interaction

[Oral anticoagulants: a literature review of herb-drug interactions or food-drug interactions]: J Pharm Belg. 2007; 62(3): 69-75 Bourget S, Baudrant M, Allenet B, Calop J

OBJECTIVE: To identify herbal medicines and food products which can interact with anticoagulant therapy. MATERIAL AND METHOD: Literature review using key words: "anticoagulants", "herb-drug interaction", "food-drug interaction", "drug chinese herbal", "medicine herbal", "plant preparation", "dietary supplements". Data sources: Medline (january 1966 to june 2006) and Pascal (1987 to 2006). Case reports, systematic reviews, in vitro studies, clinical studies published in french or in english (or with an english extract) have been undertaken. RESULTS: Eighty articles were selected (two both including a case report and a study): 14 systemic review, 43 case reports, 25 studies (17 studies in humans: nine randomized and controlled, three controlled), six controlled studies in animals and two in vitro studies. DISCUSSION: A wide range of herbal medicines and food products can interact with anticoagulants. Clinical relevance of these effects is difficult to characterise (nature of existing reports, contradiction between studies, difficult extrapolation to human). CONCLUSION: It is difficult to predict the incidence or severity of such interactions. However, awareness of these potential interactions is necessary to achieve optimal anticoagulation therapy: pharmacist can play a crucial role identifying such interactions in case of disturbed INR; clinicians should be informed to monitor closely the therapy, particularly when such products are started or discontinued.

An examination of the bleeding complications associated with herbal supplements, antiplatelet and anticoagulant medications.: J Dent Hyg. 2007;81(3):67 Authors: Spolarich A, Andrews L

Dental professionals routinely treat patients taking prescription, nonprescription, and herbal medications that are known or have the potential to alter bleeding. Prescription anticoagulant and antiplatelet medications, as well as over-the-counter drugs such as aspirin, are typically taken to reduce the risk of thromboembolic events, including stroke. Herbal supplements are widely used for a variety of indications, and both patients and health care practitioners are often unaware of the anticoagulant and antiplatelet effects that occur as either predictable pharmacologic effects or adverse side effects of herbal medicines. In addition, patient use of these herbal supplements is usually undisclosed to health care providers. The purpose of this literature review is to examine the mechanisms of action of drugs and herbs that alter bleeding, and to educate dental professionals as to the proper care and management of patients using these medications. Decision-making strategies, including interpretation of laboratory tests, and when to discontinue the use of these medications are discussed. Patients undergoing routine dental and dental hygiene procedures do not need to discontinue the use of anticoagulant and antiplatelet medications. However, alterations in drug use may be required for those patients undergoing invasive surgical procedures. It is recommended that herbal supplements must be discontinued 2 weeks prior to receiving invasive surgical procedures. Dental practitioners must learn to weigh the risks of discontinuing drug therapy against the potential risks to patients, and implement risk reduction strategies to minimize adverse bleeding complications associated with dental treatment.

PMID: 17908423 [PubMed - in process]

Dietary supplements, herbs and oral anticoagulants: the nature of the evidence.: J Thromb Thrombolysis. 2007 Sep 29; Authors: Wittkowsky AK

In the US, the use of dietary supplements, including vitamins, minerals, amino acids, and herbal products, is extensive. Nonetheless, the majority of patients report that they have little information about the risks, benefits, and adverse effects of medicines, or about their potential interactions with prescription drugs. Patients taking warfarin are at particular risk of interactions with dietary supplements, yet approximately 30% use herbal or natural product supplements on a regular basis. No current governmental regulations or voluntary programs address dietary supplement interactions with prescription drugs. Case reports represent the majority of the evidence surrounding drug interactions between warfarin and dietary supplements. Those of the highest quality include, as an assessment of causality, a modification of the recently published Drug Interaction Probability Scale. Despite positive case reports, formal drug interaction studies are often negative, suggesting that numerous patient-specific influences other than the suspected interaction alone may be responsible for a particular observation. The cranberry-juice/warfarin interaction is a recent example of such a discrepancy. Healthcare providers can play an active role in improving quantity and the quality of case reports of interactions involving warfarin and dietary supplements. A registry of anticoagulant interactions with dietary supplements has been proposed, and is currently being developed through Clotcare Online Resource ( http://www.clotcare.com ). The goal of this registry is to obtain high quality case-based evidence of drug interactions between anticoagulants and dietary supplements, to define these interactions based on clinical and monitoring outcomes, and to analyze likelihood of causation using a modification of the Drug Interaction Probability Scale.

