Beneficial herb-drug interaction of Gnaphalium affine extract on benzbromarone: A pharmacokinetic and pharmacodynamic study in rats.

BACKGROUND: Gnaphalium affine D. Don extract (GAD) enhanced efficacy and reduced toxicity of benzbromarone (BBR) in combination use. However, little is known about effects of GAD on the pharmacokinetics (PKs) and metabolic enzymes of BBR. PURPOSE: To investigate the pharmacokinetic (PK) and pharmacodynamic (PD) mechanism of the herb-drug interactions (HDIs) between GAD and BBR. STUDY DESIGN AND METHODS: Intragastric single BBR (4.5 or 50 mg/kg), single BBR (4.5 or 50 mg/kg) + single GAD (450 mg/kg, 2 h after BBR-administration), or single BBR (4.5 or 50 mg/kg) + multiple GAD (450 mg/kg/day, once daily for 7 days) were administered to both sexes for BBR PK studies in normal rats. Intragastric multiple BBR (4.5 mg/kg/day), or multiple BBR (4.5 mg/kg/day) + multiple GAD (450 mg/kg/day, 2 h after BBR-administration) were administered for BBR PK and PD studies in male rats with hyperuricemic nephropathy (HN). The cumulative anti-hyperuricemic effects of BBR and BBR+GAD were determined by plasma uric acid (UA) concentration-time curve and area under curve (AUCUA). An in vivo cocktail approach was employed to determine the effects of GAD on cytochrome P450 (CYP) 2C11(9) and 1A2 - mediated drug metabolism. RESULTS: In normal rats, the repeated dose administration of GAD induced a significant increase of BBR AUC and prolonged the mean residence time (MRT) (p < 0.05). systemic exposure to BBR and metabolically derived hydroxybenzbromarones was significantly greater in female compared with male rats (p < 0.05). In HN rats, post-administration of GAD resulted in significantly higher bioavailability and enterohepatic recycling (ER) of BBR relative to the BBR alone administrated group from the prolongation of terminal elimination half-life (T1/2) and MRT of BBR (p < 0.05). Significantly higher urate-lowering effect of BBR+GAD compared with BBR alone was generally observed at post-dosing most time points with a maximal effect of 84.3% (acute treatment), 71.4% (7-day subchronic treatment) and 82.5% (14-day subchronic treatment) reduction in UA levels. Additionally, GAD showed a significant inhibitory effect on CYP2C11(9)-mediated tolbutamide (probe substrate) metabolism with ≥ 1.25 but < 2-fold increase in AUCtolbutamide. CONCLUSIONS: PD synergism demonstrated with the BBR+GAD combination could be explained by the PK interaction observed partially from CYP2C11(9)-mediation and enterohepatic recycling.

Pharmacokinetic Interactions of a Hop Dietary Supplement with Drug Metabolism in Perimenopausal and Postmenopausal Women.

Botanical dietary supplements produced from hops (Humulus lupulus) containing the chemopreventive compound xanthohumol and phytoestrogen 8-prenylnaringenin are used by women to manage menopausal symptoms. Because of the long half-lives of prenylated hop phenols and reports that they inhibit certain cytochrome P450 enzymes, a botanically authenticated and chemically standardized hop extract was tested for Phase I pharmacokinetic drug interactions. Sixteen peri- and postmenopausal women consumed the hop extract twice daily for 2 weeks, and the pharmacokinetics of tolbutamide, caffeine, dextromethorphan, and alprazolam were evaluated before and after supplementation as probe substrates for the enzymes CYP2C9, CYP1A2, CYP2D6, and CYP3A4/5, respectively. The observed area under the time-concentration curves were unaffected, except for alprazolam which decreased 7.6% (564.6 ± 46.1 h·µg/L pre-hop and 521.9 ± 36.1 h·µg/L post-hop; p-value 0.047), suggesting minor induction of CYP3A4/5. No enzyme inhibition was detected. According to FDA guidelines, this hop dietary supplement caused no clinically relevant pharmacokinetic interactions with respect to CYP2C9, CYP1A2, CYP2D6, or CYP3A4/5. The serum obtained after consumption of the hop extract was analyzed using ultra-high performance liquid chromatography-tandem mass spectrometry to confirm compliance. Abundant Phase II conjugates of the hop prenylated phenols were observed including monoglucuronides and monosulfates as well as previously unreported diglucuronides and sulfate-glucuronic acid diconjugates.

