Pharmacokinetic Herb-Drug Interactions: Insight into Mechanisms and Consequences

Tinospora cordifolia Extract Enhances Dextromethorphan Bioavailability: Implications for Alzheimer's Disease

Tinospora cordifolia (Willd.) Miers (Menispermaceae) is a traditional rejuvenator and a conventional medicine used to manage oxidative stress-related diseases, including those associated with the central nervous system. Decreased dextromethorphan (DEM) metabolism is necessary for high bioavailability and application against Alzheimer's disease (AD). Since T. cordifolia stem extract (TCE) can potentially inhibit several metabolic enzymes, it can also enhance dextromethorphan bioavailability. This study investigates the potential of TCE to improve DEM's bioavailability and efficacy for the management of AD. In silico analysis was carried out to find the inhibition potential of phytocomponents of T. cordifolia for CYP2D6 and CYP3A4. The LC-MS method was revalidated for the analysis of DEM and metabolite dextrorphan (DEX) in the presence of quinidine (QN). The ratio of DEM to DEX was estimated with varying doses of TCE following pharmacokinetic analysis. Network pharmacology analysis was carried out to understand the complementary potential of phytocomponents. This was further validated in the scopolamine-induced dementia model through behavioral and histopathological analyses. TCE (100 mg/kg) for 14 days increased the DEM to DEX ratio by 2.8-fold compared to QN treatment. While T max was comparable to that of QN treatment at this dose (100 mg/kg) of TCE, it increased significantly at the higher dose (400 mg/kg) of TCE pretreatment. All other pharmacokinetic parameters were also enhanced at this dose with a 4.7-fold increase in DEM/DEX compared with QN. Network pharmacology analysis indicated the ability of TCE to target multiple factors associated with AD. Furthermore, it improved spatial memory and reduced hyperactivity in rodents better than the combination of QN and DEM.

Recent Advancements in Extraction Techniques of Ashwagandha (Withania somnifera) with Insights on Phytochemicals, Structural Significance, Pharmacology, and Current Trends in Food Applications

Ashwagandha, also known as Withania somnifera (WS), is an ayurvedic botanical plant with numerous applications in dietary supplements and traditional medicines worldwide. Due to the restorative qualities of its roots, WS has potent therapeutic value in traditional Indian (Ayurvedic, Unani, Siddha) and modern medicine recognized as the "Indian ginseng". The presence of phytochemical bioactive compounds such as withanolides, withanosides, alkaloids, flavonoids, and phenolic compounds has an important role in the therapeutic and nutritional properties of WS. Thus, the choice of WS plant part and extraction solvents, with conventional and modern techniques, plays a role in establishing WS as a potential nutraceutical product. WS has recently made its way into food supplements and products, such as baked goods, juices, beverages, sweets, and dairy items. The review aims to cover the key perspectives about WS in terms of plant description, phytochemistry, structural significance, and earlier reported extraction methodologies along with the analytical and pharmacological landscape in the area. It also attempts to iterate the key limitations and further insights into extraction techniques and bioactive standardization with the regulatory framework. It presents a key to the future development of prospective applications in foods such as food supplements or functional foods.

Concurrent use of herbal and prescribed medicine by patients in primary health care clinics, South Africa

BACKGROUND

The use of herbal medicine (HM) as a self-management practice for treating various diseases has gained popularity worldwide. Consumers co-administer herbal products with conventional medicine without the knowledge of possible herb-drug interaction (HDI).

AIM

This study aimed to assess patients' perception and use of HM and their knowledge of HDI.

SETTING

Participants attending primary health care (PHC) clinics in three provinces (Gauteng, Mpumalanga and Free State), South Africa, were recruited.

METHODS

Focus group discussions comprising a total of thirty (N = 30) participants were conducted using a semi-structured interview guide. Discussions were audio-recorded and then transcribed verbatim. Data were analysed using thematic content analysis.

RESULTS

Reasons for using HM, sources of information on HM, co-administration of HM and prescribed medicine, disclosure of the use of HM, PHC nurses' attitudes and not having time to engage were frequently discussed. Respondents' lack of knowledge and perceptions about HDI and their dissatisfaction with prescribed medicine because of experienced side effects were also discussed.

CONCLUSION

Because of the lack of discussions and non-disclosure about HM in PHC clinics, patients are at risk of experiencing HDIs. Primary health care providers should regularly enquire about HM use on every patient, to identify and prevent HDIs. The lack of knowledge about HDIs by patients further compromises the safety of HM.Contribution: The results highlighted the lack of knowledge of HDI by patients thus assisting the healthcare stakeholders in South Africa to implement measures to educate patients attending PHC clinics.

