Potential Herb-drug Interactions Research Articles

Warfarin Interactions with Medicinal Herbs

Recognition of the adverse effects of medicinal herbs is not routine and the reports on such effects are even less frequent in clinical practice. Potential herb-drug interactions are of a major safety concern, especially for drugs with narrow therapeutic indices like warfarin, which can lead to severe adverse reactions that are sometimes life-threatening. The interactions between warfarin and medicinal herbs described in the literature have been summarized in this paper relying on Medline database (via PubMed) using the key words: warfarin, herbal supplements and interactions. The references on the analyzed literature have been investigated in order to collect the existing data. The case reports with severe adverse effects such as spontaneous postoperative bleeding, formation of hematomas, hematemesis, melena, thrombosis, subarachnoid hemorrhage and/or subdural hematomas after concomitant use of warfarin and the medicinal herbs: Panax ginseng, Hypericum perforatum, Salvia milthiorizza, Gingko biloba, Serenoa repens, Angelica sinensis, Vaccinium species, Allium sativum, Zingiber officinale, Tanacetum parthenium, Lucium barbarum, Matricaria chamomilla, Boswellia serrata and Camellia sinensis have been estimated. Some of the interactions between warfarin and medicinal herbs have been well assessed proving that they are closely-dependent. The interactions between warfarin and medicinal herbs, not generally reported in previous reviews, are presented in our review. The health professionals who are involved in treating the patients are expected to be fully informed about the interactions between warfarin and medicinal herbs in order to minimize the health risks of the patients.

Evaluation of the transporter-mediated herb-drug interaction potential of DA-9801, a standardized dioscorea extract for diabetic neuropathy, in human in vitro and rat in vivo.

BackgroundDrug transporters play important roles in the absorption, distribution, and elimination of drugs and thereby, modulate drug efficacy and toxicity. With a growing use of poly pharmacy, concurrent administration of herbal extracts that modulate transporter activities with drugs can cause serious adverse reactions. Therefore, prediction and evaluation of drug-drug interaction potential is important in the clinic and in the drug development process. DA-9801, comprising a mixed extract of Dioscoreae rhizoma and Dioscorea nipponica Makino, is a new standardized extract currently being evaluated for diabetic peripheral neuropathy in a phase II clinical study.MethodThe inhibitory effects of DA-9801 on the transport functions of organic cation transporter (OCT)1, OCT2, organic anion transporter (OAT)1, OAT3, organic anion transporting polypeptide (OATP)1B1, OATP1B3, P-glycoprotein (P-gp), and breast cancer resistance protein (BCRP) were investigated in HEK293 or LLC-PK1 cells. The effects of DA-9801 on the pharmacokinetics of relevant substrate drugs of these transporters were also examined in vivo in rats.ResultsDA-9801 inhibited the in vitro transport activities of OCT1, OCT2, OAT3, and OATP1B1, with IC50 values of 106, 174, 48.1, and 273 μg/mL, respectively, while the other transporters were not inhibited by 300 μg/mL DA-9801. To investigate whether this inhibitory effect of DA-9801 on OCT1, OCT2, and OAT3 could change the pharmacokinetics of their substrates in vivo, we measured the pharmacokinetics of cimetidine, a substrate for OCT1, OCT2, and OAT3, and of furosemide, a substrate for OAT1 and OAT3, by co-administration of DA-9801 at a single oral dose of 1,000 mg/kg. Pre-dose of DA-9801 5 min or 2 h prior to cimetidine administration decreased the Cmax of cimetidine in rats. However, DA-9801 did not affect the elimination parameters such as half-life, clearance, or amount excreted in the urine, suggesting that it did not inhibit elimination process of cimetidine, which is governed by OCT1, OCT2, and OAT3. Moreover, DA-9801 did not affect the pharmacokinetic characteristics of furosemide, as evidenced by its unchanged pharmacokinetic parameters.ConclusionInhibitory effects of DA-9801 on OCT1, OCT2, and OAT3 observed in vitro may not necessarily translate into in vivo herb-drug interactions in rats even at its maximum effective dose.

