Evaluation of metabolism-mediated herb-drug interactions

Assessment of Pharmacokinetic Effects of Herbal Medicines on Escitalopram

Purpose

Herbal medicines are occasionally used in combination with conventional antidepressants to mitigate various depression-associated symptoms. However, there is limited information on herb-antidepressant interactions. In this study, we investigated the pharmacokinetic (PK) effects of four herbal medicines (Gami-soyosan, Banhasasim-tang, Ojeok-san, and Bojungikgi-tang) on escitalopram, a commonly used antidepressant.

Patients and Methods

In this open-label, fixed-sequence, three-period, crossover study, 18 participants were enrolled and divided into two groups. Each group received a 10 mg oral dose of escitalopram in period 1. Participants took escitalopram once daily and their assigned herbal medicines thrice a day for 7 d in periods 2 (group 1: Gami-soyosan, group 2: Ojeok-san) and 3 (group 1: Banhasasim-tang; group 2: Bojungikgi-tang). The primary endpoints were Cmax,ss and AUCtau,ss of escitalopram. Cmax,ss and AUCtau,ss in period 1 were obtained using nonparametric superposition from single-dose data. The PK endpoints were classified according to the CYP2C19 phenotype.

Results

Of 18 participants, 16 completed the study. Systemic exposure to escitalopram resulted in a minor increase in the presence of each herbal medicine. The geometric mean ratios (GMRs, combination with herbal medicines/escitalopram monotherapy) and their 90% confidence intervals (CIs) for Cmax,ss and AUCtau,ss were as follows: Gamisoyosan- 1.1454 (0.9201, 1.4258) and 1.0749 (0.8084, 1.4291), Banhasasim-tang-1.0470 (0.7779, 1.4092) and 1.0465 (0.7035, 1.5568), Ojeok-san-1.1204 (0.8744, 1.4357) and 1.1267 (0.8466, 1.4996), and Bojungikgi-tang-1.1264 (0.8594, 1.4762) and 1.1400 (0.8515, 1.5261), respectively. Furthermore, no significant differences in the GMRs of Cmax,ss and AUCtau,ss were observed across different CYP2C19 phenotypes in any of the groups.

Conclusion

The co-administration of escitalopram with Gami-soyosan, Banhasasim-tang, Ojeok-san, or Bojungikgi-tang did not exert significant PK effects on escitalopram. These findings provide valuable insights into the safe use of herbal medicines along with escitalopram.

Safety evaluation of Gamisoyo-san: genotoxicity, acute toxicity, and influence on drug-metabolizing enzymes

Gamisoyo-san is an herbal formula widely used to treat psychological issues, menopausal symptoms, and dysmenorrhea. However, there is insufficient information on its safety profile. This study aimed to confirm the genotoxic and acute toxic potential of Gamisoyo-san. We performed a battery of tests, which included a bacterial reverse mutation test (Ames test) using five bacterial strains, an in vitro chromosomal aberration test using Chinese hamster lung (CHL) cells, an in vivo micronucleus test in mice, and human Cytochrome P450 (CYP450) and UDP-glucuronosyltransferase (UGT) assays. In the acute toxicity study, male and female rats were orally administered Gamisoyo-san 1000, 2000, or 5000 mg/kg and observed for 14 days. The activities of human CYP450s and UGTs were evaluated using recombinant baculosomes. Gamisoyo-san showed no signs of genotoxicity in the five bacterial strains, CHL cells, or mouse bone marrow cells. The acute toxicity test showed that the median lethal dose (LD50) of Gamisoyo-san was greater than 5000 mg/kg in rats. Gamisoyo-san inhibited the activities of CYP1A2, CYP2C19, and UGT1A1. In conclusion, Gamisoyo-san may not exert severe toxicological events or genotoxic effects at doses up to 5000 mg/kg in rats.

In Vitro Evaluation of the Potential for Drug Interactions by Salidroside

Several studies utilizing Rhodiola rosea, which contains a complex mixture of phytochemicals, reported some positive drug-drug interaction (DDI) findings based on in vitro CYP450's enzyme inhibition, MAO-A and MAO-B inhibition, and preclinical pharmacokinetic studies in either rats or rabbits. However, variation in and multiplicity of constituents present in Rhodiola products is a cause for concern for accurately evaluating drug-drug interaction (DDI) risk. In this report, we examined the effects of bioengineered, nature-identical salidroside on the inhibition potential of salidroside on CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 utilizing human liver microsomes, the induction potential of salidroside on CYP1A2, CYP2B6 and CYP3A4 in cryopreserved human hepatocytes, the inhibitory potential of salidroside against recombinant human MAO-A and MAO-B, and the OATP human uptake transport inhibitory potential of salidroside using transfected HEK293-OATP1B1 and OATP1B3 cells. The results demonstrate that the bioengineered salidroside at a concentration exceeding the predicted plasma concentrations of <2 µM (based on 60 mg PO) shows no risk for drug-drug interaction due to CYP450, MAO enzymes, or OATP drug transport proteins. Our current studies further support the safe use of salidroside in combination with other drugs cleared by CYP or MAO metabolism or OATP-mediated disposition.

Application to Butterbur Products of a Suggested Daily Intake-Based Safety Evaluation of Individual Herbal Supplements with Cytochrome P450 Expression as a Major Index

The present paper first proposes a method for ensuring the safety of commercial herbal supplements, termed the suggested daily intake-based safety evaluation (SDI-based safety evaluation). This new method was inspired as a backward analog of the acceptable daily intake (ADI) derivation from the no observed adverse effect level (NOAEL), the basis of food additive risk analysis; namely, rats are dosed with individual herbal supplement products at the SDI for human use multiplied by 100 (the usual uncertainty factor value) per body weight for 8 d. The primary endpoint is the sign of adverse effects on liver, especially gene expression of cytochrome P450 (CYP) isoforms. The proposed method was then applied to three butterbur (Petasites hybridus) products without pyrrolizidine alkaloids but lacking clear safety information. Results showed that two oily products markedly enhanced the mRNA expression of CYP2B (>10-fold) and moderately enhanced that of CYP3A1 (<4-fold) with liver enlargement. These products also caused the renal accumulation of alpha 2-microglobulin. One powdery product showed no significant effect on liver and kidney. The large difference in effects of products was due to the difference in chemical composition revealed by liquid chromatography-mass spectroscopy. The oily and the powdery products required attention in terms of safety and effectiveness, respectively. Finally, the results from the SDI-based safety evaluation of butterbur and other herbal supplement products were grouped into four categories and cautionary notes were discussed. The SDI-based safety evaluation of their products by herbal supplement operators would contribute to safe and secure use by consumers.

Artemisia extracts differ from artemisinin effects on human hepatic CYP450s 2B6 and 3A4 in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

The Chinese medicinal herb, Artemisia annua L., has been used for >2,000 yr as traditional tea infusions to treat a variety of infectious diseases including malaria, and its use is spreading globally (along with A. afra Jacq. ex Willd.) mainly through grassroots efforts.

AIM OF THE STUDY

Artemisinin is more bioavailable delivered from the plant, Artemisia annua L. than the pure drug, but little is known about how delivery via a hot water infusion (tea) alters induction of hepatic CYP2B6 and CYP3A4 that metabolize artemisinin.

