Phase 1 study to evaluate the effects of rifampin or itraconazole on the pharmacokinetics of limertinib (ASK120067), a novel mutant-selective inhibitor of the epidermal growth factor receptor in healthy Chinese subjects.

BACKGROUND: Limertinib is a novel mutant-selective and irreversible inhibitor of the epidermal growth factor receptor under development. A phase 1 open, two-period, single-sequence, self-controlled, two-part study was initiated to characterize the effects of a strong CYP3A4 inducer (rifampin) or inhibitor (itraconazole) on the pharmacokinetics of limertinib. RESEARCH DESIGN AND METHODS: Twenty-four healthy subjects in each part received a single dose of limertinib alone (160 mg, Part A; 80 mg, Part B) and with multiple doses of rifampin 600 mg once daily (Part A) or itraconazole 200 mg twice daily (Part B). RESULTS: Coadministration of rifampin decreased exposure (area under the plasma concentration-time curve from time 0 to infinity, AUC0-inf) of limertinib and its active metabolite CCB4580030 by 87.86% (geometric least-squares mean [GLSM] ratio, 12.14%; 90% confidence interval [CI], 9.89-14.92) and 66.82% (GLSM ratio, 33.18%; 90% CI, 27.72-39.72), respectively. Coadministration of itraconazole increased the AUC0-inf of limertinib by 289.8% (GLSM ratio, 389.8%; 90% CI, 334.07-454.82), but decreased that of CCB4580030 by 35.96% (GLSM ratio, 64.04%; 90% CI, 50.78-80.77). CONCLUSIONS: Our study demonstrates that the concomitant use of limertinib with strong CYP3A inducers or inhibitors is not recommended. A single dose of limertinib, administered with or without rifampin or itraconazole, is generally safe and well tolerated in healthy Chinese subjects. CLINICAL TRIAL REGISTRATION: www.clinicaltrials.gov identifier is NCT05631678.

Simultaneous determination of maltol and maltol glucuronide in human plasma and urine by HPLC-MS/MS: Application in clinical study in patients with iron deficiency.

Ferric maltol has been used as an oral drug for iron deficiency. This study developed and fully validated the novel HPLC-MS/MS methods to determine maltol and maltol glucuronide simultaneously in plasma and urine. The protein precipitation was performed by addition of acetonitrile in the plasma samples. The dilution was performed for the urine samples to reach the suitable concentrations for injection. The multiple reaction monitoring (MRM) with an electrospray ionization (ESI) positive ion detection mode was used for the quantification. The maltol concentration linear ranges were 6.00-150 ng/mL and 0.100-10.0 µg/mL for the plasma and urine samples, respectively. The maltol glucuronide concentration linear ranges were 50.0-15000 ng/mL and 2.00-2000 µg/mL for the plasma and urine samples, respectively. These methods were applied to a single dose clinical study at a dose of 60 mg ferric maltol capsule in the patients with iron deficiency. The half-lives of maltol and maltol glucuronide were 0.90 ± 0.40 h and 1.02 ± 0.25 h in the iron deficiency patients, respectively. 39.52 ± 7.11 % maltol were excreted in urine in the form of maltol glucuronide.

Effect of Food on the Pharmacokinetics of Limertinib (ASK120067) and its Main Metabolite in Healthy Chinese Volunteers.

