Effect of Tamarindus indica L. on the bioavailability of aspirin in healthy human volunteers

Optic Nerve Neuroprotection in Glaucoma: A Narrative Review

In recent years, researchers have been interested in neuroprotective therapies as a cutting-edge therapeutic strategy to treat neurodegenerative disorders by shielding the brain system from harmful events. Millions of individuals worldwide suffer from glaucoma, an ocular neurodegenerative disease characterized by gradual excavation of the optic nerve head, retinal axonal damage, and consequent visual loss. The pathology's molecular cause is still mostly unknown, and the current treatments are not able to alter the disease's natural progression. Thus, the modern approach to treating glaucoma consists of prescribing medications with neuroprotective properties, in line with the treatment strategy suggested for other neurodegenerative diseases. For this reason, several naturally derived compounds, including nicotinamide and citicoline, have been studied throughout time to try to improve glaucoma management by exploiting their neuroprotective properties. The purpose of this review is to examine the naturally derived compounds that are currently utilized in clinical practice for neuroprotection in glaucomatous patients based on scientific data, emphasizing these compounds' pivotal mechanism of action as well as their proven therapeutic and neuroprotective benefits.

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.

Traditional Chinese medicine: herb-drug interactions with aspirin

Traditional Chinese medicine (TCM)-based herbal therapies have gained increasing popularity worldwide, raising concerns of its efficacy, safety profile and potential interactions with Western medications. Antithrombotic agents are among the most common prescription drugs involved in herb-drug interactions, and this article focused on aspirin, one of the most widely used antiplatelet agents worldwide. We discussed herbs that have potential interactions by exploring Western and TCM approaches to thrombotic events. Common TCM indications for these herbs were also highlighted, including possible scenarios of their concurrent usage with aspirin. With greater awareness and understanding of potential herb-drug interactions, TCM and Western physicians may collaborate more closely to identify, treat and, most importantly, prevent adverse drug events.

Effect of dehusked Garcinia kola seeds on the overall pharmacokinetics of quinine in healthy Nigerian volunteers

We investigated the effect of concurrent ingestion of Garcinia kola seed on the pharmacokinetics of quinine. In a randomized crossover study, 24 healthy Nigerian volunteers were assigned into 2 groups (A and B; n = 12 per group) on the basis of G. kola dose orally ingested. Each subject received 600 mg quinine sulfate before and after ingesting 12.5 g of G. kola once daily for 7 days (group A) or 12.5 g twice daily for 6 days and once on the seventh day (group B). Blood samples were collected and analyzed for plasma quinine and its metabolite (3-hydroxyquinine) using a validated high performance liquid chromatography method. Concurrent administration of quinine with G. kola reduced quinine tmax by 48% (group A), mean Cmax by 19% and 26% in groups A and B, respectively, and slight reduction in mean AUC0- ∞ of quinine in both groups. 3-hydroxyquinine Cmax also reduced by 29% and 32%; AUC0-∞ by 13% and 9%, respectively. The point estimates of the T/R ratio of the geometric means for all Cmax obtained and only the AUC0-∞ at a higher dose of G. kola were outside the 80%-125% bioequivalence range. In conclusion, an herb-drug interaction was noted with concurrent quinine and G. kola administration.

Modulation of the pharmacokinetics, therapeutic and adverse effects of NSAIDs by Chinese herbal medicines

INTRODUCTION

Concomitant use of NSAIDs and Chinese herbal medicines (CHMs) is frequent, yet summarized information on their interactions is lacking.

AREAS COVERED

A systematic review of literature in four evidence-based English databases was performed. Articles which reported CHMs altering the pharmacokinetics, therapeutic and adverse effects of NSAIDs were identified and summarized. Such interactions may lead to beneficial, detrimental or no change in outcomes. The current review covers four therapeutic effects of NSAIDs, including: i) anti-inflammatory; ii) analgesic; iii) antiplatelet, cardiovascular and cerebrovascular; and iv) anticancer effects and four adverse effects of NSAIDs, including: i) gastrointestinal ulcer; ii) nephrotoxicity; iii) hepatotoxicity; and iv) antiplatelet effects and bleeding.

