Effect of St John's wort and ginseng on the pharmacokinetics and pharmacodynamics of warfarin in healthy subjects

Metabolism and drug interactions of Korean ginseng based on the pharmacokinetic properties of ginsenosides: Current status and future perspectives

Orally administered ginsenosides, the major active components of ginseng, have been shown to be biotransformed into a number of metabolites by gastric juice, digestive and bacterial enzymes in the gastrointestinal tract and also in the liver. Attention is brought to pharmacokinetic studies of ginseng that need further clarification to better understand the safety and possible active mechanism for clinical application. Experimental results demonstrated that ginsenoside metabolites play an important role in the pharmacokinetic properties such as drug metabolizing enzymes and drug transporters, thereby can be applied as a metabolic modulator. Very few are known on the possibility of the consistency of detected ginsenosides with real active metabolites if taken the recommended dose of ginseng, but they have been found to act on the pharmacokinetic key factors in any clinical trial, affecting oral bioavailability. Since ginseng is increasingly being taken in a manner more often associated with prescription medicines, ginseng and drug interactions have been also reviewed. Considering the extensive oral administration of ginseng, the aim of this review is to provide a comprehensive overview and perspectives of recent studies on the pharmacokinetic properties of ginsenosides such as deglycosylation, absorption, metabolizing enzymes and transporters, together with ginsenoside and drug interactions.

Safety Aspects of Herb Interactions: Current Understanding and Future Prospects

BACKGROUND

The use of herbal medicines is on the rise throughout the world due to their perceived safety profile. However, incidences of herb-drug, herb-herb and herb-food interactions considering safety aspects have opened new arenas for discussion.

OBJECTIVE

The current study aims to provide comprehensive insights into the various types of herb interactions, the mechanisms involved, their assessment, and historical developments, keeping herbal safety at the central point of discussion.

METHODS

The authors undertook a focused/targeted literature review and collected data from various databases, including Science Direct, Wiley Online Library, Springer, PubMed, and Google Scholar. Conventional literature on herbal remedies, such as those by the WHO and other international or national organizations.

RESULTS

The article considered reviewing the regulations, interaction mechanisms, and detection of herb-herb, herb-drug and herb-food interactions in commonly used yet vital plants, including Glycyrrhiza glabra, Mentha piperita, Aloe barbadensis, Zingiber officinale, Gingko biloba, Withania somnifera, etc. The study found that healthcare professionals worry about patients not informing them about their herbal prescriptions (primarily used with conventional treatment), which can cause herb-drug/herb-food/herb-herb interactions. These interactions were caused by altered pharmacodynamic and pharmacokinetic processes, which might be explained using in-vivo, in-vitro, in-silico, pharmacogenomics, and pharmacogenetics. Nutrivigilance may be the greatest method to monitor herb-food interactions, but its adoption is limited worldwide.

CONCLUSION

This article can serve as a lead for clinicians, guiding them regarding herb-drug, herb-food, and herb-herb interactions induced by commonly consumed plant species. Patients may also be counseled to avoid conventional drugs, botanicals, and foods with a restricted therapeutic window.

Safety Issues of Herb-Warfarin Interactions

Warfarin is a popular anticoagulant with high global demand. However, studies have underlined serious safety issues when warfarin is consumed concomitantly with herbs or its formulations. This review aimed to highlight the mechanisms behind herb-warfarin interactions while laying special emphasis on its PKPD interactions and evidence on Herb-Warfarin Interaction (HWI) with regards to three different scenarios, such as when warfarin is consumed with herbs, taken as foods or prescribed as medicine, or when used in special situations. A targeted literature methodology involving different scientific databases was adopted for acquiring information on the subject of HWIs. Results of the present study revealed some of the fatal consequences of HWI, including post-operative bleeding, thrombosis, subarachnoid hemorrhage, and subdural hematomas occurring as a result of interactions between warfarin and herbs or commonly associated food products from Hypericum perforatum, Zingiber officinale, Vaccinium oxycoccos, Citrus paradisi, and Punica granatum. In terms of PK-PD parameters, herbs, such as Coptis chinensis Franch. and Phellodendron amurense Rupr., were found to compete with warfarin for binding with plasma proteins, leading to an increase in free warfarin levels in the bloodstream, resulting in its augmented antithrombic effect. Besides, HWIs were also found to decrease International Normalised Ratio (INR) levels following the consumption of Persea americana or avocado. Therefore, there is an urgent need for an up-to-date interaction database to educate patients and healthcare providers on these interactions, besides promoting the adoption of novel technologies, such as natural language processing, by healthcare professionals to guide them in making informed decisions to avoid HWIs.

Effect of High Altitude Environment on Pharmacokinetic and Pharmacodynamic of Warfarin in Rats

BACKGROUND

High altitude environment affects the pharmacokinetic (PK) parameters of drugs and the PK parameters are an important theoretical basis for guiding the rational clinical use of drugs. Warfarin is an oral anticoagulant of the coumarin class commonly used in clinical practice, but it has a narrow therapeutic window and wide individual variation. However, the effect of high altitude environment on PK and pharmacodynamic (PD) of warfarin is unclear.

OBJECTIVE

The objective of this study is to investigate the effect of a high altitude environment on PK and PD of warfarin in rats.

METHOD

Rats were randomly divided into plain group and high altitude group and blood samples were collected through the orbital venous plexus after administration of 2 mg/kg warfarin. Warfarin concentrations in plasma samples were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and PK parameters were calculated by the non-compartment model using WinNonlin 8.1 software. Meanwhile, the expression of PXR, P-gp and CYP2C9 in liver tissues was also determined by western blotting. The effect of high altitude environment on PD of warfarin was explored by measuring activated partial thromboplastin time (APTT) and prothrombin time (PT) values and then calculated international normalized ratio (INR) values based on PT.

RESULTS

Significant changes in PK behaviors and PD of warfarin in high altitude-rats were observed. Compared with the plain-rats, the peak concentration (Cmax) and the area under the plasma concentration-time curve (AUC) increased significantly by 50.9% and 107.46%, respectively. At the same time, high altitude environment significantly inhibited the expression of PXR, P-gp and CYP2C9 in liver tissues. The results of the PD study showed that high altitude environments significantly prolonged PT, APTT and INR values.

CONCLUSION

High altitude environment inhibited the metabolism and increased the absorption of warfarin in rats and increased the effect of anticoagulant effect, suggesting that the optimal dose of warfarin for patients at high altitude should be reassessed.

A model of purchase intention of complementary and alternative medicines: the role of social media influencers' endorsements

BACKGROUND

Social Media Influencers (SMIs) are a fashionable way of marketing products by creating electronic word-of-mouth (e-WOM) on social media. The marketing of complementary and alternative medicines (CAMs) by SMIs is becoming increasingly popular and gaining credibility within consumers on social media platforms. Nonetheless, advising about healthcare products on social media should be examined as it is different from endorsing other kinds of commercial products. The aim of this study is to develop a model that provides the underlying mechanisms of the stimuli of SMIs on social media towards consumers' purchase intention of CAMs.