Limertinib (ASK120067) is a newly developed third-generation epidermal growth factor receptor tyrosine kinase inhibitor. This phase I, open-label, 2-period crossover study was conducted to evaluate the effect of food on the pharmacokinetics (PK) of limertinib and its active metabolite CCB4580030 in Chinese healthy volunteers (HVs). HVs were randomly assigned (1:1) to receive a single dose of limertinib (160 mg) under the fasted state in period 1 and fed condition in period 2, or vice versa. Twenty-four HVs were enrolled, and 20 HVs completed both study periods. PK were assessed before dosing and ≤72 hours after dosing. PK parameters were analyzed by a noncompartmental method. Limertinib was absorbed faster in the fasted state compared with the fed state. The geometric mean ratios (fed/fast) of maximum concentration, area under the plasma concentration-time curve from time 0 to the last quantifiable concentration, and area under the plasma concentration-time curve from time 0 to infinity for ASK120067 were 145.5%, 145.4%, and 141.9%, respectively. Geometric mean ratios of the PK parameters of CCB4580030 were >125.00% and 90% confidence intervals were outside the preset bioequivalent range. Safety profiles were similar in both prandial states, and limertinib was well tolerated. Food reduced the rate and increased the extent of limertinib absorption following oral administration. Whether limertinib can be administered regardless of prandial state in patients warrants further investigation of efficacy and safety.

Development of an LC-MS/MS method for quantifying ASK120067, a novel mutant-selective inhibitor of the epidermal growth factor receptor (EGFR) as well as its main metabolite in human plasma and its application in a pharmacokinetic study.

ASK120067, an oral irreversible tyrosine kinase inhibitor (TKI) targeting the epidermal growth factor receptor (EGFR), is formulated for the management of patients with non-small cell lung cancer (NSCLC) who harbor T790M resistant and EGFR active mutations. Two rapid and high-throughput methods based on liquid chromatography-tandem mass spectrometry to detect ASK120067 and its primary metabolite CCB4580030 in human plasma were developed and applied in the clinical trials. A protein precipitation method using acetonitrile coupled with a gradient elution separation in a BEH C18 column (1.7 µm, 2.1 × 50 mm) was used to process plasma and separation analytes. The chromatographic separation was performed on the mobile phase of 5 mM ammonium acetate in water with 0.1% formic acid (A) and acetonitrile (B), and the flow rate was 0.4 mL/min. The multiple reaction monitoring (MRM) mode was selected to monitor the precursor-to-product ion transitions of m/z 546.2 â†’ m/z 431.2 for ASK120067 and m/z 532.1 â†’ m/z 420.2 for CCB4580030 at the positive ionization mode. The precision and accuracy of the two methods for ASK1200067 and CCB4580030 were within acceptable range for the linear range in 5.00-5000 ng/mL and 0.500-500 ng/mL, respectively. Further stabilities for the two analytes and internal standard were also investigated covered the entire experimental process beginning from harvesting whole blood to plasma extraction and analysis. ASK120067 was then administered without issue onto a dose-escalation, the first-in-human Phase I clinical trial in Chinese NSCLC patients to determine the pharmacokinetics of oral ASK120067 administration.

Combined Contribution of Increased Intestinal Permeability and Inhibited Deglycosylation of Ginsenoside Rb1 in the Intestinal Tract to the Enhancement of Ginsenoside Rb1 Exposure in Diabetic Rats after Oral Administration.

Panax ginseng is becoming a promising antidiabetic herbal medication. As the main active constituents of Panax ginseng, ginsenosides are well known, poorly absorbed chemicals. However, the pharmacokinetic behavior of ginsenosides under diabetic conditions is not fully understood. This study aimed to explore the alterations and potential mechanisms of pharmacokinetic behavior of ginsenoside Rb1 in diabetic rats compared with normal rats and rats fed a high-fat diet. Systemic exposure (area under the concentration-time curve extrapolated from zero to infinity) was significantly increased in diabetic rats after oral administration of Rb1. Oral bioavailability of Rb1 was significantly higher in diabetic rats (2.25%) compared with normal rats (0.90%) and rats fed a high-fat diet (0.78%). Further studies revealed that increased Rb1 exposure in diabetic rats may be mainly attributed to increased Rb1 absorption via the intestine and inhibited Rb1 deglycosylation by the intestinal microflora. Neither metabolic enzymes nor drug transporters displayed appreciable effects on Rb1 disposition. The transport of paracellular markers (fluorescein sodium and fluorescein isothiocyanate-dextran of 4 kDa) as well as Rb1 itself across the Caco-2 monolayer cultured with diabetic serum was promoted, demonstrating that increased paracellular permeability of the Caco-2 monolayer may benefit intestinal Rb1 absorption. In addition, Rb1 exposure was decreased in diabetic rats after Rb1 intravenous administration, which may result from increased Rb1 urinary excretion. In conclusion, Rb1 oral exposure was significantly increased under diabetic conditions, which is of positive significance to clinical treatment. The potential mechanism may be associated with the combined contribution of increased gut permeability and inhibited deglycosylation of ginsenoside Rb1 by intestinal microflora.