EXPERT OPINION

While majority of CHMs demonstrated effectiveness in alleviating NSAIDs-induced adverse effects and potentiating the therapeutic effects, this review provides insights for development of CHMs as add-on medications to NSAIDs therapies. However, since limited information was from well-designed clinical trials, the findings are not yet conclusive and more clinical studies are warranted to provide guidance for healthcare professionals. In future, researches on interactions between NSAIDs and CHMs are expected to grow and modern approaches such as pharmacogenomics might enhance the throughput and accuracy of identifying clinically relevant interactions.

The use of plants in the traditional management of diabetes in Nigeria: pharmacological and toxicological considerations

ETHNOPHARMACOLOGICAL RELEVANCE

The prevalence of diabetes is on a steady increase worldwide and it is now identified as one of the main threats to human health in the 21st century. In Nigeria, the use of herbal medicine alone or alongside prescription drugs for its management is quite common. We hereby carry out a review of medicinal plants traditionally used for diabetes management in Nigeria. Based on the available evidence on the species׳ pharmacology and safety, we highlight ways in which their therapeutic potential can be properly harnessed for possible integration into the country׳s healthcare system.

MATERIALS AND METHODS

Ethnobotanical information was obtained from a literature search of electronic databases such as Google Scholar, Pubmed and Scopus up to 2013 for publications on medicinal plants used in diabetes management, in which the place of use and/or sample collection was identified as Nigeria. 'Diabetes' and 'Nigeria' were used as keywords for the primary searches; and then 'Plant name - accepted or synonyms', 'Constituents', 'Drug interaction' and/or 'Toxicity' for the secondary searches.

RESULTS

The hypoglycemic effect of over a hundred out of the 115 plants reviewed in this paper is backed by preclinical experimental evidence, either in vivo or in vitro. One-third of the plants have been studied for their mechanism of action, while isolation of the bioactive constituent(s) has been accomplished for twenty three plants. Some plants showed specific organ toxicity, mostly nephrotoxic or hepatotoxic, with direct effects on the levels of some liver function enzymes. Twenty eight plants have been identified as in vitro modulators of P-glycoprotein and/or one or more of the cytochrome P450 enzymes, while eleven plants altered the levels of phase 2 metabolic enzymes, chiefly glutathione, with the potential to alter the pharmacokinetics of co-administered drugs.

CONCLUSION

This review, therefore, provides a useful resource to enable a thorough assessment of the profile of plants used in diabetes management so as to ensure a more rational use. By anticipating potential toxicities or possible herb-drug interactions, significant risks which would otherwise represent a burden on the country׳s healthcare system can be avoided.

Ayurvedic drug discovery

Ayurveda is a major traditional system of Indian medicine that is still being successfully used in many countries. Recapitulation and adaptation of the older science to modern drug discovery processes can bring renewed interest to the pharmaceutical world and offer unique therapeutic solutions for a wide range of human disorders. Eventhough time-tested evidences vouch immense therapeutic benefits for ayurvedic herbs and formulations, several important issues are required to be resolved for successful implementation of ayurvedic principles to present drug discovery methodologies. Additionally, clinical examination in the extent of efficacy, safety and drug interactions of newly developed ayurvedic drugs and formulations are required to be carefully evaluated. Ayurvedic experts suggest a reverse-pharmacology approach focusing on the potential targets for which ayurvedic herbs and herbal products could bring tremendous leads to ayurvedic drug discovery. Although several novel leads and drug molecules have already been discovered from ayurvedic medicinal herbs, further scientific explorations in this arena along with customization of present technologies to ayurvedic drug manufacturing principles would greatly facilitate a standardized ayurvedic drug discovery.