3D spheroids generated on carbon nanotube-functionalized fibrous scaffolds for drug metabolism and toxicity screening.

The mechanical and electrical stimuli have a profound effect on the cellular behavior and function. In this study, a series of conductive nanofibrous scaffolds are developed by blend electrospinning of poly(styrene-co-maleic acid) (PSMA) and multiwalled-carbon nanotubes (CNTs), followed by grafting galactose as cell adhesion cues. When the mass ratios of CNTs to PSMA increase up to 5%, the alignment, Young's modulus and conductivity of fibrous scaffolds increase, whereas the average diameter, pore size and elongation at break decrease. Primary hepatocytes cultured on the scaffolds are self-assembled into 3D spheroids, which restores the hepatocyte polarity and sufficient expression of drug metabolism enzymes over an extended period of time. Among these conductive scaffolds, hepatocytes cultured on fibers containing 3% of CNTs (F3) show the highest clearance rates of model drugs, offering a better prediction of the in vivo data with a high correlation value. Moreover, the drug metabolism capability is maintained over 15 days and is more sensitive towards the inducers and inhibitors of metabolizing enzymes, demonstrating the applicability for drug-drug interaction studies. Thus, this culture system has been demonstrated as a reliable in vitro model for high-throughput screening of metabolism and toxicity in the early phases of drug development.

Inhibition of Rat CYP1A2 and CYP2C11 by Honokiol, a Component of Traditional Chinese Medicine.

BACKGROUND AND OBJECTIVES: Honokiol, a major constituent isolated from Magnolia officinalis, is regarded as a phytochemical marker and bioactive substance present in many traditional Chinese medicines. However, the effect of honokiol on cytochrome P450 (CYP) has not been thoroughly investigated. The aim of this study was to investigate the effect of honokiol on CYP1A2 and CYP2C11 in vitro and in vivo. METHODS: The effect of honokiol on CYP1A2 and CYP2C11 was investigated with rat liver microsomes (RLMs) by measuring phenacetin and tolbutamide metabolism (probe drugs for CYP1A2 and CYP2C11, respectively), and then explored in vivo by measuring the effect of honokiol (2.5 and 5 mg/kg, intravenous injection) on the pharmacokinetics of theophylline and tolbutamide (probe drugs for CYP1A2 and CYP2C11, respectively) in rats in vivo. RESULTS: Honokiol inhibited the formation of acetaminophen from phenacetin and 4-hydroxytolbutamide from tolbutamide in RLMs, with inhibition constant (Ki) values of 1.6 µM and 16.5 µM, respectively. In vivo, honokiol (2.5 or 5.0 mg/kg) increased the half-life (t1/2) of theophylline by 40.9% and 119.9%, decreased the clearance (CL) by 23.8% and 42.9%, and increased the area under the curve (AUC) by 41.3% and 83.4%, respectively. Similarly, the t1/2 of tolbutamide increased by 25.5% and 33.8%, the CL decreased by 14.3% and 19.1%, and the AUC increased by 19.2% and 25.7%, respectively. CONCLUSION: The inhibition of CYP1A2 by honokiol is greater than the inhibition of CYP2C11. The changes in the pharmacokinetics of theophylline and tolbutamide in rats treated with honokiol are due to the inhibition of CYP1A2 and CYP2C11 activity in a dose-dependent manner.

Effects of shuanghuanglian injection on the activities of CYP1A2, 2C11, 2D1 and 3A1/2 in rats in vivo and in vitro.