Assessing potential herb-drug interactions (HDIS): Need for a common framework approach

Herbal product usage in the North American population continues to increase across all age groups. This population has ready access to conventional medications, with significant polypharmacy observed in older adults. Patients are reticent to disclose herbal product usage to their healthcare providers, and many providers still do not inquire about such usage. Dietary supplements, including herbal products, are not subject to the same regulatory guidelines for pre-market testing as drugs. Considerations such as history of safe use, literature data from toxicity studies, and constituent amounts in products may provide guidance on whether to assess HDIs experimentally. The literature is replete with reports of various herbal extracts and constituents as potent inhibitors of drug metabolizing enzymes, including the cytochromes P450. However, without the use of standard methods for herbal product characterization or in vitro testing, extrapolating these reports to clinically-relevant HDIs is difficult. This lack of a clear definition of risk prevents clinicians and consumers from making informed decisions about the safety of taking herbal products with conventional medications. A logical strategy is to borrow, as applicable, from the testing guidances for assessing drug-drug interactions established by regulatory agencies (e.g., FDA, EMA). For example, intestinal and hepatic in vitro systems can be used to assess potential HDIs. These data can be incorporated into PBPK models to help determine clinical relevance. In summary, a framework is needed that describes a flexible approach for assessing when HDI studies are warranted and an outline of standard methods when HDI testing is conducted.

Herbal medicines in Brazil: pharmacokinetic profile and potential herb-drug interactions.

A plethora of active compounds found in herbal medicines can serve as substrate for enzymes involved in the metabolism of xenobiotics. When a medicinal plant is co-administered with a conventional drug and little or no information is known about the pharmacokinetics of the plant metabolites, there is an increased risk of potential herb-drug interactions. Moreover, genetic polymorphisms in a population may act to predispose individuals to adverse reactions. The use of herbal medicines is rapidly increasing in many countries, particularly Brazil where the vast biodiversity is a potential source of new and more affordable treatments for numerous conditions. Accordingly, the Brazilian Unified Public Health System (SUS) produced a list of 71 plant species of interest, which could be made available to the population in the near future. Physicians at SUS prescribe a number of essential drugs and should herbal medicines be added to this system the chance of herb-drug interactions further increases. A review of the effects of these medicinal plants on Phase 1 and Phase 2 metabolic mechanisms and the transporter P-glycoprotein was conducted. The results have shown that approximately half of these medicinal plants lack any pharmacokinetic data. Moreover, most of the studies carried out are in vitro. Only a few reports on herb-drug interactions with essential drugs prescribed by SUS were found, suggesting that very little attention is being given to the safety of herbal medicines. Here we have taken this information to discuss the potential interactions between herbal medicines and essential drugs prescribed to Brazilian patients whilst taking into account the most common polymorphisms present in the Brazilian population. A number of theoretical interactions are pinpointed but more pharmacokinetic studies and pharmacovigilance data are needed to ascertain their clinical significance.

Evaluation of the in vitro/in vivo potential of five berries (bilberry, blueberry, cranberry, elderberry, and raspberry ketones) commonly used as herbal supplements to inhibit uridine diphospho-glucuronosyltransferase

In this study, we evaluated inhibitory potentials of popularly-consumed berries (bilberry, blueberry, cranberry, elderberry, and raspberry ketones) as herbal supplements on UGT1A1, UGT1A4, UGT1A6, UGT1A9, and UGT2B7 in vitro. We also investigated the potential herb–drug interaction via UGT1A1 inhibition by blueberry in vivo. We demonstrated that these berries had only weak inhibitory effects on the five UGTs. Bilberry and elderberry had no apparent inhibitions. Blueberry weakly inhibited UGT1A1 with an IC50 value of 62.4±4.40μg/mL and a Ki value of 53.1μg/mL. Blueberry also weakly inhibited UGT2B7 with an IC50 value of 147±11.1μg/mL. In addition, cranberry weakly inhibited UGT1A9 activity (IC50=458±49.7μg/mL) and raspberry ketones weakly inhibited UGT2B7 activity (IC50=248±28.2μg/mL). Among tested berries, blueberry showed the lowest IC50 value in the inhibition of UGT1A1 in vitro. However, the co-administration of blueberry had no effect on the pharmacokinetics of irinotecan and its active metabolite, SN-38, which was mainly eliminated via UGT1A1, in vivo. Our data suggests that these five berries are unlikely to cause clinically significant herb–drug interactions mediated via inhibition of UGT enzymes involved in drug metabolism. These findings should enable an understanding of herb–drug interactions for the safe use of popularly-consumed berries.