UGTs-mediated metabolic interactions contribute to enhanced anti-inflammation activity of Jinhongtang

ETHNOPHARMACOLOGICAL RELEVANCE

Jinhongtang, a traditional Chinese medicine (TCM) formula consisting of dry stems of Rheum palmatum L. (Polygonaceae) and Sargentodoxa cuneata (Oliv.) Rehder & E.H.Wilson (Lardizabalaceae) and whole plant of Taraxacum mongolicum Hand.-Mazz. (Asteraceae), is widely used for the treatment of infection diseases including severe sepsis and COVID-19.

AIM OF THE STUDY

The present study aimed to explore the compatibility mechanism in the prescription of Jinhongtang based on the pharmacokinetic interaction.

MATERIALS AND METHODS

CLP-induced sepsis mice and LPS-induced RAW264.7 cells were used to explore the anti-inflammatory effect of Jinhongtang and herbs in this clinical prescription. Pharmacokinetics of active components in Jinhongtang (Rhein, Emodin and Aloe emodin) was studied in rats. In vitro analysis of metabolic pathways and interactions mediated by metabolic enzymes were conducted using human liver microsomes (HLMs) and recombinant UGT isoforms.

RESULTS

Jinhongtang exhibited much more potent anti-inflammatory effect than its single herbs on CLP-induced sepsis mice and LPS-induced RAW264.7 cells. Next, the bioavailability of active ingredients (Rhein, Emodin and Aloe emodin) in R. palmatum was significantly improved through reduced metabolic clearance when co-administered with S. cuneata and T. mongolicum as Jinhongtang during the in vivo pharmacokinetic study, which presented the rational herbal compatibility mechanism. In detailed, the components in S. cuneata and T. mongolicum including Sargentodoxoside A, Chanitracin Ia, Quercetin and Luteolin inhibited the UGT1A9-mediated glucuronidation of active ingredients in R. palmatum, with K_i values of 2.72 μM, 1.25 μM, 2.84 μM and 0.83 μM, respectively.

CONCLUSION

T. mongolicum and S. cuneata, the adjuvant herbs of Jinhongtang, could reduce the metabolic clearance of key active components of R. palmatum, prolong their action time and further enhance their anti-inflammatory activity via inhibition of UGTs. Our findings provided deep insight for the rational compatibility of TCMs and useful guidance for the development of TCM formula.

Herbal medications and natural products for patients with covid-19 and diabetes mellitus: Potentials and challenges

BACKGROUND

The presence of diabetes mellitus (DM) among COVID-19 patients is associated with increased hospitalization, morbidity, and mortality. Evidence has shown that hyperglycemia potentiates SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection and plays a central role in severe COVID-19 and diabetes comorbidity. In this review, we explore the therapeutic potentials of herbal medications and natural products in the management of COVID-19 and DM comorbidity and the challenges associated with the preexisting or concurrent use of these substances.

METHODS

Research papers that were published from January 2016 to December 2021 were retrieved from PubMed, ScienceDirect, and Google Scholar databases. Papers reporting clinical evidence of antidiabetic activities and any available evidence of the anti-COVID-19 potential of ten selected natural products were retrieved and analyzed for discussion in this review.

RESULTS

A total of 548 papers (73 clinical trials on the antidiabetic activities of the selected natural products and 475 research and review articles on their anti-COVID-19 potential) were retrieved from the literature search for further analysis. A total of 517 articles (reviews and less relevant research papers) were excluded. A cumulative sum of thirty-one (31) research papers (20 clinical trials and 10 others) met the criteria and have been discussed in this review.

CONCLUSION

The findings of this review suggest that phenolic compounds are the most promising phytochemicals in the management of COVID-19 and DM comorbidity. Curcumin and propolis have shown substantial evidence against COVID-19 and DM in humans and are thus, considered the best potential therapeutic options.

Investigating the Potential Use of Andrographolide as a Coadjuvant in Sickle Cell Anemia Therapy

Andrographolide is one of the main active principles of Andrographolide paniculata and has been extensively explored for its therapeutic use. Current studies focus on phytotherapeutics-based adjuvant therapy to symptomatically treat sickle cell anemia (SCA) as there is no specific drug/gene therapy available to date. The present study aimed to explore the potential of andrographolide as an adjuvant therapy for SCA in the presence or absence of hydroxyurea (HU), a key drug for SCA treatment. A panel of ex vivo and in vivo experimentations was performed to explore the antisickling activity of andrographolide, followed by evaluating pharmacokinetic and pharmacodynamic (PK/PD) activities in the presence of HU. Andrographolide showed significant antisickling activity using blood from SCA patients (ex vivo) and did not show any deleterious effect to cause hemolysis using rat blood (ex vivo). It displayed a substantial decrease in HU-induced decline in splenic lymphocyte proliferation and cytokine level (TNF-α and IFN-γ) using rat splenocytes (ex vivo). Concomitant oral administration of andrographolide with HU in rats for 15 days exhibited a noticeable improvement in the RBC count and hemoglobin levels comparable to the efficacy of l-glutamine (in vivo). Simultaneous administration of andrographolide with HU caused no marked effect on any pharmacokinetic parameters of HU except the highest plasma concentration of HU and its corresponding time point, which significantly dropped and delayed, respectively (in vivo). No considerable effect of andrographolide was observed on urease and horseradish peroxidase activity (in vitro). Overall, results suggest that andrographolide has several beneficial actions to be an adjuvant therapy to symptomatically manage SCA, but it should be avoided during the prescribed therapy of HU.

