An update on the ability of St. John's wort to affect the metabolism of other drugs

Inhibitors of HIV-1 and Cathepsin L Proteases Identified from the Insect Gall of Hypericum kouytchense

Hypericum kouytchense Lévl is a semi-evergreen plant of the Hypericaceae family. Its roots and seeds have been used in a number of traditional remedies for antipyretic, detoxification, anti-inflammatory, antimicrobial and antiviral functions. However, to date, no bioactivity compounds have been characterized from the insect gall of H. kouytchens. In this study, we evaluated the antiviral activities of different extracts from the insect gall of H. kouytchen against cathepsin L, HIV-1 and renin proteases and identified the active ingredients using UPLC-HRMS. Four different polar extracts (HW, H30, H60 and H85) of the H. kouytchense insect gall exhibited antiviral activities with IC₅₀ values of 10.0, 4.0, 3.2 and 17.0 µg/mL against HIV-1 protease; 210.0, 34.0, 24.0 and 30.0 µg/mL against cathepsin L protease; and 180.0, 65.0, 44.0 and 39.0 µg/mL against human renin, respectively. Ten compounds were identified and quantified in the H. kouytchense insect gall extracts. Epicatechin, eriodictyol and naringenin chalcone were major ingredients in the extracts with contents ranging from 3.9 to 479.2 µg/mg. For HIV-1 protease, seven compounds showed more than 65% inhibition at a concentration of 1000.0 µg/mL, especially for hypericin and naringenin chalcone with IC₅₀ values of 1.8 and 33.0 µg/mL, respectively. However, only hypericin was active against cathepsin L protease with an IC₅₀ value of 17100.0 µg/mL, and its contents were from 0.99 to 11.65 µg/mg. Furthermore, we attempted to pinpoint the interactions between the active compounds and the proteases using molecular docking analysis. Our current results imply that the extracts and active ingredients could be further formulated and/or developed for potential prevention and treatment of HIV or SARS-CoV-2 infections.

Pharmacogenetics and Precision Medicine Approaches for the Improvement of COVID-19 Therapies

Many drugs are being administered to tackle coronavirus disease 2019 (COVID-19) pandemic situations without establishing clinical effectiveness or tailoring safety. A repurposing strategy might be more effective and successful if pharmacogenetic interventions are being considered in future clinical studies/trials. Although it is very unlikely that there are almost no pharmacogenetic data for COVID-19 drugs, however, from inferring the pharmacokinetic (PK)/pharmacodynamic(PD) properties and some pharmacogenetic evidence in other diseases/clinical conditions, it is highly likely that pharmacogenetic associations are also feasible in at least some COVID-19 drugs. We strongly mandate to undertake a pharmacogenetic assessment for at least these drug–gene pairs (atazanavir–UGT1A1, ABCB1, SLCO1B1, APOA5; efavirenz–CYP2B6; nevirapine–HLA, CYP2B6, ABCB1; lopinavir–SLCO1B3, ABCC2; ribavirin–SLC28A2; tocilizumab–FCGR3A; ivermectin–ABCB1; oseltamivir–CES1, ABCB1; clopidogrel–CYP2C19, ABCB1, warfarin–CYP2C9, VKORC1; non-steroidal anti-inflammatory drugs (NSAIDs)–CYP2C9) in COVID-19 patients for advancing precision medicine. Molecular docking and computational studies are promising to achieve new therapeutics against SARS-CoV-2 infection. The current situation in the discovery of anti-SARS-CoV-2 agents at four important targets from in silico studies has been described and summarized in this review. Although natural occurring compounds from different herbs against SARS-CoV-2 infection are favorable, however, accurate experimental investigation of these compounds is warranted to provide insightful information. Moreover, clinical considerations of drug–drug interactions (DDIs) and drug–herb interactions (DHIs) of the existing repurposed drugs along with pharmacogenetic (e.g., efavirenz and CYP2B6) and herbogenetic (e.g., andrographolide and CYP2C9) interventions, collectively called multifactorial drug–gene interactions (DGIs), may further accelerate the development of precision COVID-19 therapies in the real-world clinical settings.

Nanoparticulate Drug Delivery Strategies to Address Intestinal Cytochrome P450 CYP3A4 Metabolism towards Personalized Medicine

Drug dosing in clinical practice, which determines optimal efficacy, toxicity or ineffectiveness, is critical to patients' outcomes. However, many orally administered therapeutic drugs are susceptible to biotransformation by a group of important oxidative enzymes, known as cytochrome P450s (CYPs). In particular, CYP3A4 is a low specificity isoenzyme of the CYPs family, which contributes to the metabolism of approximately 50% of all marketed drugs. Induction or inhibition of CYP3A4 activity results in the varied oral bioavailability and unwanted drug-drug, drug-food, and drug-herb interactions. This review explores the need for addressing intestinal CYP3A4 metabolism and investigates the opportunities to incorporate lipid-based oral drug delivery to enable precise dosing. A variety of lipid- and lipid-polymer hybrid-nanoparticles are highlighted to improve drug bioavailability. These drug carriers are designed to target different intestinal regions, including (1) local saturation or inhibition of CYP3A4 activity at duodenum and proximal jejunum; (2) CYP3A4 bypass via lymphatic absorption; (3) pH-responsive drug release or vitamin-B12 targeted cellular uptake in the distal intestine. Exploitation of lipidic nanosystems not only revives drugs removed from clinical practice due to serious drug-drug interactions, but also provide alternative approaches to reduce pharmacokinetic variability.