PMID: 17906915 [PubMed - as supplied by publisher]

[Effect of chinese herbs in enhancing prednisone for treatment of refractory rheumatoid arthritis]: Zhongguo Zhong Xi Yi Jie He Za Zhi. 2007 Aug; 27(8): 742-4 Liu W, Liu XY, Wang Y

OBJECTIVE: To investigate the Chinese herbal medicine in enhancing effect of prednisone for treatment of refractory rheumatoid arthritis (RA). METHODS: One hundred and twenty patients with refraetory RA were assigned to two groups, the treated group was orally administered with Qingbi Tablet, a patent Chinese herbal preparation formulated based on the clearing heat and removing toxic substances principle, and the control group was treated with intramuscular injection of amethopterin (MTX), oral intake of voltaren 75 mg and hydroxychloroquine 0.2 g once a day. Besides prednisone was given to all patients orally, the initiating dosage used in the treated group was lesser than that in the control group. The clinical index, dosage and adverse reaction of prednisone were recorded every 2 weeks. RESULTS: The curative effect evaluated by American College of Rheumatology (ACR) standard showed no statistical difference between the two groups (P > 0.05). Either clinical or laboratory indexes were improved significantly in both groups (P < 0.05), but the improvement in resting pain, patient's self-evaluation and doctor's evaluation in the treated group were better than those in the control group, showing statistical difference (P < 0.05). The 20-week total amount of prednisone used in the treated group was less than that in the control group (32,935 mg vs. 51,170 mg), while the dosage of prednisone used in various observation time points between the two groups was also significantly different respectively (P < 0.05), the former was less than the latter. CONCLUSION: Chinese herbal medicine can enhance the effect of prednisone in patients of refractory RA and alleviate the adverse reactions of prednisone.

Research on biomodulatory effect of natural compounds.: Neuro Endocrinol Lett. 2006 Dec;27 Suppl 2:53-6 Authors: Miadoková E, Nadová S, Trebatická M, Grolmus J, Kopásková M, Rauko P, Mucaji P, Grancai D

OBJECTIVES: The purpose of this study was to determine whether the extract isolated from the artichoke Cynara cardunculus L. (ECC) had antimutagenic effect and was able to enhance the therapeutic effect of cytostatic drug cis-platinum (cis-Pt). METHODS: The potential antimutagenic activity of ECC was assayed by a test on sex-linked recessive lethal mutations detection in Drosophila melanogaster males treated with ethylmethane sulfonate (EMS). The possible enhancement of cytostatic/cytotoxic effect of cis-Pt by ECC was evaluated in the cell revitalization assay by measuring cell viability via Trypan blue exclusive assay using mouse leukemia cells L1210. RESULTS: EMS was both toxic and genotoxic in D. melanogaster males. It statistically significantly increased the frequency of sex-linked recessive lethal mutations in comparison to the negative control. Furthermore, ECC statistically significantly reduced the genotoxic effect of EMS. It acted in a desmutagenic manner via EMS inactivation. In the cell revitalization assay, ECC enhanced the cytotoxic/cytostatic effect of cis-Pt. The therapeutic potential of ECC was established on the basis of statistically significantly lowered recovery of cis-Pt pre-treated mouse leukemia cells in the presence of ECC. CONCLUSIONS: The results imply that the extract isolated from artichoke C. cardunculus L. has marked beneficial activities antimutagenic and therapeutic effect enhancing) and its potential biomedical application in the combination therapy of cancer and some neurodegenerative diseases may be suggested.

