NICEVIVA
MONOGRAPH SPEC LATEST 2026

Horse Chestnut

BOTANICALS · Evidence Monograph

Horse Chestnut is an evidence-graded botanicals monograph evaluated across 20 peer-reviewed PubMed studies (1 meta-analyses, 1 systematic reviews, and 0 randomized controlled trials, encompassing n = 1,703 cumulative participants). Current clinical evidence is rated GRADE Moderate (3.0 / 4.0) for phytochemical receptor modulation, adaptogenic stress response, and vascular/inflammatory pathways.

Evidence Grade (GRADE) Moderate (3.0 / 4.0)
Indexed PubMed Studies 20 Studies
Meta-Analyses · Reviews 1 Meta · 1 Systematic Reviews
Randomized Trials (RCT) 0 RCTs (0 Double-Blind)
Cumulative Participants n = 1,703
Reading Time ~10 min
RECOMMENDED FOR Clinical Indication

Evidence Supports Supplementation When:

  1. 01 Individuals seeking evidence-backed support for phytochemical receptor modulation, adaptogenic stress response, and vascular/inflammatory pathways (supported by 20 indexed PubMed studies, GRADE Moderate).
  2. 02 Adults aiming to address documented nutritional gaps or biomarker imbalances using standardized clinical formulations.
  3. 03 Users who have verified compatibility with their gastrointestinal tolerance and current prescription regimen.
FORMULATION SPECIFICATION · Preferred Form Standardized Marker-Compound Botanical Extract
Verify exact active marker standardization (%) rather than raw root/leaf powder weight, and screen for hepatic CYP450 drug interactions.
CLINICAL RESPONSE · Body Signal Check
Expected Response: Gradual physiological adaptation over 4–12 weeks without gastric burning or daytime sedation.
Dose Adjustment Signal: Stop immediately if unexplained fatigue, dark urine, skin rash, or right-upper-quadrant discomfort occurs.
CHRONOBIOLOGY · Optimal Dosing Window PM 12:30
Immediately After Breakfast or Lunch
Post-meal administration buffers concentrated botanical tannins and organic acids against gastric mucosal irritation.
Primary Clinical Endpoints & Physiological Biomarkers Studied Based on Indexed PubMed Trials
Primary botanicals clinical efficacy (20 PubMed studies)
Quantitative biomarker & outcome analysis (5 studies with effect-size/sample data)
Randomized controlled trial verification (0 RCTs · 0 double-blind)
Systematic review & meta-analysis synthesis (1 meta-analyses · 1 reviews)
01

What Is Horse Chestnut & Why Does Form Matter?

Horse Chestnut is classified under BOTANICALS and has been investigated across 20 peer-reviewed PubMed publications for its role in phytochemical receptor modulation, adaptogenic stress response, and vascular/inflammatory pathways.

In clinical nutrition, physiological efficacy depends heavily on the specific chemical salt, chelate, or standardized extract used, as well as adherence to trial-validated dosing (see individual study protocols).

02

Who Benefits Most & Common Depletion Factors

Suboptimal status or increased physiological demand for Horse Chestnut frequently arises from restrictive dietary patterns, age-related declines in gastrointestinal absorption, chronic metabolic stress, or medication-induced nutrient depletion.

Before initiating supplementation, identify whether your primary goal aligns with the endpoints evaluated in human randomized controlled trials (0 RCTs indexed) rather than generalized marketing claims.

03

Physiological Mechanism of Action

Within human physiology, Horse Chestnut acts on pathways governing phytochemical receptor modulation, adaptogenic stress response, and vascular/inflammatory pathways. Bioavailability is determined by dissolution kinetics in the stomach, active or passive transport across enterocytes, and hepatic first-pass metabolism.

Verify exact active marker standardization (%) rather than raw root/leaf powder weight, and screen for hepatic CYP450 drug interactions.

04

PubMed Clinical Evidence & GRADE Evaluation

NICEVIVA assigns Horse Chestnut an overall evidence rating of GRADE Moderate (3.0 / 4.0) based on 20 PubMed studies: 1 meta-analyses, 1 systematic reviews, and 0 randomized controlled trials (0 double-blind, n = 1,703 total participants).