Critical evaluation of ayurvedic plants for stimulating intrinsic antioxidant response

Oxidative damage caused by free radicals plays an important role in the causation and progression of many diseases, including aging. Free-radical damage is countered by many mechanisms, including both active antioxidant enzymatic activity in our body and passive antioxidants. Antioxidant response of our body can accommodate increased oxidative damage in diseased states to a level but beyond that level, additional antioxidants are required to combat the increased stress. Apart from the regular dietary sources of antioxidants, many traditional herbal medicines demonstrate a potential to boost antioxidant activity. Rasayana chikitsa that deals with rejuvenation and revitalization is a branch of the Indian traditional medical system of ayurveda. We review some select herbs described in rasayana chikitsa that have been assessed by modern means for stimulating intrinsic antioxidant responses in humans. A critical evaluation of rasayana chikitsa will likely provide urgently needed, actual stimulants of our physiological antioxidant responses and not just more passive antioxidants to add to an already large catalog.

Dietary supplements: altered coagulation and effects on bruising

BACKGROUND

Patient use of dietary supplements that alter coagulation or have an effect on bruising is becoming increasingly common.

OBJECTIVE

To identify and describe dietary supplements that alter coagulation or are reported to alter bruising during and after surgical procedures.

METHODS

The MEDLINE, Cochrane Collaboration, and International Bibliographic Information on Dietary Supplements databases were searched for articles using the search words "bruising," "bleeding," "coagulation," "hemostasis," "herbal medicine," "alternative medicine," and "dietary supplement." Additional sources were obtained from manual searches of recent journal articles.

RESULTS

In vivo and in vitro evidence supports the notion that many dietary supplements alter coagulation. Limited evidence is available to support anecdotal claims of diminished postoperative bruising after the use of dietary supplements.

CONCLUSION

Surgeons should be aware that many of their patients are taking dietary supplements that may alter coagulation. Because most patients will not readily volunteer this information, specific steps should be taken to obtain it prior to more extensive surgical procedures.

Herb-drug interactions: an overview of the clinical evidence

Herbal medicines are mixtures of more than one active ingredient. The multitude of pharmacologically active compounds obviously increases the likelihood of interactions taking place. Hence, the likelihood of herb-drug interactions is theoretically higher than drug-drug interactions, if only because synthetic drugs usually contain single chemical entities. Case reports and clinical studies have highlighted the existence of a number of clinically important interactions, although cause-and-effect relationships have not always been established. Herbs and drugs may interact either pharmacokinetically or pharmacodynamically. Through induction of cytochrome P450 enzymes and/or P-glycoprotein, some herbal products (e.g. St John's wort) have been shown to lower the plasma concentration (and/or the pharmacological effect) of a number of conventional drugs, including cyclosporine, indinavir, irinotecan, nevirapine, oral contraceptives and digoxin. The majority of such interactions involves medicines that require regular monitoring of blood levels. To date there is less evidence relating to the pharmacodynamic interaction. However, for many of the interactions discussed here, the understanding of the mechanisms involved is incomplete. Taking herbal agents may represent a potential risk to patients under conventional pharmacotherapy.

Screening of stimulatory effects of dietary risk factors on mouse intestinal cell kinetics

AIM

Although epidemiological and experimental studies validate influence of genetic, environmental and dietary factors in the causation of various types of cancers including colon, results from all these sources are inconclusive. Hypothesizing that high fat diet and obesity are among the major predisposing factors in the incidence of colon cancer, we evaluated the role of diet constituted with food material derived from a tropical plant, Tamarindus indica Linn (TI).

METHODS

A two part randomized double-blind study was conducted employing inbred Swiss albino mice from a single generation for the whole investigation. One day-old neonates (n = 12) were subcutaneously administered with monosodium glutamate (MSG) to induce obesity (OB). At weaning these animals were maintained on modified AIN-76 diet supplemented with 10% TI and 10% fat bolus (w/w, TIFB) for 8 wk. Subsequently, in the second part of study, four groups of animals belonging to the same generation, age and gender (n = 12 per group), were maintained on: AIN-76 control diet (CD); AIN-76 mixed with 10% TI extract (TI); and, mixed with 10% TI and 10% FB (TIFB) for 8 wk, to determine intestinal crypt cell proliferation, functionally-specific enzyme activities, fermentation profile, and energy preferences.