Potential pharmacokinetic and pharmacodynamic herb-drug interactions of Andrographis paniculata (Burm. f.) and andrographolide: A systematic review

Introduction: Herb–drug interactions (HDIs) in pharmacokinetics and pharmacodynamics can occur when natural compounds are used in combination with drugs. This study aimed to review the potential interaction of Andrographis paniculata (Burm. f.) extract (APE) and its primary compound andrographolide (AND) with several drugs exhibiting various pharmacological activities.Methods: In this systematic review, articles were collected from international databases such as PubMed, Science Direct, Springer Link, and Scopus until August 2021. The following keywords were used: Andrographis paniculata, andrographolide, HDI, drug interaction, pharmacokinetics, and pharmacology. This review was written in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA), SYRCLE’s risk of bias (RoB) tool for animal intervention studies, and Cochrane RoB 2 tool to analyze the RoB for qualitative assessment.Results: Twelve articles were included in accordance with the inclusion and exclusion criteria of this study. Five studies explored the potential of HDIs for combining APE with drugs and AND with theophylline, etoricoxib, nabumetone, naproxen, and tolbutamide. Five studies focused on AND in combination with aminophylline and doxofylline, meloxicam, glyburide, glimepiride, metformin, and warfarin. Two studies tested the combination of APE with gliclazide and midazolam. The HDI mechanism involving the inhibition or induction of cytochrome P450 enzyme expression was dominant in influencing the drug’s pharmacokinetic profile. Pharmacological studies on the combination of several drugs, particularly anti-inflammatory and antidiabetic drugs, showed a synergistic activity.Conclusion: APE and AND have potential pharmacokinetic and pharmacodynamic HDIs with various drugs. This study can be used as a therapeutic consideration in clinical aspects related to the possibility of HDIs of A. paniculata (Burm. f.).

Influence of methylxanthines isolated from Bancha green tea on the pharmacokinetics of sildenafil in rats

BACKGROUND

Sildenafil is used to treat erectile dysfunction and pulmonary arterial hypertension and is metabolized in the liver mainly by CYP3A4, thus co-administration with drugs or herbal extracts that affect CYP3A4 activity may lead to drug-drug or drug-herb interactions, respectively. The aim of the present study was to evaluate the influence of single and multiple oral doses of methylxanthine fraction, isolated from Bancha green tea leaves on the pharmacokinetics of sildenafil in rats.

METHODS

Rats were given sildenafil alone as well as simultaneously with methylxanthines or ketoconazole. The plasma concentrations of sildenafil were measured with high-performance liquid chromatography method with ultraviolet detection. The pharmacokinetic parameters of sildenafil were calculated by non-compartmental analysis.

RESULTS

Concomitant use of sildenafil with a single oral dose of methylxanthines resulted in a decrease in C_max (p > 0.05), AUC_0-t (p < 0.05) and AUC_0-inf (p < 0.05), while the administration of sildenafil after methylxanthines pretreatment resulted in an increase in C_max (p < 0.0001), AUC_0-t (p < 0.0001) and AUC_0-inf (p < 0.001) compared to the sildenafil group. After co-administration of sildenafil and ketoconazole, a significant increase in C_max, AUC_0-t and AUC_0-inf was observed in both of the experiments.

CONCLUSION

Drug-herb interactions were observed when sildenafil was co-administered with Bancha methylxanthines in rats. Further in vivo studies about the potential drug interactions between sildenafil and methylxanthines, especially caffeine, are needed to clarify mechanisms underlying the observed changes in sildenafil pharmacokinetics.

A Practical Perspective on the Use of Botanicals During the COVID-19 Pandemic: From Proven to Potential Interactions

In this review, we examined the top 10 nutraceutical products sold in Italian pharmacies and parapharmacies as well as hypermarkets and supermarkets; in the first, three product categories saw the greatest increase in sales (vitamins and minerals, immunostimulants, and sleep products) for the 12-month period between October 2019 and October 2020 (including first pandemic wave of SARS-CoV-2). We are investigating their respective formulas and isolating the botanicals that are used to make them. Many of these products have undergone preclinical and clinical studies. We performed a systematic literature search in the MEDLINE database using PubMed and Google Scholar from November 15, 2020 to December 15, 2020 (including studies carried out between 1980 and 2020). The search terms that were used included the complete name of the medicinal plant in English or Latin and the terms "cytochrome" or "drug interactions," crossing, respectively, the Latin name and English common names with "cytochrome" and "drug interactions." The search included in vitro and in vivo studies describing the effects of interaction between the plant (extract or botanical medicine) and human cytochromes. Despite their great complexity, there is decidedly limited clinical data on botanical medicine. In fact, of the 28 botanicals that were examined, only 2 (Citrus paradisi and Rhodiola rosea) show in vivo pharmacological interactions in human subjects. On the contrary, for the other botanicals, there is only weak evidence of dubious clinical significance or potential interactions shown in animal models or in vitro without clinical confirmation. This study provides a rational assessment of the most widely used products, including those used in self-medication, to simplify patient management during the COVID-19 health emergency.