Prediction of drug disposition in diabetic patients by means of a physiologically based pharmacokinetic model.

BACKGROUND AND OBJECTIVE: Accumulating evidence has shown that diabetes mellitus may affect the pharmacokinetics of some drugs, leading to alteration of pharmacodynamics and/or toxic effects. The aim of this study was to develop a novel physiologically based pharmacokinetic (PBPK) model for predicting drug pharmacokinetics in patients with type 2 diabetes mellitus quantitatively. METHODS: Contributions of diabetes-induced alteration of physiological parameters including gastric emptying rates, intestinal transit time, drug metabolism in liver and kidney functions were incorporated into the model. Plasma concentration-time profiles and pharmacokinetic parameters of seven drugs (antipyrine, nisoldipine, repaglinide, glibenclamide, glimepiride, chlorzoxazone, and metformin) in non-diabetic and diabetic patients were predicted using the developed model. The PBPK model coupled with a Monte-Carlo simulation was also used to predict the means and variability of pharmacokinetic parameters. RESULTS: The predicted area under the plasma concentration-time curve (AUC) and maximum (peak) concentration (C max) were reasonably consistent (<2-fold errors) with the reported values. Sensitivity analysis showed that gut transit time, hepatic enzyme activity, and renal function affected the pharmacokinetic characteristics of these drugs. Shortened gut transit time only decreased the AUC of controlled-released drugs and drugs with low absorption rates. Impairment of renal function markedly altered pharmacokinetics of drugs mainly eliminated via the kidneys. CONCLUSION: All of these results indicate that the developed PBPK model can quantitatively predict pharmacokinetic alterations induced by diabetes.

Association of GLP-1 secretion with anti-hyperlipidemic effect of ginsenosides in high-fat diet fed rats.

OBJECTIVE: Ginsenosides, major bioactive constituents in Panax ginseng, have been shown to exert anti-hyperlipidemia effects. However, the underlying mechanism was not well-elucidated due to the low bioavailability of ginsenosides. Glucagon-like peptide-1 (GLP-1) was considered to be a critical regulator of energy homeostasis. Our previous studies have showed that ginseng total saponins (GTS) exhibited antidiabetic effects partly via modulating GLP-1 release. The aim of this study was to investigate the potential role of GLP-1 in anti-hyperlipidemia effect of GTS in rats fed with high-fat diet. MATERIAL AND METHODS: Male Sprague-Dawley rats were fed with normal diet (CON) or high-fat diet (HFD) for 4 weeks. Then, the HFD rats orally received vehicle (HFD), 150 mg/kg/day (HFD-GL) and 300 mg/kg/day of GTS (HFD-GH) for another 4 weeks, respectively. RESULTS: Four-week GTS treatment significantly ameliorated hyperlipidemia, decreased body fat, liver weight and improved insulin resistance. It was found that high-dose GTS treatment increased portal GLP-1 level induced by glucose loading, accompanied by increased intestinal GLP-1 content, L-cell number and prohormone convertase 3 mRNA expression. Data from NCI-H716 cells showed that both GTS and ginsenoside Rb1 significantly increased GLP-1 secretion as well as proglucagon mRNA level in NCI-H716 cells supplemented with 10% HFD-rat serum. CONCLUSIONS: Hyperlipidemia and insulin resistance were attenuated effectively in response to GTS treatment. These improvements may be associated with the increased secretion of GLP-1.