RESULTS

We observed a significant increase in the crypt cell production rate in distal colonic segment of experimental animals when compared with the controls. This segment also contained significantly low butyrate levels compared to control and TIFB groups. All the experimental groups showed a gross decrease in the enzyme activities viz., succinate dehydrogenase, acid-galactosidase and dipeptidyl amino peptidase IV demonstrating pathological stress caused by the test regimens, and an altered metabolic flux in the cellular environment.

CONCLUSION

We have demonstrated a cumulative response to the three dietary factors, one of which (TI) is reported, herein, for the first time to modulate kinetics of large intestinal mucosa, contributing to total risk posed by these test agents.

Cardiovascular pharmacotherapy and herbal medicines: the risk of drug interaction

Use of herbal medicines among patients under cardiovascular pharmacotherapy is widespread. In this paper, we have reviewed the literature to determine the possible interactions between herbal medicines and cardiovascular drugs. The Medline database was searched for clinical articles published between January 1996 and February 2003. Forty-three case reports and eight clinical trials were identified. Warfarin was the most common cardiovascular drug involved. It was found to interact with boldo, curbicin, fenugreek, garlic, danshen, devil's claw, don quai, ginkgo, papaya, lycium, mango, PC-SPES (resulting in over-anticoagulation) and with ginseng, green tea, soy and St. John's wort (causing decreased anticoagulant effect). Gum guar, St. John's wort, Siberian ginseng and wheat bran were found to decrease plasma digoxin concentration; aspirin interactions include spontaneous hyphema when associated with ginkgo and increased bioavailability if combined with tamarind. Decreased plasma concentration of simvastatin or lovastatin was observed after co-administration with St. John's wort and wheat bran, respectively. Other adverse events include hypertension after co-administration of ginkgo and a diuretic thiazide, hypokalemia after liquorice and antihypertensives and anticoagulation after phenprocoumon and St. John's wort. Interaction between herbal medicine and cardiovascular drugs is a potentially important safety issue. Patients taking anticoagulants are at the highest risk.

Herbal therapies

In summary, herbs are commonly used, and it is the physician's responsibility to have better documentation of this practice by encouraging patients to report use of herbs, and to look for any unusual side effects that can occur in terms of herb-drug or herb-herb interactions.

Effect of Tamarindus indica. L on the bioavailability of ibuprofen in healthy human volunteers

The influence of Tamarindus indica L fruit extract incorporated in a traditional meal on the bioavailability of Ibuprofen tablets 400 mg dose when given concurrently was studied in 6 healthy human volunteers. There was a statistically significant increase in the plasma levels of Ibuprofen and its metabolites hydroxy-ibuprofen and carboxy-ibuprofen respectively, when the meal containing Tamarindus indica fruit extract was administered with the ibuprofen tablets than when taken under fasting state or with the meal without the fruit extract. The C(max), AUC(0-6 hr) and Ka for ibuprofen increased from 38 +/- 0.70 microg/ml to 42 +/- 0.98 microg/ml (p > 0.05); and 28.03 +/- 2.40 microg/ml x hr to 56.51 +/- 0.16 microg/ml x hr (p < 0.05) and 1.048 +/- 0.02hr(-1) to 2.781 +/- 0.11 hr(-1) (p < 0.05) respectively. There was no change in the t(max) (120.00 +/- 0.43m) but there was a decrease in the k(el) from 0.63 +/- 0.20 hr(-1) to 0.46 +/- 0.11 hr(-1) (p<0.05). Similarly the C(max), AUC(0-6 h) and Ka for hydroxy-ibuprofen rose from 43 +/- 0.76 microg/ml to 45 +/- 0.16 microg/ml (p < 0.05); 39.04 +/- 2.30 microg/ml x hr to 59.49 +/- 2.39 microg/ml.hr in (p < 0.05) and 1.498 +/- 0.79hr(-1) to 3.442 +/- 0.23 hr(-1) (p < 0.05) respectively; while the C(max), AUC(0-6 h) and Ka for carboxy-ibuprofen rose from 48 +/- 0.7 microg/ml to 51 +/- 0.16 microg/ml (p < 0.05); 41.972 +/- 0.68 microg/ml x hr to 63.948 +/- 0.12 microg/ml x hr (p < 0.05) and 1.649 +/- 0.08 hr(-1) to 4.187 +/- 0.42 hr(-1) (p < 0.05) respectively. The study has indicated that Tamarindus indica L. fruit extract significantly increased the bioavailability of Ibuprofen.