Unpredictable adverse effects of herbal products

Herbal products are being increasingly used all over the world for preventive and therapeutic purposes because of the belief of their safety. They have become an important part of health care system in many countries since they can easily be purchased in the health food stores or online. However, the lack of sufficient study on their efficacy and toxicity, inadequate controls of their availability, reduce their safety. Unlike conventional drugs, herbal products are not regulated for purity and potency. Herbal products contain substances which can induce or inhibit enzymes that take part in drug metabolism. Therefore the concurrent use of drugs with some medicinal plants can cause serious adverse effects and can also decrease the efficacy of the therapy. Particularly, drugs with narrow therapeutic index and plants which can affect drug metabolizing enzymes when used together, may lead to unpredictable adverse reactions. Impurities, contaminants and adulterants found in the herbal products, are the most common malpractises in herbal raw-material trade. In this review the unpredictable adverse effects of herbal products due to their possible interactions with drugs and also due to the adulteration and contamination with prohibited chemicals will be discussed in detail.

Coprescription Trends in Western Medicine, Chinese Herbal Medicine and Dental Medicine among Older Adults in Taiwan from 1997 to 2013

BACKGROUND

Coprescription is a potential medical problem for older adults that could induce polypharmacy and subsequent complications. In Taiwan, Chinese herbal medicine (CHM) is popular among the older adults. Investigating the coprescription trends in Western medicine, CHM and dental medicine is important to avoid possible polypharmacy.

METHODS

We analyzed data from the Longitudinal Health Insurance Database 2000 (LHID 2000) in Taiwan. Patients ≥ 60 years old who received coprescription of Western medicine, CHM and drugs for dental care from 1997 to 2013 were included. The odds ratio (OR) and 95% confidence interval (95% CI) were estimated by a logistic regression model for evaluating the correlation between baseline characteristics and coprescription.

RESULTS

A total of 266,034 patients were included for the analysis. Most patients receiving coprescriptions lived in the northern Taiwan and with a monthly income lower than 20,000 new Taiwan dollars. The trends in older adults using Western medicine alone or CHM alone decreased over time, but the cohort using dental medicine alone had the opposite result. Decreased trends in coprescription with age were noted. The trends in the proportion of coprescription and the number of days of coprescription increased with the calendar year. Increased trends in the proportion of patients with coprescription were also found, except for the cohort of patients who used both Western medicine and CHM. Patients who were female, and aged 70-79 years were prone to receive coprescription.

CONCLUSIONS

Coprescription in older patients is not uncommon in Taiwan. Healthcare providers and policymakers should be aware of the complex coprescription pattern in the older adults.

Coronavirus Disease 2019 and Herbal Therapy: Pertinent Issues Relating to Toxicity and Standardization of Phytopharmaceuticals

Coronavirus disease 2019 (COVID-19) is a virulent viral disease that has now become a public health emergency of global significance and still without an approved treatment regimen or cure. In the absence of curative drugs and with vaccines development still in progress, alternative approaches to stem the tide of the pandemic are being considered. The potential of a phytotherapeutic approach in the management of the dreaded disease has gained attention, especially in developing countries, with several claims of the development of anti-COVID-19 herbal formulations. This is a plausible approach especially with the increasing acceptance of herbal medicine in both alternative and orthodox medical practices worldwide. Also, the established efficacy of herbal remedies in the treatment of numerous viral diseases including those caused by coronaviruses, as well as diseases with symptoms associated with COVID-19, presents a valid case for serious consideration of herbal medicine in the treatment of COVID-19. However, there are legitimate concerns and daunting challenges with the use of herbs and herbal products. These include issues of quality control, unethical production practice, inadequate information on the composition, use and mechanisms, weak regulatory policies, herb-drug interactions and adverse reactions, and the tendency for abuse. This review discusses the feasibility of intervention with herbal medicine in the COVID-19 pandemic and the need to take proactive measures to protect public health by improving the quality and safety of herbal medicine deployed to combat the disease. Graphical abstract.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43450-021-00132-x.