METHODS

This study used best fit framework synthesis methods to develop the model. A priori theory selection was conducted by identifying a BeHEMoTh strategy (Behavior of Interest, Health context, Exclusions and Models or Theories) to systematically approach identifying relevant models and theories relative to the research aim. Further evidence derived from primary research studies that describe the behavior identified is coded against selected a priori theory to develop the model.

RESULTS

This study presents a novel model for understanding the purchase behavior of CAMs using SMIs as a marketing strategy. The model included two well-known theories (theory of planned behaviour theory and source credibility theory) as well as extensive existing research from a multidisciplinary perspective. The model is exclusively designed to help identify elements affecting perceived source credibility and factors that have an influence over consumers' preferences to purchase CAMs by taking into consideration SMIs' endorsements.

CONCLUSIONS

This study provides unique insights introducing new research areas to health literature and offers, new roles for healthcare professionals in this digital era by gaining new skills and competencies required to provide more credible and accurate information about CAMs. The study also highlights the new marketing era of online health-related product endorsements and recommends that policymakers and researchers carefully evaluate the impact of SMI's on the use of CAMs, as well as to regulate the content of these promotional materials.

Effect of St. John's Wort (Hypericum perforatum L.) on Male Sexual and Reproductive Health: A Narrative Review

BACKGROUND

Hypericum species are widely acknowledged for their biological attributes, with notable attention being paid to Hypericum perforatum, commonly known as St. John's wort (SJW) within the Hypericum section of the Hypericaceae family. This species is among the most thoroughly investigated herbal medicines, particularly in terms of its application in the management of mild to moderate depression. SJW is used to treat depression, menopausal symptoms, attention-deficit hyperactivity disorder (ADHD), somatic symptom disorder, obsessive-compulsive disorder, and skin conditions, such as wounds and muscle pain. However, the usefulness and effectiveness of SJW for male sexual and reproductive health (SRH) are not well known.

OBJECTIVE

To assess the current evidence in the literature on the effect of SJW on male SRH.

METHODS

This narrative review followed a predetermined protocol and used MEDLINE and PubMed to identify articles published in English on the effects of SJW on male SRH. The search used various keywords, such as "Hypericum Perforatum", "St. John's Wort", and terms related to sexual and reproductive health issues. Articles published between the inception of the database and August 2023 were included.

RESULTS

We identified 12 articles published from 1999 to 2019, the majority of which were experimental and conducted on animals. These studies demonstrate variability in terms of design, sample size, type of SJW extract used, the dosage administered, and duration of treatment. Studies have indicated potential sexual dysfunction (SD) due to SJW, which includes reduced libido, delayed ejaculation, delayed orgasm, and erectile dysfunction. Additionally, reproductive toxicity has been suggested, as evidenced by spermicidal effects through the inhibition of sperm motility, abnormal spermatozoa, chromosomal aberrations, and DNA denaturation. Furthermore, some studies have reported potential adverse events during maternal exposure, inhibition of fertilization, and disruption of reproductive parameters.

CONCLUSIONS

Our review suggests that the safety and efficacy of SJW in the treatment of human SRH remain unclear. Further comprehensive, well-designed studies with larger samples, longer exposure periods, and specific dosages are needed to clarify SJW's effects of SJW. Therefore, consultation with healthcare professionals before using herbal remedies or supplements is crucial.

Utility of Therapeutic Drug Monitoring in Identifying Clinically Significant Interactions Between St. John's Wort and Prescription Drugs

BACKGROUND

The general population widely uses herbal medicines, as they are regarded as effective and safe. St. John's wort, which is an effective herbal antidepressant, exhibits both pharmacokinetic and pharmacodynamic interactions with several drugs. The aim of this review was to highlight the clinically significant interactions of St. John's wort with drugs that require to be monitored to assess their therapeutic effect.

METHODS

Published literature was searched using electronic databases, such as MEDLINE, PubMed, and Elsevier ScienceDirect using terms such as "herbal medicine," "herbal toxicity," "legislation herbal medicine," "drug-herb interactions," "St. John's wort," and "St. John's wort-drug interactions." Searches were limited to the English language, and there was no restriction on the date of publication.

RESULTS

St. John's wort exhibits a number of pharmacokinetic and pharmacodynamic interactions with drugs. The most dangerous interactions occurred when used concurrently with the immunosuppressants, cyclosporine, and tacrolimus (treatment failure or organ rejection) or warfarin (treatment failure resulting in thromboembolic events) or antiretroviral agents (treatment failure and the emergence of new viral variants that are resistant to conventional drugs).

CONCLUSIONS

Patients should consult their health care providers before consuming herbal supplements, especially St. John's wort, to avoid potentially dangerous drug-herb interactions.

Dilemmas in the Choice of Adequate Therapeutic Treatment in Patients with Acute Pulmonary Embolism—From Modern Recommendations to Clinical Application

Pulmonary thromboembolism is a very common cardiovascular disease, with a high mortality rate. Despite the clear guidelines, this disease still represents a great challenge both in diagnosis and treatment. The heterogeneous clinical picture, often without pathognomonic signs and symptoms, represents a huge differential diagnostic problem even for experienced doctors. The decisions surrounding this therapeutic regimen also represent a major dilemma in the group of patients who are hemodynamically stable at initial presentation and have signs of right ventricular (RV) dysfunction proven by echocardiography and positive biomarker values (pulmonary embolism of intermediate–high risk). Studies have shown conflicting results about the benefit of using fibrinolytic therapy in this group of patients until hemodynamic decompensation, due to the risk of major bleeding. The latest recommendations give preference to new oral anticoagulants (NOACs) compared to vitamin K antagonists (VKA), except for certain categories of patients (patients with antiphospholipid syndrome, mechanical valves, pregnancy). When using oral anticoagulant therapy, special attention should be paid to drug–drug interactions, which can lead to many complications, even to the death of the patient. Special population groups such as pregnant women, obese patients, patients with antiphospholipid syndrome and the incidence of cancer represent a great therapeutic challenge in the application of anticoagulant therapy. In these patients, not only must the effectiveness of the drugs be taken into account, but great attention must be paid to their safety and possible side effects, which is why a multidisciplinary approach is emphasized in order to provide the best therapeutic option.

Hypericum perforatum: Traditional uses, clinical trials, and drug interactions

Hypericum perforatum (Hypericaceae), known as Saint John’s wort (SJW), has been used in different systems of traditional medicine such as Chinese traditional medicine, Greek traditional medicine, and Islamic traditional medicine. The plant and its active constituents such as hyperforin and hypericin have a wide range of medicinal uses, particularly as anti-depressant, wound-healing, and antibacterial agents. In recent decades, many clinical trials have been performed to investigate the safety and efficacy of this medicinal plant. However, to the best on our knowledge, there is no comprehensive review article in this regard. In the current study, we aim to have a comprehensive review of the clinical trials of SJW to evaluate its efficacy and safety as well as its application in traditional medicine. Clinical studies investigating the safety, interactions, and efficacy of SJW were identified and summarized, including contributions from 2000 until December 2021. According to the results, these clinical studies were divided into three main categories based on the type of disease: psychiatric, endocrine, and skin problems. Important details of the studies, including the type and duration of the study, the type and percentage of the effective compounds or the extract used, the number of patients, and the obtained results were also discussed. In addition, co-administration and drug interaction of SJW with other drugs were summarized. SJW is a valuable medicinal plant, especially for psychiatric disorders. However, precautions should be taken while administrating the plant.