Influence of traditional Chinese medicines on the in vivo metabolism of lopinavir/ritonavir based on UHPLC-MS/MS analysis

A fast, reliable, and cost-effective liquid chromatography-tandem mass spectrometry method was established to determine the effects of the traditional Chinese medicine employed to treat coronavirus disease 2019, namely, Lianhua Qingwen granules, Huoxiang Zhengqi capsules, Jinhua Qinggan granules, Shufeng Jiedu capsules, and Angong Niuhuang pills, on the pharmacokinetics of lopinavir/ritonavir in rats. Blood samples were prepared using the protein precipitation method and atazanavir was selected as the internal standard (IS). Separation was performed on an Agilent ZORBAX eclipse plus C₁₈ (2.1 mm × 50 mm, 1.8 μm) column using acetonitrile and water containing 0.1% formic acid as the mobile phase for gradient elution. The flow rate was 0.4 mL/min and the injection volume was 2 μL. Agilent Jet Stream electrospray ionization was used for mass spectrometry detection under positive ion multiple reaction monitoring mode at a transition of m/z 629.3→447.3 for lopinavir, m/z 721.3→296.1 for ritonavir, and m/z 705.4→168.1 for the IS. The method showed good linearity in the concentration range of 25–2500 ng/mL (r=0.9981) for lopinavir and 5–500 ng/mL (r=0.9984) for ritonavir. The intra-day and inter-day precision and accuracy were both within ±15%. Items, such as dilution reliability and residual effect, were also within the acceptable limits. The method was used to determine the effects of five types of traditional Chinese medicines on the pharmacokinetics of lopinavir/ritonavir in rats. The pharmacokinetic results showed that the half-life of ritonavir in the groups administered Lianhua Qingwen granules and Huoxiang Zhengqi capsules combined with lopinavir/ritonavir was prolonged by approximately 1.5- to 2-fold relative to that in the control group. Similarly, the pharmacokinetic parameters of lopinavir were altered. Overall, the results of this study offer important theoretical parameters for the effective clinical use of five types of traditional Chinese medicines combined with lopinavir/ritonavir to reduce the occurrence of clinical adverse reactions.

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In this study, a rapid, reliable and sensitive LC-MS/MS method was established.

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Study the effect of Chinese medicine on pharmacokinetics of lopinavir/ritonavir.

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This study can provide reference for clinical medication.

Current use of rivaroxaban in elderly patients with venous thromboembolism (VTE)

Venous thromboembolism (VTE), which is characterized by pulmonary embolism and deep vein thrombosis, has become a serious public concern. Notably, over half of the patients with VTE are over 70 years of age, but elderly patients are at high risk of anti-coagulation and bleeding, which increase with age. Moreover, risk factors and frailty also show a difference between elderly patients and ordinary patients diagnosed with VTE. Rivaroxaban is a direct inhibitor of activated factor Xa and has the advantage of predictable pharmacodynamics and pharmacokinetics, no coagulation monitoring, and few drug interactions. As a first-line therapy for VTE, this drug is more advantageous than traditional therapy and exhibits good efficacy and safety for ordinary patients. However, the effectiveness and safety of rivaroxaban in elderly patients have not been fully elucidated. This article reviewed the use of rivaroxaban in elderly patients, including drug interactions, monitoring, reversal agents of rivaroxaban, and the use of small dosages of rivaroxaban in elderly patients.

Anti-Tumor Activity of Hypericum perforatum L. and Hyperforin through Modulation of Inflammatory Signaling, ROS Generation and Proton Dynamics

In this paper we review the mechanisms of the antitumor effects of Hypericum perforatum L. (St. John's wort, SJW) and its main active component hyperforin (HPF). SJW extract is commonly employed as antidepressant due to its ability to inhibit monoamine neurotransmitters re-uptake. Moreover, further biological properties make this vegetal extract very suitable for both prevention and treatment of several diseases, including cancer. Regular use of SJW reduces colorectal cancer risk in humans and prevents genotoxic effects of carcinogens in animal models. In established cancer, SJW and HPF can still exert therapeutic effects by their ability to downregulate inflammatory mediators and inhibit pro-survival kinases, angiogenic factors and extracellular matrix proteases, thereby counteracting tumor growth and spread. Remarkably, the mechanisms of action of SJW and HPF include their ability to decrease ROS production and restore pH imbalance in tumor cells. The SJW component HPF, due to its high lipophilicity and mild acidity, accumulates in membranes and acts as a protonophore that hinders inner mitochondrial membrane hyperpolarization, inhibiting mitochondrial ROS generation and consequently tumor cell proliferation. At the plasma membrane level, HPF prevents cytosol alkalization and extracellular acidification by allowing protons to re-enter the cells. These effects can revert or at least attenuate cancer cell phenotype, contributing to hamper proliferation, neo-angiogenesis and metastatic dissemination. Furthermore, several studies report that in tumor cells SJW and HPF, mainly at high concentrations, induce the mitochondrial apoptosis pathway, likely by collapsing the mitochondrial membrane potential. Based on these mechanisms, we highlight the SJW/HPF remarkable potentiality in cancer prevention and treatment.

Effects of Hypericum perforatum (St John's wort) on the pharmacokinetics and pharmacodynamics of rivaroxaban in humans

AIMS

To investigate the influence of a cytochrome P450 CYP3A4 and efflux transporter P-glycoprotein (P-gp) inducing Hypericum perforatum extract on the pharmacokinetics and pharmacodynamics of rivaroxaban.

METHODS

Open-label, nonrandomized, sequential treatment interaction study. Following CYP3A4 and P-gp phenotyping using low-dose midazolam and fexofenadine, 12 healthy volunteers received a single oral dose of 20 mg rivaroxaban and rivaroxaban plasma concentrations and inhibition of the activated coagulation factor X (factor Xa) activity were measured prior to and up to 48 h postdosing. The procedures were repeated after 2 weeks' treatment with the H. perforatum extract.

RESULTS

The geometric mean ratios for the area under the concentration-time curve and C_max of rivaroxaban after/before induction with the H. perforatum extract were 0.76 (90% confidence interval [CI] 0.70, 0.82) and 0.86 (90% CI 0.76, 0.97), respectively. Inhibition of factor Xa activity was reduced with a geometric mean area under the effect-time curve ratio after/before induction of 0.80 (90% CI 0.71, 0.89). No clinically significant differences were found regarding T_max (median 1.5 vs 1 h, P = .26) and terminal elimination half-life (mean 10.6 vs 10.8 h, P = .93) of rivaroxaban. The H. perforatum extract significantly induced CYP3A4 and P-gp activity, as evidenced by phenotyping.

CONCLUSION

The CYP3A4/P-gp inducing H. perforatum extract caused a decrease of rivaroxaban exposure with a proportional decrease of the pharmacodynamic effect. Although the data do not justify a contraindication for the combination or a systematic adjustment of rivaroxaban dosage, avoidance of the combination or laboratory monitoring should be considered in patients taking hyperforin-containing H. perforatum extracts with rivaroxaban.