Increased levels of fatty acids contributed to induction of hepatic CYP3A4 activity induced by diabetes - in vitro evidence from HepG2 cell and Fa2N-4 cell lines.

Accumulating evidences have shown that diabetes upregulated the function and expression of CYP3A4, but the mechanism remained unclear. In this study, HepG2 cells were incubated with serum from diabetic rats induced by streptozotocin, and the activity of CYP3A4 was measured by substrate metabolism. Results showed that incubation with diabetic serum significantly induced CYP3A4 activity in HepG2 cells. To identify the specific factors contributing to the regulation, the abnormally altered components in diabetic serum, including glucose, insulin, cholesterol, and free fatty acids were screened. It was found that only fatty acids concentration-dependently up-regulated CYP3A4 activity, and the induction by fatty acids was further confirmed in Fa2N-4 cells. Data from western blotting and QT-PCR showed that induction of CYP3A4 activity was associated with up-regulation of CYP3A4 protein and mRNA levels. In addition, effects of pharmacological inhibitors on fatty acid-induced CYP3A4 activity were studied. The results indicated that the induction of CYP3A4 activity by oleic acid may be partly via AMPK-, PKC-, and NF-κB-dependent pathways, whereas that by palmitic acid was possibly associated with the PKC-dependent pathway. In conclusion, the increased levels of fatty acids may be one of the reasons leading to the elevated function and expression of CYP3A4 under diabetic conditions.

Impaired hepatic and intestinal ATP-binding cassette transporter G5/8 was associated with high exposure of ß-sitosterol and the potential risks to blood-brain barrier integrity in diabetic rats.

OBJECTIVES: Plant sterols are thought to treat hypercholesterolemia via inhibiting intestinal cholesterol absorption. The aim of this study was to evaluate the contribution of impaired ATP-binding cassette transporter G5/8 (ABCG5/8) expression by diabetes to the increased ß-sitosterol (BS) exposure and impact of increased BS on integrity of blood-brain barrier (BBB). METHODS: Basal BS level in tissues of streptozotocin-inducted rats and ABCG5/8 protein levels in liver and intestine were investigated; pharmacokinetics of BS was studied following oral dose; and primarily cultured rat brain microvessel endothelial cells (rBMECs) were used to study BS transportation across BBB and effect of BS on BBB integrity. KEY FINDINGS: Diabetic rats showed greatly upgraded basal levels of BS in plasma, intestine, cerebral and hippocampus, accompanied by impairment of ABCG5/8 protein expression in liver and intestine. Pharmacokinetics studies demonstrated higher AUC0-48 and Cmax , and lower faecal recoveries of BS after oral administration, indicating enhancement of absorption or efflux impairment. In-vitro data showed increased ratio of BS/cholesterol in high levels BS-treated rBMECs was associated with increased BBB permeability of some biomarkers including BS itself. CONCLUSIONS: Impaired ABCG5/8 protein expression by diabetes led to increase in BS exposure, which may be harmful to BBB function.

A mechanistic physiologically based pharmacokinetic-enzyme turnover model involving both intestine and liver to predict CYP3A induction-mediated drug-drug interactions.

Cytochrome P450 (CYP) 3A induction-mediated drug-drug interaction (DDI) is one of the major concerns in drug development and clinical practice. The aim of the present study was to develop a novel mechanistic physiologically based pharmacokinetic (PBPK)-enzyme turnover model involving both intestinal and hepatic CYP3A induction to quantitatively predict magnitude of CYP3A induction-mediated DDIs from in vitro data. The contribution of intestinal P-glycoprotein (P-gp) was also incorporated into the PBPK model. First, the pharmacokinetic profiles of three inducers and 14 CYP3A substrates were predicted successfully using the developed model, with the predicted area under the plasma concentration-time curve (AUC) [area under the plasma concentration-time curve] and the peak concentration (Cmax ) [the peak concentration] in accordance with reported values. The model was further applied to predict DDIs between the three inducers and 14 CYP3A substrates. Results showed that predicted AUC and Cmax ratios in the presence and absence of inducer were within twofold of observed values for 17 (74%) of the 23 DDI studies, and for 14 (82%) of the 17 DDI studies, respectively. All the results gave us a conclusion that the developed mechanistic PBPK-enzyme turnover model showed great advantages on quantitative prediction of CYP3A induction-mediated DDIs.