Drug Interactions Affecting Oral Anticoagulant Use

Oral anticoagulants (OACs) are medications commonly used in patients with atrial fibrillation and other cardiovascular conditions. Both warfarin and direct oral anticoagulants are susceptible to drug-drug interactions (DDIs). DDIs are an important cause of adverse drug reactions and exact a large toll on the health care system. DDI for warfarin mainly involve moderate to strong inhibitors/inducers of cytochrome P450 (CYP) 2C9, which is responsible for the elimination of the more potent S-isomer of warfarin. However, inhibitor/inducers of CYP3A4 and CYP1A2 may also cause DDI with warfarin. Recognition of these precipitating agents along with increased frequency of monitoring when these agents are initiated or discontinued will minimize the impact of warfarin DDI. Direct oral anticoagulants are mainly affected by medications strongly affecting the permeability glycoprotein (P-gp), and to a lesser extent, strong CYP3A4 inhibitors/inducers. Dabigatran and edoxaban are affected by P-gp modulation. Strong inducers of CYP3A4 or P-gp should be avoided in all patients taking direct oral anticoagulant unless previously proven to be otherwise safe. Simultaneous strong CYP3A4 and P-gp inhibitors should be avoided in patients taking apixaban and rivaroxaban. Concomitant antiplatelet/anticoagulant use confers additive risk for bleeding, but their combination is unavoidable in many cases. Minimizing duration of concomitant anticoagulant/antiplatelet therapy as indicated by evidence-based clinical guidelines is the best way to reduce the risk of bleeding.

Drug-Drug Interactions With Over-The-Counter Medicines: Mind the Unprescribed

BACKGROUND

This review provides a summary of the currently available clinical data on drug-drug interactions (DDIs) involving over-the-counter (OTC) medicines. It aims to educate and increase awareness among health care providers and to support decisions in daily practice.

METHODS

An extensive literature search was performed using bibliographic databases available through PubMed.gov. An initial structured search was performed using the keywords "drug-drug-interaction AND (over-the-counter OR OTC)," without further restrictions except for the language. The initial results were screened for all described DDIs involving OTC drugs, and further information was gathered specifically on these drugs using dedicated database searches and references found in the bibliography from the initial hits.

RESULTS

From more than 1200 initial hits (1972-June 2021), 408 relevant publications were screened for DDIs involving OTC drugs, leading to 2 major findings: first, certain types of drug regimens are more prone to DDIs or have more serious DDI-related consequences, such as antiretroviral, anti-infective, and oral anticancer therapies. Second, although most DDIs involve OTC drugs as the perpetrators, some prescription drugs (statins or phosphodiesterase-5 inhibitors) that currently have OTC status can be identified as the victims in DDIs. The following groups were identified to be frequently involved in DDIs: nonsteroidal anti-inflammatory drugs, food supplements, antacids, proton-pump inhibitors, H2 antihistamines, laxatives, antidiarrheal drugs, and herbal drugs.

CONCLUSIONS

The most significant finding was the lack of high-quality evidence for commonly acknowledged interactions. High-quality interaction studies involving different phenotypes in drug metabolism (cytochrome P450) and distribution (transporters) are urgently needed. This should include modern and critical drugs, such as oral anticancer medications and direct oral anticoagulants.

Over-The-Counter Remedies in Older Adults: Patterns of Use, Potential Pitfalls, and Proposed Solutions

Over-the-counter (OTC) products such as pharmaceuticals, dietary supplements, vitamins, and herbal remedies are widely available and copiously used by older adults for health maintenance and symptom management. Owing to physiology, multimorbidity, and polypharmacy, this population is particularly vulnerable to inappropriate use of OTC products, adverse effects, and drug interactions. While OTC pharmaceuticals are bound by FDA-approved standards, dietary supplements are regulated differently, resulting in variable quality and increased possibility for adulteration. Internationally, standards for OTC products vary widely. Accessible educational information, improved provider-patient communication, and revision of regulatory policy could improve safety for older adult users of OTC products.

Interaction Between Chinese Medicine and Warfarin: Clinical and Research Update

Background: Warfarin is a commonly used oral anticoagulant. It has a narrow therapeutic window and wide variation in individualized dosing, and is used clinically for the treatment of thromboembolic diseases. Due to the widespread use of traditional Chinese medicine (TCM) in China and the complex composition and diverse mechanisms of action of TCM, the combination of TCM and warfarin in patients has led to fluctuations in the international normalized ratio of warfarin or bleeding. To ensure rational clinical use, we summarize the TCMs with which warfarin interacts and the possible mechanisms, with a view to providing a clinical reference. Aim of the study: To summarize the mechanisms by which Chinese herbal medicines affect the enhancement or weakening of the anticoagulant effect of warfarin, to provide theoretical references for clinicians and pharmacists to use warfarin safely and rationally, and to avoid the adverse effects associated with the combination of Chinese herbal medicines and warfarin. Methods: A computerized literature search of electronic databases, including PubMed, MEDLINE, Cochrane Library, Web of Science (WOS), China National Knowledge Infrastructure (CNKI) and WANFANG Data was performed. Key words used in the literature search were "warfarin", "Chinese medicine", "traditional Chinese medicine", "Chinese patent medicine" etc. and their combinations in a time limit from January 1, 1990 to May 1, 2021. A total of 64 articles were obtained following the selection process, including clinical reports, pharmacological experiments and in vitro experiments which were reviewed to determine the mechanism of the anticoagulant effect of herbal medicine on warfarin. Results: The mechanisms affecting the anticoagulant effect of warfarin are complex, and herbal medicines may enhance and diminish the anticoagulant effect of warfarin through a variety of mechanisms; thus, clinical use needs to be cautious. Some herbal medicines have shown inconsistent results in both in vivo and ex vivo experiments, pharmacology and clinical studies, and should be the focus of future research. Conclusion: With the widespread use of TCM, the combination of warfarin and TCM is more common. This article will promote clinicians' knowledge and understanding of the TCMs which interact with warfarin, in order to avoid the occurrence of adverse clinical treatment processes, and improve the efficacy and safety.

Herb-Drug Interactions: Worlds Intersect with the Patient at the Center

This review examines three bodies of literature related to herb-drug interactions: case reports, clinical studies, evaluations found in six drug interaction checking resources. The aim of the study is to examine the congruity of resources and to assess the degree to which case reports signal for further study. A qualitative review of case reports seeks to determine needs and perspectives of case report authors. Methods: Systematic search of Medline identified clinical studies and case reports of interacting herb-drug combinations. Interacting herb-drug pairs were searched in six drug interaction resources. Case reports were analyzed qualitatively for completeness and to identify underlying themes. Results: Ninety-nine case-report documents detailed 107 cases. Sixty-five clinical studies evaluated 93 mechanisms of interaction relevant to herbs reported in case studies, involving 30 different herbal products; 52.7% of these investigations offered evidence supporting reported reactions. Cohen's kappa found no agreement between any interaction checker and case report corpus. Case reports often lacked full information. Need for further information, attitudes about herbs and herb use, and strategies to reduce risk from interaction were three primary themes in the case report corpus. Conclusions: Reliable herb-drug information is needed, including open and respectful discussion with patients.