MATERIALS AND METHODS

HepaRG cells were treated with 10 μM artemisinin or rifampicin (positive control), and teas (10 g/L) of A. annua SAM, and A. afra SEN and MAL with 1.6, 0.05 and 0 mg/g DW artemisinin in the leaves, respectively; qPCR and Western blots were used to measure CYP2B6 and CYP3A4 responses. Enzymatic activity of these P450s was measured using human liver microsomes and P450-Glo assays.

RESULTS

All teas inhibited activity of CYP2B6 and CYP3A4. Artemisinin and the high artemisinin-containing tea infusion (SAM) induced CYP2B6 and CYP3A4 transcription, but artemisinin-deficient teas, MAL and SEN, did not. Artemisinin increased CYP2B6 and CYP3A4 protein levels, but none of the three teas did, indicating a post-transcription inhibition by all three teas.

CONCLUSIONS

This study showed that Artemisia teas inhibit activity and artemisinin autoinduction of CYP2B6 and CYP3A4 post transcription, a response likely the effect of other phytochemicals in these teas. Results are important for understanding Artemisia tea posology.

Interactions between Food and Drugs, and Nutritional Status in Renal Patients: A Narrative Review

Drugs and food interact mutually: drugs may affect the nutritional status of the body, acting on senses, appetite, resting energy expenditure, and food intake; conversely, food or one of its components may affect bioavailability and half-life, circulating plasma concentrations of drugs resulting in an increased risk of toxicity and its adverse effects, or therapeutic failure. Therefore, the knowledge of these possible interactions is fundamental for the implementation of a nutritional treatment in the presence of a pharmacological therapy. This is the case of chronic kidney disease (CKD), for which the medication burden could be a problem, and nutritional therapy plays an important role in the patient’s treatment. The aim of this paper was to review the interactions that take place between drugs and foods that can potentially be used in renal patients, and the changes in nutritional status induced by drugs. A proper definition of the amount of food/nutrient intake, an adequate definition of the timing of meal consumption, and a proper adjustment of the drug dosing schedule may avoid these interactions, safeguarding the quality of life of the patients and guaranteeing the effectiveness of drug therapy. Hence, a close collaboration between the nephrologist, the renal dietitian, and the patient is crucial. Dietitians should consider that food may interact with drugs and that drugs may affect nutritional status, in order to provide the patient with proper dietary suggestions, and to allow the maximum effectiveness and safety of drug therapy, while preserving/correcting the nutritional status.

Moringa oleifera Leaves Extract Alters Exercise-Induced Cardiac Hypertrophy Adaptation

&lt;b&gt;Background and Objective:&lt;/b&gt; Cardiomyocyte adaptation to exercise might require ROS as a central regulator. There is a limited study regarding the importance of ROS for inducing exercise-induced adaptation and its correlations with changes in histological scoring of cardiac muscles. The study aimed to explore the importance of physiological ROS induced by exercise and its correlation with Cardiomyocyte' histological appearance that is altered by &lt;i&gt;Moringa oleifera&lt;/i&gt; leaves extract in Wistar rats. &lt;b&gt;Materials and Methods:&lt;/b&gt; This was an animal experimental study, which use 4 groups of 24 Wistar rats divided into Control (Co), &lt;i&gt;Moringa&lt;/i&gt; leaves extract (Mo), Exercise (Ex) and a combination of &lt;i&gt;Moringa &lt;/i&gt;leaves extract and Exercise (MoEx). The &lt;i&gt;Moringa&lt;/i&gt; leaves extract were given orally, 5 days a week, for 4 consecutive weeks. The exercise was given in moderate intensity, 5 days a week, also for 4 consecutive weeks. &lt;b&gt;Results:&lt;/b&gt; This study found significant differences in heart weight and heart weight/body weight ratio in Ex group compared to the control. As for histology scoring, found that MoEx group has 16.7% cardiac hypertrophy and myofiber disarray compared to 83.3% mild hypertrophy and 50% mild disarray in Ex group. &lt;b&gt;Conclusion:&lt;/b&gt; In summary, the study showed that the potential central role of exercise-induced physiological ROS for cardiac hypertrophy adaptation is altered by &lt;i&gt;Moringa oleifera &lt;/i&gt;leaves extract treatment.

Phytochemical and Over-The-Counter Drug Interactions: Involvement of Phase I and II Drug-Metabolizing Enzymes and Phase III Transporters

Consumption of plant-derived natural products and over-the-counter (OTC) drugs is increasing on a global scale, and studies of phytochemical-OTC drug interactions are becoming more significant. The intake of dietary plants and herbs rich in phytochemicals may affect drug-metabolizing enzymes (DMEs) and transporters. These effects may lead to alterations in pharmacokinetics and pharmacodynamics of OTC drugs when concomitantly administered. Some phytochemical-drug interactions benefit patients through enhanced efficacy, but many interactions cause adverse effects. This review discusses possible mechanisms of phytochemical-OTC drug interactions mediated by phase I and II DMEs and phase III transporters. In addition, current information is summarized for interactions between phytochemicals derived from fruits, vegetables, and herbs and OTC drugs, and counseling is provided on appropriate and safe use of OTC drugs.

Tanzanian primary healthcare workers' experiences of antibiotic prescription and understanding of antibiotic resistance in common childhood infections: a qualitative phenomenographic study

Background

Antibiotic resistance is a threat to global child health. Primary healthcare workers play a key role in antibiotic stewardship in the community, but few studies in low-income countries have described their experiences of initiating antibiotic treatment in children. Thus, the present study aimed to describe primary healthcare workers’ experiences of antibiotic prescription for children under 5 years of age and their conceptions of antibiotic resistance in Northern Tanzania.

Methods

A qualitative study involving individual in-depth interviews with 20 prescribing primary healthcare workers in Moshi urban and rural districts, Northern Tanzania, was performed in 2019. Interviews were transcribed verbatim, translated from Kiswahili into English and analysed according to the phenomenographic approach.

Findings

Four conceptual themes emerged during the analysis; conceptions in relation to the prescriber, the mother and child, other healthcare actors and in relation to outcome. The healthcare workers relied mainly on clinical examination and medical history provided by the mother to determine the need for antibiotics. Confidence in giving advice concerning non-antibiotic treatment varied among the participants and expectations of antibiotic treatment were perceived to be common among the mothers. Antibiotic resistance was mainly perceived as a problem for the individual patient who was misusing the antibiotics.

Conclusions

To increase rational antibiotic prescription, an awareness needs to be raised among Tanzanian primary healthcare workers of the threat of antibiotic resistance, not only to a few individuals, but to public health. Guidelines on childhood illnesses should be updated with advice concerning symptomatic treatment when antibiotics are not necessary, to support rational prescribing practices and promote trust in the clinician and mother relationship.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-021-00952-5.

Effects of Shengmai San on key enzymes involved in hepatic and intestinal drug metabolism in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Shengmai San (SMS) has been commonly used as a traditional Chinese medicine for the treatment of cardiovascular disorders, of which drug interactions need to be assessed for the safety concern. There is little evidence for the alterations of hepatic and intestinal drug-metabolizing enzymes after repeated SMS treatments to assess drug interactions.