Increased glucagon-like peptide-1 secretion may be involved in antidiabetic effects of ginsenosides.

Panax ginseng is one of the most popular herbal remedies. Ginsenosides, major bioactive constituents in P. ginseng, have shown good antidiabetic action, but the precise mechanism was not fully understood. Glucagon-like peptide-1 (GLP1) is considered to be an important incretin that can regulate glucose homeostasis in the gastrointestinal tract after meals. The aim of this study was to investigate whether ginseng total saponins (GTS) exerts its antidiabetic effects via modulating GLP1 release. Ginsenoside Rb1 (Rb1), the most abundant constituent in GTS, was selected to further explore the underlying mechanisms in cultured NCI-H716 cells. Diabetic rats were developed by a combination of high-fat diet and low-dose streptozotocin injection. The diabetic rats orally received GTS (150 or 300 mg/kg) daily for 4 weeks. It was found that GTS treatment significantly ameliorated hyperglycemia and dyslipidemia, accompanied by a significant increase in glucose-induced GLP1 secretion and upregulation of proglucagon gene expression. Data from NCI-H716 cells showed that both GTS and Rb1 promoted GLP1 secretion. It was observed that Rb1 increased the ratio of intracellular ATP to ADP concentration and intracellular Ca2+ concentration. The metabolic inhibitor azide (3 mM), the KATP channel opener diazoxide (340 µM), and the Ca2+ channel blocker nifedipine (20 µM) significantly reversed Rb1-mediated GLP1 secretion. All these results drew a conclusion that ginsenosides stimulated GLP1 secretion both in vivo and in vitro. The antidiabetic effects of ginsenosides may be a result of enhanced GLP1 secretion.

P-glycoprotein and multidrug resistance-associated protein 2 are oppositely altered in brain of rats with thioacetamide-induced acute liver failure.

BACKGROUND: P-glycoprotein (P-GP) and multidrug resistance-associated protein 2 (MRP2) are involved in transport of many drugs across blood-brain barrier (BBB). The function and expression of P-GP and MRP2 may be modulated by different pathologies. Acute liver failure (ALF) was reported to impair BBB function, resulting in the increased BBB permeability. AIMS: We investigated whether ALF altered function and expression of P-GP and MRP2 in brain of thioacetamide-induced ALF rats. METHODS: ALF was induced by intraperitoneal injection of thioacetamide (300 mg/kg) for 2 days with a 24-h interval. The rats were used for experiments at 6, 12 and 24 h after the second administration. P-GP and MRP2 function in brain were determined using the brain-to-plasma ratios of corresponding substrates (rhodamine 123 and vincristine for P-GP; sulfobromophthalein and dinitrophenyl-S-glutathione for MRP2). Evans blue was used for examining the BBB integrity. Western blot was accomplished to determine P-GP and MRP2 protein expression. RESULTS: The brain-to-plasma ratios of rhodamine 123 and vincristine were significantly increased in ALF-6 h rats and almost returned to normal levels in ALF-24 h rats, whereas those of sulfobromophthalein and dinitrophenyl-S-glutathione were decreased in all ALF rats. Western blot results showed that ALF decreased brain P-GP levels at 6 and 12 h, whereas increased MRP2 levels at 6, 12 and 24 h. No significant difference of Evans blue concentrations in brain was found among the four groups. CONCLUSIONS: Function and expression of P-GP and MRP2 in brain of thioacetamide-induced ALF rats were oppositely altered.

Pharmacokinetic-pharmacodynamic modeling of diclofenac in normal and Freund's complete adjuvant-induced arthritic rats.