Inhibition of major drug metabolizing CYPs by common herbal medicines used by HIV/AIDS patients in Africa-- implications for herb-drug interactions.

The purpose of this study was to evaluate the potential risk of common herbal medicines used by HIV-infected patients in Africa for herb-drug interactions (HDI). High throughput screening assays consisting of recombinant Cytochrome P450 enzymes (CYPs) and fluorescent probes, and parallel artificial membrane permeability assays (PAMPA) were used. The potential of herbal medicines to cause HDI was ranked according to FDA guidelines for reversible inhibition and categorization of time dependent inhibition was based on the normalized ratio. CYPs 1A2 and 3A4 were most inhibited by the herbal extracts. H. hemerocallidea (IC50 = 0.63 µg/mL and 58 µg/mL) and E. purpurea (IC50 = 20 µg/mL and 12 µg/mL) were the potent inhibitors of CYPs 1A2 and 3A4 respectively. L. frutescens and H. hemerocallidea showed clear time dependent inhibition on CYP3A4. Furthermore, the inhibitory effect of both H. hemerocallidea and L. frutescens before and after PAMPA were identical. The results indicate potential HDI of H. hemerocallidea, L. frutescens and E. purpurea with substrates of the affected enzymes if maximum in vivo concentration is achieved.

Potent inhibitory effect of alpha-viniferin on human cytochrome P450

α-Viniferin isolated from Caragana chamlagu is a trimer of resveratrol, and has several biological activities, which include anti-inflammatory, anti-oxidant, anti-arthritis, and anti-tumor activities. Herb–drug interactions are the source of the most harmful complications in patients coadministered herbal and modern medicines, and are caused by modulation of the activities of drug metabolizing enzymes. Here, the authors investigated the inhibitory effects of α-viniferin on the activities of 9 human cytochrome P450 (CYP) isoforms using a cocktail of probe substrates and LC–MS/MS in pooled human liver microsomes (HLMs). α-Viniferin strongly inhibited 7 of the 9 CYP isoforms (except CYP2A6 and CYP2E1). Furthermore, α-viniferin strongly inhibited CYP2C19-mediated omeprazole 5-hydroxylation and CYP3A4-catalyzed midazolam 1-hydroxylation with IC50 values of 0.93 and 1.2μM, respectively. α-Viniferin strongly inhibited the activities of these two CYPs dose dependently, but not time-dependently. Lineweaver–Burk plots and secondary plots indicated a typical pattern of mix-mode inhibition for CYP2C19 and 3A4. This is the first investigation conducted on the inhibitory effect of α-viniferin on CYP2C19 and 3A4 in HLMs to predict a potential herb–drug interaction.

Effect of Icariin on UDP-Glucuronosyltransferases in Mouse Liver

Icariin is a flavonol glycoside isolated from Epimedium genus and has been used in the treatment of sexual dysfunction and osteoporosis. Our laboratory has shown that icariin is beneficial in brain disorders and cardiovascular diseases. Since icariin is widely used with other herbs and drugs, to understand its potential herb-drug interactions is of importance. Recently, icariin was shown to inhibit UDP-glucuronosyltransferases, particularly the Ugt1 family enzymes in vitro, but little is known about such effects in vivo. This study investigated the effects of icariin on the expression of UDP-glucuronosyltransferases and cytochrome P450 enzymes in the livers of mice. Adult mice were treated with icariin at doses of 0, 40, 80, 160, and 320 mg/kg, p. o., for 7 days. Phenobarbital (120 mg/kg, p.o.) and rifampin (360 mg/kg, p. o.) were given twice daily for 3 days as positive controls. The livers were removed to determine UDP-glucuronosyltransferase activity and total RNA isolation. The UDP-glucuronosyltransferase activities towards 2-aminophenol were basically unaltered by the treatments. The expression of Cyp2b10 was increased 35-fold by phenobarbital, and Cyp3a11 was increased 4.5-fold by rifampin. Icariin did not affect Cyp2b10 and Cyp3a11 expression, but unexpectedly increased Cyp4a14 expression. Both phenobarbital and rifampin increased Ugt1a1, Ugt1a6, Ugt1a9, and icariin but did not show any suppressive effects on the Ugt1 family genes. Icariin at the highest dose (320 mg/kg) slightly increased Ugt2b1, Ugt2b5, and Ugt2b36. These findings indicate that icariin did not suppress UDP-glucuronosyltransferase expression, instead, it increased the mRNA of Cyp4a14 and slightly increased Ugt2b isoforms in mouse livers.