Interactions between clopidogrel and traditional Chinese medicine

The use of traditional Chinese medicine (TCM) has obtained more and more acceptance all over the world due to its multi-target and multi-level function characteristics. Clopidogrel is a major therapeutic option to reduce atherothrombotic events in patients with acute coronary syndrome, recent myocardial infarction, recent stroke or established peripheral arterial disease. These patients probably take TCM. Are there any interactions between clopidogrel and TCM? Whether TCM will affect the efficacy of clopidogrel or increase the adverse reactions of bleeding? Clarifying this information will help physicians make better use of TCM. A literature search was carried out using Web of Science, PubMed and the Cochrane Library to analyze the pharmacokinetic or pharmacodynamic interactions of clopidogrel and TCM. Some herbs can increase the AUC or C_max of clopidogrel, such as Scutellarin, Danggui, Gegen, Sauchinone and Dengzhan Shengmai capsules. Whereas others can decrease clopidogrel, for example, Ginkgo and Danshen. Furthermore, some herbs can increase the AUC or C_max of clopidogrel active metabolite, including Ginkgo and Xuesaitong tablet. And others can decrease the clopidogrel active metabolite, such as Scutellarin, Danshen, Fufang Danshen Dripping Pill and Dengzhan Shengmai capsules. Additionally, Schisandra chinensis, Danggui, Gegen and Fufang Danshen Dripping Pill can decrease the AUC or C_max of the clopidogrel inactive metabolite, while Curcumin on the contrary. The pharmacodynamics of Panax notoginseng, Notoginsenoside Ft1, Hypericum perforatum, Shexiang baoxin pills, Naoxintong capsule increased the antiplatelet activity compared with clopidogrel alone, while Danshen decreased the platelet inhibition. In adverse reactions, Danggui can enhance the adverse effects of clopidogrel on the bleeding time. With more awareness and understanding on potential drug-herb interactions of clopidogrel and TCM, it may be possible to combine clopidogrel with TCM herbs to yield a better therapeutic outcome.

Herbal Medicines for Irinotecan-Induced Diarrhea

Irinotecan (CPT-11), a water-soluble derivative of camptothecin, belongs to the class of DNA topoisomerase I inhibitors and has been approved worldwide for the treatment of advanced colorectal cancer, lung cancer, and malignant lymphoma. Although CPT-11-based chemotherapy is widely used, severe gastrointestinal (GI) toxicity, especially late-onset diarrhea, is a common adverse reaction, limiting clinical application of the drug. The incidence of grade 3 or 4 diarrhea is high, with 20-40% of CPT-11-treated patients experiencing this adverse effect. High-dose loperamide and octreotide are generally recommended for treatment of CPT-11-induced diarrhea. However, in clinical practice, loperamide is associated with a significant failure rate and the beneficial effects of octreotide are controversial. An accumulating number of recent studies have suggested that medicinal herbs and their derived phytocompounds may be effective complementary treatments for CPT-11-induced diarrhea. In this mini-review, we briefly summarize currently available literatures regarding the formulae and herbs/natural products used as adjuvants in animal and clinical studies for the treatment of diarrhea caused by CPT-11.

No Clinically Relevant Interactions of St. John's Wort Extract Ze 117 Low in Hyperforin With Cytochrome P450 Enzymes and P-glycoprotein

Hypericum perforatum L. (St. John's wort) is used to treat mild-to-moderate depression. Its potential safety risks are pharmacokinetic drug interactions via cytochrome P450 (CYP) enzymes and P-glycoprotein, presumably caused by hyperforin. In a phase I, open-label, nonrandomized, single-sequence study, the low-hyperforin Hypericum extract Ze 117 was investigated using a drug cocktail in 20 healthy volunteers. No pharmacokinetic interactions of Ze 117 were observed for CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP3A4, and P-glycoprotein. Area under the curve (AUC) and peak plasma concentration (C_max ) of the used probe drugs showed 90% confidence intervals (CIs) of the geometric mean ratios of the drugs taken together with Ze 117 vs. probe drug alone, well within the predefined bioequivalence range of 80-125%. Though Ze 117 did not induce dextromethorphan metabolism by CYP2D6, it weakly increased dextromethorphan AUC ratio (mean 147.99, 95% CI 126.32-173.39) but not the corresponding metabolic ratio. Ze 117 does not show clinically relevant pharmacokinetic interactions with important CYPs and P-glycoprotein.

PharmActa: Empowering Patients to Avoid Clinical Significant Drug⁻Herb Interactions

Herbal medicinal products (HMPs) are the subject of increasing interest regarding their benefits for health. However, a serious concern is the potential appearance of clinically significant drug⁻herb interactions in patients. This work provides an overview of drug⁻herb interactions and an evaluation of their clinical significance. We discuss how personalized health services and mobile health applications can utilize tools that provide essential information to patients to avoid drug⁻HMP interactions. There is a specific mention to PharmActa, a dedicated mobile app for personalized pharmaceutical care with information regarding drug⁻HMPs interactions. Several studies over the years have shown that for some HMPs, the potential to present clinically significant interactions is evident, especially for many of the top selling HMPs. Towards that, PharmActa presents how we can improve the way that information regarding potential drug⁻herb interactions can be disseminated to the public. The utilization of technologies focusing on medical information and context awareness introduce a new era in healthcare. The exploitation of eHealth tools and pervasive mobile monitoring technologies in the case of HMPs will allow the citizens to be informed and avoid potential drug⁻HMPs interactions enhancing the effectiveness and ensuring safety for HMPs.

The cytochrome P450 isoenzyme and some new opportunities for the prediction of negative drug interaction in vivo

Cytochrome (CYP) 450 isoenzymes are the basic enzymes involved in Phase I biotransformation. The most important role in biotransformation belongs to CYP3A4, CYP2D6, CYP2C9, CYP2C19 and CYP1A2. Inhibition and induction of CYP isoenzymes caused by drugs are important and clinically relevant pharmacokinetic mechanisms of drug interaction. Investigation of the activity of CYP isoenzymes by using phenotyping methods (such as the determination of the concentration of specific substrates and metabolites in biological fluids) during drug administration provides the prediction of negative side effects caused by drug interaction. In clinical practice, the process of phenotyping of CYP isoenzymes and some endogenous substrates in the ratio of cortisol to 6β-hydroxycortisol in urine for the evaluation of CYP3A4 activity has been deemed to be a quite promising, safe and minimally invasive method for patients nowadays.

Phytotherapeutics: The Emerging Role of Intestinal and Hepatocellular Transporters in Drug Interactions with Botanical Supplements

In herbalism, botanical supplements are commonly believed to be safe remedies, however, botanical supplements and dietary ingredients interact with transport and metabolic processes, affecting drug disposition. Although a large number of studies have described that botanical supplements interfere with drug metabolism, the mode of their interaction with drug transport processes is not well described. Such interactions may result in serious undesired effects and changed drug efficacy, therefore, some studies on interaction between botanical supplement ingredients and drug transporters such as P-gp and OATPs are described here, suggesting that the interaction between botanical supplements and the drug transporters is clinically significant.