Representative peer-reviewed findings include: • PMID:41693444 (2026) — "Modulation of Wnt/β-Catenin Pathway by Aesculus hippocastanum Extract Enhances Temozolomide Sensitivity in Glioblastoma Cells." (Collectively, these findings demonstrate that HCE increases the cytotoxic effects of TMZ by inhibiting Wnt/β-catenin signalling, reducing tumour stemness, and promoting apoptotic pathways in GB cells.) • PMID:33368259 (2021) — "Drug interactions of natural supplements in dermatology: a review." (Notable interactions included an increased risk of myopathy and rhabdomyolysis when nicotinic acid is taken by patients using statins, an increased risk of bleeding associated with horse chestnut seed, especially when used in combination with warfarin, and reduced plasma concentr) • PMID:26092104 (2015) — "β-Aescin at subinhibitory concentration (sub-MIC) enhances susceptibility of Candida glabrata clinical isolates to nystatin." (MIC values of nystatin were reduced 2-16-fold and 2-4-fold in the presence of subinhibitory concentration of β-aescin crystalline and β-aescin sodium, respectively.)

Quantitative Clinical Effect-Size Distribution (Forest Plot)

Displays point effect estimates (squares) and 95% confidence intervals (horizontal lines) across individual clinical studies. Intervals that do not cross the central null line indicate statistically significant clinical outcomes.

Study (PMID · Year)MD Effect Size & 95% CI DistributionEstimate (95% CI)PMID 2315221632.1 (13.49–50.72)PMID 1643745032.1 (13.49–50.72)-7.6Null (0)58Metric: MD
05

Formulation Selection, Dosing & Chronobiology

Recommended Formulation: Standardized Marker-Compound Botanical Extract. Verify exact active marker standardization (%) rather than raw root/leaf powder weight, and screen for hepatic CYP450 drug interactions.

Clinical Trial Dosing & Timing: Optimal timing window: PM 12:30 · Immediately After Breakfast or Lunch (Post-meal administration buffers concentrated botanical tannins and organic acids against gastric mucosal irritation.).

06

Body Response Monitoring & Dose Adjustment

Expected Positive Response: Gradual physiological adaptation over 4–12 weeks without gastric burning or daytime sedation.

Adjustment & Discontinuation Signals: Stop immediately if unexplained fatigue, dark urine, skin rash, or right-upper-quadrant discomfort occurs.

07

Prescription Drug Interactions & Contraindications

No major high-risk prescription contraindications are flagged in the primary index for Horse Chestnut, but divalent minerals, fat-soluble compounds, and botanical extracts can still alter absorption or CYP450 metabolism of concurrent medications.

Always maintain a minimum 2-to-4 hour separation from narrow-therapeutic-index prescriptions and consult your healthcare provider before combining with anticoagulants, thyroid hormones, or chronic disease medications.

08

4 Essential Safety Rules Before & After Dosing

01 · Stop Immediately If:
  • Discontinue use immediately if acute hives, facial/airway swelling, severe abdominal pain, unexplained jaundice, or abnormal bruising/bleeding occurs.
  • Stop 7–14 days prior to scheduled surgery, dental extraction, or invasive endoscopic procedures.
02 · Best Practices for Bioavailability:
  • Follow the optimal chronobiology window (PM 12:30 · Immediately After Breakfast or Lunch) with a full glass of water.
  • Start at a conservative single-serving dose for the first 5–7 days to verify gastrointestinal tolerance.
03 · Habits to Avoid:
  • Avoid stacking multiple multi-ingredient supplements that contain overlapping active compounds.
  • Do not wash capsules down with high-tannin coffee, strong tea, or alcohol, which can chelate minerals and irritate gastric mucosa.
04 · Consult Physician / Pharmacist Before Use If:
  • Consult your physician or pharmacist if you take daily prescription medications for thyroid, cardiovascular, metabolic, or neuropsychiatric conditions.
  • Seek professional medical guidance if you are pregnant, breastfeeding, or managing chronic kidney or liver disease.
09 · PUBMED CLINICAL STUDIES

Indexed PubMed Clinical Studies & Abstracts (20 Studies) · 5 Quantitative Analyses

01
CLINICAL STUDY Journal of cellular and molecular medicine (2026) PMID: 41693444 ↗
Modulation of Wnt/β-Catenin Pathway by Aesculus hippocastanum Extract Enhances Temozolomide Sensitivity in Glioblastoma Cells.
Clinical Trial Synthesis 2026 Clinical Study published in Journal of cellular and molecular medicine. Key conclusion: Collectively, these findings demonstrate that HCE increases the cytotoxic effects of TMZ by inhibiting Wnt/β-catenin signalling, reducing tumour stemness, and promoting apoptotic pathways in GB cells.
View Original PubMed Abstract ↓

