Potential Pharmacokinetic Herb-Drug Interactions: Have we Overlooked the Importance of Human Carboxylesterases 1 and 2?

Regulation of carboxylesterases and its impact on pharmacokinetics and pharmacodynamics: an up-to-date review

INTRODUCTION

Carboxylesterase 1 (CES1) and carboxylesterase 2 (CES2) are among the most abundant hydrolases in humans, catalyzing the metabolism of numerous clinically important medications, such as methylphenidate and clopidogrel. The large interindividual variability in the expression and activity of CES1 and CES2 affects the pharmacokinetics (PK) and pharmacodynamics (PD) of substrate drugs.

AREAS COVERED

This review provides an up-to-date overview of CES expression and activity regulations and examines their impact on the PK and PD of CES substrate drugs. The literature search was conducted on PubMed from inception to January 2024.

EXPERT OPINION

Current research revealed modest associations of CES genetic polymorphisms with drug exposure and response. Beyond genomic polymorphisms, transcriptional and posttranslational regulations can also significantly affect CES expression and activity and consequently alter PK and PD. Recent advances in plasma biomarkers of drug-metabolizing enzymes encourage the research of plasma protein and metabolite biomarkers for CES1 and CES2, which could lead to the establishment of precision pharmacotherapy regimens for drugs metabolized by CESs. Moreover, our understanding of tissue-specific expression and substrate selectivity of CES1 and CES2 has shed light on improving the design of CES1- and CES2-activated prodrugs.

Cannabidiol's impact on drug-metabolization

IMPORTANCE

Products containing cannabidiol(CBD) are easily accessible. CBD is reported to inhibit the drug-metabolizing proteins(DMP) Cytochrome P450(CYP)3A4/5, CYP2C9, CYP2B6, CYP2D6, CYP2E1, CYP1A2, CYP2C19, carboxylesterase 1(CES1), uridine 5'diphospho-glucoronosyltransferase(UGT)1A9, UGT2B7, P-glycoprotein(P-gp) and Breast Cancer Resistance Protein(BCRP). The relevance of CBD-drug interactions is largely unknown. Aim of the study was to identify drugs, potentially interacting with orally ingested CBD, to assess whether CBD-drug interactions have been reported, and if substrates of DMP are frequently prescribed drugs.

OBSERVATIONS

Identified were 403 drugs as substrates of DMP. CBD-drug interactions were reported for 53/403 substrates in humans (n = 25), in vivo (n = 13) or in vitro (n = 15). In 31/53 substrates, CBD induced an increase, in 1/53 a decrease, in 4/53 no change in the substrate level. For 5/53 substrates, the results were controversial, and in 12/53 no substrate levels were reported. Among the 30 most frequently prescribed drugs in Germany were 67% substrates of DMP and among the 50 most frequently prescribed drugs in the USA 68%.

RELEVANCE AND CONCLUSIONS

There is an urgent need for pharmacologic studies on CBD-drug interactions. Patients should be educated on the potential risk and awareness should be increased among physicians. Regulatory authorities should become aware of the problem and start an initiative on an international level to increase the safety of CBD.

An in vitro evaluation of kratom (Mitragyna speciosa) on the catalytic activity of carboxylesterase 1 (CES1)

Kratom, (Mitragyna Speciosa Korth.) is a plant indigenous to Southeast Asia whose leaves are cultivated for a variety of medicinal purposes and mostly consumed as powders or tea in the United States. Kratom use has surged in popularity with the lay public and is currently being investigated for possible therapeutic benefits including as a treatment for opioid withdrawal due to the pharmacologic effects of its indole alkaloids. A wide array of psychoactive compounds are found in kratom, with mitragynine being the most abundant alkaloid. The drug-drug interaction (DDI) potential of mitragynine and related alkaloids have been evaluated for effects on the major cytochrome P450s (CYPs) via in vitro assays and limited clinical investigations. However, no thorough assessment of their potential to inhibit the major hepatic hydrolase, carboxylesterase 1 (CES1), exists. The purpose of this study was to evaluate the in vitro inhibitory potential of kratom extracts and its individual major alkaloids using an established CES1 assay and incubation system. Three separate kratom extracts and the major kratom alkaloids mitragynine, speciogynine, speciociliatine, paynantheine, and corynantheidine displayed a concentration-dependent reversible inhibition of CES1. The experimental Ki values were determined as follows for mitragynine, speciociliatine, paynantheine, and corynantheidine: 20.6, 8.6, 26.1, and 12.5 μM respectively. Speciociliatine, paynantheine, and corynantheidine were all determined to be mixed-type reversible inhibitors of CES1, while mitragynine was a purely competitive inhibitor. Based on available pharmacokinetic data, determined Ki values, and a physiologically based inhibition screen mimicking alkaloid exposures in humans, a DDI mediated via CES1 inhibition appears unlikely across a spectrum of doses (i.e., 2-20g per dose). However, further clinical studies need to be conducted to exclude the possibility of a DDI at higher and extreme doses of kratom and those who are chronic users.