AIM OF THE STUDY

The studies aim to illustrate the effects of repeated treatments with SMS on cytochrome P450s (CYPs), reduced nicotinamide adenine dinucleotide (phosphate)-quinone oxidoreductase (NQO), uridine diphosphate-glucuronosyltransferase (UGT), and glutathione S-transferase (GST) using in vivo rat model.

MATERIALS AND METHODS

The SMS was prepared using Schisandrae Fructus, Ginseng Radix, and Ophiopogonis Radix (OR) (1:2:2). Chromatographic analyses of decoctions were performed using ultra-performance liquid chromatography (UPLC) and LC-mass spectrometry. Sprague-Dawley rats were orally treated with the SMS and its component herbal decoctions for 2 or 3 weeks. Hepatic and intestinal enzyme activities were determined. CYP3A expression and the kinetics of intestinal nifedipine oxidation (NFO, a CYP3A marker reaction) were determined.

RESULTS

Schisandrol A, schisandrin B, ginsenoside Rb1 and ophiopogonin D were identified in SMS. SMS selectively suppressed intestinal, but not hepatic, NFO activity in a dose- and time-dependent manner. Hepatic and intestinal UGT, NQO and GST activities were not affected. A 3-week SMS treatment decreased the maximal velocity of intestinal NFO by 50%, while the CYP3A protein level remained unchanged. Among SMS component herbs, the decoction of OR decreased intestinal NFO activity.

CONCLUSIONS

These findings demonstrate that 3-week treatment with SMS and OR suppress intestinal, but not hepatic CYP3A function. It suggested that the potential interactions of SMS with CYP 3A drug substrates should be noticed, especially the drugs whose bioavailability depends heavily on intestinal CYP3A.

Tetrahydrofurofuranoid Lignans, Eudesmin, Fargesin, Epimagnolin A, Magnolin, and Yangambin Inhibit UDP-Glucuronosyltransferase 1A1 and 1A3 Activities in Human Liver Microsomes

Eudesmin, fargesin, epimagnolin A, magnolin, and yangambin are tetrahydrofurofuranoid lignans with various pharmacological activities found in Magnoliae Flos. The inhibition potencies of eudesmin, fargesin, epimagnolin A, magnolin, and yangambin on six major human uridine 5'-diphospho-glucuronosyltransferase (UGT) activities in human liver microsomes were evaluated using liquid chromatography-tandem mass spectrometry and cocktail substrates. Eudesmin, fargesin, epimagnolin A, magnolin, and yangambin inhibited UGT1A1 and UGT1A3 activities, but showed negligible inhibition of UGT1A4, UGT16, UGT1A9, and UGT2B7 activities at 200 μM in pooled human liver microsomes. Moreover, eudesmin, fargesin, epimagnolin A, magnolin, and yangambin noncompetitively inhibited UGT1A1-catalyzed SN38 glucuronidation with K_i values of 25.7, 25.3, 3.6, 26.0, and 17.1 μM, respectively, based on kinetic analysis of UGT1A1 inhibition in pooled human liver microsomes. Conversely, the aforementioned tetrahydrofurofuranoid lignans competitively inhibited UGT1A3-catalyzed chenodeoxycholic acid 24-acyl-glucuronidation with 39.8, 24.3, 15.1, 37.6, and 66.8 μM, respectively in pooled human liver microsomes. These in vitro results suggest the necessity of evaluating whether the five tetrahydrofurofuranoid lignans can cause drug-drug interactions with UGT1A1 and UGT1A3 substrates in vivo.

CYP3A4 mediated pharmacokinetics drug interaction potential of Maha-Yogaraj Gugglu and E, Z guggulsterone

Maha yogaraja guggulu (MYG) is a classical herbomineral polyherbal formulation being widely used since centuries. The aim of this study was to investigate the effect of MYG formulation and its major constituents E & Z guggulsterone on CYP3A4 mediated metabolism. In vitro inhibition of MYG and Guggulsterone isomers on CYP3A4 was evaluated by high throughput fluorometric assay. Eighteen Adult male Sprague–Dawley rats (200 ± 25 g body weight) were randomly divided into three groups. Group A, Group B and Group C were treated with placebo, MYG and Standard E & Z guggulsterone for 14 days respectively by oral route. On 15th day, midazolam (5 mg/kg) was administered orally to all rats in each group. Blood samples (0.3 mL) were collected from the retro orbital vein at 0.25, 0.5, 0.75, 1, 2, 4, 6, 12 and 24 h of each rat were collected. The findings from the in vitro & in vivo study proposed that the MYG tablets and its guggulsterone isomers have drug interaction potential when consumed along with conventional drugs which are CYP3A4 substrates. In vivo pharmacokinetic drug interaction study of midazolam pointed out that the MYG tablets and guggulsterone isomers showed an inhibitory activity towards CYP3A4 which may have leads to clinically significant interactions.

Compound danshen dripping pills affect the pharmacokinetics of azisartan by regulating the expression of cytochrome P450 2B1, 2C6, and 2C11 in rats

Combination therapies of compound danshen dripping pill (CDDP) and Azilsartan (AZ) represent a promising treatment option in clinical practice in China, but there are no reports on drug-drug interactions between CDDP and AZ. This study investigated the effects of CDDP on the pharmacokinetics of AZ and clarified its potential mechanism. The pharmacokinetic profiles of oral administration of AZ (2 mg/kg) in Sprague-Dawley rats, with or without pre-treatment of CDDP (81, 405, 810 mg/kg/d for 7 d) were investigated using UPLC-MS/MS. The main pharmacokinetic parameters were calculated and compared. The MS analysis was performed in positive ionization mode. The purpose of chromatographic separation of AZ and the internal standard (IS, Valsartan) was finished on a Waters XBridge BEH C18 column (2.1 × 100 mm, 2.5 μm). The mobile phase was acetonitrile and 0.1 % formic acid-water with gradient elution at a flow rate of 0.4 mL/min. The mRNA and protein levels of CYP2B1, CYP2C6, and CYP2C11 in the rat liver were detected by qRT-PCR and western blot, respectively. The results indicated that low, medium and high doses of CDDP significantly increased the C_max (6.47 ± 2.28, 6.51 ± 1.99, 7.04 ± 1.31 vs. 3.30 ± 1.87) of AZ, compared with that in the AZ single-drug group (p<0.05). The AUC_0-t of AZ (47.77 ± 23.41, 50.69 ± 25.46, 54.50 ± 11.57 vs. 26.85 ± 16.79) tended to increase in combination with CDDP. The gene and protein expression levels of CYP2B1, CYP2C6, and CYP2C11 were significantly reduced in the rat liver by CDDP. CDDP may diminish the AZ metabolism in vivo by suppressing the expression of the CYP2B1, CYP2C6, and CYP2C11 enzymes. This observation suggested the occurrence of potential interactions between CDDP and AZ when clinically administered as combination therapy, which may require adjustment of the clinical dose of AZ.

Assessment of Herb-drug Interactions Based on the Pharmacokinetic Changes of Probe Drug, Midazolam

BACKGROUND

In healthy volunteers, the probe drug method is widely practised to assess the pharmacokinetic mediated herb-drug interactions (HDI). We analyzed the clinical evidence of CYP3 A4 probe drug, Midazolam.

