势,但差异不显著。结论 丹参、红花配伍后对CYP450亚型CYP1A2和CYP2E1有抑制作用,这可能是丹参、红花配伍协同增效的作用机制之一。     

豆腐果苷对人肝微粒体CYP450酶体外抑制作用研究

目的:通过评价豆腐果苷在体外对人肝微粒体CYP450酶的7种亚型酶活性的影响,预测服用豆腐果苷可能出现的食物-药物及药物-药物代谢的影响。方法:将豆腐果苷与CYP450酶7种亚型的特异性探针底物咖啡因(CYP1A2)、右美沙芬(CYP2D6)、甲苯磺丁脲(CYP2C9)、S-美芬妥因(CYP2C19)、氯唑沙宗(CYP2E1)、香豆素(CYP2A6)及咪达唑仑(CYP3A4)与人肝微粒体进行孵育反应,采用HPLC和LC-MS/MS法测定对应的7种代谢产物(1,7-二甲基黄嘌呤、去甲右美沙芬、4-羟基甲苯磺丁脲、4-羟基美芬妥因、6-羟基氯唑沙宗、7-羟基香豆素和1-羟基咪达唑仑)的浓度,与对照组比较,确定豆腐果苷对以上7种亚酶活性的影响。结果:豆腐果苷在1～100μmol.L-1时对7种酶的抑制作用均无明显统计学意义(P>0.05)。结论:豆腐果苷可能不会引起有临床意义的CYP450酶抑制现象的发生。     

Effects of Alismatis rhizome on rat cytochrome P450 enzymes

Context: Alismatis rhizome (RA) (Water Plantain Family, also called “Zexie” in Chinese), one of the commonly used components of traditional Chinese medicines, is derived from the dried rhizomes of Alisma orientalis (Sam.) Juzep. (Alismataceae).

Objective: This study explores the RA influences on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9, CYP2E1 and CYP3A4) by using cocktail probe drugs in vivo.

Materials and methods: A cocktail solution at a dose of 5?mL/kg, which contained phenacetin (20?mg/kg), tolbutamide (5?mg/kg), chlorzoxazone (20?mg/kg) and midazolam (10?mg/kg), was orally administration to rats treated twice daily with RA (10, 20 and 40?g/kg) for consecutive 14?days. Blood samples (0.2?mL) were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by HPLC-MS/MS. The corresponding pharmacokinetic parameters were calculated by the software of DAS 2.0 (Wenzhou Medical College, Zhejiang, China).

Results: In the experiment, there was a statistically significant difference in the t_1/2, C_max, AUC_(0-∞) and CL for phenacetin and midazolam, while there was no statistical pharmacokinetics difference for tolbutamide and chlorzoxazone. Our study showed that treatment with multiple doses of RA had an inductive effect on rat CYP1A2 and an inhibitory effect on rat CYP3A4 enzyme activity. However, RA has no inductive or inhibitory effect on the activities of CYP2C9 and CYP2E1.

Conclusions: Caution is needed when RA is co-administration with some CYP1A2 or CYP3A4 substrates in clinic, because it may result in treatment failure and herb–drug interactions.     

Pharmacokinetic and pharmacodynamic assessment of a five-probe metabolic cocktail for CYPs 1A2, 3A4, 2C9, 2D6 and 2E1