Shuanghuanglian Injection (SHLI), one of the most popular herbal prescription in China, has been commonly used to treat pneumonia, tonsillitis, and other respiratory diseases caused by bacterium and virus. This study is to investigate the effects of SHLI on the activities of Cytochrome P450 (CYP) 1A2, 2C11, 2D1 and 3A1/2 in rats. Sixteen rats were randomly divided into two groups (SHLI-treated and blank control). They were administered SHLI or physiological saline for consecutive seven days. On day eight, 16 animals were administrated cocktail drugs as probe substrates of the four CYP in vivo. In addition, other four probe drugs were added, respectively, into incubation systems of rat liver microsomes (RLM) to assess the effects of SHLI on the four CYP isoforms in vitro. SHLI exhibited an inductive effect on CYP2C11 in vivo by decreasing Cmax, t1/2 and AUC0-∞ of tolbutamide, while the main pharmacokinetic parameters of caffeine, metoprolol and dapsone have no significant changes. In vitro study, SHLI showed no significant effects on the activities of CYP1A2, 2D1 and 3A1/2, but increasing the metabolism of tolbutamide in RLM. SHLI induced the activities of CYP2C11, but had no significant effects on the activities of CYP1A2, CYP2D1 and CYP3A1/2 in rats.

In vivo pharmacokinetic interaction by ethanolic extract of Gymnema sylvestre with CYP2C9 (Tolbutamide), CYP3A4 (Amlodipine) and CYP1A2 (Phenacetin) in rats.

Gymnema sylvestre (GS) is a medicinal herb used for diabetes mellitus (DM). Herbs are gaining popularity as medicines in DM for its safety purpose. The aim of the present study was to evaluate in vivo pharmacokinetic (PK) interaction between allopathic drugs tolbutamide (TOLBU), amlodipine (AMLO), and phenacetin (PHENA) at low (L) and high (H) doses with ethanolic extract (EL) from GS. EL was extracted and subjected to TLC, total triterpenoid content (19.76 ± 0.02 W/W) and sterol content (0.1837 ± 0.0046 W/W) estimation followed by identification of phytoconstituents using HRLC-MS and GC-MS. PK interaction study with CYP2C9, CYP3A4 and CYP1A2 enzymes were assessed using TOLBU, AMLO and PHENA respectively to index cytochrome (CYP) mediated interaction in rats after concomitant administration of EL extract (400 mg/kg) from GS for 7 days. The rats were divided into four groups for each PK study where, group I and II were positive control for low and high dose of test drugs (CYP substrates) while group II and IV were orally administered EL. The PK study result of PHENA indicated that area under the plasma concentration-time curve (AUC0-24) was significantly (P < 0.0001) increased by 1.4 (L) and 1.3-fold (H), plasma concentration (Cmax) was significantly (P < 0.001) increased by 1.6 (L) and 1.4-fold (H). Whereas for TOLBU; clearance rate (CL) was significantly (P < 0.0001) decreased by 2.4 (L) and 2.3-fold (H), Cmax, was significantly (P < 0.001) decreased by 26.5% (L) and 50.4% (H) and AUC0-24 was significantly (P < 0.0001) decreased by 59.8% (L) and 57.5% (H). Thus, EL is seen to be interacting with CYP1A2 by inhibiting its metabolic activity. HRLC-MS and GC-MS helped identify the presence of gymnemic acid (GA), triterpenoids and steroids in EL which could be the reason for PK interaction of CYP1A2 and CYP2C9. Also, in silico structure based site of metabolism study showed Fe accessibility and intrinsic activity for GA-IV, GA-VI, GA-VII and GA-X with CYP2C9. PK parameters of AMLO were not significantly affected by pre-treatment of EL. Thereby our findings indicate that co-administration of GS with drugs that are metabolized by CYP2C9 and CYP1A2 could lead to potential HDI.

Effect of Evodiamine on CYP Enzymes in Rats by a Cocktail Method.