METHODS

Literatures, where Midazolam was used as a probe drug for prediction of herb-drug interaction, were surveyed through an online database such as google scholar, Scopus, Cochrane, PubMed and clinicaltrials.gov.

RESULTS

Midazolam was considered a sensitive probe for CYP3A4 substrates due to its bioavailability. We observed that not all the herbs are causing drug interaction. However, significant changes of the Midazolam pharmacokinetics were found after high-dose and long-term intake of some herbs and food supplements, suggesting the induction and/or inhibition of CYP activities.

CONCLUSION

Probe drug technique is one of the easiest ways for predicting CYP enzyme-mediated herb-drug interactions. Midazolam shows a good response in clinical studies because of short halflife and low harmfulness compared with other probe drugs.

A Short Exploration of Selected Sensitive CYP3A4 Substrates (Probe Drug)

BACKGROUND

CYP450 enzymes in the liver have a significant role in the metabolism of xenobiotics. Probe drug strategy is broadly used to evaluate the pharmacodynamic and pharmacokinetic drug/ herb-drug interactions/ food-drug interactions. Probe drugs reveal the exact pathway of drug metabolism in the liver by their targeted tractability property. The CYP3A4 isoenzyme metabolizes the majority of the drugs (65%).

METHODS

The characteristics of targeted probe drugs were observed from the admetSAR (version2) online database.

RESULTS

Midazolam is widely used as a probe drug because of its peculiar character. Midazolam affirms the accurate and consistent prediction of pharmacokinetic mediated drug interactions even in nanogram concentrations with or without a potent CYP3A inhibitor. Remarkably, midazolam is used as a CYP3A4 substrate in the majority of in vivo studies.

CONCLUSION

It is concluded that midazolam shows a good response in all clinical studies because of its lesser half-life and bioavailability when compared with other probe drugs.

Differential Effects of Components in Artemisia annua Extract on the Induction of Drug-Metabolizing Enzyme Expression Mediated by Nuclear Receptors

Artemisia annua tea is a popular dosage form used to treat and prevent malaria in some developing countries. However, repeated drinking leads to an obviously decreased efficacy, which may be related to the induction of metabolizing enzymes by artemisinin. In the present study, the ability of different components in A. annua to activate the pregnane X receptor and constitutive androstane receptor was evaluated by the dual luciferase reporter gene system. The changes in mRNA and protein expression of CYP3A4 and CYP2B6 were determined by quantitative real-time PCR and Western blotting. Results showed that in the pregnane X receptor-mediated CYP3A4 reporter gene system, chrysosplenetin and arteannuin B exhibited a weak induction effect on pregnane X receptor wt, while arteannuin A had a strong induction effect on pregnane X receptor wt and pregnane X receptor 370 and a weak induction effect on pregnane X receptor 163. In the pregnane X receptor-mediated CYP2B6 reporter gene system, arteannuin A had a moderate induction effect on pregnane X receptor wt and pregnane X receptor 379, and a weak induction effect on pregnane X receptor 403, while arteannuin B had a weak induction effect on pregnane X receptor wt and pregnane X receptor 379. Arteannuin A had a strong induction effect on constitutive androstane receptor 3 in constitutive androstane receptor-mediated CYP3A4/2B6 reporter gene systems, while arteannuin B showed a weak induction effect on constitutive androstane receptor 3 in the constitutive androstane receptor-mediated CYP2B6 reporter gene system. The mRNA and protein expressions of CYP3A4 and CYP2B6 were increased when the pregnane X receptor or constitutive androstane receptor was activated. Various components present in A. annua differentially affect the activities of pregnane X receptor isoforms and the constitutive androstane receptor, which indicates the possibility of a drug-drug interaction. This partly explains the decline in efficacy after repeated drinking of A. annua tea.

Herbal Medicine of the 21st Century: A Focus on the Chemistry, Pharmacokinetics and Toxicity of Five Widely Advocated Phytotherapies

Widely advocated for their health benefits worldwide, herbal medicines (HMs) have evolved into a billion dollar generating industry. Much is known regarding their wellness inducing properties, prophylactic and therapeutic benefits for the relief of both minor to chronic ailment conditions given their long-standing use among various cultures worldwide. On the other hand, their equally meaningful chemistry, pharmacokinetic profile in humans, interaction and toxicity profile have been poorly researched and documented. Consequently, this review is an attempt to highlight the health benefits, pharmacokinetics, interaction, and toxicity profile of five globally famous HMs. A systematic literature search was conducted by browsing major scientific databases such as Bentham Science, SciFinder, ScienceDirect, PubMed, Google Scholar and EBSCO to include 196 articles. In general, ginsenosides, glycyrrhizin and curcumin demonstrate low bioavailability when orally administered. Ginkgo biloba L. induces both CYP3A4 and CYP2C9 and alters the AUC and Cmax of conventional medications including midazolam, tolbutamide, lopinavir and nifedipine. Ginsenosides Re stimulates CYP2C9, decreasing the anticoagulant activity of warfarin. Camellia sinensis (L.) Kuntze increases the bioavailability of buspirone and is rich in vitamin K thereby inhibiting the activity of anticoagulant agents. Glycyrrhiza glabra L. displaces serum bound cardiovascular drugs such as diltiazem, nifedipine and verapamil. Herbal medicine can directly affect hepatocytes leading to hepatoxicity based on both intrinsic and extrinsic factors. The potentiation of the activity of concurrently administered conventional agents is potentially lethal especially if the drugs bear dangerous side effects and have a low therapeutic window.

Herb-Drug Interaction of Red Ginseng Extract and Ginsenoside Rc with Valsartan in Rats

The purpose of this study was to investigate the herb-drug interactions involving red ginseng extract (RGE) or ginsenoside Rc with valsartan, a substrate for organic anion transporting polypeptide (OATP/Oatp) transporters. In HEK293 cells overexpressing drug transporters, the protopanaxadiol (PPD)-type ginsenosides- Rb1, Rb2, Rc, Rd, Rg3, compound K, and Rh2-inhibited human OATP1B1 and OATP1B3 transporters (IC50 values of 7.99-68.2 µM for OATP1B1; 1.36-30.8 µM for OATP1B3), suggesting the herb-drug interaction of PPD-type ginsenosides involving OATPs. Protopanaxatriol (PPT)-type ginsenosides-Re, Rg1, and Rh1-did not inhibit OATP1B1 and OATP1B3 and all ginsenosides tested didn't inhibit OCT and OAT transporters. However, in rats, neither RGE nor Rc, a potent OATP inhibitor among PPD-type ginsenoside, changed in vivo pharmacokinetics of valsartan following repeated oral administration of RGE (1.5 g/kg/day for 7 days) or repeated intravenous injection of Rc (3 mg/kg for 5 days). The lack of in vivo herb-drug interaction between orally administered RGE and valsartan could be attributed to the low plasma concentration of PPD-type ginsenosides (5.3-48.4 nM). Even high plasma concentration of Rc did not effectively alter the pharmacokinetics of valsartan because of high protein binding and the limited liver distribution of Rc. The results, in conclusion, would provide useful information for herb-drug interaction between RGE or PPD-type ginsenosides and Oatp substrate drugs.