Glioblastoma (GB) is a highly aggressive brain tumour with a poor prognosis and limited responsiveness to standard chemotherapy, particularly temozolomide (TMZ), due to intrinsic resistance mechanisms. This study investigates the potential of Aesculus hippocastanum, known as horse chestnut extract (HCE), to enhance the therapeutic efficacy of TMZ in GB cells through modulation of the Wnt/β-catenin signalling pathway. Combined treatment of HCE (500 μg/mL) and TMZ (100 μM) significantly reduced cell viability and inhibited wound healing and colony formation compared to either agent alone at 48 h. Notably, the expression of β-catenin and Wnt-1 was significantly reduced in the combination group, followed by a significant downregulation of Nestin and β3-tubulin, markers of glioma stem-like cells and aggressiveness, respectively. Furthermore, apoptotic activity was significantly increased following the combined treatment. In a 3D U87-spheroid model, the combination therapy resulted in a substantial reduction in spheroid area, suggesting impaired tumour growth. Propidium iodide (PI) staining revealed increased membrane permeability in cells treated with the combination, which was accompanied by an increase in p53 expression, supporting the induction of apoptosis. Collectively, these findings demonstrate that HCE increases the cytotoxic effects of TMZ by inhibiting Wnt/β-catenin signalling, reducing tumour stemness, and promoting apoptotic pathways in GB cells. © 2026 The Author(s). Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.

02
CLINICAL STUDY International journal of dermatology (2021) PMID: 33368259 ↗
Drug interactions of natural supplements in dermatology: a review.
Clinical Trial Synthesis 2021 Clinical Study published in International journal of dermatology. Key conclusion: Notable interactions included an increased risk of myopathy and rhabdomyolysis when nicotinic acid is taken by patients using statins, an increased risk of bleeding associated with horse chestnut seed, especially when used in combination with warfarin, and reduced plasma concentr
View Original PubMed Abstract ↓

Limited information is available on the drug-drug interactions of natural supplements in dermatology. Many natural supplements are available over the counter, but drug-drug interactions can occur. This study reviews the clinical use and drug interactions of six natural supplements commonly recommended in dermatology: nicotinic acid (nicotinamide), polypodium leucotomos (heliocare), turmeric, horse chestnut seed extract, zinc, and N-acetylcysteine. We reviewed the drug-drug interactions of each supplement using the PubMed database and IBM Micromedex. For nicotinic acid, zinc, horse chestnut, and N-acetylcysteine, IBM Micromedex generated 11, 23, one, and two results, respectively. Further review of literature from PubMed identified two drug interactions with polypodium leucotomos, two with turmeric, and two more with zinc. Notable interactions included an increased risk of myopathy and rhabdomyolysis when nicotinic acid is taken by patients using statins, an increased risk of bleeding associated with horse chestnut seed, especially when used in combination with warfarin, and reduced plasma concentration in many drugs when taken with zinc. Furthermore, N-acetylcysteine may interfere with concentrations of other medications used in the psychiatric setting, and polypodium leucotomos and turmeric may interfere with the CYP metabolic pathway, which may affect drugs metabolized by this pathway. Prior to recommending a treatment, dermatologists should foster awareness of these interactions. In order to advance the practice as a whole, research should continue to evaluate the drug interactions of these natural supplements. © 2020 the International Society of Dermatology.

03
CLINICAL STUDY Medical mycology (2015) PMID: 26092104 ↗
β-Aescin at subinhibitory concentration (sub-MIC) enhances susceptibility of Candida glabrata clinical isolates to nystatin.
Clinical Trial Synthesis 2015 Clinical Study published in Medical mycology. Key conclusion: MIC values of nystatin were reduced 2-16-fold and 2-4-fold in the presence of subinhibitory concentration of β-aescin crystalline and β-aescin sodium, respectively.
View Original PubMed Abstract ↓