The aim of this study was to assess the influence of evodiamine on the activities of the drug-metabolizing enzymes cytochrome P450 (CYP) 1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 in rats. The activities of CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 were measured using specific probe drugs. After pretreatment for 1 week with evodiamine or physiological saline (control group) by oral administration, probe drugs phenacetin (5.0 mg/kg; CYP1A2 activity), tolbutamide (1.0 mg/kg; CYP2C9 activity), omeprazole (10 mg/kg; CYP2C19 activity), metoprolol (20 mg/kg; CYP2D6 activity) and midazolam (10 mg/kg; CYP3A4 activity) were administered to rats by oral administration. The blood was then collected at different times for ultra-performance liquid chromatography-tandem mass spectrometry analysis. The data showed that evodiamine exhibits an inhibitory effect on CYP1A2, CYP2C9 and CYP2D6 by increasing t(1/2), Cmax and AUC(0-∞), and decreasing CL/F compared with those of the control group. However, no significant changes in CYP2C19 and CYP3A4 activities were observed. In conclusion, the results indicated that evodiamine could inhibit CYP1A2, CYP2C9 and CYP2D6, which may affect the disposition of medicines primarily dependent on these pathways. Our work may be the basis of related herb-drug interactions in the clinic.

Effects of suberoylanilide hydroxamic acid on rat cytochrome P450 enzyme activities.

Vorinostat (suberoylanilide hydroxamic acid, SAHA) is the first approved histone deacetylase (HDAC) inhibitor for the treatment of cutaneous T-cell lymphoma after progressive disease following two systemic therapies. The rats were randomly divided into SAHA groups (low, medium and high dosage) and control group. The SAHA group rats were given 12.3, 24.5, and 49 mg/kg SAHA, respectively, by continuous intragastric administration for 7 days. The influence of SAHA on the activities of CYP450 isoforms CYP2B6, CYP1A2, CYP2C19, CYP2D6 and CYP2C9 were evaluated by cocktail method, they were responsed by the changes of pharmacokinetic parameters of bupropion, phenacetin, tolbutamide, metroprolol and omeprazole. The five probe drugs were given to rats through intragastric administration, and the plasma concentration were determined by UPLC-MS/MS. The result of SAHA group compared to control group, there were statistical pharmacokinetics difference for bupropion, phenacetin, tolbutamide and metroprolol. Continuous intragastric administration for 7 days may induce the activities of CYP2C19 of rats, inhibit CYP1A2 and slightly inhibit CYP2B6 and CYP2D6 of rats. This may give advising for reasonable drug use after co-used with SAHA. The results indicated that drug co-administrated with SAHA may need dose adjustment. Furthermore, continuous intragastric administration of SAHA for 7 days, liver cell damaged, causing liver cell edema, in liver metabolism process.

Effects of vitexin on the pharmacokinetics and mRNA expression of CYP isozymes in rats.

In traditional therapy with Chinese medicine, vitexin has several pharmacological properties, including antinociceptive, antispasmodic, antioxidant, antimyeloperoxidase, and α-glucosidase inhibitory activities. Recently, vitexin was shown to protect the heart against ischemia/reperfusion injury in an in vitro model by inhibiting apoptosis. The purpose of this study was to find out whether vitexin influences the effect on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C11, and CYP3A1) by using cocktail probe drugs in vivo; the influence on the levels of CYP mRNA was also studied. A cocktail solution at a dose of 5 mL/kg, which contained phenacetin (10 mg/kg), tolbutamide (1 mg/kg), and midazolam (5 mg/kg), was given as oral administration to rats treated with short or long period of intravenous vitexin via the caudal vein. Blood samples were collected at a series of time points, and the concentrations of probe drugs in plasma were determined by HPLC-mass spectrometry (MS)/MS. The corresponding pharmacokinetic parameters were calculated by the software of DAS 2.0. In addition, real-time reverse transcription-polymerase chain reaction was performed to determine the effects of vitexin on the mRNA expression of CYP1A2, CYP2C11, and CYP3A1 in rat liver. Treatment with short or long period of vitexin had no effects on rat CYP1A2. However, CYP3A1 enzyme activity was inhibited by vitexin in a concentration-dependent and time-dependent manner. Furthermore, CYP2C11 enzyme activity was induced after short period treatment but inhibited after long period of vitexin treatment. The mRNA expression results were in accordance with the pharmacokinetic results. In conclusion, vitexin can either inhibit or induce activities of CYP2C11 and CYP3A1. Therefore, caution is needed when vitexin is co-administered with some CYP2C11 or CYP3A1 substrates in clinic, which may result in treatment failure and herb-drug interactions.