Ginsenosides for cardiovascular diseases; update on pre-clinical and clinical evidence, pharmacological effects and the mechanisms of action

Cardiovascular disease (CVD) remains the major cause of death worldwide, accounting for almost 31% of the global mortality annually. Several preclinical studies have indicated that ginseng and the major bioactive ingredient (ginsenosides) can modulate several CVDs through diverse mechanisms. However, there is paucity in the translation of such experiments into clinical arena for cardiovascular ailments due to lack of conclusive specific pathways through which these activities are initiated and lack of larger, long-term well-structured clinical trials. Therefore, this review elaborates on current pharmacological effects of ginseng and ginsenosides in the cardiovascular system and provides some insights into the safety, toxicity, and synergistic effects in human trials. The review concludes that before ginseng, ginsenosides and their preparations could be utilized in the clinical treatment of CVDs, there should be more preclinical studies in larger animals (like the guinea pig, rabbit, dog, and monkey) to find the specific dosages, address the toxicity, safety and synergistic effects with other conventional drugs. This could lead to the initiation of large-scale, long-term well-structured randomized, and placebo-controlled clinical trials to test whether treatment is effective for a longer period and test the efficacy against other conventional therapies.

The potential of drug-herbal interaction among patients with chronic diseases in Saudi Arabia

AIMS

This study aimed to estimate the prevalence of the potential drug-herbal interaction among patients with chronic diseases in Al-Kharj, Saudi Arabia and to explore factors associated with the potential of drug-herbal interaction.

METHOD

A cross-sectional study was conducted through interview-based questionnaire at outpatient clinics in Al-Kharj. The study included patients with chronic diseases who used herbal products.

RESULTS

This study included 336 patients in total. The mean age of participants was 52.4 ± 12.0 years, and their most-used medications were metformin, atorvastatin, and aspirin, while their most-used herbs were ginger (74.7%), mint (72%), and cumin (66.7%). In 310 out of 336 (92.26%) cases, at least one potential drug-herbal interaction was found, and most of these interactions (84%) were moderate.

CONCLUSION

A substantial percentage of potential drug-herbal interactions were found among patients with chronic diseases. Healthcare providers are encouraged to discuss the safety and efficacy of herbal products with their patients.

Inhibition and induction of CYP enzymes in humans: an update

The cytochrome P450 (CYP) enzyme family is the most important enzyme system catalyzing the phase 1 metabolism of pharmaceuticals and other xenobiotics such as herbal remedies and toxic compounds in the environment. The inhibition and induction of CYPs are major mechanisms causing pharmacokinetic drug–drug interactions. This review presents a comprehensive update on the inhibitors and inducers of the specific CYP enzymes in humans. The focus is on the more recent human in vitro and in vivo findings since the publication of our previous review on this topic in 2008. In addition to the general presentation of inhibitory drugs and inducers of human CYP enzymes by drugs, herbal remedies, and toxic compounds, an in-depth view on tyrosine-kinase inhibitors and antiretroviral HIV medications as victims and perpetrators of drug–drug interactions is provided as examples of the current trends in the field. Also, a concise overview of the mechanisms of CYP induction is presented to aid the understanding of the induction phenomena.

A physiologically based pharmacokinetic/pharmacodynamic modeling approach for drug-drug interaction evaluation of warfarin enantiomers with sorafenib

Sorafenib was suggested to cause drug-drug interaction (DDI) with the common anticoagulant, warfarin based on published studies. The inhibition on CYP2C9 enzyme was thought to be the mechanism, but further studies are warranted. Thus, a mechanistic PBPK/PD model for warfarin enantiomers was developed to predict DDI potential with sorafenib, aiming at providing reference for the rational use of both drugs. PBPK models of warfarin enantiomers were constructed by Simcyp software. A mechanistic PK/PD model was built in NONMEM software. PBPK model of sorafenib was fitted via a top-down method. The final PBPK/PD model of warfarin enantiomers was verified and validated by different dosing regimens, ethnicities and genetic polymorphisms, and used to perform DDI simulations between warfarin racemate and sorafenib among general populations and sub-populations with various CYP2C9 and VKORC1 genotypes. Results suggested low DDI risk between warfarin and sorafenib for general populations. Potentially serious consequence was seen for those carrying both CYP2C9 ∗2 and ∗3 and VKORC1 A/A genotypes. This PBPK/PD modeling approach for warfarin enantiomers enabled DDI evaluation with sorafenib. Close monitoring and warfarin dosage adjustment were recommended for patients carrying mutant genotypes. The novel model could be applied to investigate other drugs that may interact with warfarin.

Pharmacokinetic Interactions between Herbal Medicines and Drugs: Their Mechanisms and Clinical Relevance

The therapeutic efficacy of a drug or its unexpected unwanted side effects may depend on the concurrent use of a medicinal plant. In particular, constituents in the medicinal plant extracts may influence drug bioavailability, metabolism and half-life, leading to drug toxicity or failure to obtain a therapeutic response. This narrative review focuses on clinical studies improving knowledge on the ability of selected herbal medicines to influence the pharmacokinetics of co-administered drugs. Moreover, in vitro studies are useful to anticipate potential herbal medicine-drug interactions. In particular, they help to elucidate the cellular target (metabolic or transporter protein) and the mechanism (induction or inhibition) by which a single constituent of the herbal medicine acts. The authors highlight the difficulties in predicting herbal–drug interactions from in vitro data where high concentrations of extracts or their constituents are used and pharmacokinetics are missed. Moreover, the difficulty to compare results from human studies where different kinds of herbal extracts are used is discussed. The herbal medicines discussed are among the best sellers and they are reported in the “Herbal Medicines for Human Use” section of the European Medicinal Agency (EMA).

Warfarin and food, herbal or dietary supplement interactions: A systematic review

AIMS

To present an updated overview on the safety of concurrent use of food, herbal or dietary supplement and warfarin.

METHODS

A systematic literature review was performed on 5 databases from inception up to 31 December 2019. These interactions were classified depending on the likelihood of interaction and supporting evidences.

RESULTS

A total of 149 articles describing 78 herbs, food or dietary supplements were reported to interact with warfarin. These reports described potentiation with 45 (57.7%) herbs, food or dietary supplements while 23 (29.5%) reported inhibition and 10 (12.8%) reported limited impact on warfarin pharmacokinetics and pharmacodynamics. Twenty unique herb and dietary supplements also reported to result in minor bleeding events, such as purpura and gum bleeding as well as major events such as intracranial bleeding that led to death.

CONCLUSION

While most food, herbs and supplements can be safely taken in moderation, healthcare professionals should be aware of the increased risk of bleeding when taking several food and herbs. These include Chinese wolfberry, chamomile tea, cannabis, cranberry, chitosan, green tea, Ginkgo biloba, ginger, spinach, St. John's Wort, sushi and smoking tobacco. Patients should be counselled to continue to seek advice from their healthcare professionals when starting any new herbs, food or supplement.