Heart Toxicity Related to Herbs and Dietary Supplements: Online Table of Case Reports. Part 4 of 5

BACKGROUND

The purpose of this review was to create an online research summary table of heart toxicity case reports related to dietary supplements (DS; includes herbs).

METHODS

Documented PubMed case reports of DS appearing to contribute to heart-related problems were used to create a "Toxic Table" that summarized the research (1966 to April, 2016, and cross-referencing). Keywords included "herb," "dietary supplement," and cardiac terms. Case reports were excluded if they were herb combinations (some exceptions), Chinese herb mixtures, teas of mixed herb contents, mushrooms, poisonous plants, self-harm (e.g. suicide), excess dose (except vitamins/minerals), drugs or illegal drugs, drug-herbal interactions, and confounders of drugs or diseases. The spectrum of heart toxicities included hypertension, hypotension, hypokalemia, bradycardia, tachycardia, arrhythmia, ventricular fibrillation, heart attack, cardiac arrest, heart failure, and death.

RESULTS

Heart related problems were associated with approximately seven herbs: Four traditional Chinese medicine herbs - Don quai (Angelica sinensis), Jin bu huan (Lycopodium serratum), Thundergod vine or lei gong teng (Tripterygium wilfordii Hook F), and Ting kung teng (Erycibe henryi prain); one an Ayruvedic herb - Aswagandha, (Withania somnifera); and two North American herbs - blue cohosh (Caulophyllum thalictroides), and Yohimbe (Pausinystalia johimbe). Aconitum and Ephedra species are no longer sold in the United States. The DS included, but are not limited to five DS - bitter orange, caffeine, certain energy drinks, nitric oxide products, and a calming product. Six additional DS are no longer sold. Licorice was the food related to heart problems.

CONCLUSION

The online "Toxic Table" forewarns clinicians, consumers and the DS industry by listing DS with case reports related to heart toxicity. It may also contribute to Phase IV post marketing surveillance to diminish adverse events that Government officials use to regulate DS.

Pharmacokinetic interactions of curcuminoids with conventional drugs: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Herb-drug interactions are of great concern in health practices. Curcumin is a natural polyphenol extracted from turmeric, a spice widely used all over the world. Curcumin is clinically used due to its acceptable safety profile and therapeutic efficacy.

AIM OF THE STUDY

Current paper aims to highlight the effect of curcumin on concomitantly used drugs.

METHODS

Electronic databases including PubMed, Scopus and Science Direct were searched with the keywords "curcumin" in the title/abstract and "drug interaction," "drug metabolism," "cytochrome," "P-glycoprotein" and "P450" in the whole text.

RESULTS

Curcumin can induce pharmacokinetic alterations such as changes in C_max and AUC when concomitantly used with pharmacological agents like cardiovascular drugs, antidepressants, anticoagulants, antibiotics, chemotherapeutic agents, and antihistamines. The underlying mechanisms of these interactions include inhibition of cytochrome (CYP) isoenzymes and P-glycoprotein. There is only one clinical trial which proved a significant alteration of conventional drugs in concomitant use with curcumin indicating the need for further human studies.

CONCLUSIONS

Although in vitro and in vivo studies do not provide enough evidence to judge the clinical drug interactions of curcumin, physicians must remain cautious and avoid drug combinations which may lead to curcumin-drug interactions.

Hyperoside protects against chronic mild stress-induced learning and memory deficits

Hyperoside (quercetin-3-O-b-d-galactosidepyranose) is a plant-derived flavonoid mainly found in fruits, fruit juices (most notably flavanols, flavanones, and anthocyanins) and Chinese traditional medicines. It has been applied to relieve pain and improve cardiovascular functions in clinic. However, the effects of hyperoside on cognitive impairment induced by chronic stress and the underlying molecular mechanisms remain unclear. In the current study, we used chronic mild stress (CMS) rats to investigate the effects of hyperoside on learning and memory and further explore the possible mechanisms. Our results demonstrated that hyperoside reduced the escape latency and the swimming distance of CMS rats in Morris water maze test and reversed depressive symptoms in forced swim test (FST) and sucrose preference test. In addition, hyperoside increased the expression of brain-derived neurotrophic factor (BDNF) in hippocampus of CMS rats without influencing the corticosterone (CORT) level in blood plasma. Furthermore, K252a, an inhibitor of the BDNF receptor TrkB, prevented the protective effects of hyperoside on learning and memory in CMS rats. Taken together, these results indicate that hyperoside reverses the cognitive impairment induced by CMS, which is associated with the regulation of BDNF signaling pathway.

Hypericum perforatum (St John's wort) beyond depression: A therapeutic perspective for pain conditions

ETHNOPHARMACOLOGICAL RELEVANCE

Hypericum perforatum L. (Hypericaceae), popularly called St. John's wort (SJW), has a rich historical background being one of the oldest used and most extensively investigated medicinal herbs. Many bioactivities and applications of SJW are listed in popular and in scientific literature, including antibacterial, antiviral, anti-inflammatory. In the last three decades many studies focused on the antidepressant activity of SJW extracts. However, several studies in recent years also described the antinociceptive and analgesic properties of SJW that validate the traditional uses of the plant in pain conditions.

AIM OF THE REVIEW

This review provides up-to-date information on the traditional uses, pre-clinical and clinical evidence on the pain relieving activity of SJW and its active ingredients, and focuses on the possible exploitation of this plant for the management of pain.

MATERIALS AND METHODS

Historical ethnobotanical publications from 1597 were reviewed for finding local and traditional uses. The relevant data on the preclinical and clinical effects of SJW were searched using various databases such as PubMed, Science Direct, Scopus, and Google Scholar. Plant taxonomy was validated by the database Plantlist.org.

RESULTS

Preclinical animal studies demonstrated the ability of low doses of SJW dry extracts (0.3% hypericins; 3-5% hyperforins) to induce antinociception, to relieve from acute and chronic hyperalgesic states and to augment opioid analgesia. Clinical studies (homeopathic remedies, dry extracts) highlighted dental pain conditions as a promising SJW application. In vivo and in vitro studies showed that the main components responsible for the pain relieving activity are hyperforin and hypericin. SJW analgesia appears at low doses (5-100mg/kg), minimizing the risk of herbal-drug interactions produced by hyperforin, a potent inducer of CYP enzymes.