The effects of milk thistle (Silybum marianum) on human cytochrome P450 activity.

Milk thistle (Silybum marianum) extracts are widely used as a complementary and alternative treatment of various hepatic conditions and a host of other diseases/disorders. The active constituents of milk thistle supplements are believed to be the flavonolignans contained within the extracts. In vitro studies have suggested that some milk thistle components may significantly inhibit specific cytochrome P450 (P450) enzymes. However, determining the potential for clinically significant drug interactions with milk thistle products has been complicated by inconsistencies between in vitro and in vivo study results. The aim of the present study was to determine the effect of a standardized milk thistle supplement on major P450 drug-metabolizing enzymes after a 14-day exposure period. CYP1A2, CYP2C9, CYP2D6, and CYP3A4/5 activities were measured by simultaneously administering the four probe drugs, caffeine, tolbutamide, dextromethorphan, and midazolam, to nine healthy volunteers before and after exposure to a standardized milk thistle extract given thrice daily for 14 days. The three most abundant falvonolignans found in plasma, following exposure to milk thistle extracts, were silybin A, silybin B, and isosilybin B. The concentrations of these three major constituents were individually measured in study subjects as potential perpetrators. The peak concentrations and areas under the time-concentration curves of the four probe drugs were determined with the milk thistle administration. Exposure to milk thistle extract produced no significant influence on CYP1A2, CYP2C9, CYP2D6, or CYP3A4/5 activities.

Effects of icaritin on cytochrome P450 enzymes in rats.

The purpose of this study was to find out whether icaritin influences the effect on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9, CYP2E1 and CYP3A4) using cocktail probe drugs in vivo. 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 administered to rats treated with multiple doses of icaritin. 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. Treatment with multiple doses of icaritin had inhibitive effects on rat CYP1A2, CYP2C9 and CYP3A4 enzyme activities. However, icaritin has no inductive or inhibitory effect on the activity of CYP2E1. Therefore, caution is needed when icaritin is co-administered with some CYP1A2, CYP2C9 or CYP3A4 substrates, which may result in treatment failure and herb-drug interactions.

Effect of myricetin on cytochrome P450 isoforms CYP1A2, CYP2C9 and CYP3A4 in rats.

Myricetin is one of the main ingredients of Chinese bayberry, which is used as a traditional medicine. The purpose of this study was to find out whether myricetin influences the rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9 and CYP3A4) by using cocktail probe drugs in vivo. A cocktail solution at a dose of 5 mL/kg, which contained phenacetin (20 mg/kg), tolbutamide (5 mg/kg) and midazolam (10 mg/kg), was orally administered to rats treated for 14 days with myricetin. 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. Our study showed that treatment with multiple doses of myricetin had no effects on rat CYP1A2. However, CYP2C9 and CYP3A4 enzyme activities were inhibited after multiple doses of myricetin. Therefore, caution is needed when myricetin is co-administered with CYP2C9 or CYP3A4 substrates, which may result in herb-drug interactions.