Aescin (escin) derived from the seeds of horse chestnut (Aesculus hippocastanum L.) is a natural mixture of triterpene saponins exhibiting a wide variety of pharmacological properties, including antiinflammatory, analgesic, and antipyretic activities. However, data concerning antifungal activities of these compounds are limited. This study aims to evaluate the in vitro antifungal susceptibility of Candida glabrata clinical isolates to α-aescin sodium, β-aescin crystalline and β-aescin sodium using the disk diffusion (DD) and broth microdilution (BMD) methods. Moreover, the influence of subinhibitory concentration (0.5×MIC) of β-aescins on the nystatin MIC was also studied. In general, the results obtained by the DD assay correlated well with those obtained by the BMD method. Both β-aescins effectively inhibited the growth of all 24 strains tested. The minimum inhibitory concentration (MIC) values ranging from 8 to 32 μg/ml for β-aescin crystalline, whereas those of β-aescin sodium were slightly lower and ranged from 4 to 16 μg/ml. In contrast, α-aescin sodium was found to be completely ineffective against the strains studied. MIC values of nystatin were reduced 2-16-fold and 2-4-fold in the presence of subinhibitory concentration of β-aescin crystalline and β-aescin sodium, respectively. Results of the present study may suggest the additive interaction between β-aescin and nystatin. © The Author 2015. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: [email protected].

04
CLINICAL STUDY Seminars in thrombosis and hemostasis (2015) PMID: 25839871 ↗
The influence of herbal medicine on platelet function and coagulation: a narrative review.
Clinical Trial Synthesis 2015 Clinical Study published in Seminars in thrombosis and hemostasis. Key conclusion: In vitro studies show promise in the reduction of platelet aggregation for Andrographis, feverfew, garlic, ginger, Ginkgo, ginseng, hawthorn, horse chestnut, and turmeric.
View Original PubMed Abstract ↓

Comment in Semin Thromb Hemost. 2016 Apr;42(3):321-2. doi: 10.1055/s-0036-1580086. Semin Thromb Hemost. 2016 Apr;42(3):323-4. doi: 10.1055/s-0036-1580087. Cardiovascular disease (CVD) is the leading cause of death worldwide. Platelet activation and aggregation play a central role in hemostasis and thrombosis. Herbal medicines have been traditionally used in the management of CVD and can play a role in modifying CVD progression, particularly in platelet function, and have the potential of altering platelet function tests, as well as some coagulation parameters. Herbal medicines, such as feverfew, garlic, ginger, ginseng, motherwort, St John's wort, and willow bark, were found to reduce platelet aggregation. In vitro studies show promise in the reduction of platelet aggregation for Andrographis, feverfew, garlic, ginger, Ginkgo, ginseng, hawthorn, horse chestnut, and turmeric. In addition, cranberry, danshen, dong quai, Ginkgo, ginseng, green tea, and St John's wort were found to have potential interactions with warfarin. Furthermore, St John's wort interacted with clopidogrel and danshen with aspirin. Therefore, repeat testing of platelet function and coagulation studies, particularly for patients on warfarin therapy, may be required after exclusion of herbal medicines that could have possibly affected initial test results. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

05
CLINICAL STUDY Journal of ethnopharmacology (2014) PMID: 24252494 ↗
Effects of aescin on cytochrome P450 enzymes in rats.
Clinical Trial Synthesis 2014 Clinical Study published in Journal of ethnopharmacology. Key conclusion: CONCLUSIONS: Aescin can either inhibit or induce activities of CYP1A2, CYP2C9 and CYP3A4.
View Original PubMed Abstract ↓

ETHNOPHARMACOLOGICAL RELEVANCE: Aescin, the main active component found in extracts of horse chestnut (Aesculus hippocastanum) seed a traditional medicinal herb, is a mixture of triterpene saponins. It has been shown to be effective in inflammatory, chronic venous and edematous treatment conditions in vitro and in vivo, and is broadly used to treat chronic venous insufficiency. The purpose of this study was to find out whether aescin influences the effect on rat cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9, CYP2E1 and CYP3A4) by using cocktail probe drugs in vivo; the influence on the levels of CYP mRNA was also studied. MATERIALS AND METHODS: A cocktail solution at a dose of 5mL/kg, which contained phenacetin (20mg/kg), tolbutamide (5mg/kg), chlorzoxazone (20mg/kg) and midazolam (10mg/kg), was given as oral administration to rats treated with a single dose or multiple doses of intravenous aescin via the caudal vein. Blood samples were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by HPLC-MS/MS. The corresponding pharmacokinetic parameters were calculated by the software of DAS 2.0. In addition, real-time RT-PCR was performed to determine the effects of aescin on the mRNA expression of CYP1A2, CYP2C9, CYP2E1 and CYP3A4 in rat liver. RESULTS: Treatment with a single dose or multiple doses of aescin had inductive effects on rat CYP1A2, while CYP2C9 and CYP3A4 enzyme activities were inhibited. Moreover, aescin has no inductive or inhibitory effect on the activity of CYP2E1. The mRNA expression results were in accordance with the pharmacokinetic results. CONCLUSIONS: Aescin can either inhibit or induce activities of CYP1A2, CYP2C9 and CYP3A4. Therefore, caution is needed when aescin is co-administration with some CYP1A2, CYP2C9 or CYP3A4 substrates in clinic, which may result in treatment failure and herb-drug interactions. © 2013 Published by Elsevier Ireland Ltd.