AIMS: The primary objectives of the present study were to establish whether there was a pharmacokinetic or pharmacodynamic interaction between the probe drugs caffeine (CYP1A2), tolbutamide (CYP2C9), debrisoquine (CYP2D6), chlorzoxazone (CYP2E1) and midazolam (CYP3A4), when administered in combination as a cocktail. Furthermore, the tolerability of these probe drugs, both alone and in combination as a cocktail was assessed. METHODS: Twelve healthy volunteer subjects (age range 22-48 years) were entered into an open, fixed sequence, 6-limb, single centre study. The randomization was such that all drugs were given individually followed by the full "cocktail" as the last treatment limb. The phenotypic index used to assess the intrinsic activity of the CYP isoforms included metabolite/parent ratios in plasma and urine (CYPs 1A2, 2E1 & 2C9), parent/metabolite ratios in urine (CYP2D6) and plasma AUClast (CYP3A4). Blood pressure and blood glucose measurements were used to assess pharmacodynamic interactions. Tolerability was assessed through reporting of adverse events RESULTS: Overall, there was little evidence that the probe drugs interacted metabolically when co-administered as the cocktail. The ratio of the geometric mean (and 90% confidence interval) of the phenotypic index, obtained after administration of the probe as part of the cocktail and when given alone were: caffeine, 0.86 (0.67-1.10), midazolam, 0.96 (0.74-1.24), tolbutamide, 0.86 (0.72-1.03), debrisoquine 1.04 (0.97-1.12) and chlorzoxazone, 0.95 (0.86-1.05). There was no difference in blood pressure and blood glucose concentrations following the cocktail and dosing of the individual probes. There was no effect on ECG recordings at any time-point. The adverse events reported for individual drug administrations were mild, transient and expected. Overall no more adverse events were reported on the cocktail study days than on the days when the drugs were administered alone. CONCLUSIONS: The five probe drugs when coadministered, in this dosing regimen, demonstrated no evidence of either a metabolic or pharmacodynamic interaction that might confound the conclusions drawn during a cocktail study. The present cocktail methodology has the potential to become a useful tool to aid the detection of clinically important drug-drug interactions during drug development.     

A convenient five-drug cocktail for the assessment of major drug metabolizing enzymes: a pilot study

AIMS: To assess the feasibility of administering at the same time low doses of five probe drugs, metoprolol (25 mg), chlorzoxazone (250 mg), tolbutamide (250 mg), dapsone (100 mg) and caffeine (100 mg) to determine simultaneously the activities of CYP2D6, CYP2E1, CYP2C9, CYP3A4, CYP1A2, N-acetyltransferase-2 and xanthine oxidase. METHODS: Ten healthy young non-smoking males received the following drugs or combinations of drugs over a 5-week period: week 1) metoprolol; 2) tolbutamide; 3) caffeine, chlorzoxazone and dapsone; 4) caffeine, chlorzoxazone, dapsone and metoprolol; 5) caffeine, chlorzoxazone, dapsone, metoprolol and tolbutamide. The drugs were self-administered at bedtime and urine was collected for the following 8 h. RESULTS: Mean molar phenotypic ratios obtained after administering metoprolol (mean change of -11%) or tolbutamide (mean change of -0.3%) alone, were not significantly different from those obtained when other drugs were co-administered (P > 0.05). The mean within-subject coefficients of variation were 33%, 18%, 22%, 13%, 16%, 13% and 5% for CYP3A4, CYP2D6, CYP2C9, CYP2E1, CYP1A2, N-acetyltransferase 2 and xanthine oxidase metabolic ratios, respectively. No significant interactions (P > 0.5) were observed during the simultaneous administration of various combinations of the five probe drugs. CONCLUSIONS: We propose that this cocktail, composed of five widely available drugs, constitutes a promising means of simultaneously determining the activities of the major CYP enzymes in large populations.     

Effect of kanglaite on rat cytochrome P450

Abstract

Context: Kanglaite (KLT) is an oily substance extracted from Coix lacryma-jobi Linn. (Cramineae) and has been proved to significantly improve the life span and quality of life of patients, when combined with chemotherapy, radiotherapy, or surgery.

Objective: The purpose of this study was to find out whether KLT influences the effect on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2B6, CYP2C9, CYP2C19, and CYP3A4) by using cocktail probe drugs in vivo.

Materials and methods: A cocktail solution at a dose of 5?mL/kg, which contained phenacetin (20?mg/kg), bupropion (20?mg/kg), tolbutamide (5?mg/kg), omeprazole (20?mg/kg), and midazolam (10?mg/kg), was given as oral administration to rats treated with 7?d intraperitoneal injection of KLT. Blood samples were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by HPLC-MS/MS. The corresponding pharmacokinetic parameters were calculated by the software of DAS 2.0 (SPPS Inc., Chicago, IL).

Results: In the experiment, there was a statistically significant difference in the t_1/2, C_max, AUC_(0–∞), and CL for phenacetin, bupropion, tolbutamide, omeprazole, and midazolam. Our study showed that treatment with multiple doses of KLT had induction effect on rat CYP1A2, while CYP2B6, CYP2C9, CYP2C19, and CYP3A4 enzyme activities had been inhibited after multiple doses of KLT treatment.

Conclusions: KLT can either induce or inhibit activities of CYP. Therefore, caution is needed when KLT is co-administration with some CYP substrates in clinic, which may result in herb–drug interactions.