Hormetic effects of EGC and EGCG on CES1 activity and its rescue from oxidative stress in rat liver S9

Carboxylesterase 1 (CES1) is a hydrolytic enzyme that plays an important role in the activation or deactivation of many therapeutic agents, thus affecting their pharmacokinetic and pharmacodynamic outcomes. Using rat liver S9 as an enzyme source and enalapril as a CES1 substrate, the present study examined effects of a number of flavonoids on the formation of enalaprilat (the active form of enalapril) produced by CES1-mediated hydrolysis. While a majority of flavonoids tested showed inhibition on CES1, an unexpected hormetic effect was observed for epigallocatechin (EGC) and epigallocatechin gallate (EGCG), i.e., stimulatory effect at low concentrations and enzyme inhibition at high concentrations. Further experiments revealed that oxidative stress caused by hydrogen peroxide, arachidonic acid plus iron, and oxidized low density lipoproteins (oxLOL) reduced CES1 activity in rat liver S9 and the loss of CES1 enzyme activity could be rescued largely by EGC or EGCG. In contrast, such effects were minimal in human liver S9, probably due to the presence of a higher ratio of reduced vs oxidized forms of glutathione. The above findings suggest that the polyphenolic nature of EGC or EGCG might be responsible for rescuing CES1 activity under oxidative stress. Because of the importance of CES1 in drug activation or deactivation and rat liver S9 as a versatile in vitro system used for drug metabolism studies and drug safety assessment, caution should be exercised to avoid potential biases for data interpretation and decision making when CES1 activity in rat liver S9 is evaluated with dependency on experimental conditions.

In vitro inhibition of carboxylesterase 1 by Kava (Piper methysticum) Kavalactones

Kava refers to the extracts from the rhizome of the plant Piper methysticum which is of particular significance to various indigenous cultures in the South Pacific region. Kavalactones are the active constituents of kava products and are associated with sedative and anxiolytic effects. Kavalactones have been evaluated in vitro for their potential to alter the activity of various CYP450 enzymes but have undergone little systematic investigation as to their potential influence on esterases. This study investigated the inhibition effects of kava and its kavalactones on carboxylesterase 1 (CES1) in an in vitro system and established associated kinetic parameters. Kava and its kavalactones were found to produce reversible inhibition of CES1 to varying degrees. Kavain, dihydrokavain, and desmethoxyyangonin displayed competitive type inhibition, while methysticin, dihydromethysticin, and yangonin displayed a mixed competitive-noncompetitive type inhibition. The inhibition constants (Ki) values for each of the kavalactones were as follows: methysticin (35.2 μM), dihydromethysticin (68.2 μM), kavain (81.6 μM), dihydrokavain (105.3 μM), yangonin (24.9 μM), and desmethoxyyangonin (25.2 μM). With consideration to the in vitro Ki for each evaluated kavalactone as well as available clinical kavalactone concentrations in blood circulation, co-administration of CES1 substrate medications and kava products at the recommended daily dose is generally free of drug interaction concerns. However, uncertainty around kavalactone exposure in humans has been noted and a clinically relevant CES1 inhibition by kavain, dihydrokavain, and dihydromethysticin is indeed possible if the kavalactone consumption is higher than 1000 mg in the context of over-the-counter usage. Further clinical studies would be required to assess the possibility of clinically significant kava drug-drug interactions with CES1 substrate medications.

Determination of candesartan or olmesartan in hypertensive patient plasma using UPLC-MS/MS

Candesartan and olmesartan are angiotensin II receptor blockers (ARBs) used for the treatment of hypertension and heart failure. Quantitation methods for candesartan and olmesartan were developed using ultra-high performance liquid chromatography-tandem mass spectrometry following protein precipitation. Candesartan was separated using 5 mM ammonium formate (A) and 100% acetonitrile (B) and olmesartan was separated using 2 mM ammonium formate with 0.1% formic acid (A) and 100% acetonitrile (B). Separation was performed using an isocratic method with a Thermo hypersil GOLD C18 column. Electrospray ionization was used for analyte ionization and detection of candesartan, olmesartan, and the internal standards by multiple reaction monitoring. Developed method showed excellent linearity (r > 0.99) in the concentration range of 2-500 ng/mL for candesartan and 5-2,500 ng/mL for olmesartan. Accuracies were 86.70-108.8% for candesartan and 87.87-112.6% for olmesartan. These methods were able to successfully measure plasma candesartan or olmesartan concentrations in hypertensive patients. This study can be used for pharmacokinetic studies of candesartan or olmesartan in humans.