Interactions of ginseng with therapeutic drugs

Ginseng is the most frequently used herbal medicine for immune system stimulation and as an adjuvant with prescribed drugs owing to its numerous pharmacologic activities. It is important to investigate the beneficial effects and interaction of ginseng with therapeutic drugs. This review comprehensively discusses drug metabolizing enzyme- and transporter-mediated ginseng-drug interaction by analyzing in vitro and clinical results with a focus on ginsenoside, a pharmacologically active marker of ginseng. Impact of ginseng therapy or ginseng combination therapy on diabetic patients and of ginseng interaction with antiplatelets and anticoagulants were evaluated based on ginseng origin and ginsenoside content. Daily administration of Korean red ginseng (0.5-3 g extract; dried ginseng > 60%) did not cause significant herb-drug interaction with drug metabolizing enzymes and transporters. Among various therapeutic drugs administered in combination with ginseng, adjuvant chemotherapy, comprising ginseng (1-3 g extract) and anticancer drugs, was effective for reducing cancer-related fatigue and improving the quality of life and emotional scores. Limited information regarding ginsenoside content in each ginseng product and plasma ginsenoside concentration among patients necessitates standardization of ginseng product and establishment of pharmacokinetic-pharmacodynamic correlation to further understand beneficial effects of ginseng-therapeutic drug interactions in future clinical studies.

Pharmacokinetic Interactions between Cardiovascular Medicines and Plant Products

The growing use of plant products among patients with cardiovascular pharmacotherapy raises the concerns about their potential interactions with conventional cardiovascular medicines. Plant products can influence pharmacokinetics or/and pharmacological activity of coadministered drugs and some of these interactions may lead to unexpected clinical outcomes. Numerous studies and case reports showed various pharmacokinetic interactions that are characterized by a high degree of unpredictability. This review highlights the pharmacokinetic clinically relevant interactions between major conventional cardiovascular medicines and plant products with an emphasis on their putative mechanisms, drawbacks of herbal products use, and the perspectives for further well-designed studies.

Interaction between phytotherapy and oral anticancer agents: prospective study and literature review

Cancer is becoming more prevalent in elderly patient. Due to polypharmacy, older adults with cancer are predisposed to drug-drug interactions. There is also an increasing interest in the use of complementary and alternative medicine (CAM). Thirty to seventy percent of patients with cancer have used CAM. Through pharmaceutical counseling sessions, we can provide advices on herb-drug interactions (HDI). All the patients seen in pharmaceutical counseling sessions were prospectively included. Information was collected during these sessions: prescribed medication (oral anticancer agents (OAA) and other drugs), CAM (phytotherapy especially), and use of over-the-counter (OTC) drugs. If pharmacist considered an interaction or an intervention clinically relevant, the oncologist was notified. Then, a literature review was realized to identify the potential HDI (no interactions, precautions for use, contraindication). Among 201 pharmacist counseling sessions, it resulted in 104 interventions related to 46 HDI, 28 drug-drug interactions and 30 others (wrong dosage, omission…). To determine HDI, we review 73 medicinal plants which are used by our patients with cancer and 31 OAA. A total of 1829 recommendations were formulated about 59 (75%) medical plants and their interaction with an OAA. Herb-drug interactions should not be ignored by healthcare providers in their management of cancer patients in daily practice.

Synthetic cannabinoids are substrates and inhibitors of multiple drug-metabolizing enzymes

Synthetic cannabinoids, a new class of psychoactive substances, are potent agonists of cannabinoid receptors, which mimic the psychoactive effects of the principal psychoactive component of cannabis, ∆9-tetrahydrocannabinol. Despite governmental scheduling as illicit drugs, new synthetic cannabinoids are being produced. The abuse of synthetic cannabinoids with several drugs containing different chemical groups has resulted in large numbers of poisonings. This has increased the urgency for forensic and public health laboratories to identify the metabolites of synthetic cannabinoids and apply this knowledge to the development of analytical methods and for toxicity prediction. It is necessary to determine whether synthetic cannabinoids are involved in drug-metabolizing enzyme-mediated drug-drug interactions. This review describes the metabolic pathways of 13 prevalent synthetic cannabinoids and various drug-metabolizing enzymes responsible for their metabolism, including cytochrome P450 (CYP), UDP-glucuronosyltransferases (UGTs), and carboxylesterases. The inhibitory effects of synthetic cannabinoids on CYP and UGT activities are also reviewed to predict the potential of synthetic cannabinoids for drug-drug interactions. The drug-metabolizing enzymes responsible for metabolism of synthetic cannabinoids should be characterized and the effects of synthetic cannabinoids on CYP and UGT activities should be determined to predict the pharmacokinetics of synthetic cannabinoids and synthetic cannabinoid-induced drug-drug interactions in the clinic.

Simultaneous determination of intestinal permeability and potential drug interactions of complex mixtures using Caco-2 cells and high-resolution mass spectrometry: Studies with Rauwolfia serpentina extract

Caco-2 cells are a commonly used model for estimating the intestinal bioavailability of single chemical entity pharmaceuticals. Caco-2 cells, when induced with calcitriol, also express other biological functions such as phase I (CYP) and phase II (glucuronosyltransferases) drug metabolizing enzymes which are relevant to drug-supplement interactions. Intestinal bioavailability is an important factor in the overall safety assessment of products consumed orally. Foods, including herbal dietary supplements, are complex substances with multiple chemical components. Because of potential interactions between components of complex mixtures, more reliable safety assessments can be obtained by studying the commercial products "as consumed" rather than by testing individual chemical components one at a time. The present study evaluated the apparent intestinal permeability (P_app) of a model herbal extract, Rauwolfia serpentina, using both whole plant extracts and the individual purified Rauwolfia alkaloids. All test compounds, endpoint substrates, and their metabolites were quantified using liquid chromatography and high-resolution mass spectrometry. The P_app values for individual Rauwolfia alkaloids were comparable whether measured individually or as components of the complete extract. Both Rauwolfia extract and all individual Rauwolfia alkaloids except yohimbine inhibited CYP3A4 activity (midazolam 1'-hydroxylation). Both Rauwolfia extract and all individual Rauwolfia alkaloids except corynanthine and reserpic acid significantly increased glucuronosyltransferase activity (glucuronidation of 4-methylumbelliferone). The positive control, ketoconazole, significantly inhibited both CYP3A4 and glucuronosyltransferase activities. These findings suggest that the Caco-2 assay is capable of simultaneously identifying both bioavailability and potentially hazardous intestinal drug-supplement interactions in complex mixtures.

A regulatory science viewpoint on botanical-drug interactions

There is a continued predisposition of concurrent use of drugs and botanical products. Consumers often self-administer botanical products without informing their health care providers. The perceived safety of botanical products with lack of knowledge of the interaction potential poses a challenge for providers and both efficacy and safety concerns for patients. Botanical–drug combinations can produce untoward effects when botanical constituents modulate drug metabolizing enzymes and/or transporters impacting the systemic or tissue exposure of concomitant drugs. Examples of pertinent scientific literature evaluating the interaction potential of commonly used botanicals in the US are discussed. Current methodologies that can be applied to advance our efforts in predicting drug interaction liability is presented. This review also highlights the regulatory science viewpoint on botanical–drug interactions and labeling implications.