Effect of Sophora flavescens on the pharmacokinetics of carbamazepine in rats

Carbamazepine (CBZ), an antiepileptic with narrow therapeutic window, is a substrate of CYP 3A4 which metabolizes CBZ to carbamazepine-10,11-epoxide (CBZE). CBZE is an active and toxicity metabolite, and it is a substrate of MRP-2. Using CBZ for a long time can cause hepatic injury. Sophora flavescens (SF) is a medicinal herb used for the protected hepatic injury. This study investigated the acute and chronic effects of SF on the pharmacokinetics of CBZ in rats. The concentrations of CBZ and CBZE in plasma and tissues were determined by HPLC method. The results showed that SF which significantly decreased the AUC0-t of CBZ, increased CBZE conversely. Tissue analysis showed that the concentrations of CBZ and CBZE in brain and liver were decreased by SF. In addition, the distribution of CBZE in kidney was reduced significantly, which influenced the CBZE excretion and increased the drug toxic potentially. Results in the current study suggest that patients using CBZ might be cautioned in the use of SF extract or Sophora-derived products. Meanwhile, patients receiving drugs which are substrates of CYP 3A4 and/or MRP-2 should be advised of the potential herb-drug interaction to reduce the risk of therapeutic failure or increased toxicity of conventional drug therapy.

Cytochrome P450 inhibitory potential and RP-HPLC standardization of trikatu—A Rasayana from Indian Ayurveda

Ethnopharmacological relevanceTrikatu is a very well known ‘Rasayana’ in Ayurveda and widely used as a polyherbal ayurvedic formulation in India. It consists of three well known plants, viz., Piper longum (PL), Piper nigrum (PN) and Zingiber officinale (ZO) in equal ratio. Trikatu has been prescribed for cough, cold, fever, asthma, respiratory problems and improvement of digestive disorders. The aim of the present study was to investigate the effect of individual ingredients of trikatu namely PL, PN, and ZO and formulations [Marketed formulation (MF) and laboratory formulation (LF)] on drug metabolizing enzymes (CYP3A4 and CYP2D6), to assess its herb–drug interaction potential through cytochrome P450 inhibition assays. Further this work was aimed to develop an RP-HPLC method for the identification and quantification of piperine and 6-gingerol in the crude drug trikatu. Materials and methodsEnzyme inhibition effect of LF, MF, PL, PN and ZO was explored through CYP450–CO complex assay using rat liver microsomes (RLM) and a fluorescence screening method using individual isoenzymes (CYP3A4 and CYP2D6). The RP-HPLC method was developed for the identification and quantification of piperine and 6-gingerol in LF, MF and individual plant materials at the concentration of 1mg/mL. ResultsRP-HPLC analysis confirmed the presence of piperine and 6-gingerol in LF and MF [Piperine: 7.89±2.12% (w/w) (MF), 6.70±2.13% (w/w) (LF)]; [6-gingerol: 5.3±1.21% (w/w) (MF), 4.95±2.34% (w/w) (LF)]. Inhibitory potential of MF and LF in CYP450–CO complex assay was found to be 37.54±3.12% (MF) and 35.12±2.31% (LF) and against CYP2D6 and CYP3A4 was estimated to be IC50 251.30±3.98 and 245.23±1.92μg/mL and IC50 225.50±1.02 and 223.254±0.92μg/mL respectively. ConclusionsDifferent concentrations of the trikatu formulation and its individual components showed significantly (p<0.001) less inhibitory activity on individual isoenzymes as compared to the positive control. The crude drug exhibited inhibitory potential against the CYP450 enzymes in a concentration dependent manner. Outcome of the present study demonstrated that trikatu has less interaction potential with drug metabolizing enzymes.