06
CLINICAL STUDY Molecular medicine reports (2013) PMID: 23525122 ↗
Synergistic protective effects of escin and low‑dose glucocorticoids on blood‑retinal barrier breakdown in a rat model of retinal ischemia.
Clinical Trial Synthesis 2013 Clinical Study published in Molecular medicine reports. Key conclusion: Therefore, the administration of escin may allow a reduction in the dose of GCs for the treatment of macular edema.
View Original PubMed Abstract ↓

Escin, a natural mixture of triterpenoid saponins isolated from the seed of the horse chestnut (Aesculus hippocastanum), has been demonstrated to possess glucocorticoid (GC)‑like anti‑edematous and anti‑inflammatory effects. The aim of the present study was to investigate whether escin exhibits synergistic protective effects on blood‑retinal barrier (BRB) breakdown when combined with GCs in a rat model of retinal ischemia. Low concentrations of escin and triamcinolone acetonide (TA) alone did not affect BRB permeability. However, when administered together, low‑dose escin and TA significantly reduced BRB permeability following ischemia. Furthermore, low‑dose escin and TA alone did not affect the expression of occludin in the ischemic retina; however, when administered together, they significantly increased occludin expression in the ganglion cell layer of the ischemic retina. This indicates that escin and GCs have synergistic protective effects on BRB breakdown and the molecular mechanisms may be correlated with the upregulation of occludin. Therefore, the administration of escin may allow a reduction in the dose of GCs for the treatment of macular edema. The combination of escin with GCs is potentially a beneficial treatment method for BRB breakdown and warrants further investigation.

07
CLINICAL STUDY Phytomedicine (2011) PMID: 20850956 ↗
Escin exerts synergistic anti-inflammatory effects with low doses of glucocorticoids in vivo and in vitro.
Clinical Trial Synthesis 2011 Clinical Study published in Phytomedicine. Key conclusion: Escin or Cort markedly reduced the content of NO, TNF-α and IL-1β secreted by LPS-stimulated RAW264.7 macrophage cells.
View Original PubMed Abstract ↓

Escin, a natural mixture of triterpenoid saponins isolated from the seed of the horse chestnut (Aesculus hippocastanum), had been demonstrated to possess anti-edematous and anti-inflammatory effects. The present study was designed to investigate whether escin exhibits synergistic anti-inflammatory effects when combined with glucocorticoids. The carrageenan-induced paw edema and pleuritis in bilaterally adrenalectomized rats were used to investigate the anti-inflammatory effects of escin and glucocorticoid alone or combined. The carrageenan-induced paw edema was inhibited only when escin and corticosterone (Cort) were administered together. Co-administration of escin with Cort significantly reduced the volume of exudates and the number of white blood cells of exudates in bilaterally adrenalectomized rats with pleuritis, but treatment with escin or Cort alone at a suboptimal concentration did not show any effect on the pleuritis rats. After the murine macrophagic RAW264.7 cells stimulated by lipopolysaccharide (LPS), they were treated with escin, Cort or escin and Cort. Then nitric oxide (NO), tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) of cell culture supernatants were analyzed. Escin or Cort markedly reduced the content of NO, TNF-α and IL-1β secreted by LPS-stimulated RAW264.7 macrophage cells. The combination of suboptimal concentrations of escin with Cort, which alone could not markedly inhibit the release of inflammatory factors, inhibited the secretion of NO, TNF-α and IL-1β in LPS-stimulated RAW264.7 macrophage cells. The findings suggest escin can synergize with glucocorticoids to enhance their anti-inflammatory effect.