Ginseng integrative supplementation for seasonal acute upper respiratory infections: A systematic review and meta-analysis

BACKGROUND

The aim of the review was to assess whether ginseng can be a useful supplementation for seasonal acute upper respiratory infections (SAURIs).

METHODS

All clinical studies investigating ginseng efficacy for the treatment or prevention of SAURIs were included in the review. Medline, EMBASE, Web of Science, Scopus, Cochrane Library, Google Scholar were systematically screened for relevant articles up to May 26th, 2020. The risk of bias was assessed with the Cochrane tool (RoB 2).

RESULTS

Nine articles (describing ten trials about P. ginseng or P. quinquefolius) were included in the review. Evidence globally indicated some useful activity of intervention when administered in adjunct to influenza vaccination. The results of our quantitative synthesis suggested a significant effect on SAURIs incidence (RR = 0.69 [95 % C.I. 0.52 to 0.90], p < 0.05), as well as a significant reduction of their duration if only studies with healthy individuals were included in the analysis (MD=-3.11 [95 % C.I.-5.81 to -0.40], p < 0.05). However, the risk of bias was high-to-unclear for most included trials, and publication bias couldn't be excluded.

DISCUSSION

Limitations of existing evidence don't allow to draw conclusions on the topic. Nevertheless, it is not excluded that ginseng supplementation in adjunct to influenza vaccination and standard care might be useful for SAURIs prevention and management in healthy adult subjects, but further high-quality trials are needed to support this hypothesis.

OTHER

This research was not funded. The protocol was registered in PROSPERO under the following code: CRD42020156235.

The effects of ginsenosides on platelet aggregation and vascular intima in the treatment of cardiovascular diseases: From molecular mechanisms to clinical applications

Thrombosis initiated by abnormal platelet aggregation is a pivotal pathological event that precedes most cases of cardiovascular diseases (CVD). Recently, growing evidence indicates that platelet could be a potential target for CVD prevention. However, as the conventional antithrombotic management strategy, applications of current antiplatelet agents are somewhat limited by their various side effects, such as bleeding risk and drug resistance. Hence, efforts have been made to search for agents as complementary therapies. Ginsenoside, the principal active component extracted from Panax ginseng, has gained much attention for its regulations on multiple crucial events of platelet aggregation. From structural characteristics to clinical applications, this review anatomized the intrinsic structure-function relationship of antiplatelet potency of ginsenosides, and the involved signal pathways were specifically summarized. Additionally, the emphasis was placed on clinical studies that investigate the antithrombotic efficacy of ginsenosides in the treatment of CVD. Further, a broad overview of approaches for improving the bioavailability of ginsenosides was concluded. Limitations and prospects of current studies were also discussed. This study may provide some new insights into the systematic understanding of ginsenosides in CVD treatment and lay a foundation for future research.

Medication with caution: Analysis of adverse reactions caused by a combination of Chinese medicine and warfarin sodium tablets

ETHNOPHARMACOLOGICAL RELEVANCE

With the extensive recent use of warfarin and traditional Chinese medicine (TCM) in combination, TCM has been found to affect warfarin's pharmacokinetic and pharmacodynamic parameters. Warfarin is a widely used oral anticoagulant, which has a narrow therapeutic window and a high likelihood of interacting with other drugs and resulting in serious adverse reactions. Contrary to widespread public expectations, TCM, despite being natural, is not always safe.

AIM OF THE STUDY

To report the adverse drug reactions (ADR) resulting from the use of Chinese medicine and warfarin sodium tablets in combination.

METHODS

According to a hospital ADR monitoring report, we collected data on four clinical cases involving warfarin and single Chinese herbal medicine, warfarin and proprietary traditional Chinese medicine product, warfarin and Chinese medicinal injection, and warfarin and compound decoction. The Naranjo ADR score evaluation scale was used to analyze the relationships between warfarin and Chinese medicines.

RESULTS

Fluctuations in the international normalized ratio (INR) were accompanied by bleeding in some patients who regularly and simultaneously utilized warfarin and Chinese medicine. The potential risk of bleeding due to the interaction between TCM and warfarin is easily and often overlooked by both Western and TCM doctors.

CONCLUSIONS

Warfarin in combination with different traditional Chinese herbal medicines poses risks of INR fluctuations and adverse reactions such as bleeding. In the future, the safety awareness regarding reasonable administration of warfarin and herbal medicine should be emphasized.

The Genetics of Warfarin Dose-Response Variability in Africans: An Expert Perspective on Past, Present, and Future

Coumarins such as warfarin are prescribed for prevention and treatment of thromboembolic disorders. Warfarin remains the most widely prescribed and an anticoagulant of choice in Africa. Warfarin use is, however, limited by interindividual variability in pharmacokinetics and a narrow therapeutic index. The difference in patients' pharmacodynamic responses to warfarin has been attributed to genetic variation in warfarin metabolism and molecular targets (e.g., CYP2C9 and VKORC1) and host-environment interactions. This expert review offers a synthesis of human genetics studies in Africans with respect to pharmacogenetics-informed warfarin dosing. We identify areas that need future research attention or could benefit from harnessing existing pharmacogenetics knowledge toward rational and optimal therapeutics with warfarin in African patients. A literature search was conducted until January 2019. A total of 343 articles were retrieved from nine African countries: Botswana, Ethiopia, Egypt, Ghana, Kenya, South Africa, Sudan, Tanzania, and Mozambique. We found 19 studies on genetics of warfarin treatment specifically among Africans. Genes examined included CYP2C9, VKORC1, CYP4F2, APOE, CALU, GGCX, and EPHX1. CYP2C9*2 and *3 alleles were highly frequent among Egyptians, while rare in other African populations. CYP2C9*5, *8, *9, and *11, and VKORC1 Asp36Tyr genetic variants explained warfarin variability in Africans better, compared to CYP2C9*2 and *3. In Africa, there is limited pharmacogenetics data on warfarin. Therefore, future research and funding commitments should be prioritized to ensure safe and effective use of warfarin in Africa. Lessons learned in Africa from the science of pharmacogenetics would inform rational therapeutics in hematology, cardiology, and surgical specialties worldwide.

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.

A study to evaluate herb-drug interaction underlying mechanisms: An investigation of ginsenosides attenuating the effect of warfarin on cardiovascular diseases

Warfarin and ginseng have been widely used in the treatment of cardiovascular diseases. However, the clinical safety and effectiveness of herb-drug combination treatment are still controversial. Therefore, it is very essential to probe the interaction between warfarin and ginseng. In this study, in vitro and in vivo study was carried out to demonstrate that whether there is an interaction between warfarin and ginsenosides (GS), which is the main component of ginseng. In vitro study showed that the adhesion ability between endothelial cells and matrigel/platelets was enhanced due to the up-regulating expression of intercellular adhesion molecule (ICAM-1) and vascular cell adhesion molecule (VCAM-1) proteins by treatment of warfarin+GS combination compared to warfarin/GS treatment alone. Moreover, GS could weaken the anticoagulation effect of warfarin in hyperlipemia rats owning to the increased expression levels of coagulation factors and hepatic cytochrome P450 enzymes in plasma after long-term co-administration of warfarin with GS. The results of both in vitro and in vivo study demonstrated that there is a serious interaction between warfarin and ginseng, which may deteriorate atherosclerosis and thrombosis after combined use of warfarin and GS.