Effects of hydroxysafflor yellow A on the activity and mRNA expression of four CYP isozymes in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: In traditional therapy with Chinese medicine, hydroxysafflor yellow A (HSYA), a main active component isolated from the dried flower of Carthamus tinctorius L., is the principal efficiency ingredient of Safflor Yellow Injection. Now HSYA has been demonstrated to have good pharmacological activities of antioxidation, myocardial and cerebral protective and neuroprotective effects. The purpose of this study was to find out whether HSYA influences the effect on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C11, CYP2D4 and CYP3A1) by using cocktail probe drugs in vivo; the influence on the levels of CYP mRNA was also studied. MATERIALS AND METHODS: A cocktail solution at a dose of 5 mL/kg, which contained phenacetin (20 mg/kg), tolbutamide (5 mg/kg), dextromethorphan (20 mg/kg) and midazolam (10 mg/kg), was given as oral administration to rats treated with short or long period of intravenous HSYA via the caudal vein. 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. In addition, real-time RT-PCR was performed to determine the effect of HSYA on the mRNA expression of CYP1A2, CYP2C11, CYP2D4 and CYP3A1 in rat liver. RESULTS: HSYA had significant inhibition effects on CYP1A2 and CYP2C11 in rats as oriented from the pharmacokinetic profiles of the probe drugs. Furthermore, HSYA had no effects on rat CYP2D4. However, CYP3A1 enzyme activity was induced by HSYA. The mRNA expression results were in accordance with the pharmacokinetic results. CONCLUSIONS: HSYA can either inhibit or induce activities of CYP1A2, CYP2C11 and CYP3A1. Therefore, co-administration of some CYP substrates with HSYA may need dose adjustment to avoid an undesirable herb-drug interaction.

Effects of aescin on cytochrome P450 enzymes in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Aescin, the main active component found in extracts of horse chestnut (Aesculus hippocastanum) seed a traditional medicinal herb, is a mixture of triterpene saponins. It has been shown to be effective in inflammatory, chronic venous and edematous treatment conditions in vitro and in vivo, and is broadly used to treat chronic venous insufficiency. The purpose of this study was to find out whether aescin influences the effect on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9, CYP2E1 and CYP3A4) by using cocktail probe drugs in vivo; the influence on the levels of CYP mRNA was also studied. MATERIALS AND METHODS: A cocktail solution at a dose of 5mL/kg, which contained phenacetin (20mg/kg), tolbutamide (5mg/kg), chlorzoxazone (20mg/kg) and midazolam (10mg/kg), was given as oral administration to rats treated with a single dose or multiple doses of intravenous aescin via the caudal vein. 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. In addition, real-time RT-PCR was performed to determine the effects of aescin on the mRNA expression of CYP1A2, CYP2C9, CYP2E1 and CYP3A4 in rat liver. RESULTS: Treatment with a single dose or multiple doses of aescin had inductive effects on rat CYP1A2, while CYP2C9 and CYP3A4 enzyme activities were inhibited. Moreover, aescin has no inductive or inhibitory effect on the activity of CYP2E1. The mRNA expression results were in accordance with the pharmacokinetic results. CONCLUSIONS: Aescin can either inhibit or induce activities of CYP1A2, CYP2C9 and CYP3A4. Therefore, caution is needed when aescin is co-administration with some CYP1A2, CYP2C9 or CYP3A4 substrates in clinic, which may result in treatment failure and herb-drug interactions.

Effects of unprocessed vs. cooked-processed Gastrodia elata on cytochrome P450 enzymes in rats.

CONTEXT: Gastrodia elata Blume (GE) has been used as a traditional herb and is considered one of the most important medicinal plants in Oriental countries since centuries. OBJECTIVE: The purpose of this study was to find out the differences between the effects of unprocessed and cooked-processed GE (CGE) on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9 and CYP3A4) by using cocktail probe drugs in vivo. METHODS: A cocktail solution at a dose of 5 mL/kg, which contained phenacetin (20 mg/kg), tolbutamide (5 mg/kg) and midazolam (10 mg/kg), was orally administration to rats treated with GE or CGE for 14 days orally. 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. RESULTS: Both GE and CGE did not have significant influences on the pharmacokinetic parameters of phenacetin (P>0.05). In addition, CGE decreased the t1/2, Cmax, AUC(0-∞) of tolbutamide (P<0.05) and it increased CL significantly (P<0.01). Furthermore, the trend in CGE was similar but far more significant than GE on t1/2, Cmax, AUC(0-∞), and other parameters of midazolam (P<0.05). CONCLUSIONS: In conclusion, GE and CGE had no effects on rat CYP1A2. GE did not affect CYP2C9 activity, but CGE induced the CYP2C9 activity. Moreover, CGE was more potent than GE for inhibitory effect on CYP3A4 activity. These results provide useful scientific data for the safe clinical application of either extract of GE or in combination with other drugs, which should lack the side effects induced by other herb-drug interactions.