CONCLUSION

Preclinical studies indicate a potential use of SJW in medical pain management. However, clinical research in this field is still scarce and the few studies available on chronic pain produced negative results. Prospective randomized controlled clinical trials performed at low doses are needed to validate its potential efficacy in humans.

Comprehensive assessment of Cucurbitacin E related hepatotoxicity and drug-drug interactions involving CYP3A and P-glycoprotein

BACKGROUND

Cucurbitacin E (CuE), a tetracyclic triterpenoid isolated from Cucurbitaceae, possesses many pharmacological activities especially anti-cancer.

PURPOSE

The aim of this investigation was to comprehensively assess CuE related hepatotoxicity and potential drug-drug interactions involving CYP3A and P-glycoprotein (P-gp).

STUDY DESIGN AND METHODS

Four common cytotoxicity assays (MTS, SRB, NRU and apoptosis assays) were used to evaluate the hepatotoxicity of CuE in human hepatocellular carcinoma HepG2 cells. Human and rat liver microsomes incubation system, Caco-2 transport model and 3D organoids model were used to investigate the effects of CuE on CYP3A and P-gp in vitro. The oral pharmacokinetics of indinavir was employed to evaluate the effects of CuE on CYP3A and P-gp in vivo.

RESULTS

CuE induced the HepG2 apoptosis and exhibited acute cytotoxicity in MTS, SRB, and NRU assays with IC₅₀ value at 15.98µM, 0.31µM, and 1.11µM, respectively. Moreover, CuE not only presented mechanism-based inhibition on human CYP3A4, but also decreased the efflux ratio of digoxin (P-gp substrate) across Caco-2 cell monolayers in vitro. Furthermore, CuE significantly inhibited the transport of Rh123 into 3D organoids, which was caused by the inhibition on P-gp. In Sprague-Dawley rat studies in vivo, acute administration of CuE significantly increased the maximum serum concentration (C_max) and area under the concentration-time curve (AUC) of indinavir. In contrast, CuE treatment for three consecutive days significantly decreased indinavir C_max and AUC in rats.

CONCLUSION

These studies demonstrated that CuE has strong hepatotoxicity, and CuE presents potent inhibition on both CYP3A and P-gp activities in vitro. In animal in vivo studies, CuE induces CYP3A and P-gp after a long-term treatment but inhibits the activities of CYP3A and P-gp after an acute dosing. Therefore, CuE as a dual functional regulator of both CYP3A and P-gp may cause complex drug-drug interactions.

Pharmacokinetic Herb-Drug Interactions: Insight into Mechanisms and Consequences

Herbal medicines are currently in high demand, and their popularity is steadily increasing. Because of their perceived effectiveness, fewer side effects and relatively low cost, they are being used for the management of numerous medical conditions. However, they are capable of affecting the pharmacokinetics and pharmacodynamics of coadministered conventional drugs. These interactions are particularly of clinically relevance when metabolizing enzymes and xenobiotic transporters, which are responsible for the fate of many drugs, are induced or inhibited, sometimes resulting in unexpected outcomes. This article discusses the general use of herbal medicines in the management of several ailments, their concurrent use with conventional therapy, mechanisms underlying herb-drug interactions (HDIs) as well as the drawbacks of herbal remedy use. The authors also suggest means of surveillance and safety monitoring of herbal medicines. Contrary to popular belief that "herbal medicines are totally safe," we are of the view that they are capable of causing significant toxic effects and altered pharmaceutical outcomes when coadministered with conventional medicines. Due to the paucity of information as well as sometimes conflicting reports on HDIs, much more research in this field is needed. The authors further suggest the need to standardize and better regulate herbal medicines in order to ensure their safety and efficacy when used alone or in combination with conventional drugs.

Intestinal and Hepatocellular Transporters: Therapeutic Effects and Drug Interactions of Herbal Supplements

Herbal supplements are generally considered safe; however, drug disposition is influenced by the interactions of herbal supplements and food constituents with transport and metabolic processes. Although the interference of herbal supplements with drug metabolism has been studied extensively, knowledge of how they interact with the drug transport processes is less advanced. Therefore, we describe here specific examples of experimental and human interaction studies of herbal supplement components with drug transporters addressing, for example, organic anion transporting polypeptides or P-glycoprotein, as such interactions may lead to severe side effects and altered drug efficacy. Hence, it is clearly necessary to increase the awareness of the clinical relevance of the interference of herbal supplements with the drug transport processes.

A systematic review of St. John's wort for major depressive disorder

BACKGROUND

This systematic review evaluated St. John's wort (SJW) for the treatment of Major Depressive Disorder (MDD). The objectives of this review are to (1) evaluate the efficacy and safety of SJW in adults with MDD compared to placebo and active comparator and (2) evaluate whether the effects vary by severity of MDD.

METHODS

We searched PubMed, CINAHL, PsycINFO, CENTRAL, Embase, AMED, MANTIS, Web of Science, and ICTRP and existing reviews to November 2014. Two independent reviewers screened the citations, abstracted the data, and assessed the risk of bias. We included randomized controlled trials (RCTs) examining the effect of at least a 4-week administration of SJW on depression outcomes against placebo or active comparator in adults with MDD. Risk of bias was assessed using the Cochrane Risk of Bias tool and USPSTF criteria. Quality of evidence (QoE) was assessed using the GRADE approach.

RESULTS

Thirty-five studies examining 6993 patients met inclusion criteria; eight studies evaluated a hypericum extract that combined 0.3 % hypericin and 1-4 % hyperforin. The herb SJW was associated with more treatment responders than placebo (relative risk [RR] 1.53; 95 % confidence interval [CI] 1.19, 1.97; I(2) 79 %; 18 RCTs; N = 2922, moderate QoE; standardized mean differences [SMD] 0.49; CI 0.23, 0.74; 16 RCTs; I(2) 89 %, N = 2888, moderate QoE). Compared to antidepressants, SJW participants were less likely to experience adverse events (OR 0.67; CI 0.56, 0.81; 11 RCTs; moderate QoE) with no difference in treatment effectiveness (RR 1.01; CI 0.90, 1.14; 17 RCTs, I(2) 52 %, moderate QoE; SMD -0.03; CI -0.21, 0.15; 14 RCTs; I(2) 74 %; N = 2248, moderate QoE) in mild and moderate depression.