Patient Disclosure of Complementary and Integrative Health Approaches in an Academic Health Center

Background

Effective patient–doctor communication about complementary and integrative health (CIH) is crucial to coordinate multimodal treatment for complex conditions. While rates of patient disclosure of CIH use to physicians have increased in the United States over the last 30 years, many patients still do not disclose these facts. Integrating CIH approaches within academic medical centers may enhance the communication, but this has not been explicitly studied.

Objective

To examine rates of patient disclosure of CIH to physicians and reasons for nondisclosure.

Methods

We surveyed 1177 patients at an academic center’s CIH clinic regarding their CIH use and disclosure of CIH use to their physician.

Results

Of the 1067 who responded to the disclosure questions, 80.1% had discussed their CIH use with their physician, while 19.9% did not. Of those who did not disclose, lack of physician inquiry was reported by 58% as the principal reason.

Discussion

Within an academic center, there is still a need to improve communication about CIH use. Possible strategies might include continued education of both patients and physicians about CIH and communication skills and integration of CIH disclosure into routine patient health questionnaires.

Clinically relevant drug interactions between newer antidepressants and oral anticoagulants

Introduction: This is a review of the drug interactions (DIs) between newer antidepressants and oral anticoagulants (OACs): vitamin K antagonists (VKAs) and direct-acting OACs (DOACs).Areas covered: Articles were obtained from PubMed searches performed for each of the newer antidepressants and oral anticoagulants. The basic pharmacokinetic and pharmacodynamic mechanisms for DIs with these drugs were summarized. Some newer antidepressants are inhibitors of a number of cytochrome P450 (CYP) isoforms and many antidepressants appear to have potential to impair serotonin platelet function and increase bleeding risk.Expert opinion: Clinicians should not forget that the DIs between newer antidepressants and VKAs can be potentially lethal. Among SSRIs, fluoxetine and fluvoxamine appear to be associated with the highest DI risk with warfarin, the most commonly prescribed VKA worldwide. Case reports featuring duloxetine, mirtazapine and trazadone suggested potential for interaction with warfarin. As CYP3A4 is an important metabolic pathway for all DOACs except dabigatran, it appears reasonable to recommend avoiding the co-prescription of fluoxetine and fluvoxamine (weak to moderate CYP3A4 inhibitors) and St John's wort (CYP3A4 inducer). Many package inserts for the newer antidepressants include a warning regarding an increased risk of bleeding events with concomitant use of these agents with OACs.

Interaction between Traditional Chinese Medicine and Anticoagulant/Antiplatelet Drugs

Background:

Traditional Chinese medicine (TCM) has been used for medical purposes since the ancient time and has gradually gained recognition worldwide. Nowadays, patients with thrombus presiding to anticoagulant/ antiplatelet drugs prefer taking TCM. However, an increasing number of studies on herb–drug interactions have been shown. Nevertheless, findings are frequently conflicting and vague. In this review, we discuss the herb–drug interactions between TCM and anticoagulant/antiplatelet drugs to provide guidance on concomitant ingestion with anticoagulant/antiplatelet drugs.

Methods:

We undertook a structured search of medicine and drug databases for peer-reviewed literature using focused review questions.

Results:

Danshen, Ginkgo, Ginger, H. Perforatum, SMY and Puerarin injection had directional regulation effects on the efficacy of anticoagulant drugs by altering the CYPs, pharmacokinetic indexs and hemorheological parameters. H. Perforatum inhibited the efficacy of Clopidogrel by enhancing the CYP3A4 activity and Ginkgo increased the efficacy of Ticlopidine. Additionally, Renshen, the formulae except SMY and injections except Puerarin injection could increase or decrease the efficacy of anticoagulant/antiplatelet drugs via regulating the CYPs, platelet aggregation, hemorheological parameters and others.

Conclusion:

Some cases have reported that TCMs may increase the bleeding risk or has no effect on coagulation when anticoagulant/antiplatelet drugs are concurrently used. However, pharmacokinetic studies have presented either consistent or slightly varying results. So it is difficult to ascertain whether the concurrent use of TCM may increase or reduce the pharmacologic effects of anticoagulant/antiplatelet drugs with adverse reactions. Therefore, herb–drug interactions of TCM and anticoagulant/antiplatelet drugs should be further explored and defined.

Interactions of ginseng with therapeutic drugs

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

Pharmacokinetic Interactions between Cardiovascular Medicines and Plant Products

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

Understanding the relevance of herb-drug interaction studies with special focus on interplays: a prerequisite for integrative medicine

Integrative medicine refers to the blending of conventional and evidence-based complementary medicines and therapies with the aim of using the most appropriate of either or both modalities for ultimate patient benefits. One of the major hurdles for the same is the chances of potential herb–drug interactions (HDIs). These HDIs could be beneficial or harmful, or even fatal; therefore, a thorough understanding of the eventualities of HDIs is essential so that a successful integration of the modern and complementary alternative systems of medicine could be achieved. Here, we summarize all the important points related to HDIs, including types, tools/methods for study, and prediction of the HDIs, along with a special focus on interplays between drug metabolizing enzymes and transporters. In addition, this article covers future perspective, with a focus on background endogenous players of interplays and approaches to predict the drug–disease–herb interactions so as to fetch the desired effects of these interactions.

Critical pharmacokinetic and pharmacodynamic drug-herb interactions in rats between warfarin and pomegranate peel or guava leaves extracts

BACKGROUND

In-depth information of potential drug-herb interactions between warfarin and herbal compounds with suspected anticoagulant blood thinning effects is needed to raise caution of concomitant administration. The current study aimed to investigate the impact of co-administration of pomegranate peel and guava leaves extracts, including their quality markers namely; ellagic acid and quercetin, respectively, on warfarin's in vivo dynamic activity and pharmacokinetic actions, in addition to potential in vitro cytochrome P450 enzymes (CYP) inhibition.

METHODS

Influence of mentioned extracts and their key constituents on warfarin pharmacodynamic and kinetic actions and CYP activity were evaluated. The pharmacodynamic interactions were studied in Sprague Dawley rats through prothrombin time (PT) and International Normalized Ratio (INR) measurements, while pharmacokinetic interactions were detected in vivo using a validated HPLC method. Furthermore, potential involvement in CYP inhibition was also investigated in vitro on isolated primary rat hepatocytes.

RESULTS

Preparations of pomegranate peel guava leaf extract, ellagic acid and quercetin in combination with warfarin were found to exert further significant increase on PT and INR values (p < 0.01) than when used alone (p < 0.05). Pomegranate peel extract showed insignificant effects on warfarin pharmacokinetics (p > 0.05), however, its constituent, namely, ellagic acid significantly increased warfarin Cmax (p < 0.05). Guava leaves extract and quercetin resulted in significant increase in warfarin Cmax when compared to control (p < 0.01). Furthermore, guava leaves extract showed a significant effect on changing the AUC, CL and Vz. Significant reduction in CYP2C8, 2C9, and 3A4 was seen upon concomitant use of warfarin with ellagic acid, guava leaves and quercetin, unlike pomegranate that insignificantly affected CYP activities.