Current Role of Herbal and Natural Preparations

Depression remains difficult to manage, despite the many registered treatments available. For many depressed individuals, particularly those who have not responded to and/or had adverse effects from standard therapies, herbal and natural medications represent a potentially valuable alternative. This chapter will review several natural remedies used in the treatment of depression. Specific remedies covered include St. John's wort (SJW), S-adenosyl-L-methionine (SAMe), omega-3 fatty acids, rhodiola, and others. We will begin by providing some historical and social context about these remedies. Then we will review efficacy and safety data, as well as biological mechanisms of action of these therapies. Finally, we will discuss the limitations of the current state of knowledge and provide suggestions for a productive research agenda focused on natural remedies. While many questions about these treatments remain unanswered and much work needs to be done before we determine their place in the psychiatric armamentarium, we believe that this chapter will give psychiatrists a good perspective on the pros and cons of herbal and natural antidepressants as part of the pharmacological armamentarium and sensible guidelines on how and when they should be used.

Recent developments in our understanding of the implications of traditional African medicine on drug metabolism

INTRODUCTION

The use of traditional herbal medicines has become increasingly popular globally, but in some countries, it is the main or sometimes even the only healthcare service available in the most rural areas. This is especially true for Africa where herbal medicines form a key component of traditional medicinal practices and there is access to a diversity of medicinal plants. Although many benefits have been derived from the use of traditional herbal medicines, many concerns are associated with their use of which herb-drug interactions have been identified to have a rising impact on patient treatment outcome. One type of pharmacokinetic interaction involves the modulation of drug metabolizing enzymes, which may result in enhanced or reduced bioavailability of co-administered drugs. Areas covered: This review highlights the current information available on drug metabolism-associated information with regards to traditional African medicines related to some of the most prevalent diseases burdening the African continent. Expert opinion: It is clear from previous studies that enzyme modulation by traditional African medicines plays a significant role in the pharmacokinetics of some co-administered drugs, but more research is needed to provide detailed information on these interactions, specifically for treatment of prevalent diseases such as tuberculosis and hypertension.

Assessment of cytochrome P450 inhibition and induction potential of lupeol and betulin in rat liver microsomes

BACKGROUND

Lupeol and betulin are triterpenoids that are majorly found in dietary substances. The aim of present study was to investigate the inhibition and induction potential of lupeol and betulin on cytochrome P450 (CYP)1A2, CYP2C11, CYP2D6 and CYP3A2 activities in rat liver microsomes.

METHODS

The inhibition and induction studies were conducted using ethoxy resorufin-O-deethylase (CYP1A2), tolbutamide hydroxylase (CYP2C9), and midazolam hydroxylase (CYP3A4) activity assays. In vitro inhibition study was evaluated by incubating lupeol and betulin (1, 3, 10, 30 and 100 μM) with rat liver microsomes, and the metabolite formation was analyzed by high-performance liquid chromatography. The induction study was conducted by administering lupeol (20 mg/kg) and betulin (50 mg/kg) intraperitoneally for 14 days to rats followed by liver isolation and microsome preparation.

RESULTS

The IC50 values in inhibition studies were found to be 59.42 μM (CYP1A2), >100 μM (CYP2C11, CYP2D6, CYP3A2) for lupeol, 52.24 μM (CYP1A2), and >100 μM (CYP2C9, CYP2D6, CYP3A2) for betulin. There was no significant modification observed in the CYP450 isoforms, indicating neither inhibition nor induction potential of lupeol and betulin.

CONCLUSIONS

Lupeol and betulin have very low propensity to interact with CYP enzyme, suggesting no CYP inhibitory and inducing potential in rat liver microsomes.

Inhibitory Effects of Dimethyllirioresinol, Epimagnolin A, Eudesmin, Fargesin, and Magnolin on Cytochrome P450 Enzyme Activities in Human Liver Microsomes

Magnolin, epimagnolin A, dimethyllirioresinol, eudesmin, and fargesin are pharmacologically active tetrahydrofurofuranoid lignans found in Flos Magnoliae. The inhibitory potentials of dimethyllirioresinol, epimagnolin A, eudesmin, fargesin, and magnolin on eight major human cytochrome P450 (CYP) enzyme activities in human liver microsomes were evaluated using liquid chromatography-tandem mass spectrometry to determine the inhibition mechanisms and inhibition potency. Fargesin inhibited CYP2C9-catalyzed diclofenac 4′-hydroxylation with a K_i value of 16.3 μM, and it exhibited mechanism-based inhibition of CYP2C19-catalyzed [S]-mephenytoin 4′-hydroxylation (K_i, 3.7 μM; k_inact, 0.102 min⁻¹), CYP2C8-catalyzed amodiaquine N-deethylation (K_i, 10.7 μM; k_inact, 0.082 min⁻¹), and CYP3A4-catalyzed midazolam 1′-hydroxylation (K_i, 23.0 μM; k_inact, 0.050 min⁻¹) in human liver microsomes. Fargesin negligibly inhibited CYP1A2-catalyzed phenacetin O-deethylation, CYP2A6-catalyzed coumarin 7-hydroxylation, CYP2B6-catalyzed bupropion hydroxylation, and CYP2D6-catalyzed bufuralol 1′-hydroxylation at 100 μM in human liver microsomes. Dimethyllirioresinol weakly inhibited CYP2C19 and CYP2C8 with IC₅₀ values of 55.1 and 85.0 μM, respectively, without inhibition of CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6, and CYP3A4 activities at 100 μM. Epimagnolin A, eudesmin, and magnolin showed no the reversible and time-dependent inhibition of eight major CYP activities at 100 μM in human liver microsomes. These in vitro results suggest that it is necessary to investigate the potentials of in vivo fargesin-drug interaction with CYP2C8, CYP2C9, CYP2C19, and CYP3A4 substrates.

Simultaneous evaluation of substrate-dependent CYP3A inhibition using a CYP3A probe substrates cocktail

Cytochrome P450 (P450) 3A (CYP3A) is an enzyme responsible for the metabolism of therapeutic drugs such as midazolam, nifedipine, testosterone and triazolam. It is involved in 40% of all cases of P450-mediated metabolism of marketed drugs. Therefore, it is important to evaluate the CYP3A-mediated drug interaction potential of new chemical entities (NCEs). In the past, one P450 isoform-specific probe substrate has been used at a time to evaluate the degree of inhibition of P450 isoforms by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). However, CYP3A enzymes have been shown to have a multi-substrate binding site. Therefore, multiple CYP3A substrates should be used to evaluate precisely the drug interaction potential of NCEs with the enzyme CYP3A. In this study, a method of screening NCEs for their potential to inhibit by CYP3A enzyme activity was developed. It involves the employment of a CYP3A substrate cocktail (including midazolam, testosterone and nifedipine). The concentration of each CYP3A probe substrate in vitro was optimized (0.1 μm for midazolam, 2 μm for testosterone and 2 μm for nifedipine) to minimize mutual drug interactions among probe substrates. The method was validated by comparing inhibition data obtained from the incubation of CYP3A with each individual substrate with data from incubation with a cocktail of all three substrates. The CYP3A inhibition profiles from the substrate cocktail approach were similar to those from the individual substrates approach. This new method could be an effective tool for the robust and accurate screening of the CYP3A inhibition potential of NCEs in drug discovery. Copyright © 2016 John Wiley & Sons, Ltd.