CONCLUSIONS

SJW monotherapy for mild and moderate depression is superior to placebo in improving depression symptoms and not significantly different from antidepressant medication. However, evidence of heterogeneity and a lack of research on severe depression reduce the quality of the evidence. Adverse events reported in RCTs were comparable to placebo and fewer compared with antidepressants. However, assessments were limited due to poor reporting of adverse events and studies were not designed to assess rare events. Consequently, the findings should be interpreted with caution.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015016406 .

Liver toxicity related to herbs and dietary supplements: Online table of case reports. Part 2 of 5 series

BACKGROUND

No online current list of potentially life-threatening, hepatotoxic herbs and dietary supplements based on PubMed case reports exists in a summarized tabular form.

METHODS

Documented case reports of herbs or dietary supplements (DS; includes herbs) appearing to contribute to liver injury were used to create an online "DS Toxic Table" of potentially hepatotoxic herbs and dietary supplements (PubMed, 1966 to June, 2016, and cross-referencing). The spectrum of DS induced liver injuries (DSILI) included elevated liver enzymes, hepatitis, steatosis, cholestasis, hepatic necrosis, hepatic fibrosis, hepatic cirrhosis, veno-occlusive disease, acute liver failure requiring a liver transplant, and death.

RESULTS

Over the past 50 years, approximately 21 herbs (minus germander and usnic acid that are no longer sold) and 12 dietary supplements (minus the nine no longer sold and vitamin A & niacin due to excess intake) posed a possible risk for liver injures in certain individuals. The herbs with the most number of reported publications (but not cases studies) in descending order, were germander, black cohosh, kava extract, and green tea extract.

CONCLUSION

These online DS Toxic Tables will contribute to continued Phase IV post marketing surveillance to detect possible liver toxicity cases and serve to forewarn consumers, clinicians, and corporations.

Herbal medicines: challenges in the modern world. Part 2. European Union and Russia

INTRODUCTION

Herbal medicines (HMs) have been well known to people of the European Union (EU) and Russia for centuries. Currently, Western HMs can be classified into two categories, plant-derived conventional medicines and dietary supplements. Interest to HMs has grown rapidly in all countries during the past two decades.

AREAS COVERED

The main goal of this review article is to present the history of HMs in the EU and Russia, forms of modern HMs, including Oriental Medicines that are popular among consumers of both countries. Additional discussion points comprise safety and adulteration issues associated with HMs, including regulatory changes and new legislative measures undertaken by the authorities. Materials available from legislative and governmental websites, PubMed and news media were used. Expert commentary: Due to cultural diversities in the EU and Russia, traditional HMs of other regions, particularly Chinese Traditional and Ayurvedic medicines, are also popular. Recently, dietary supplements containing multiple herbal and other natural products have flooded the EU and Russian markets. Pharmacovigilance in these markets is challenging in terms of establishing quality and safety of ingredients, determining efficacy, and defining risks of herb-herb and herb-drug interactions. Both the EU and Russia have introduced new legislation aimed to overcome these deficiencies.

Intake of St John's wort improves the glucose tolerance in healthy subjects who ingest metformin compared with metformin alone

AIMS

Our objective was to investigate the steady-state pharmacokinetic and pharmacodynamic interaction between the antidepressive herbal medicine St John's wort and the antidiabetic drug metformin.

METHODS

We performed an open cross-over study in 20 healthy male subjects, who received 1 g of metformin twice daily for 1 week with and without 21 days of preceding and concomitant treatment with St John's wort. The pharmacokinetics of metformin was determined, and a 2 h oral glucose tolerance test was performed.

RESULTS

St John's wort decreased the renal clearance of metformin but did not affect any other metformin pharmacokinetic parameter. The addition of St John's wort decreased the area under the glucose concentration-time curve [702 (95% confidence interval, 643-761) vs. 629 min*mmol/L (95% confidence interval, 568-690), P = 0.003], and this effect was caused by a statistically significant increase in the acute insulin response.

CONCLUSIONS

St John's wort improves glucose tolerance by enhancing insulin secretion independently of insulin sensitivity in healthy male subjects taking metformin.

Interactions between CYP3A4 and Dietary Polyphenols

The human cytochrome P450 enzymes (P450s) catalyze oxidative reactions of a broad spectrum of substrates and play a critical role in the metabolism of xenobiotics, such as drugs and dietary compounds. CYP3A4 is known to be the main enzyme involved in the metabolism of drugs and most other xenobiotics. Dietary compounds, of which polyphenolics are the most studied, have been shown to interact with CYP3A4 and alter its expression and activity. Traditionally, the liver was considered the prime site of CYP3A-mediated first-pass metabolic extraction, but in vitro and in vivo studies now suggest that the small intestine can be of equal or even greater importance for the metabolism of polyphenolics and drugs. Recent studies have pointed to the role of gut microbiota in the metabolic fate of polyphenolics in human, suggesting their involvement in the complex interactions between dietary polyphenols and CYP3A4. Last but not least, all the above suggests that coadministration of drugs and foods that are rich in polyphenols is expected to stimulate undesirable clinical consequences. This review focuses on interactions between dietary polyphenols and CYP3A4 as they relate to structural considerations, food-drug interactions, and potential negative consequences of interactions between CYP3A4 and polyphenols.

Natural products-friends or foes?

A trend in the general population has been observed in recent years regarding the orientation toward preventive measures in health; in this context the increased interest from the users and researchers concerning the active effect of food supplements on the health state and on longevity, is noticeable. All over the world, the consumption of natural foods and of vegetal supplements has increased spectacularly over the last 5-10 years. The decreased prevalence of cardio-vascular diseases associated with Mediterranean diet, as well as the French paradox convinced researchers to scientifically document the beneficial outcomes pointed out by traditional use of plants, and to try to develop supplements that would have the same positive effects as these noticed for diet components. The intense research dedicated to this topic revealed the fact that food supplements are linked to some problematic aspects, such as toxicological side effects when associated with classical synthetic drugs. The food supplement-drug interactions are submitted to complex issues regarding pharmacokinetic interactions leading to changes in absorption, distribution, metabolism and excretion processes with direct impact on effect and toxicological potential. The present review based on recent literature aims at discussing the food-drug interactions with direct impact on efficacy and toxicity of drugs.