CONCLUSION

All combinations enhanced the anticoagulant activity of warfarin as the results of in vivo and in vitro studies were consistent. The current investigation confirmed serious drug herb interactions between warfarin and pomegranate peel or guava leaf extracts. Such results might conclude a high risk of bleeding from the co-administration of the investigated herbal drugs with warfarin therapy. In addition, the results raise attention to the blood-thinning effects of pomegranate peel and guava leaves when used alone.

Interaction of herbal products with prescribed medications: A systematic review and meta-analysis

Although several studies on pharmacokinetic and/or pharmacodynamic herb-drug interactions (HDI) have been conducted in healthy volunteers, there is large uncertainty on the validity of these studies. A qualitative review and a meta-analysis were performed to establish the clinical evidence of these interaction studies. Out of 4026 screened abstracts, 32 studies were included into the qualitative analysis. The meta-analysis was performed on eleven additional studies. St. John's wort (SJW) significantly decreased the AUC (p < 0.0001) and clearance (p = 0.007) of midazolam. Further subgroup analysis identified age to affect C_max of midazolam (p < 0.01) in the presence of SJW. Echinacea purpurea (EP) significantly increased the clearance of midazolam (p = 0.01). Evidence of publication bias (p > 0.001) was shown on the effect of the herbal products o half-life of midazolam. Green tea (GT) showed significant 85% decrease in plasma concentration of nadolol. The study findings suggest that GT, SJW and EP perpetuate significant interactions with prescribed medications via CYP3A4 or OATP1A2. Our studies show that meta-analyses are important in the area of natural products to provide necessary information on their use in overall medication plans in order to avoid unintended interactions.

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.

Pharmacokinetic drug interactions of the non-vitamin K antagonist oral anticoagulants (NOACs)

The use of warfarin, the most commonly prescribed oral anticoagulant, is being questioned by clinicians worldwide due to warfarin several limitations (a limited therapeutic window and significant variability in dose-response among individuals, in addition to a potential for drug-drug interactions). Therefore, the need for non-vitamin K antagonist oral anticoagulants (NOACs) with a rapid onset of antithrombotic effects and a predictable pharmacokinetic (PK) and pharmacodynamic (PD) profile led to the approval of five new drugs: the direct factor Xa (F-Xa) inhibitors rivaroxaban, apixaban, edoxaban and betrixaban (newly approved by FDA) and the direct thrombin (factor-IIa) inhibitor dabigatran etexilate. The advantages of NOACs over warfarin are a fixed-dosage, the absence of the need for drug monitoring for changes in anti-coagulation and fewer clinically significant PK and PD drug-drug interactions. NOACs exposure will likely be increased by the administration of strong P-glycoprotein (P-gp) and cytochrome P450 (CYP) 3A4-inhibitors and may increase the risk of bleeds. On the contrary, P-gp inducers could significantly decrease the NOACs plasma concentration with an associated reduction in their anticoagulant effects. This manuscript gives an overview of NOACs PK profiles and their drug-drug interactions potential. This is meant to be of help to physicians in choosing the best therapeutic approach for their patients.

A regulatory science viewpoint on botanical-drug interactions

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

Understanding drug interactions with St John's wort (Hypericum perforatum L.): impact of hyperforin content

Objective

The aim of this study was to review herb–drug interaction studies with St John's wort (Hypericum perforatum L.) with a focus on the hyperforin content of the extracts used in these studies.

Methods

PUBMED was systematically searched to identify studies describing pharmacokinetic interactions involving St John's wort. Data on study design and the St John's wort extract or product were gathered to extract hyperforin content and daily dose used in interaction studies.

Key findings

This analysis demonstrates that significant herb–drug interactions (resulting in a substantial change in systemic exposure) with St John's wort products were associated with hyperforin daily dosage. Products that had a daily dose of &lt;1 mg hyperforin were less likely to be associated with major interaction for drugs that were CYP3A4 or p-glycoprotein substrates. Although a risk of interactions cannot be excluded even for low-dose hyperforin St. John's wort extracts, the use of products that result in a dose of not more than 1 mg hyperforin per day is recommended to minimise the risk of interactions.

Conclusions

This review highlights that the significance of herb–drug interactions with St John's wort is influenced by the nature of the herbal medicines product, particularly the hyperforin content.

Evaluation of the Potential for Drug Interactions With Patiromer in Healthy Volunteers

INTRODUCTION

Patiromer is a potassium-binding polymer that is not systemically absorbed; however, it may bind coadministered oral drugs in the gastrointestinal tract, potentially reducing their absorption.

METHODS

Twelve randomized, open-label, 3-period, 3-sequence crossover studies were conducted in healthy volunteers to evaluate the effect of patiromer (perpetrator drug) on absorption and single-dose pharmacokinetics (PK) of drugs (victims) that might be commonly used with patiromer. Subjects received victim drug alone, victim drug administered together with patiromer 25.2 g (highest approved dose), and victim drug administered 3 hours before patiromer 25.2 g. The primary PK endpoints were area under the curve (AUC), extrapolated to infinity (AUC0-∞), and maximum concentration ( Cmax). Results were reported as 90% confidence intervals (CIs) about the geometric mean AUC0-∞ and Cmax ratios with prespecified equivalence limits of 80% to 125%.

RESULTS

Overall, 370 subjects were enrolled, with 365 receiving ≥1 dose of patiromer; 351 subjects completed the studies and all required treatments. When coadministered with patiromer, the 90% CIs for AUC0-∞ remained within 80% to 125% for 9 drugs (amlodipine, cinacalcet, clopidogrel, furosemide, lithium, metoprolol, trimethoprim, verapamil, and warfarin). The AUC0-∞ point estimate ratios for levothyroxine and metformin with patiromer coadministration were ≥80%, with the lower bounds of the 90% CIs at 76.8% and 72.8%, respectively. For ciprofloxacin, the point estimate for AUC0-∞ was 71.5% (90% CI: 65.3-78.4). For 8 of 12 drugs, point estimates for Cmax were ≥80% with patiromer coadministration; for ciprofloxacin, clopidogrel, metformin, and metoprolol, the point estimates were <80%. When patiromer was administered 3 hours after each victim drug, the 90% CIs for AUC0-∞ and Cmax for each drug were within the prespecified 80% to 125% limits.

CONCLUSION

For 9 of the 12 drugs coadministered with patiromer, there were no clinically significant drug-drug interactions. For 3 drugs (ciprofloxacin, levothyroxine, and metformin), a 3-hour separation between patiromer and their administration resulted in no clinically significant drug-drug interactions.