[CYP450 enzyme inhibition of berberine in pooled human liver microsomes by cocktail probe drugs].

OBJECTIVE: To investigate the effect of CYP450 enzyme inhibition of berberine in pooled human liver microsomes by cocktail probe drugs. METHOD: Cocktail probe drugs method has been established, an LC-MS/MS analytical method has been established to determine the five probes of midazolam, phenacetin, dextromethorphan, tolbutamide, chlorzoxazone and the internal standard was benzhydramine to evaluate the effect of CYP450 activity following administration of berberine in pooled human liver microsomes. RESULT: Compared with control group, the pharmacokinetics of midazolam, phenacetin and tolbutamide were no significant differences, but the pharmacokinetics of chlorzoxazone was significantly decreased. There were no significant differences for the pharmacokinetics of dextromethorphan when the concentration of berberine was 50 microg x L(-1). The pharmacokinetics of dextromethorphan was significantly decreased when the concentration of berberine was exceed 200 microg x L(-1). CONCLUSION: Berberine has no influence on the activities of CYP3A4, CYP1A2 and CYP2C19 below 2 000 microg x L(-1), but can inhibit the activity of CYP2E1 and CYP2D6 in concentration-dependent.

Is pomegranate juice a potential perpetrator of clinical drug-drug interactions? Review of the in vitro, preclinical and clinical evidence.

The area of fruit juice-drug interaction has received wide attention with numerous scientific and clinical investigations performed and reported for scores of drugs metabolized by CYP3A4/CYP2C9. While grapefruit juice has been extensively studied with respect to its drug-drug interaction potential, numerous other fruit juices such as cranberry juice, orange juice, grape juice, pineapple juice and pomegranate juice have also been investigated for its potential to show drug-drug interaction of any clinical relevance. This review focuses on establishing any relevance for clinical drug-drug interaction potential with pomegranate juice, which has been shown to produce therapeutic benefits over a wide range of disease areas. The review collates and evaluates relevant published in vitro, preclinical and clinical evidence of the potential of pomegranate juice to be a perpetrator in drug-drug interactions mediated by CYP3A4 and CYP2C9. In vitro and animal pharmacokinetic data support the possibility of CYP3A4/CYP2C9 inhibition by pomegranate juice; however, the human relevance for drug-drug interaction was not established based on the limited case studies.

Influences of processed rhubarbs on the activities of four CYP isozymes and the metabolism of saxagliptin in rats based on probe cocktail and pharmacokinetics approaches.

ETHNOPHARMACOLOGICAL RELEVANCE: Cooked rhubarb and wine processed rhubarb are the processed rhubarbs of raw rhizomes from Rheum palmatum L., Rheum tanguticum Maxim. ex Balf. or Rheum officinale Baill. They are clinically used in traditional Chinese medicine to compose anti-diabetic formulas and remove pathogenic heat or toxin from the body. AIM OF THE STUDY: To elucidate potential influences processed rhubarbs might have on the activities of four cytochrome P450 (CYP) isozyme in rats (CYP1A2, CYP2C6, CYP2E1, and CYP3A1) and on the pharmacokinetics of saxagliptin. MATERIALS AND METHODS: Relative activity estimation of four isozymes or influence on saxagliptin was carried out by comparing plasma pharmacokinetics of four respective substrates (theophylline for CYP1A2, tolbutamide for CYP2C6, chlorzoxazone for CYP2E1, and dapsone for CYP3A1) or saxagliptin between control and processed rhubarbs pretreated groups. Plasma concentrations of substrates and saxagliptin were quantified using UPLC-UV and UPLC-MS/MS methods, respectively. RESULTS: Wine processed rhubarb induced CYP1A2 activity; both the processed rhubarbs inhibited the CYP2C6 activity and induced CYP2E1; cooked rhubarb induced CYP3A1 activity. Both the processed rhubarbs reduced the absorbance and bioavailability, but increased the clearance of saxagliptin. CONCLUSIONS: Processed rhubarbs can either induce or inhibit activities of CYP1A2, CYP2C6, CYP2E1, and CYP3A1, and modify the metabolism of saxagliptin. The results indicated that drug co-administrated with processed rhubarbs may need dose adjustment.