Interactions between modern and Chinese medicinal drugs: a general review

While the use of health food and over-the-counter drugs for health promotion and adjuvant therapy is becoming increasingly popular, the concern about adverse effects is mounting. The possible adverse effects that may arise from drug interactions between these herbal preparations and standard modem therapy are equally worrying. Herbal toxicity and adverse effects are well documented in classical Chinese medicinal volumes. Interactions between herbal preparations and standard modem therapy are known. Extensive work needs to be done before useful guidelines can be established. However, based on available reports and clinical observations, some commonly used herbs and Chinese medicines have already demonstrated the need for special attention when used together with modern therapy. This paper analyzes the important material already available, and would serve as a preliminary checklist for patients who are taking herbal preparations, while at the same time receiving treatment from modern medicine.

Effect of sodium/potassium salt (potash) on the bioavailability of ibuprofen in healthy human volunteers

The influence of sodium/potassium salt water extract incorporated in a traditional meal on the bioavailability of Ibuprofen tablets 400mg dose was studied in 6 healthy human volunteers. There was a statistically significant decrease in the plasma levels of ibuprofen, and its metabolites, hydroxy-ibuprofen and carboxy-ibuprofen, respectively, when the meal containing sodium/potassium salt extract was administered with the ibuprofen tablets than when taken under fasting state or with the meal without the fruit extract. The Cmax, AUC0-6hr and Ka for ibuprofen decreased from 38.04 +/- 0.70microg/ml to 20.06 +/- 1.21microg/ml (p<0.05); 28.030 +/- 2.40microg/ml.hr to 14.180 +/- 1.12microg/ml.hr (p<0.05) and 1.048 +/- 0.02hr(-1) to 0.602 +/- 0.03hr(-1). Similarly, the Cmax for hydroxy-ibuprofen and carboxy-ibuprofen decreases from 43.04 +/- 0.76microg/ml to 27.21 +/- 0.24microg/ml (p<0.05) and 48 +/- 0.71microg/ml to 31.08 +/- 0.12microg/ml (p<0.05) respectively; while AUC0-6hr for hydroxy-ibuprofen decreased from 34.120 +/- 0.49microg/ml.hr to 16.410 +/- 0.27microg/ml.hr while that of carboxy-ibuprofen decreased from 36.121 +/- 1.97microg/ml.hr to 19.278 +/- 0.92microg/ml.hr respectively. The Kel for hydroxy-ibuprofen increased from 0.71 +/- 0.94 hr(-1) to 0.81 +/- 0.21 hr(-1) (p<0.05) respectively. The study has indicated that sodium/potassium salt extract significantly decreased the bioavailability of ibuprofen.