Uncertain Associations of Major Bleeding and Concurrent Use of Antiplatelet Agents and Chinese Medications: A Nested Case-Crossover Study

Despite the evidence that some commonly used Chinese medications (CMs) have antiplatelet/anticoagulant effects, many patients still used antiplatelets combined with CMs. We conducted a nested case-crossover study to examine the associations between the concomitant use of antiplatelets and CMs and major bleeding using population-based health database in Taiwan. Among the cohort of 79,463 outpatients prescribed antiplatelets (e.g., aspirin and clopidogrel) continuously, 1,209 patients hospitalized with new occurring bleeding in 2012 and 2013 were included. Those recruited patients served as their own controls to compare different times of exposure to prespecified CMs (e.g., Asian ginseng and dong quai) and antiplatelet agents. The periods of case, control 1, and control 2 were defined as 1–4 weeks, 6–9 weeks, and 13–16 weeks before hospitalization, respectively. Conditional logistic regression analyses found that concurrent use of antiplatelet drugs with any of the prespecified CMs in the case period might not significantly increase the risks of bleeding over that in the control periods (OR = 1.00, 95% CI 0.51 to 1.95 and OR = 1.13, 95% CI 0.65 to 1.97). The study showed no strong relationships between hospitalization for major bleeding events and concurrent use of antiplatelet drugs with the prespecified CMs.

A systematic review of the pharmacokinetic and pharmacodynamic interactions of herbal medicine with warfarin

Objectives

The aim of this study was to systematically review data regarding pharmacokinetic (PK)-pharmacodynamic (PD) parameters from randomized controlled trials relating to interactions between herbal medicines and warfarin.

Methods

Three electronic databases were searched to identify relevant trials. Two reviewers independently performed the study selection and data extraction. The risk of bias and reporting quality were also assessed independently by two reviewers using the Cochrane risk of bias tool and the consolidated standards of reporting trials (CONSORT). Outcomes were measured for all reported PK-PD parameters and adverse events.

Results

Nine randomized controlled trials met our inclusion criteria. Most of the included studies were unclear regarding the risk of bias and had a low quality of methodology. Using CONSORT, the reporting percentages for the articles ranged from 36.5% to 61.5% and the mean percentage for all articles was 45.6%. St John’s wort and echinacea affected the PK parameters of warfarin. Ginseng, ginger, garlic, and cranberry had no significant effect on the PK parameters. American ginseng altered the PD parameters of warfarin. St John’s wort, ginseng, Korea red ginseng, ginkgo, ginger, garlic, aged garlic, and echincea did not significantly alter the PD parameters. Studies of ginkgo and cranberry showed conflicting results on the PK parameters and PD parameters, respectively. The incidence of adverse events in all trials was low and no major adverse events were reported.

Conclusions

It was difficult to determine whether ten herbal medicines had significant effects on the PK-PD parameters of warfarin. Low quality of evidence, different compounds within and different compositions of the herbs, and methodological limitations of the crossover study, which is a clinical study in which subjects receive a sequence of different interventions, made it difficult to form conclusions. Additional studies that remedy these vulnerabilities are necessary to verify these results.

Therapeutic Risk and Benefits of Concomitantly Using Herbal Medicines and Conventional Medicines: From the Perspectives of Evidence Based on Randomized Controlled Trials and Clinical Risk Management

Despite increased awareness of the potential of herb-drug interactions (HDIs), the lack of rigorous clinical evidence regarding the significance provides a challenge for clinicians and consumers to make rational decisions about the safe combination of herbal and conventional medicines. This review addressed HDIs based on evidence from randomized controlled trials (RCTs). Literature was identified by performing a PubMed search till January 2017. Risk description and clinical risk management were described. Among 74 finally included RCTs, 17 RCTs (22.97%) simply addressed pharmacodynamic HDIs. Fifty-seven RCTs (77.03%) investigated pharmacokinetic HDIs and twenty-eight of them showed potential or actual clinical relevance. The extent of an HDI may be associated with the factors such as pharmacogenomics, dose of active ingredients in herbs, time course of interaction, characteristics of the object drugs (e.g., administration routes and pharmacokinetic profiles), modification of herbal prescription compositions, and coexistence of inducers and inhibitors. Clinical professionals should enhance risk management on HDIs such as increasing awareness of potential changes in therapeutic risk and benefits, inquiring patients about all currently used conventional medicines and herbal medicines and supplements, automatically detecting highly substantial significant HDI by computerized reminder system, selecting the alternatives, adjusting dose, reviewing the appropriateness of physician orders, educating patients to monitor for drug-interaction symptoms, and paying attention to follow-up visit and consultation.

Patients on psychotropic medications and herbal supplement combinations: clinical considerations

Populations using herbs and herbal preparations are widespread and growing. As many herbal ingredients exert actions on psychotropic drug targets, psychiatrists should be well informed and aware of potential drug-drug interactions in clinical practice. Reliable and clinically useful information in this area, however, is fragmented, if not deficient. This paper reviewed the clinical aspects of herb-drug interactions, focusing in particular on the monoamine oxidase enzyme and P450 cytochrome enzyme-inhibitory properties of herbs and their potential interference with psychotropic drug actions and clinical judgement.

The time-dependent effects of St John's wort on cytochrome P450, uridine diphosphate-glucuronosyltransferase, glutathione S-transferase, and NAD(P)H-quinone oxidoreductase in mice

Hypericum perforatum [St. John’s wort (SJW)] is known to cause a drug interaction with the substrates of cytochrome P450 (P450, CYP) isoforms, mainly CYP3A. This study aims to determine the dose response and time course of the effects of SJW extract on P450s, UDP-glucuronosyltransferase (UGT), glutathione S-transferase (GST), and NAD(P)H-quinone oxidoreductase (NQO) in mice. The oral administration of SJW extract to male mice at 0.6 g/kg/d for 21 days increased hepatic oxidation activity toward a Cyp3a substrate nifedipine. By extending the SJW treatment to 28 days, hepatic nifedipine oxidation (NFO) and warfarin 7-hydroxylation (WOH) (Cyp2c) activities were increased by 95% and 34%, respectively. Immunoblot analysis of liver microsomal proteins revealed that the Cyp2c protein level was elevated by the 28-day treatment. However, the liver microsomal activities of the oxidation of the respective substrates of Cyp1a, Cyp2a, Cyp2b, Cyp2d, and Cyp2e1 remained unchanged. In the kidney, SJW increased the NFO, but not the WOH activity. The extended 28-day treatment did not alter mouse hepatic and renal UGT, GST, and NQO activities. These findings demonstrate that SJW stimulates hepatic and renal Cyp3a activity and hepatic Cyp2c activity and expression. The induction of hepatic Cyp2c requires repeated treatment for a period longer than the initial induction of Cyp3a.

Old and new oral anticoagulants: Food, herbal medicines and drug interactions

The most commonly prescribed oral anticoagulants worldwide are the vitamin K antagonists (VKAs) such as warfarin. Factors affecting the pharmacokinetics of VKAs are important because deviations from their narrow therapeutic window can result in bleedings due to over-anticoagulation or thrombosis because of under-anticoagulation. In addition to pharmacodynamic interactions (e.g., augmented bleeding risk for concomitant use of NSAIDs), interactions with drugs, foods, herbs, and over-the-counter medications may affect the risk/benefit ratio of VKAs. Direct oral anticoagulants (DOACs) including Factor Xa inhibitors (rivaroxaban, apixaban and edoxaban) and thrombin inhibitor (dabigatran) are poised to replace warfarin. Phase-3 studies and real-world evaluations have established that the safety profile of DOACs is superior to those of VKAs. However, some pharmacokinetic and pharmacodynamic interactions are expected. Herein we present a critical review of VKAs and DOACs with focus on their potential for interactions with drugs, foods, herbs and over-the-counter medications.