AIM: To characterize pharmacokinetic-pharmacodynamic modeling of diclofenac in Freund's complete adjuvant (FCA)-induced arthritic rats using prostaglandin E(2) (PGE(2)) as a biomarker. METHODS: The pharmacokinetics of diclofenac was investigated using 20-day-old arthritic rats. PGE(2) level in the rats was measured using an enzyme immunoassay. A pharmacokinetic-pharmacodynamic (PK-PD) model was developed to illustrate the relationship between the plasma concentration of diclofenac and the inhibition of PGE(2) production. The inhibition of diclofenac on lipopolysaccharide (LPS)-induced PGE(2) production in blood cells was investigated in vitro. RESULTS: Similar pharmacokinetic behavior of diclofenac was found both in normal and FCA-induced arthritic rats. Diclofenac significantly decreased the plasma levels of PGE(2) in both normal and arthritic rats. The inhibitory effect on PGE(2) levels in the plasma was in proportion to the plasma concentration of diclofenac. No delay in the onset of inhibition was observed, suggesting that the effect compartment was located in the central compartment. An inhibitory effect sigmoid I(max) model was selected to characterize the relationship between the plasma concentration of diclofenac and the inhibition of PGE(2) production in vivo. The I(max) model was also used to illustrate the inhibition of diclofenac on LPS-induced PGE(2) production in blood cells in vitro. CONCLUSION: Arthritis induced by FCA does not alter the pharmacokinetic behaviors of diclofenac in rats, but the pharmacodynamics of diclofenac is slightly affected. A PK-PD model characterizing an inhibitory effect sigmoid I(max) can be used to fit the relationship between the plasma PGE(2) and diclofenac levels in both normal rats and FCA-induced arthritic rats.

Biphasic regulation of P-glycoprotein function and expression by NO donors in Caco-2 cells.

AIM: To investigate the effects of nitric oxide (NO) donors on the function and expression of P-glycoprotein (P-gp) in Caco-2 cells. METHODS: Caco-2 cells were exposed to NO donors for designated times. P-gp function and expression were assessed using Rhodamine123 uptake assay and Western blotting, respectively. Intracellular reactive oxygen species (iROS) and intracellular reactive nitrogen species (iRNS) levels were measured using ROS and RNS assay kits, respectively. RESULTS: Exposure of Caco-2 cells to 0.1 or 2 mmol/L of sodium nitroprusside (SNP) affected the function and expression of P-gp in concentration- and time-dependent manners. A short-term (4 h) exposure reduced P-gp function and expression accompanied with significantly increased levels of iROS and iRNS. In contrast, a long-term (24 h) exposure stimulated the P-gp function and expression. The stimulatory effects of 2 mmol/L SNP was less profound as compared to those caused by 0.1 mmol/L SNP. The other NO donors SIN-1 and SNAP showed similar effects. Neither the NO scavenger PTIO (2 mmol/L) nor soluble guanylate cyclase inhibitor ODQ (50 µmol/L) reversed the SNP-induced alteration of P-gp function. On the other hand, free radical scavengers ascorbate, glutathione and uric acid (2 mmol/L for each), PKC inhibitor chelerythrine (5 µmol/L), PI3K/Akt inhibitor wortmannin (1 µmol/L) and p38 MAPK inhibitor SB203580 (10 µmol/L) reversed the upregulation of P-gp function by the long-term exposure to SNP, but these agents had no effect on the impaired P-gp function following the short-term exposure to SNP. CONCLUSION: NO donors time-dependently regulate P-gp function and expression in Caco-2 cells: short-term exposure impairs P-gp function and expression, whereas long-term exposure stimulates P-gp function and expression. The regulation occurs via a NO-independent mechanism.

Combined contributions of impaired hepatic CYP2C11 and intestinal breast cancer resistance protein activities and expression to increased oral glibenclamide exposure in rats with streptozotocin-induced diabetes mellitus.