Role of P-glycoprotein in the intestinal absorption of glabridin, an active flavonoid from the root of Glycyrrhiza glabra.: Drug Metab Dispos. 2007 Apr;35(4):539-53 Authors: Cao J, Chen X, Liang J, Yu XQ, Xu AL, Chan E, Wei D, Huang M, Wen JY, Yu XY, Li XT, Sheu FS, Zhou SF

Glabridin is a major constituent of the root of Glycyrrhiza glabra, which is commonly used in the treatment of cardiovascular and central nervous system diseases. This study aimed to investigate the role of P-glycoprotein (PgP/MDR1) in the intestinal absorption of glabridin. The systemic bioavailability of glabridin was approximately 7.5% in rats, but increased when combined with verapamil. In single-pass perfused rat ileum with mesenteric vein cannulation, the permeability coefficient of glabridin based on drug disappearance in luminal perfusates (P(lumen)) was approximately 7-fold higher than that based on drug appearance in the blood (P(blood)). Glabridin was mainly metabolized by glucuronidation, and the metabolic capacity of intestine microsomes was 1/15 to 1/20 of that in liver microsomes. Polarized transport of glabridin was found in Caco-2 and MDCKII monolayers. Addition of verapamil in both apical (AP) and basolateral (BL) sides abolished the polarized transport of glabridin across Caco-2 cells. Incubation of verapamil significantly altered the intracellular accumulation and efflux of glabridin in Caco-2 cells. The transport of glabridin in the BL-AP direction was significantly higher in MDCKII cells overexpressing PgP/MDR1 than in the control cells. Glabridin inhibited PgP-mediated transport of digoxin with an IC(50) value of 2.56 microM, but stimulated PgP/MDR1 ATPase activity with a K(m) of 25.1 microM. The plasma AUC(0-24h) of glabridin in mdr1a(-/-) mice was 3.8-fold higher than that in wild-type mice. These findings indicate that glabridin is a substrate for PgP and that both PgP/MDR1-mediated efflux and first-pass metabolism contribute to the low oral bioavailability of glabridin.

Differences in perceived risks and benefits of herbal, over-the-counter conventional, and prescribed conventional, medicines, and the implications of this for the safe and effective use of herbal products.: Complement Ther Med. 2007 Jun; 15(2): 84-91. Authors: Lynch N, Berry D

OBJECTIVES: To investigate people's views about the efficacy and specific risks of herbal, over-the-counter (OTC) conventional, and prescribed conventional medicines, and their likelihood of taking a second (herbal or OTC conventional) product in addition to a prescribed medicine. METHODS: Experiment 1 (1 factor within-participant design); Experiment 2 (1 factor between-participant design). Convenience samples of general population were given a hypothetical scenario and required to make a number of judgements. RESULTS: People believed herbal remedies to be less effective, but less risky than OTC and prescribed conventional medicines. Herbal medicines were not seen as being safer simply because of their easier availability. Participants indicated that they would be more likely to take a herbal medicine than a conventional OTC medicine in addition to a prescribed medicine, and less likely to consult their doctor in advance. CONCLUSION: People believe that herbal medicines are natural and relatively safe and can be used with less caution. People need to be given clear information about the risks and benefits of herbal medicines if they are to use such products safely and effectively.