Effects of Seijo‐bofu‐to, a Traditional Japanese Herbal Medicine Containing Furanocoumarin Derivatives, on the Drug‐Metabolizing Enzyme Activities in Healthy Male Volunteers

Seijo-bofu-to, a traditional medicine used to treat acne in Asian countries, contains twelve herbal components, including Angelica dahurica root, a source of furanocoumarin derivatives. In this study, we investigated potential herb-drug interactions of seijo-bofu-to in healthy male volunteers. Thirty-two young, healthy, non-smoking males were assessed for the baseline activity of cytochrome P450 (CYP) 1A2, CYP3A, CYP2D6, N-acetyltransferase 2 and xanthine oxidase according to the urinary metabolic indices of 8-hr urine samples collected after the administration of a 150-mg dose of caffeine and a 30-mg dose of dextromethorphan, and the ratio of urinary excretion of 6β-hydroxycortisol to cortisol. Thereafter, the volunteers received 3.75 g of seijo-bofu-to twice daily for 7 days and underwent the same tests on post-dose day 7. The geometric mean ratio of the CYP1A2 activity on day 7 to that observed at baseline was 0.66 (95% CI, 0.55-0.79, p = 0.001). The geometric mean phenotypic indices for CYP3A, CYP2D6, N-acetyltransferase 2 and xanthine oxidase on day 7 did not differ from the baseline values. The findings of the present study suggest that seijo-bofu-to may inhibit the activity of CYP1A2, whereas it is unlikely to participate in herb-drug interactions involving medications predominantly metabolized by CYP3A, CYP2D6, N-acetyltransferase 2 or xanthine oxidase.

Herb–drug interaction prediction based on the high specific inhibition of andrographolide derivatives towards UDP-glucuronosyltransferase (UGT) 2B7

Herb–drug interaction strongly limits the clinical application of herbs and drugs, and the inhibition of herbal components towards important drug-metabolizing enzymes (DMEs) has been regarded as one of the most important reasons. The present study aims to investigate the inhibition potential of andrographolide derivatives towards one of the most important phase II DMEs UDP-glucuronosyltransferases (UGTs). Recombinant UGT isoforms (except UGT1A4)-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction and UGT1A4-catalyzed trifluoperazine (TFP) glucuronidation were employed to firstly screen the andrographolide derivatives' inhibition potential. High specific inhibition of andrographolide derivatives towards UGT2B7 was observed. The inhibition type and parameters (Ki) were determined for the compounds exhibiting strong inhibition capability towards UGT2B7, and human liver microsome (HLMs)-catalyzed zidovudine (AZT) glucuronidation probe reaction was used to furtherly confirm the inhibition behavior. In combination of inhibition parameters (Ki) and in vivo concentration of andrographolide and dehydroandrographolide, the potential in vivo inhibition magnitude was predicted. Additionally, both the in vitro inhibition data and computational modeling results provide important information for the modification of andrographolide derivatives as selective inhibitors of UGT2B7. Taken together, data obtained from the present study indicated the potential herb–drug interaction between Andrographis paniculata and the drugs mainly undergoing UGT2B7-catalyzed metabolic elimination, and the andrographolide derivatives as potential candidates for the selective inhibitors of UGT2B7.

Physiologically Based Pharmacokinetic Modeling Framework for Quantitative Prediction of an Herb–Drug Interaction

Herb–drug interaction predictions remain challenging. Physiologically based pharmacokinetic (PBPK) modeling was used to improve prediction accuracy of potential herb–drug interactions using the semipurified milk thistle preparation, silibinin, as an exemplar herbal product. Interactions between silibinin constituents and the probe substrates warfarin (CYP2C9) and midazolam (CYP3A) were simulated. A low silibinin dose (160 mg/day × 14 days) was predicted to increase midazolam area under the curve (AUC) by 1%, which was corroborated with external data; a higher dose (1,650 mg/day × 7 days) was predicted to increase midazolam and (S)-warfarin AUC by 5% and 4%, respectively. A proof-of-concept clinical study confirmed minimal interaction between high-dose silibinin and both midazolam and (S)-warfarin (9 and 13% increase in AUC, respectively). Unexpectedly, (R)-warfarin AUC decreased (by 15%), but this is unlikely to be clinically important. Application of this PBPK modeling framework to other herb–drug interactions could facilitate development of guidelines for quantitative prediction of clinically relevant interactions.