The purpose of this study was to evaluate the contributions of impaired cytochrome P450 and breast cancer resistance protein (BCRP) activity and expression to drug pharmacokinetics under diabetic conditions. Diabetes was induced in rats with the intraperitoneal administration of streptozocin. Glibenclamide (GLB), a substrate of BCRP, served as a model drug. The pharmacokinetics of orally administered GLB (10 mg/kg) were studied. The results showed that diabetes mellitus significantly increased exposure (area under the curve and peak concentration) to GLB after oral administration. Data from hepatic microsomes suggested impairment of GLB metabolism in diabetic rats. GLB metabolism in hepatic microsomes was significantly inhibited by a selective inhibitor (sulfaphenazole) of CYP2C11 and an anti-CYP2C11 antibody. Western blotting further indicated the contribution of impaired CYP2C11 expression to the impairment of GLB metabolism. Excretion data showed that ∼72% of the orally administered dose was excreted in the feces of normal rats, which indicates an important role for intestinal BCRP. Diabetes significantly decreased the recovery from feces, which was only 40% of the orally administered dose. Results from in situ, single-pass, intestinal perfusion experiments revealed that diabetes significantly increased the apparent effective permeability and decreased the efflux of GLB through the intestine; this suggests impairment of intestinal BCRP function, which may play a role in the increased exposure to orally administered GLB in diabetic rats. Insulin treatment partly or completely reversed the changes in diabetic rats. All results yielded the conclusion that impaired hepatic CYP2C11 and intestinal BCRP expression and activity induced by diabetes contributed to the increased exposure of orally administered GLB.

Induction of multidrug resistance-associated protein 2 in liver, intestine and kidney of streptozotocin-induced diabetic rats.

Many studies have demonstrated that Mrp2 is highly regulated in some physiopathological situations. The aim of this study was to investigate effects of diabetes mellitus on function and expression of multidrug resistance-associated protein 2 (Mrp2) in rat liver, kidney and intestine. Diabetic rats were induced by an intraperitoneal administration of streptozotocin (65 mg/kg) and randomly divided into diabetic (DM) rats and insulin-treated diabetic rats. Sulfobromophthalein (BSP), a substrate of Mrp2, was used to evaluate Mrp2 function in vivo. Data from excretion experiments demonstrated that compared with normal rats, diabetes markedly enhanced BSP excretion via bile, urine and intestinal perfusate, which contributed to the elevated plasma clearance of BSP after intravenous administration of 45 µmol/kg BSP. Western blot results showed higher levels of hepatic, renal and intestinal Mrp2 protein in DM rats, although no difference was observed in renal Mrp2. Insulin treatment partly reversed these alterations. Induction of Mrp2 by diabetes was in parallel with the increase in bile flow, levels of biliary and plasma total bile acid (TBA), and plasma conjugated bilirubin in DM rats. Diabetes may enhance Mrp2 function and expression in liver, kidney and intestine, which might be due to insulin deficiency, increased TBA and conjugated bilirubin.

[Effects of salvianolic A on rat liver microsomal cytochrome P450 system].

OBJECTIVE: To study the effects of salvianolic acid A on content of cytochrome P450,cytochrome b5 and CYP1A2, CYP2E1 activities of rats. METHOD: The rats were randomly divided into two groups and each group contained 5 male rats and 5 female rats. One is control group, another is dosage group. The dosage group was injected salvianolic acid A into a rat tail vein at doses of 20 mg x kg(-1) x d(-1) for 5 days. The control group was injected placebo into a rat tail vein at the same doses as the dosage group. The content of cytochrome P450 and cytochrome b5 of rats were assayed using UV and CYP1A2, CYP2E1 activities were evaluated using probe substrate. RESULT: After salvianolic acid A was injected into rats tail vein for 5 days, the total content of cytochrome P450 and cytochrome b5 and CYP1A2 and CYP2E1 activities have no statistical significance of differences than the control group. CONCLUSION: Salvianolic acid A has no effects on CYP1A2 and CYP2E1 activities, indicating that there is no internation between salvianolic acid A and the drugs metabolized by CYP1A2 or CYP2E1.