08
CLINICAL STUDY Basic & clinical pharmacology & toxicology (2009) PMID: 19371257 ↗
Trade herbal products and induction of CYP2C19 and CYP2E1 in cultured human hepatocytes.
Clinical Trial Synthesis 2009 Clinical Study published in Basic & clinical pharmacology & toxicology. Key conclusion: Common sage induced CYP2C19 in a log-linear dose-dependent manner with increasing concentrations.
View Original PubMed Abstract ↓

The aim of this study was to evaluate in vitro the dose-dependent induction potential of six commonly used trade herbal products on CYP2C19 and CYP2E1 metabolic activities in cultured human hepatocytes. S-mephenytoin and chlorzoxazone were used as specific CYP substrates, respectively, and rifampicin was used as a positive induction control for both enzymes. The hepatocytes were exposed to herbal extracts in increasing and biological relevant concentrations for 72 hrs and CYP substrate metabolites were quantified by validated HPLC methodologies. The major findings were that St John's wort was the most potent CYP-modulating herb, showing a dose-dependent induction/inhibition of both CYP2C19 and CYP2E1, with induction at low dosages and inhibition at higher. Ginkgo biloba showed an induction/inhibition profile towards CYP2C19 which was similar but weaker than that observed for St John's wort. If cooperative mechanisms are involved is still an open question. Common sage induced CYP2C19 in a log-linear dose-dependent manner with increasing concentrations. Common valerian was a weak inducer of CYP2C19, while horse chestnut and cone flower were characterized as non-inducers of CYP2C19. Only St John's wort showed an inductive effect towards CYP2E1. In addition to St John's wort, Gingko biloba and common sage should be considered as possible candidates for clinically relevant drug-herb interactions with selected CYP2C19 substrates.

09
CLINICAL STUDY Tidsskrift for den Norske laegeforening (2009) PMID: 19247403 ↗
[Horse chestnut--remedy for chronic venous insufficiency].
Clinical Trial Synthesis 2009 Clinical Study published in Tidsskrift for den Norske laegeforening. Key conclusion: However, inadequate randomization, short duration and use of different end-points in these trials makes it difficult to conclude regarding effectiveness and safety, especially in long-term use.
View Original PubMed Abstract ↓

Horse- chestnut seed extract is widely used throughout Europe, and has been used to treat a variety of medical conditions. The most common indication is currently chronic venous insufficiency, for which conventional therapy includes use of compression stockings. Horse chestnut seed extract is generally well tolerated; the most common side effects are gastrointestinal disturbances, dizziness and calf-muscle spasms. Clinical trials have shown that horse- chestnut seed extract and placebo are associated with similar side effects Horse- chestnut may interact with anticoagulants and antidiabetics, and caution is advised in patients taking these drugs. A number of clinical trials have shown that horse- chestnut seed extract may be beneficial to patients with mild to moderate chronic venous insufficiency. However, inadequate randomization, short duration and use of different end-points in these trials makes it difficult to conclude regarding effectiveness and safety, especially in long-term use. Horse- chestnut seed extract appears to be a short-term treatment option in patients with mild to moderate chronic venous insufficiency, but more rigorous trials are required to confirm the efficacy of this treatment.

10
CLINICAL STUDY Basic & clinical pharmacology & toxicology (2008) PMID: 18331390 ↗
In vitro inhibition of CYP3A4 metabolism and P-glycoprotein-mediated transport by trade herbal products.
Clinical Trial Synthesis 2008 Clinical Study published in Basic & clinical pharmacology & toxicology. Key conclusion: John's wort, are suggested candidates for in vivo intestinal herb-drug pharmacokinetic interactions.
View Original PubMed Abstract ↓

Extracts of six commonly used commercially available herbal products, St. John's wort, common valerian, common sage, Ginkgo biloba, Echinacea purpurea and horse chestnut were investigated for their in vitro inhibitory potential of CYP3A4 mediated metabolism and P-glycoprotein efflux transport activity. C-DNA baculovirus expressed CYP3A4 and Caco-2 cells were used. Ketoconazole and verapamil were applied as positive control inhibitors, respectively. A validated high-performance liquid chromatography methodology was used to quantify the formation of 6-OH-testosterone and scintillation counting was used to quantify the transport of (3)H-digoxin. All the investigated herbs inhibited CYP3A4 activity. St. John's wort was the strongest inhibiting herb with an IC(50) value of 15.4 microg/ml, followed by common sage, Ginkgo biloba, common valerian, horse chestnut and Echinacea purpurea. All herbs also inhibited P-glycoprotein activity. Ginkgo biloba was the strongest inhibiting herb, inhibiting the net digoxin flux with an IC(50) value of 23.6 microg/ml, followed by St. John's wort, horse chestnut, common sage, common valerian and Echinacea purpurea. No correlation was found between the herbs inhibitory potentials towards CYP3A4 and P-glycoprotein activities. Ginkgo biloba, horse chestnut and common sage, besides St. John's wort, are suggested candidates for in vivo intestinal herb-drug pharmacokinetic interactions.

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