Inhibition of Human Cytochrome P450 Enzymes by Bacopa monnieri Standardized Extract and Constituents

Bacopa monnieri and the constituents of this plant, especially bacosides, possess various neuropharmacological properties. Like drugs, some herbal extracts and the constituents of their extracts alter cytochrome P450 (CYP) enzymes, causing potential herb-drug interactions. The effects of Bacopa monnieri standardized extract and the bacosides from the extract on five major CYP isoforms in vitro were analyzed using a luminescent CYP recombinant human enzyme assay. B. monnieri extract exhibited non-competitive inhibition of CYP2C19 (IC50/Ki = 23.67/9.5 µg/mL), CYP2C9 (36.49/12.5 µg/mL), CYP1A2 (52.20/25.1 µg/mL); competitive inhibition of CYP3A4 (83.95/14.5 µg/mL) and weak inhibition of CYP2D6 (IC50 = 2061.50 µg/mL). However, the bacosides showed negligible inhibition of the same isoforms. B. monnieri, which is orally administered, has a higher concentration in the gut than the liver; therefore, this herb could exhibit stronger inhibition of intestinal CYPs than hepatic CYPs. At an estimated gut concentration of 600 µg/mL (based on a daily dosage of 300 mg/day), B. monnieri reduced the catalytic activities of CYP3A4, CYP2C9 and CYP2C19 to less than 10% compared to the total activity (without inhibitor = 100%). These findings suggest that B. monnieri extract could contribute to herb-drug interactions when orally co-administered with drugs metabolized by CYP1A2, CYP3A4, CYP2C9 and CYP2C19.

Down-regulation of P-gp expression and function after Mulberroside A treatment: Potential role of protein kinase C and NF-kappa B

P-Glycoprotein (P-gp) plays a major role in drug–drug and herb–drug interactions. Mulberroside A (Mul A) is one of the main bioactive constituents of Sangbaipi, the dried root-bark of Morus alba L. (white mulberry), which is officially listed in the Chinese Pharmacopoeia. In the present study, we investigated the effect of Mul A treatment on mRNA expression and protein expression of P-gp in the Caco-2 cells by real-time qPCR and Western blot analysis. The effect of Mul A treatment on the function of P-gp in vitro and in vivo was assessed by Rho123 transport assay and a pharmacokinetic study. The potential roles of protein kinase C (PKC) and nuclear factor kappa B (NF-κB) in the expression regulation of P-gp after Mul A treatment were also investigated. The results revealed that Mul A treatment significantly decreased the mRNA and protein expression of P-gp in Caco-2 cells after treatment with Mul A (5–20μM). Furthermore, Mul A treatment displayed apparently inhibitory effect on the function of P-gp both in vitro and in vivo. In addition, activation of PKC activity and NF-κB nuclear translocation were observed in the presence of Mul A, which suggested that PKC and NF-κB might play crucial roles in Mul A-induced suppression of P-gp. Our study demonstrated that Mul A treatment could down-regulate P-gp expression and function accompanied by the activation of PKC and NF-κB, and this should be taken into consideration in potential herb–drug interactions when Mul A or M. alba are co-administered with other drugs transported by P-gp.