Isochlorogenic acid A affects P450 and UGT enzymes in vitro and in vivo

Isochlorogenic acid A (ICQA), which has anti-inflammatory, hepatoprotective, and antiviral properties, is commonly presented in fruits, vegetables, coffee, plant-based food products, and herbal medicines. These herbal medicines are usually used in combination with other medicines in the clinic. However, little is known about the regulatory effects of ICQA on drug-metabolizing enzymes and the herb-drug interactions. In the present study, we evaluated the inhibitory potentials of ICQA on CYP1A2, CYP2C9, CYP2C19, CYP3A4, CYP2D6, and CYP2E1 in vitro based on a cocktail approach. The P450 and UGT activities in mice treated with ICQA for a prolonged period were also determined. Our results demonstrated that ICQA exhibited a weak inhibitory effect on CYP2C9 in human liver microsomes with IC₅₀ being 57.25 μmol·L^-1 and Ki being 26.77 μmol·L^-1. In addition, ICQA inhibited UGT1A6 activity by 25%, in the mice treated with ICQA (i.p.) at 30 mg·kg^-1 for 14 d, compared with the control group. Moreover, ICQA showed no mechanism-based inhibition on CYP2C9 or UGT1A6. In conclusion, our results further confirm a safe use of ICQA in clinical practice.

Putative Role of Red Wine Polyphenols against Brain Pathology in Alzheimer's and Parkinson's Disease

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common age-related neurodegenerative disorders and hence pose remarkable socio-economical burdens to both families and state. Although AD and PD have different clinical and neuropathological features, they share common molecular mechanisms that appear to be triggered by multi-factorial events, such as protein aggregation, mitochondrial dysfunction, oxidative stress (OS), and neuroinflammation, ultimately leading to neuronal cell death. Currently, there are no established and validated disease-modifying strategies for either AD or PD. Among the various lifestyle factors that may prevent or slow age-related neurodegenerative diseases, epidemiological studies on moderate consumption of red wine, especially as part of a holistic Mediterranean diet, have attracted increasing interest. Red wine is particularly rich in specific polyphenolic compounds that appear to affect the biological processes of AD and PD, such as quercetin, myricetin, catechins, tannins, anthocyanidins, resveratrol, and ferulic acid. Indeed, there is now a consistent body of in vitro and in vivo data on the neuroprotective effects of red wine polyphenols (RWP) showing that they do not merely possess antioxidant properties, but may additionally act upon, in a multi-target manner, the underlying key mechanisms featuring in both AD and PD. Furthermore, it is important that bioavailability issues are addressed in order for neuroprotection to be relevant in a clinical study scenario. This review summarizes the current knowledge about the major classes of RWP and places into perspective their potential to be considered as nutraceuticals to target neuropathology in AD and PD.

Inhibition of Cytochrome P450 by Propolis in Human Liver Microsomes

Although propolis is one of the most popular functional foods for human health, there have been no comprehensive studies of herb-drug interactions through cytochrome P450 (CYP) inhibition. The purpose of this study was to determine the inhibitory effects of propolis on the activities of CYP1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1 and 3A4 using pooled human liver microsomes (HLMs). Propolis inhibited CYP1A2, CYP2E1 and CYP2C19 with an IC₅₀ value of 6.9, 16.8, and 43.1 μg/mL, respectively, whereas CYP2A6, 2B6, 2C9, 2D6, and 3A4 were unaffected. Based on half-maximal inhibitory concentration shifts between microsomes incubated with and without nicotinamide adenine dinucleotide phosphate, propolis-induced CYP1A2, CYP2C19, and CYP2E1 inhibition was metabolism-independent. To evaluate the interaction potential between propolis and therapeutic drugs, the effects of propolis on metabolism of duloxetine, a serotonin-norepinephrine reuptake inhibitor, were determined in HLMs. CYP1A2 and CYP2D6 are involved in hydroxylation of duloxetine to 4-hydroxy duloxetine, the major metabolite, which was decreased following propolis addition in HLMs. These results raise the possibility of interactions between propolis and therapeutic drugs metabolized by CYP1A2.

Inhibitory Effects of Aschantin on Cytochrome P450 and Uridine 5'-diphospho-glucuronosyltransferase Enzyme Activities in Human Liver Microsomes

Aschantin is a bioactive neolignan found in Magnolia flos with antiplasmodial, Ca²⁺-antagonistic, platelet activating factor-antagonistic, and chemopreventive activities. We investigated its inhibitory effects on the activities of eight major human cytochrome P450 (CYP) and uridine 5′-diphospho-glucuronosyltransferase (UGT) enzymes of human liver microsomes to determine if mechanistic aschantin–enzyme interactions were evident. Aschantin potently inhibited CYP2C8-mediated amodiaquine N-de-ethylation, CYP2C9-mediated diclofenac 4′-hydroxylation, CYP2C19-mediated [S]-mephenytoin 4′-hydroxylation, and CYP3A4-mediated midazolam 1′-hydroxylation, with K_i values of 10.2, 3.7, 5.8, and 12.6 µM, respectively. Aschantin at 100 µM negligibly inhibited CYP1A2-mediated phenacetin O-de-ethylation, CYP2A6-mediated coumarin 7-hydroxylation, CYP2B6-mediated bupropion hydroxylation, and CYP2D6-mediated bufuralol 1′-hydroxylation. At 200 µM, it weakly inhibited UGT1A1-catalyzed SN-38 glucuronidation, UGT1A6-catalyzed N-acetylserotonin glucuronidation, and UGT1A9-catalyzed mycophenolic acid glucuronidation, with IC₅₀ values of 131.7, 144.1, and 71.0 µM, respectively, but did not show inhibition against UGT1A3, UGT1A4, or UGT2B7 up to 200 µM. These in vitro results indicate that aschantin should be examined in terms of potential interactions with pharmacokinetic drugs in vivo. It exhibited potent mechanism-based inhibition of CYP2C8, CYP2C9, CYP2C19, and CYP3A4.

Key factors which concur to the correct therapeutic evaluation of herbal products in free radical-induced diseases

For many years now the world's scientific literature has been perfused with articles on the therapeutic potential of natural products, the vast majority of which have herbal origins, as in the case of free radical-induced diseases. What is often overlooked is the effort of researchers who take into consideration the preclinical and clinical evaluation of these herbal products, in order to demonstrate the therapeutic efficacy and safety. The first critical issue to be addressed in the early stages of the preclinical studies is related to pharmacokinetics, which is sometimes not very favorable, of some of these products, which limits the bioavailability after oral intake. In this regard, it is worthy underlining how it is often unethical to propose the therapeutic efficacy of a compound on the basis of preclinical results obtained with far higher concentrations to those which, hopefully, could be achieved in organs and tissues of subjects taking these products by mouth. The most widely used approach to overcome the problem related to the low bioavailability involves the complexation of the active ingredients of herbal products with non-toxic carriers that facilitate the absorption and distribution. Even the induction or inhibition of drug metabolizing enzymes by herbal products, and the consequent variations of plasma concentrations of co-administered drugs, are phenomena to be carefully evaluated as they can give rise to side-effects. This risk is even greater when considering that people lack the perception of the risk arising from an over use of herbal products that, by their very nature, are considered risk-free.