Effect of valerian, valerian/hops extracts, and valerenic acid on glucuronidation in vitro.: Xenobiotica. 2007 Feb;37(2):113-23 Authors: Alkharfy KM, Frye RF

Valerian preparations alone or in combination with hops are popular over-the-counter products used for sleep disturbances or anxiety. Therefore, it is important to characterize the effect of these products on the activity of human drug-metabolizing enzymes. The inhibitory effects of valerian and valerian/hops extracts as well as valerenic acid (a major constituent of valerian) on glucuronidation were evaluated in human liver microsomes and with expressed uridine 5'-diphosphate (UDP)-glucuronosyltransferases (UGT). Methanolic extracts of two herbal preparations caused significant reductions in the rate of formation of acetaminophen, oestradiol, morphine, and testosterone glucuronides. Oestradiol glucuronidation at the 3-hydroxy position was inhibited by nearly 87% in microsomal incubations. In addition, marked reductions in UGT1A1 and UGT2B7 activities were observed in the presence of the herbal extracts using oestradiol and morphine as probe substrates, respectively. Valerenic acid also demonstrated significant inhibitory effects on the glucuronidation of acetaminophen, oestradiol, and morphine with both microsomes and expressed UGTs. The relatively low IC50 values obtained for valerenic acid in microsomal incubations may indicate that this essential oil contributes to the effects observed with herbal extracts in inhibiting glucuronidation in vitro. Overall, these findings suggest that valerian-containing products may interfere with the glucuronidation of endo- and xenobiotics.

[Effects of the flavonoids on cytochrome P-450 CYP1, 2E1, 3A4 and 19]: Yao Xue Xue Bao. 2007 Jan;42(1):8-12 Authors: Zheng J, Zhou HH

Flavonoids are present in fruits, vegetables and beverages derived from plants, and in many dietary supplements or herbal remedies. A number of naturally occurring flavonoids have been shown to modulate the CYP450 system, including the induction or inhibition of these enzymes. This review focuses on the flavonoid effects on cytochrome P450 (CYP) enzyme CYP1, 2E1, 3A4 and 19. Flavonoids alter CYPs by various mechanisms, including the stimulation of gene expression via specific receptors and/or CYP protein, or mRNA stabilization and so on. But in vivo and in vitro, the effects of flavonoids are not always coincident as a result of concentrations of flavonoids, genetic and environmental factors. As well, flavonoids may interact with drugs through the induction or inhibition of their metabolism. Much attention should be paid to the metabolism interaction of the flavonoids when coadministered with other drugs.

Adverse interactions between herbal and dietary substances and prescription medications: a clinical survey.: Altern Ther Health Med. 2007 Mar-Apr;13(2):30-5 Authors: Bush TM, Rayburn KS, Holloway SW, Sanchez-Yamamoto DS, Allen BL, Lam T, So BK, Tran de H, Greyber ER, Kantor S, Roth LW

CONTEXT: Patients often combine prescription medications with herbal and dietary substances (herein referred to as herbal medicines). A variety of potential adverse herb-drug interactions exist based on the pharmacological properties of herbal and prescription medications. OBJECTIVE: To determine the incidence of potential and observed adverse herb-drug interactions in patients using herbal medicines with prescription medications. DESIGN: Consecutive patients were questioned about their use of herbal medicines in 6 outpatient clinics. Patients reporting use of these products provided a list of their prescription medications, which were reviewed for any potential adverse herb-drug interactions using a comprehensive natural medicine database. Any potential adverse herb-drug interactions prompted a review of the patient's chart for evidence of an observed adverse herb-drug interaction. MAIN OUTCOME MEASURE: The rate of potential and observed adverse herb-drug interactions. RESULTS: Eight hundred four patients were surveyed, and 122 (15%) used herbal medicines. Eighty-five potential adverse herb-drug interactions were found in 49 patients (40% of herbal medicine users). Twelve possible adverse herb-drug interactions in 8 patients (7% of herbal medicine users) were observed. In all 12 cases, the severity scores were rated as mild, including 8 cases of hypoglycemia in diabetics taking nopal (prickly pear cactus). CONCLUSIONS: A substantial number of potential adverse herb-drug interactions were detected and a small number of adverse herb-drug interactions observed, particularly in diabetics taking nopal. Screening for herbal medicine usage in 804 patients did not uncover any serious adverse interactions with prescription medications.