Stepping from traditional to integrative medicine: perspectives of Israeli-Arab patients on complementary medicine's role in cancer care

Limited research is available on the perspectives of patients with cancer regarding integration of complementary medicine (CM) in conventional supportive cancer care. The purpose of this study was to explore patients' perspectives concerning CM integration within conventional oncology settings. A 27-item questionnaire was constructed and administered to a convenient sample of Arab patients receiving cancer care in three oncology centers in northern Israel. Of the 324 respondents (94.7% response rate), 124 of 313 (39.6%) reported the use of CM for cancer-related outcomes. A logistic regression model indicated that CM was used with active chemo- or radiotherapy treatment [EXP [B], 2.926, 95% confidence interval (CI) 1.276-6.708; P=0.011] and a higher degree of spiritual quest (EXP [B], 3.425, 95% CI 1.042-11.253; P=0.043). Herbal medicine was the leading CM modality (87.9% of CM users), which included the use of 28 plants and traditional remedies, of which 17 were used to improve QOL, with 5 of the herbs having potential interactions with chemotherapy. 83.1% of respondents stated that they would consult with a CM provider if CM were to be integrated into the oncology department. Patients' expectation of CM consultation was clearly associated with expectations of QOL improvement, coping with cancer, and alleviating chemotherapy's side-effects when compared with expectations of cancer cure (P<0.0001). The three leading concerns which patients expected to be improved by integrative CM treatment were gastrointestinal symptoms (63.2%), fatigue (51.9%), and pain (40.5%). Integrative CM consultations should focus on the improvement of QOL concomitant with safety concerns regarding potential drug-herb interactions. The need to integrate a nonjudgmental yet evidence-based CM consultation service may also be applicable to oncology institutions challenged with culturally diverse populations with a high prevalence of traditional medicine use.

Comparison of the Inhibitory Potential of Bavachalcone and Corylin against UDP-Glucuronosyltransferases.

Bavachalcone and corylin are two major bioactive compounds isolated from Psoralea corylifolia L., which has been widely used as traditional Chinese medicine for many years. As two antibiotic or anticancer drugs, bavachalcone and corylin are used in combination with other drugs; thus it is necessary to evaluate potential pharmacokinetic herb-drug interactions (HDI) of the two bioactive compounds. The aim of the present study was to compare the effects of liver UDP-glucuronosyltransferase (UGT) 1A1, UGT1A3, UGT1A7, UGT1A8, UGT 1A10, and UGT2B4 inhibited by bavachalcone and corylin. 4-Methylumbelliferone (4-MU) was used as a nonspecific “probe” substrate. Bavachalcone had stronger inhibition on UGT1A1 and UGT1A7 than corylin which did not inhibit UGT1A1, UGT1A3, UGT1A7, UGT1A8, UGT1A10, and UGT2B4. Data fitting using Dixon and Lineweaver-Burk plots demonstrated the noncompetitive inhibition of bavachalcone against UGT1A1 and UGT1A7-mediated 4-MU glucuronidation reaction. The values of inhibition kinetic parameters (Ki) were 5.41 μM and 4.51 μM for UGT1A1 and UGT1A7, respectively. The results of present study suggested that there was a possibility of UGT1A1 and UGT1A7 inhibition-based herb-drug interaction associated with bavachalcone and provided the basis for further in vivo studies to investigate the HDI potential between bavachalcone and UGT substrates.

Prevalence on the Use of Traditional Medicine in Brunei Darussalam

The use of traditional medicines (TM) and Complementary Alternative Medicines (CAM) are common in Western Pacific countries including Brunei and Singapore. Our cross-sectional study assessed the prevalence of TM use amongst Brunei population. The objectives are to compare the practices on the use of TM with conventional medicines and to address the safety and cost implication. This study was conducted for a period of 12 months from October 2007. It was a cross-sectional study using a structured self-administered questionnaire which was pretested from the pilot study. Questionnaires were randomly administered to all patients attending the tertiary hospitals and health centres in Brunei. The questionnaires are bilingual and consists of 27-item questions. Both sexes were included in the study, and participants had to be mentally competent and of age between 16 years and 85 years. Data entry and analysis were done using SPSS version 16.0. Information leaflets were given to participants, and their written-informed consent was obtained. There were 2,400 respondent for this study of which 32% (n=777) were male and 68% (n=1,623) were female, 85 % were Malays, and 55% were in employment status. The proportion of Bruneians who have used some form of TM during their lifetime was 59%, (n=1,396). Use of TM is equal in proportion among Chinese (62%) and Malay ethnicities (59%). Use of TM was highest in the 56 years and above age group (71%), p<0.01. It was higher amongst female respondents compared to males p<0.001. 64% respondents indicated that TM was safe. 76% (n= 1,804) of respondents answered that TM are easily available. Majority of TM users (91%) used local herbs and 63% used TM for general health and vitality. 43% of users of prescribed medicines (common cold remedies, antipyretics and antibiotics) reported using TM as well. 73% of respondents did not report their use of TM to their doctors. 94% (n=1,284) of the respondents claimed that there were no adverse effects accompanying use of TM. 62% perceived TM is safe due to the traditional practices and natural sources. 82% of TM users spend less than BND $50 on TM every month. We concluded from this study that there is a high prevalence of TM use in Brunei despite the free health care services provided in the country. Doctors need to understand TM better and communicate more with their patients regarding TM use. This can be due to their use as maintenance of health rather than for treatment of illness. TM is also easily available and perceived to be safe because it had been used for generations and of natural sources despite their limited scientific evidence. The lack of regulation and perceptions of TM being safe needs extra cautions to avoid any potential serious adverse herb-drug interactions. Therefore, medical and health care workers should not ignore this perceptions and patients’ education is utmost important.