Oral contraception

Oral contraception (OC) remains a popular noninvasive, readily reversible approach for pregnancy prevention and, largely off label, for control of acne, hirsutism, dysmenorrhea, irregular menstruation, menorrhagia, and other menstrual-related symptoms. Many OC formulations exist, with generics offering lower cost and comparable efficacy. Certain medical conditions, including hypertension, migraine, breast cancer, and risk of venous thromboembolism (VTE), present contraindications. Blood pressure measurement is the only physical examination or testing needed before prescription. Although no OC is clearly superior to others, OCs containing the second-generation progestin levonorgestrel have been associated with lower VTE risk than those containing other progestins.

In vivo and in vitro metabolites from the main diester and monoester diterpenoid alkaloids in a traditional chinese herb, the aconitum species

Diester diterpenoid alkaloids (DDAs), such as aconitine (AC), mesaconitine (MA), and hypaconitine (HA), are both pharmacologically active compounds and toxic ingredients in a traditional Chinese herb, the Aconitum species. Many DDA metabolism studies have been performed to explore mechanisms for reducing toxicity in these compounds and in Aconitum species extracts for safe clinical administration. In this review, we summarize recent progress on the metabolism of toxic AC, MA, and HA and corresponding monoester diterpenoid alkaloids (MDAs) in the gastrointestinal tract and liver in different animal species and humans in vivo and/or in vitro, where these alkaloids are primarily metabolized by cytochrome P450 enzymes, carboxylesterases, and intestinal bacteria, which produces phase I metabolites, ester hydrolysed products, and lipoalkaloids. Furthermore, we classify metabolites detected in the blood and urine, where the aforementioned metabolites are absorbed and excreted. Less toxic MDAs and nontoxic alcohol amines are the primary DDA metabolites detected in the blood. Most other DDAs metabolites produced in the intestine and liver detected in the urine have not been reported in the blood. We propose an explanation for this nonconformity. Finally, taking AC, for instance, we generalize a process of toxicity reduction in the body after oral AC administration for the first time.

Size and surface modification of amorphous silica particles determine their effects on the activity of human CYP3A4 in vitro

Because of their useful chemical and physical properties, nanomaterials are widely used around the world - for example, as additives in food and medicines - and such uses are expected to become more prevalent in the future. Therefore, collecting information about the effects of nanomaterials on metabolic enzymes is important. Here, we examined the effects of amorphous silica particles with various sizes and surface modifications on cytochrome P450 3A4 (CYP3A4) activity by means of two different in vitro assays. Silica nanoparticles with diameters of 30 and 70 nm (nSP30 and nSP70, respectively) tended to inhibit CYP3A4 activity in human liver microsomes (HLMs), but the inhibitory activity of both types of nanoparticles was decreased by carboxyl modification. In contrast, amine-modified nSP70 activated CYP3A4 activity. In HepG2 cells, nSP30 inhibited CYP3A4 activity more strongly than the larger silica particles did. Taken together, these results suggest that the size and surface characteristics of the silica particles determined their effects on CYP3A4 activity and that it may be possible to develop silica particles that do not have undesirable effects on metabolic enzymes by altering their size and surface characteristics.

Understanding the role of adjunctive nonpharmacological therapies in management of the multiple pathways to depression

Major depressive disorder (MDD) is a common disorder with a lifetime prevalence of 16.2% and the fourth highest cause of disability globally. It is hypothesized to be a syndromatic manifestation of multiple pathological processes leading to similar clinical manifestation. MDD is associated with at least three categories of peripheral hormone-type factors including neurotrophic factors, proinflammatory cytokines, and processes that impair regulation of the hypothalamic-pituitary-adrenocortical axis. Neuroimaging studies have identified functional abnormalities including subcortical systems associated with reward and emotion processing, medial prefrontal and anterior cingulate cortical regions and the lateral prefrontal cortical systems involved in cognitive control and voluntary emotion regulation. Studies investigating the effects of psychotherapy and pharmacotherapy on functional brain measures show normalization of brain function with return to euthymia. Nevertheless, approximately 50% of patients with MDD will not respond sufficiently and 60 to 70% will not achieve full remission with first-line pharmacotherapy, therefore clinicians strive to improve patient responses through the use of adjunct therapies. This review discusses recent research in the various biological processes associated with MDD as well as recent data in support of the use of adjunctive non-pharmacological therapies including psychotherapy, bibliotherapy, Internet therapy, "natural" or herbal approaches, exercise therapy, and somatic therapies.

Effect of honokiol on the induction of drug-metabolizing enzymes in human hepatocytes

Honokiol, 2-(4-hydroxy-3-prop-2-enyl-phenyl)-4-prop-2-enyl-phenol, an active component of Magnolia officinalis and Magnolia grandiflora, exerts various pharmacological activities such as antitumorigenic, antioxidative, anti-inflammatory, neurotrophic, and antithrombotic effects. To investigate whether honokiol acts as a perpetrator in drug interactions, messenger ribonucleic acid (mRNA) levels of phase I and II drug-metabolizing enzymes, including cytochrome P450 (CYP), UDP-glucuronosyltransferase (UGT), and sulfotransferase 2A1 (SULT2A1), were analyzed by real-time reverse transcription polymerase chain reaction following 48-hour honokiol exposure in three independent cryopreserved human hepatocyte cultures. Honokiol treatment at the highest concentration tested (50 μM) increased the CYP2B6 mRNA level and CYP2B6-catalyzed bupropion hydroxylase activity more than two-fold in three different hepatocyte cultures, indicating that honokiol induces CYP2B6 at higher concentrations. However, honokiol treatment (0.5–50 μM) did not significantly alter the mRNA levels of phase I enzymes (CYP1A2, CYP3A4, CYP2C8, CYP2C9, and CYP2C19) or phase II enzymes (UGT1A1, UGT1A4, UGT1A9, UGT2B7, and SULT2A1) in cryopreserved human hepatocyte cultures. CYP1A2-catalyzed phenacetin O-deethylase and CYP3A4-catalyzed midazolam 1′-hydroxylase activities were not affected by 48-hour honokiol treatment in cryopreserved human hepatocytes. These results indicate that honokiol is a weak CYP2B6 inducer and is unlikely to increase the metabolism of concomitant CYP2B6 substrates and cause pharmacokinetic-based drug interactions in humans.