Integrative Oncology Education: An Emerging Competency for Oncology Providers

A growing number of cancer patients use complementary and alternative therapies during and after conventional cancer treatment. Patients are often reluctant to discuss these therapies with their oncologist, and oncologists may have limited knowledge and confidence on how to advise patients on the appropriate use. Integrative oncology is a patient-centered, evidence-informed field that utilizes mind-body practices, lifestyle modifications and/or natural products interwoven with conventional cancer treatment. It prioritizes safety and best available evidence to offer appropriate interventions alongside conventional care. There are few opportunities for oncologists to learn about integrative oncology. In this commentary, we highlight the Integrative Oncology Scholars (IOS) program as a means to increase competency in this growing field. We provide an overview of several integrative oncology modalities that are taught through this program, including lifestyle modifications, physical activity, and mind-body interventions. We conclude that as more evidence is generated in this field, it will be essential that oncology healthcare providers are aware of the prevalent use of these modalities by their patients and cancer centers include Integrative Oncology trained physicians and other healthcare professionals in their team to discuss and recommend evidence-based integrative oncology therapies alongside conventional cancer treatments to their patients.

Anticancer Potential of Sutherlandia frutescens and Xysmalobium undulatum in LS180 Colorectal Cancer Mini-Tumors

Colorectal cancer remains to be one of the leading causes of death worldwide, with millions of patients diagnosed each year. Although chemotherapeutic drugs are routinely used to treat cancer, these treatments have severe side effects. As a result, the use of herbal medicines has gained increasing popularity as a treatment for cancer. In this study, two South African medicinal plants widely used to treat various diseases, Sutherlandia frutescens and Xysmalobium undulatum, were evaluated for potential activity against colorectal cancer. This potential activity for the treatment of colorectal cancer was assessed relative to the known chemotherapeutic drug, paclitaxel. The cytotoxic activity was considered in an advanced three-dimensional (3D) sodium alginate encapsulated LS180 colorectal cancer functional spheroid model, cultured in clinostat-based rotating bioreactors. The LS180 cell mini-tumors were treated for 96 h with two concentrations of each of the crude aqueous extracts or paclitaxel. S. frutescens extract markedly decreased the soluble protein content, while decreasing ATP and AK per protein content to below detectable limits after only 24 h exposure. X. undulatum extract also decreased the soluble protein content, cell viability, and glucose consumption. The results suggested that the two phytomedicines have potential to become a source of new treatments against colorectal cancer.

Impact of quercetin on pharmacokinetics of quetiapine: insights from in-vivo studies in wistar rats

Quercetin (QCN) is commonly used in high doses as a dietary supplement for weight loss. Psychotic patients are at greater risk of developing obesity than the general population. The present study was designed to understand the impact of QCN on the exposure of quetiapine (QTE), an anti-psychotic drug with narrow therapeutic index and brain penetrating capability. The content of QTE in rat plasma was analyzed through liquid chromatography-tandem mass spectrometry. The results showed a significant (p < 0.05) increase in exposure of QTE (peroral dosed) in the animals pre-treated with QCN as compared to the control group. All the animals pre-treated with QCN, succumbed to death within 3-5 min of intravenous dosing of QTE (1 mg/kg). The studies in rat liver S9 fraction indicated that QCN could increase the metabolic stability of QTE by inhibiting the activity of CYP enzymes. The brain to plasma ratio of QTE increased upon QCN pre-treatment (2.6 vs 7.7), which could be attributed to P-glycoprotein inhibition at the blood-brain barrier by QCN. The current set of studies indicated that serious herb-drug interaction between QCN and QTE might occur when they are co-administered. Caution is advised for concomitant use of QCN rich dietary supplements with QTE.

Effect of Hibiscus sabdariffa and Zingiber officinale on the antihypertensive activity and pharmacokinetic of losartan in hypertensive rats

The present study aimed to determine the effect of Hibiscus sabdariffa and Zingiber officinale on antihypertensive activity and pharmacokinetic of losartan in hypertensive rats.Hypertension was induced in rats by oral administration of L-NAME (40 mg/kg per day). Pharmacodynamics and pharmacokinetics of losartan were evaluated without and with herbal treatment in hypertensive rats.Treatment of hypertensive rats with investigated herbs substantially reduced systolic blood pressure (SBP), and diastolic blood pressure (DBP) of rats. Treatment of rats (n = 5) with L-NAME plus H. sabdariffa plus losartan and L-NAME plus Z. officinale plus losartan reduced SBP by 16.20% and 14.88% and DBP by 14.82% and 17.52% respectively after 12 h, as compared to L-NAME alone treated rats. In a pharmacokinetic study, the Cmax and AUC0-t of losartan in L-NAME plus H. sabdariffa plus losartan and L-NAME plus Z. officinale plus losartan treated rats was increased by 0.7, 1.99 and 1.51, 3.00 fold respectively in comparison to the Cmax and AUC0-t obtained for L-NAME plus losartan treated group. In conclusion, both the investigated herbs significantly increased the antihypertensive effect and plasma concentration of losartan in L-NAME induced hypertensive rats. The current study predicted that the herb-drug interaction between H. sabdariffa-losartan and Z. officinale-losartan could occur; hence these results in rats may warrant further studies in humans, either in humans or in in vitro human liver microsomes.