Drug Interactions Between Herbal and Prescription Medicines

Until reports of interactions between St John's wort and drugs such as digoxin, warfarin, protease inhibitors and oral contraceptives began to appear, very few herb-drug interactions were documented. These are now becoming more common, although still rare compared with drug-drug interactions. In the absence of hard data, potential interactions are being highlighted, and this review attempts to distinguish between the speculative and the proven. The subject is approached from a therapeutic point of view since in most cases the patient is already taking one or more prescription drugs, and the question is whether or not it is safe for a particular herb to be added to the regimen. Although many of the examples of herb-drug interactions are minor or theoretical at present, the fact remains that some are serious and life threatening, and these almost exclusively concern cyclosporin, anticoagulants, digoxin, antidepressants and protease inhibitors, taken with the herb St John's wort. Ginkgo and ginseng are implicated in a number of reports, but many of these are unsubstantiated. To date, the cardiovascular, central nervous and immune systems are the most common therapeutic categories cited in the literature and other than those, examples are very limited. Although many herbal drugs have good safety profiles, it must be borne in mind that herbal supplements are intended to be taken over an extended period of time, which provides the opportunity for enzyme induction and other mechanisms of interaction to take effect.

Herbal medication: potential for adverse interactions with analgesic drugs

The use of herbal supplements in the US has increased dramatically in recent years. These products are not regulated by the Food and Drug Administration (FDA) with the same scrutiny as conventional drugs. Patients who use herbal supplements often do so in conjunction with conventional drugs. This article is a review of potential adverse interactions between some of the commonly used herbal supplements and analgesic drugs. Non-steroidal anti-inflammatory drugs (NSAIDs), particularly aspirin, have the potential to interact with herbal supplements that are known to possess antiplatelet activity (ginkgo, garlic, ginger, bilberry, dong quai, feverfew, ginseng, turmeric, meadowsweet and willow), with those containing coumarin (chamomile, motherworth, horse chestnut, fenugreek and red clover) and with tamarind, enhancing the risk of bleeding. Acetaminophen may also interact with ginkgo and possibly with at least some of the above herbs to increase the risk of bleeding. Further, the incidences of hepatotoxicity and nephrotoxicity may be augmented by acetaminophen when concomitantly used with the potentially hepatotoxic herbs Echinacea and kava, and with herbs containing salicylate (willow, meadowsweet), respectively. The concomitant use of opioid analgesics with the sedative herbal supplements, valerian, kava and chamomile, may lead to increased central nervous system (CNS) depression. The analgesic effect of opioids may also be inhibited by ginseng. It is suggested that health-care professionals should be more aware of the potential adverse interactions between herbal supplements and analgesic drugs, and take appropriate precautionary measures to avoid their possible occurrences. However, as most of the interaction information available is based on individual case reports, animal studies and in vitro data, further research is needed to confirm and assess the clinical significance of these potential interactions.

Herb-drug interactions

Concurrent use of herbs may mimic, magnify, or oppose the effect of drugs. Plausible cases of herb-drug interactions include: bleeding when warfarin is combined with ginkgo (Ginkgo biloba), garlic (Allium sativum), dong quai (Angelica sinensis), or danshen (Salvia miltiorrhiza); mild serotonin syndrome in patients who mix St John's wort (Hypericum perforatum) with serotonin-reuptake inhibitors; decreased bioavailability of digoxin, theophylline, cyclosporin, and phenprocoumon when these drugs are combined with St John's wort; induction of mania in depressed patients who mix antidepressants and Panax ginseng; exacerbation of extrapyramidal effects with neuroleptic drugs and betel nut (Areca catechu); increased risk of hypertension when tricyclic antidepressants are combined with yohimbine (Pausinystalia yohimbe); potentiation of oral and topical corticosteroids by liquorice (Glycyrrhiza glabra); decreased blood concentrations of prednisolone when taken with the Chinese herbal product xaio chai hu tang (sho-salko-to); and decreased concentrations of phenytoin when combined with the Ayurvedic syrup shankhapushpi. Anthranoid-containing plants (including senna [Cassia senna] and cascara [Rhamnus purshiana]) and soluble fibres (including guar gum and psyllium) can decrease the absorption of drugs. Many reports of herb-drug interactions are sketchy and lack laboratory analysis of suspect preparations. Health-care practitioners should caution patients against mixing herbs and pharmaceutical drugs.