Influence of Panax ginseng on the steady state pharmacokinetic profile of lopinavir-ritonavir in healthy volunteers

STUDY OBJECTIVE

Panax ginseng has been shown in preclinical studies to modulate cytochrome P450 enzymes involved in the metabolism of HIV protease inhibitors. Therefore, the purpose of this study was to determine the influence of P. ginseng on the pharmacokinetics of the HIV protease inhibitor combination lopinavir-ritonavir (LPV-r) in healthy volunteers.

DESIGN

Single-sequence, open-label, single-center pharmacokinetic investigation.

SETTING

Government health care facility.

SUBJECTS

Twelve healthy human volunteers.

MEASUREMENTS AND MAIN RESULTS

Twelve healthy volunteers received LPV-r (400-100 mg) twice/day for 29.5 days. On day 15 of LPV-r administration, serial blood samples were collected over 12 hours for determination of lopinavir and ritonavir concentrations. On study day 16, subjects began taking P. ginseng 500 mg twice/day, which they continued for 2 weeks in combination with LPV-r. On day 30 of LPV-r administration, serial blood samples were again collected over 12 hours for determination of lopinavir and ritonavir concentrations. Lopinavir and ritonavir pharmacokinetic parameter values were determined using noncompartmental methods, and preadministration and postadministration ginseng values were compared using a Student t test, where p<0.05 was accepted as statistically significant.

CONCLUSION

Neither lopinavir nor ritonavir steady-state pharmacokinetics were altered by 2 weeks of P. ginseng administration to healthy human volunteers. Thus, a clinically significant interaction between P. ginseng and LPV-r is unlikely to occur in HIV-infected patients who choose to take these agents concurrently. It is also unlikely that P. ginseng will interact with other ritonavir-boosted protease inhibitor combinations, although confirmatory data are necessary.

Can valproic acid be an inducer of clozapine metabolism?

INTRODUCTION

Prior clozapine studies indicated no effects, mild inhibition or induction of valproic acid (VPA) on clozapine metabolism. The hypotheses that (i) VPA is a net inducer of clozapine metabolism, and (ii) smoking modifies this inductive effect were tested in a therapeutic drug monitoring study.

METHODS

After excluding strong inhibitors and inducers, 353 steady-state total clozapine (clozapine plus norclozapine) concentrations provided by 151 patients were analyzed using a random intercept linear model.

RESULTS

VPA appeared to be an inducer of clozapine metabolism since total plasma clozapine concentrations in subjects taking VPA were significantly lower (27% lower; 95% confidence interval, 14-39%) after controlling for confounding variables including smoking (35% lower, 28-56%).

DISCUSSION

Prospective studies are needed to definitively establish that VPA may (i) be an inducer of clozapine metabolism when induction prevails over competitive inhibition, and (ii) be an inducer even in smokers who are under the influence of smoking inductive effects on clozapine metabolism.

Therapeutic targeting of CPT-11 induced diarrhea: a case for prophylaxis

CPT-11 (irinotecan), a DNA topoisomerase I inhibitor is one of the main treatments for colorectal cancer. The main dose limiting toxicities are neutropenia and late onset diarrhea. Though neutropenia is manageable, CPT-11 induced diarrhea is frequently severe, resulting in hospitalizations, dose reductions or omissions leading to ineffective treatment administration. Many potential agents have been tested in preclinical and clinical studies to prevent or ameliorate CPT-11 induced late onset diarrhea. It is predicted that prophylaxis of CPT-11 induced diarrhea will reduce sub-therapeutic dosing as well as hospitalizations and will eventually lead to dose escalations resulting in better response rates. This article reviews various experimental agents and strategies employed to prevent this debilitating toxicity. Covered topics include schedule/dose modification, intestinal alkalization, structural/chemical modification, genetic testing, anti-diarrheal therapies, transporter (ABCB1, ABCC2, BCRP2) inhibitors, enzyme (β-glucuronidase, UGT1A1, CYP3A4, carboxylesterase, COX-2) inducers and inhibitors, probiotics, antibiotics, adsorbing agents, cytokine and growth factor activators and inhibitors and other miscellaneous agents.

Toxicological and pharmacological concerns on oxidative stress and related diseases

Although reactive oxygen species (ROS) such as superoxide, hydrogen peroxide and hydroxyl radical are generated as the natural byproduct of normal oxygen metabolism, they can create oxidative damage via interaction with bio-molecules. The role of oxidative stress as a remarkable upstream part is frequently reported in the signaling cascade of inflammation as well as chemo attractant production. Even though hydrogen peroxide can control cell signaling and stimulate cell proliferation at low levels, in higher concentrations it can initiate apoptosis and in very high levels may create necrosis. So far, the role of ROS in cellular damage and death is well documented with implicating in a broad range of degenerative alterations e.g. carcinogenesis, aging and other oxidative stress related diseases (OSRDs). Reversely, it is cleared that antioxidants are potentially able to suppress (at least in part) the immune system and to enhance the normal cellular protective responses to tissue damage. In this review, we aimed to provide insights on diverse OSRDs, which are correlated with the concept of oxidative stress as well as its cellular effects that can be inhibited by antioxidants. Resveratrol, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, statins, nebivolol and carvedilol, pentaerythritol tetranitrate, mitochondria-targeted antioxidants, and plant-derived drugs (alone or combined) are the potential medicines that can be used to control OSRD.

Hypericum perforatum: pharmacokinetic, mechanism of action, tolerability, and clinical drug-drug interactions

Hypericum perforatum (HP) belongs to the Hypericaceae family and is one of the oldest used and most extensively investigated medicinal herbs. The medicinal form comprises the leaves and flowering tops of which the primary ingredients of interest are naphthodianthrones, xanthones, flavonoids, phloroglucinols (e.g. hyperforin), and hypericin. Although several constituents elicit pharmacological effects that are consistent with HP's antidepressant activity, no single mechanism of action underlying these effects has thus far been found. Various clinical trials have shown that HP has a comparable antidepressant efficacy as some currently used antidepressant drugs in the treatment of mild/moderate depression. Interestingly, low-hyperforin-content preparations are effective in the treatment of depression. Moreover, HP is also used to treat certain forms of anxiety. However, HP can induce various cytochrome P450s isozymes and/or P-glycoprotein, of which many drugs are substrates and which are the main origin of HP-drug interactions. Here, we analyse the existing evidence describing the clinical consequence of HP-drug interactions. Although some of the reported interactions are based on findings from in vitro studies, the clinical importance of which remain to be demonstrated, others are based on case reports where causality can, in some cases, be determined to reveal clinically significant interactions that suggest caution, consideration, and disclosure of potential interactions prior to informed use of HP.