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.

Evaluation of bioactive compounds and antioxidant capacity of edible feijoa (Acca sellowiana (O. Berg) Burret) flower extracts

Abstract

The research aimed to evaluate the polyphenolic composition and the antioxidant capacity of edible extracts of feijoa (Acca sellowiana (O. Berg) Burret) flowers. Phenolic compounds of whole feijoa flower (FM), feijoa petals (PM) and feijoa petals juice (PJ) were identified by high-performance liquid chromatography coupled with electrospray mass spectrometry and quantified by liquid chromatography coupled with ultraviolet/visible detection. Moreover, the total polyphenol (TP) content was measured spectrophotometrically and the antioxidant capacities of the extracts were evaluated by FRAP, CUPRAC, DPPH^·, and ABTS^·+ assays. The FM showed TP content (395.14 ± 7.91 mg GAE/L) higher than PM and PJ, and exhibited better antioxidant capacities. FM extracts were characterized by the high content of anthocyanins (115.3 ± 3.6 mg/L), flavonols (42.9 ± 3.3 mg/L) and the presence of ellagic acid (7.9 ± 0.2 mg/L) and other galloyltannins. In addition, cyanidin-3-O-glucoside and apigenin were detected in all the three extracts. The present study provided an overview on particular bioactive compounds that characterise different parts of edible feijoa flowers. Among the latter, FM proved to be the most suitable for exploitation in the food and health manufactory.

Graphic abstract

Interactions of clinical relevance associated with concurrent administration of prescription drug and food or medicinal plants: a systematic review protocol

BACKGROUND

An inadequate combination of prescription drugs with food or medicinal plants could cause adverse effects in patients or produce negative therapeutic results. Therefore, this generic systematic review protocol aims to identify and synthesize the literature on clinical characteristics and safety issues of these types of pharmacological interactions occurring in children, adolescents, adults, pregnant/lactating women, and older adults.

METHODS/DESIGN

This generic protocol follows the stated guidelines from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) statement. A literature search will be performed in PubMed, Scopus, and Virtual Health Library (VHL) electronic databases from 1960 till present for studies reporting clinical characteristics and safety issues associated with pharmacological interactions occurring between prescription drugs and food or medicinal plants in participants from birth-age to ≥ 65-year-old, including pregnant/lactating women. Lateral searching will be carried out in PubMed via related citation. Two reviewers will carry out an independent evaluation of eligible studies as well as the corresponding data extraction of the selected ones. Subsequently, the methodological quality evaluation of the selected articles will be completed using the corresponding Joanna Briggs Institute Checklists. Moreover, the quality of evidence will be graded according to the criteria of the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) Working Group. Quantitative research in humans comprising clinical trials and clinical, comparative and, observational studies will be included. The main outcomes of this protocol involve reported potential food-drug and herb-drug interactions, associated safety issues, and adverse reactions along with the generic name of the prescribed drug and the scientific name of the food and medicinal plants involved in these types of pharmacological interactions. Finally, findings extracted from the selected studies will be summarized in a narrative synthesis.

DISCUSSION

This generic systematic review protocol seeks to synthesize and critically evaluate current knowledge besides to identify any comprehension gaps in the concurrent administration of prescription drugs with food and herbs. By achieving a better understanding of this topic, this information will allow healthcare professionals to develop useful strategies to recognize, manage, and prevent these types of pharmacological interactions at different age stages, including pregnant/lactating women.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018117308.

Reviewing the mechanisms of natural product-drug interactions involving efflux transporters and metabolic enzymes

The World Health Organization (WHO) and other worldwide health agencies have recently taken initiatives to encourage the use of traditional medicine and/or complementary/alternative medicine in order to promote well-being and public health. In this way, one of the WHO's concerns is the safe use of these therapies. Phytotherapy is a strategy consisting of the use of medicinal plants (MP) and/or herbal medicinal products (HMP) for medicinal purposes. The use of phytotherapy concomitantly with drugs may cause interactions compromising the expected pharmacological action or generating toxic effects. These interactions are complex processes that may occur with multiple medications targeting different metabolic pathways, and involving different compounds present in MP and HMP. Thus, the aim of this review was to summarize the main MP- and HMP-drug interactions that involve specific transporters (P-glycoprotein and BCRP) and CYP450 enzymes (CYP3A4 and CYP2D6), which play relevant roles in the mechanisms of interactions. Firstly, multiple databases were used to search studies describing in vitro or in vivo MP and HMP-drug interactions and, after that, a systematic note-taking and appraisal of the literature was conducted. It was observed that several MP and HMP, metabolic pathways and transcription factors are involved in the transporters and enzymes expression or in the modulation of their activity having the potential to provide such interactions. Thus, the knowledge of MP- and HMP-drug interaction mechanisms could contribute to prevent harmful interactions and can ensure the safe use of these products to help the establishment of the therapeutic planning in order to certify the best treatment strategy to be used.