Simultaneous Screening of Activities of Five Cytochrome P450 and Four Uridine 5'-Diphospho-glucuronosyltransferase Enzymes in Human Liver Microsomes Using Cocktail Incubation and Liquid Chromatography-Tandem Mass Spectrometry

Cytochrome P450 (P450) and uridine 5'-diphospho-glucuronosyltransferase (UGT) are major metabolizing enzymes in the biotransformation of most drugs. Altered P450 and UGT activities are a potential cause of adverse drug-drug interaction. A method for the simultaneous evaluation of the activities of five P450s (CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A) and four UGTs (UGT1A1, UGT1A4, UGT1A9, and UGT2B7) was developed using in vitro cocktail incubation and tandem mass spectrometry. The nine probe substrates used in this assay were phenacetin (CYP1A2), diclofenac (CYP2C9), S-mephenytoin (CYP2C19), dextromethorphan (CYP2D6), midazolam (CYP3A), 7-ethyl-10-hydroxy-camptothecin (SN-38) (UGT1A1), trifluoperazine (UGT1A4), mycophenolic acid (UGT1A9), and naloxone (UGT2B7). This new method involves incubation of two cocktail doses and single cassette analysis. The two cocktail doses and the concentration of each probe substrate in vitro were determined to minimize mutual drug interactions among substrates. Cocktail A comprised phenacetin, diclofenac, S-mephenytoin, dextromethorphan, and midazolam, whereas cocktail B comprised SN-38, trifluoperazine, mycophenolic acid, and naloxone. In the incubation study of these cocktails, the reaction mixtures were pooled and simultaneously analyzed using liquid chromatography-tandem mass spectrometry. The method was validated by comparing inhibition data obtained from the incubation of each probe substrate alone with data from the cocktail method. The IC50 values obtained in both cocktail and individual incubations were in agreement with values previously reported in the literature. This cocktail method offers a rapid and robust way to simultaneously evaluate phase I and II enzyme inhibition profiles of many new chemical entities. This new method will also be useful in the drug discovery process and for advancing the mechanistic understanding of drug interactions.

Effects of Buyang Huanwu Decoction on antioxidant and drug-metabolizing enzymes in rat liver

AIM

To study the effect of Buyang Huanwu Decoction (BYHWD) on the antioxidant enzymes and drug-metabolizing enzymes in rat liver.

METHOD

Following treatment of rats with BYHWD at 6.42, 12.83, or 25.66 g·kg(-1) per day for 15 days, microsomes and cytosols isolated from the liver tissues were prepared by differential centrifugation according to standard procedures. The activities of the antioxidant enzymes and cytochrome b5, NADPH-cytochrome P450 reductase, CYP3A, CYP2E1, UGT, and GST of the rat livers were determined by UV-Vis spectrophotometer.

RESULTS

The activities of ALT, AST, antioxidant enzymes, and the Hepatosomatic Index in serum were not significantly affected. In cytosols, the activity of CAT was significantly increased at the dosage of 12.83 g·kg(-1), and all the other antioxidant activities and MDA levels were not affected by this treatment. BYHWD had no effect on cytochrome b5, NADPH-cytochrome P450 reductase, CYP3A, and UGT. At the highest dose (25.66 g·kg(-1)), the activity of CYP2E1 was significantly inhibited, and the activities of GST and the level of GSH were increased.

CONCLUSION

BYHWD is safe for the liver, and has the functions of detoxification and antioxidant. Patients should be cautioned about the herb-drug interaction of BYHWD and CYP2E1 substrates.

Screening of six UGT enzyme activities in human liver microsomes using liquid chromatography/triple quadrupole mass spectrometry

RATIONALE

Uridine 5'-diphosphoglucuronosyltransferase (UGT) enzymes are essential for the clearance of many drugs; however, altered UGT activity is a potential cause of adverse drug-drug interactions (DDI). The early detection of potential DDI is an important aspect of drug discovery that has led to the development of new screening methods for drug interactions. We developed a screening method for the simultaneous evaluation of six human liver UGT enzyme activites using in vitro cocktail incubation and tandem mass spectrometry.

METHODS

The two in vitro cocktail doses were developed to minimize drug interactions among substrates. The method is based on liquid chromatography/tandem mass spectrometry (LC/MS/MS). Electrospray ionization (ESI) in both positive and negative modes was used to quantify the metabolites and the diagnostic loss of the glucuronosyl moiety to form the aglycone product was estimated using the selected reaction monitoring (SRM) mode.

RESULTS

The method was validated by comparing inhibition data obtained from the incubation of each individual probe substrate alone with data from the cocktail method. The intra- and inter-day accuracy and precision data for the six UGT metabolites ranged from 92.2 to 100.3% and less than 15.2%, respectively. The IC(50) values showed no significant differences between individual and cocktail incubations.

CONCLUSIONS

As a screening technique for inhibitory interactions of these six human liver UGT enzymes, this method will be useful for advancing mechanistic understanding of drug interactions.

Effect of honokiol on the induction of drug-metabolizing enzymes in human hepatocytes

Honokiol, 2-(4-hydroxy-3-prop-2-enyl-phenyl)-4-prop-2-enyl-phenol, an active component of Magnolia officinalis and Magnolia grandiflora, exerts various pharmacological activities such as antitumorigenic, antioxidative, anti-inflammatory, neurotrophic, and antithrombotic effects. To investigate whether honokiol acts as a perpetrator in drug interactions, messenger ribonucleic acid (mRNA) levels of phase I and II drug-metabolizing enzymes, including cytochrome P450 (CYP), UDP-glucuronosyltransferase (UGT), and sulfotransferase 2A1 (SULT2A1), were analyzed by real-time reverse transcription polymerase chain reaction following 48-hour honokiol exposure in three independent cryopreserved human hepatocyte cultures. Honokiol treatment at the highest concentration tested (50 μM) increased the CYP2B6 mRNA level and CYP2B6-catalyzed bupropion hydroxylase activity more than two-fold in three different hepatocyte cultures, indicating that honokiol induces CYP2B6 at higher concentrations. However, honokiol treatment (0.5–50 μM) did not significantly alter the mRNA levels of phase I enzymes (CYP1A2, CYP3A4, CYP2C8, CYP2C9, and CYP2C19) or phase II enzymes (UGT1A1, UGT1A4, UGT1A9, UGT2B7, and SULT2A1) in cryopreserved human hepatocyte cultures. CYP1A2-catalyzed phenacetin O-deethylase and CYP3A4-catalyzed midazolam 1′-hydroxylase activities were not affected by 48-hour honokiol treatment in cryopreserved human hepatocytes. These results indicate that honokiol is a weak CYP2B6 inducer and is unlikely to increase the metabolism of concomitant CYP2B6 substrates and cause pharmacokinetic-based drug interactions in humans.