Inhibitory effects of kale ingestion on metabolism by cytochrome P450 enzymes in rats.

Kale (Brassica oleracea L. var acephala DC) is a leafy green vegetable belonging to the cabbage family (Brassicaceae) that contains a large amount of health-promoting phytochemicals. There are any reports about the effects of kale ingestion on the chemoprevention function and mechanism, but the interactions between kale and drugs have not been researched. We investigated the effects of kale intake on cytochrome P450 (CYP) metabolism by using cocktail probe drugs, including midazolam (for CYP3A4), caffeine (for CYP1A2), dextromethorphan (for CYP2D6), tolbutamide (for CYP2C9), omeprazole (for CYP2C19), and chlorzoxazone (for CYP2E1). Cocktail drugs were administered into rats treated with kale and cabbage (2000 mg/kg) for a week. The results showed that kale intake induced a significant increase in plasma levels and the AUC of midazolam, caffeine, and dextromethorphan. In addition, the plasma concentration and AUC of omeprazole tended to increase. Additionally, no almost differences in the mRNA expression levels of CYP enzymes in the liver were observed. In conclusion, kale ingestion was considered to have an inhibitory effect on the activities of CYP3A4, 1A2, 2D6, and 2C19 for a reason competitive inhibition than inhibitory changes in the mRNA expressions.

Effects of Bu-Zhong-Yi-Qi-Tang on hepatic drug-metabolizing enzymes and plasma tolbutamide concentration in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Bu-Zhong-Yi-Qi-Tang (BT) is the dry powder derived from the aqueous extract of a mixture of 10 medicinal herbs. It is a traditional Chinese medicine being used for the treatment of various immune-related diseases. AIM OF THE STUDY: To investigate the effect of BT on hepatic drug-metabolizing enzymes and its effect on plasma concentrations of tolbutamide, a substrate of CYP2C, in rats. MATERIALS AND METHODS: EXP 1: Thirty-two male Wistar rats were divided into four groups. Rats were fed a control diet and a control diet containing 1, 2.5 and 5% (w/w) of BT, respectively, for eight weeks. The activities of the major CYP and Phase II conjugating enzymes in rat liver microsomes as well as the antioxidant system in rat liver were assessed. Exp 2: Male Wistar rats were fed a control diet or a control diet containing 2.5% of BT, respectively, for eight weeks. A single 20-mg/kg oral dose of tolbutamide was then administered to each rat. Plasma samples were collected from each rat at 0.5, 1, 2, 4 and 8h after dosing. The concentrations of tolbutamide and glucose level in plasma were determined by high-performance liquid chromatography-mass spectrometer (HPLC/MS) and enzymatic method, respectively. RESULTS: Significant decrease in microsomal CYP2C-catalyzed diclofenac 4-hydroxylation in the liver of rats fed the BT diet was observed. Increased UDP-glucuronosyltransferase (UGT) and glutathione S-transferase (GST) activities were also observed in the liver of rats fed the diet containing 2.5 and 5% of BT. Immunoblot analyses also showed decreases of CYP2C11 proteins in the liver of BT fed rats. In addition, rats fed the 2.5% BT diet for eight weeks had no effects on the disposition of tolbutamide and reduction of glucose level in plasma after orally administered of tolbutamide. CONCLUSIONS: Rats fed the BT diet for eight weeks may decrease CYP2C enzyme activity and protein expression and increase Phase II conjugating enzyme activities in liver. However, BT may not affect the disposition and efficacy of tolbutamide.