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.

Rhinacanthin-C Mediated Herb-Drug Interactions with Drug Transporters and Phase I Drug-Metabolizing Enzymes

Rhinacanthin-C is a major active constituent in Rhinacanthus nasutus (L.) Kurz, a plant widely used in herbal remedies. Its potential for pharmacokinetic herb-drug interaction may exist with drug transporters and drug metabolizing enzymes. This study assessed the possibility for rhinacanthin-C-mediated drug interaction by determining its inhibitory effects against major human efflux and influx drug transporters as well as various human cytochrome P450(CYP) isoforms. Rhinacanthin-C demonstrated a moderate permeability through the Caco-2 monolayers [P_{app (AP-to-BL)} = 1.26 × 10^-6 cm/s]. It significantly inhibited transport mediated by both P-glycoprotein (P-gp) (IC₅₀ = 5.20 µM) and breast cancer resistance protein (BCRP) (IC₅₀ = 0.83 µM) across Caco-2 and BCRP-overexpressing Madin-Darby canine kidney II cells (MDCKII) cells. This compound also strongly inhibited uptake mediated by organic anion-transporting polypeptide 1B1 (OATP1B1) (IC₅₀ = 0.70 µM) and OATP1B3 (IC₅₀ = 3.95 µM) in OATP1B-overexpressing HEK cells. In addition to its inhibitory effect on these drug transporters, rhinacanthin-C significantly inhibited multiple human CYP isoforms including CYP2C8 (IC₅₀ = 4.56 µM), 2C9 (IC₅₀ = 1.52 µM), 2C19 (IC₅₀ = 28.40 µM), and 3A4/5 (IC₅₀ = 53 µM for midazolam and IC₅₀ = 81.20 µM for testosterone), but not CYP1A2, 2A6, 2B6, 2D6, and 2E1. These results strongly support a high propensity for rhinacanthin-C as a perpetrator of clinical herb-drug interaction via inhibiting various influx and efflux drug transporters (i.e., P-gp, BCRP, OATP1B1, and OATP1B3) and CYP isoforms (i.e., CYP2C8, CYP2C9, and CYP2C19). Thus, the potential for significant pharmacokinetic herb-drug interaction should be addressed when herbal products containing rhinacanthin-C are to be used in conjunction with other prescription drugs.

The Effect of Tanreqing Injection on the Pharmacokinetics of Sirolimus in Rats

To evaluate the effect of Tanreqing injection on the pharmacokinetics of sirolimus in rats, a high performance liquid chromatography tandem mass spectrometry method was developed for sirolimus assay in whole blood. Calibration curve of sirolimus was acquired over a concentration ranging from 2.5 to 100 ng/mL with r²= 0.9955. The matrix effects and extraction recoveries of sirolimus ranged from 144% to 152% and from 80% to 96%, respectively. The inter- and intraday relative standard deviations were both <10%. The stability investigation showed that the blood samples were stable for 30-day-storage at −20°C, for 8 h storage at room temperature, for 24 h storage in the auto-sampler at 4°C, and for three freeze-thaw cycle process. The pharmacokinetic results demonstrated that the C_max, AUC, and AUMC of sirolimus in rats (7.5 mg/kg, i.g.) were increased after beincoadministration with Tanreqing Injection at 2.5, 5.0, and 7.5 mL/kg (i.v.), respectively, or at 5 min, 2 h, and 4 h (5.0 mL/kg, i.v.) after SRL dosing, respectively. For the first time, the results proved the herb-drug interaction between Tanreqing Injection and sirolimus and accordingly suggested avoiding concurrent reception of those two drugs for patients.

Evidence for the efficacy and safety of herbal weight loss preparations

Rising rates of obesity across the globe have been associated with an increase in the use of herbal preparations for weight control. However, the mechanisms of action for these substances are often not known, as is the potential for interaction with other herbal preparations or prescription pharmaceutical drugs. To investigate the reported efficacy and safety of herbal weight loss preparations, we conducted a review of the literature focusing on herbs that are most commonly used in weight loss preparations, specifically, Garcinia cambogia, Camellia sinensis, Hoodia gordonii, Citrus aurantium and Coleus forskohlii. There was no clear evidence that the above herbal preparations would cause sustained long-term weight loss in humans in the long term. Serious illness and even death have occasionally resulted from the use of herbal weight loss preparations. Few clinical trials have been undertaken to evaluate the efficacy and/or safety of herbal weight loss preparations. In addition, potential issues of herb-herb and herb-drug interactions are often not considered. Regulation of these products is much less rigorous than for prescription medications, despite documented cases of associated hepatotoxicity.