Assessing potential herb-drug interactions: A clinical decision-making guideline to mitigate patient risk

Complementary and Alternative (CAM) therapy use has been and continues to be prevalent in cancer patients, some of whom are taking herbal supplements. Studies indicate that 20% to 77% of these patients do not disclose their CAM use to their physician. Herb-drug interactions pose a considerable risk to the oncology patient population. The potential impact of any given herbal supplement on cytochrome isoenzymes, P-glycoprotein, UDP-Glucuronosyltransferase (UGT) enzymes, and other drug metabolism pathways needs to be evaluated to establish the risk of interactions with each medication that a cancer patient is taking. A review of the available literature reveals a varying array of human volunteer studies, case reports, in vitro and in vivo studies, often with contradictory results. Individual herbal products can greatly differ in the composition of their constituents, bioavailability, and thus interaction risk. A simplified clinical decision making guideline was developed to assist in easing the burden for physicians when faced with the question of whether a patient can safely take a particular herbal product. The guideline provides different scenarios with recommendations on how to approach each situation, as well as, recommendations for evidence-based non-herbal options to actively engage patients in their symptoms, while avoiding potentially deleterious interactions. Open dialogue about whether or not herbal supplements are appropriate, given the phase of treatment the patient is currently in, and having other options to suggest as alternatives may improve patient disclosure of herbal supplement use and compliance with their physician’s recommendations to discontinue supplements when necessary.

Herbal medicines supplied by community pharmacies in Lagos, Nigeria: pharmacists´ knowledge

The use of herbal medicines is on the increase globally and they are usually supplied in pharmacies as non-prescription medicines. Pharmacists are, therefore, responsible for educating and informing the consumers about rational use of herbal medicines. To evaluate the knowledge of pharmacists in Lagos, Nigeria with regards to the herbal medicines they supplied by their pharmacies. Pharmacists in charge of randomly selected 140 community pharmacies from 20 Local Government Areas in Lagos were required to fill out a self-administered questionnaire. We gathered information on their knowledge of the indications, adverse effects, potential drug-herb interactions and contraindications of the herbal medicines they supply in their pharmacies. Of the 140 questionnaires distributed, 103 (72.9%) participants completed the questionnaire appropriately. The majority (74; 71.8%) of the participants were males and 36-50 years (56; 54.4%). The pharmacies supplied mostly Yoyo cleanser bitters® (101; 98.5%), ginseng (97; 98.5%), Jobelyn® (91; 88.3%), Ciklavit® (68; 66.6%), gingko (66; 64.1%), herbal tea (66; 64.1%), and Aloe vera (57; 55.3%). The pharmacists self-rated their knowledge of herbal medicines mostly as fair (39%) and good (42%), but they exhibited poor knowledge with regards to the indications, contraindications and safety profiles. Seventy participants consulted reference materials such as leaflet insert in the herbal medicines (56%) and internet (20%) before supplying herbal medicines. The information most frequently sought was herb-drug interactions (85%), contraindications (75%) and adverse effects (70%). Community pharmacists need to be informed about the indications and safety profiles of herbal medicines.