Consumption of plant food supplements in the Netherlands

The use of food supplements containing herbs or other botanical ingredients (plant food supplements, PFS) is on the rise. In some cases, PFS can contain compounds that are toxic and may pose a health risk. To assess the potential health risks, information on the consumption of PFS is required, however, this was lacking for the Netherlands. In the current study, the consumption of PFS was investigated for several subgroups in the Dutch population, including children. Data from the Dutch National Food Consumption Surveys were used to get a first impression on the consumption of PFS. To obtain more detailed information, a specific PFS consumption survey was performed using online questionnaires. First, a screening survey was performed among a representative sample of 75 100 adults and children of the Dutch population, followed by a main survey among 739 selected PFS users in eight different age and gender subgroups. The prevalence of PFS users in the Dutch population was approximately 10% for men, 17% for women and 13% for children. A wide variety of PFS was used, with around 600 different PFS reported, containing 345 different botanicals. The most frequently used botanicals were echinacea (Echinacea purpurea), ginkgo (Ginkgo biloba), cranberry (Vaccinium macrocarpon), ginseng (Panax ginseng) and algae (such as species belonging to the genus Spirulina or Chlorella). Because PFS are widely used in the Dutch population, it is important to evaluate the potential risks associated with PFS consumption in the Netherlands, including potential herb-drug interactions. The data collected in this study are of great value to assess these risks.

Pharmacokinetics of Chinese medicines: strategies and perspectives

The modernization and internationalization of Chinese medicines (CMs) are hampered by increasing concerns on the safety and the efficacy. Pharmacokinetic (PK) study is indispensable to establish concentration-activity/toxicity relationship and facilitate target identification and new drug discovery from CMs. To cope with tremendous challenges rooted from chemical complexity of CMs, the classic PK strategies have evolved rapidly from PK study focusing on marker/main drug components to PK-PD correlation study adopting metabolomics approaches to characterize associations between disposition of global drug-related components and host metabolic network shifts. However, the majority of PK studies of CMs have adopted the approaches tailored for western medicines and focused on the systemic exposures of drug-related components, most of which were found to be too low to account for the holistic benefits of CMs. With an area under concentration-time curve- or activity-weighted approach, integral PK attempts to understand the PK-PD relevance with the integrated PK profile of multiple co-existing structural analogs (prototyes/metabolites). Cellular PK-PD complements traditional PK-PD when drug targets localize inside the cells, instead of at the surface of cell membrane or extracellular space. Considering the validated clinical benefits of CMs, reverse pharmacology-based reverse PK strategy was proposed to facilitate target identification and new drug discovery. Recently, gut microbiota have demonstrated multifaceted roles in drug efficacy/toxicity. In traditional oral intake, the presystemic interactions of CMs with gut microbiota seem inevitable, which can contribute to the holistic benefits of CMs through biotransforming CMs components, acting as the peripheral target, and regulating host drug disposition. Hence, we propose a global PK-PD approach which includes the presystemic interaction of CMs with gut microbiota and combines omics with physiologically based pharmacokinetic modeling to offer a comprehensive understanding of the PK-PD relationship of CMs. Moreover, validated clinical benefits of CMs and poor translational potential of animal PK data urge more research efforts in human PK study.

Alterations in Pharmacokinetics of Gemcitabine and Erlotinib by Concurrent Administration of Hyangsayukgunja-Tang, a Gastroprotective Herbal Medicine

Gemcitabine and erlotinib are the chemotherapeutic agents used in the treatment of various cancers and their combination is being accepted as a first-line treatment of advanced pancreatic cancer. Hyangsayukgunja-tang (HYT) is a traditional oriental medicine used in various digestive disorders and potentially helpful to treat gastrointestinal adverse effects related to chemotherapy. The present study was aimed to evaluate the effect of HYT on the pharmacokinetics of gemcitabine and erlotinib given simultaneously in rats. Rats were pretreated with HYT at an oral dose of 1200 mg/kg/day once daily for a single day or 14 consecutive days. Immediately after pretreatment with HYT, gemcitabine and erlotinib were administered by intravenous injection (10 mg/kg) and oral administration (20 mg/kg), respectively. The effects of HYT on pharmacokinetics of the two drugs were estimated by non-compartmental analysis and pharmacokinetic modeling. The pharmacokinetics of gemcitabine and erlotinib were not altered by single dose HYT pretreatment. However, the plasma levels of OSI-420 and OSI-413, active metabolites of erlotinib, were significantly decreased in the multiple dose HYT pretreatment group. The pharmacokinetic model estimated increased systemic clearances of OSI-420 and OSI-413 by multiple doses of HYT. These data suggest that HYT may affect the elimination of OSI-420 and OSI-413.