Microbiota-Host-Irinotecan Axis: A New Insight Toward Irinotecan Chemotherapy

Irinotecan (CPT11) and its active metabolite ethyl-10-hydroxy-camptothecin (SN38) are broad-spectrum cytotoxic anticancer agents. Both cause cell death in rapidly dividing cells (e.g., cancer cells, epithelial cells, hematopoietic cells) and commensal bacteria. Therefore, CPT11 can induce a series of toxic side-effects, of which the most conspicuous is gastrointestinal toxicity (nausea, vomiting, diarrhea). Studies have shown that the gut microbiota modulates the host response to chemotherapeutic drugs. Targeting the gut microbiota influences the efficacy and toxicity of CPT11 chemotherapy through three key mechanisms: microbial ecocline, catalysis of microbial enzymes, and immunoregulation. This review summarizes and explores how the gut microbiota participates in CPT11 metabolism and mediates host immune dynamics to affect the toxicity and efficacy of CPT11 chemotherapy, thus introducing a new concept that is called "microbiota-host-irinotecan axis". Also, we emphasize the utilization of bacterial β-glucuronidase-specific inhibitor, dietary interventions, probiotics and strain-engineered interventions as emergent microbiota-targeting strategies for the purpose of improving CPT11 chemotherapy efficiency and alleviating toxicity.

Potentiation of flutamide-induced hepatotoxicity in mice by Xian-Ling-Gu-Bao through induction of CYP1A2

ETHNOPHARMACOLOGICAL RELEVANCE

Xian-Ling-Gu-Bao (XLGB) Fufang is herbal formula widely used to treat osteoporosis and other bone disorders. Because of its commonality in the clinical use, there is a safety concern over the use of XLGB combined with other androgen deprivation therapy (ADT) drugs such as flutamide (FLU) that is associated with reduced bone density. To date, there have been no evaluations on the side effects of the drug-drug interaction between XLGB and FLU.

AIM OF THE STUDY

The present study was designed to investigate the hepatotoxicity in the context of the combined treatment of XLGB and FLU in a mouse model, and to determine whether the metabolic activation of FLU through induction of CYP1A2 plays a role in the increased hepatoxicity caused by the combination of XLGB and FLU.

MATERIALS AND METHODS

C57 mice were administered with either XLGB (6,160 mg/kg), FLU (300 mg/kg), or with the combination of the two drugs. Animals were treated with XLGB for 5 days before the combined administration of XLGB and FLU for another 4 days. The serum of mice from single or the combined administration groups was collected for biochemical analysis. The mouse liver was collected to examine liver morphological changes, evaluate liver coefficient, as well as determine the mRNA expression of P450 isozymes (Cyp1a2, Cyp3a11 and Cyp2c37). For metabolism analysis, mice were treated with XLGB, FLU, or the combination of XLGB and FLU for 24 h. The urine samples were collected for the analysis of FLU-NAC conjugate by UPLC-Q-Orbitrap MS. The liver microsomes were prepared from fresh livers to determine the activity of metabolizing enzyme CYP1A2.

RESULTS

The combined treatment of XLGB and FLU caused loss of mice body weight and elicited significant liver toxicity as evidenced by an increased liver coefficient and serum lactate dehydrogenase (LDH) activity as well as pathological changes of fatty lesion of liver tissue. FLU increased hepatic expression of Cyp1a2 mRNA that was further elevated in the liver of mice when administered with both FLU and XLGB. Treatment of FLU resulted in an increase in the expression of Cyp3a11 mRNA that was negated when mice were co-treated with FLU and XLGB. No significant difference in Cyp2c37 mRNA expression was observed among the different treatment groups as compared to the control. Analysis of metabolic activity showed that the combined administration caused a synergic effect in elevating the activity of the CYP1A2 enzyme. Mass spectrometry analysis identified the presence of FLU reactive metabolite derived FLU-NAC conjugate in the urine of mice treated with FLU. Strikingly, about a two-fold increase of the FLU-NAC conjugate was detected when treated with both FLU and XLGB, indicating an elevated amount of toxic metabolite produced from FLU in the present of XLGB.

CONCLUSION

FLU and XLGB co-treatment potentiated FLU-induced hepatoxicity. This increased hepatoxicity was mediated through the induction of CYP1A2 activity which in turn enhanced bioactivation of FLU leading to over production of FLU-NAC conjugate and oxidative stress. These results offer warnings about serious side effects of the FLU-XLGB interaction in the clinical practice.

Preparation, evaluation, and in vitro release of chitosan-alginate tanshinone self-microemulsifying sustained-release microcapsules

OBJECTIVE

In this study we explore the method to prepare tanshinone self-microemulsifying sustained-release microcapsules using tanshinone self-microemulsion as the core material, and chitosan and alginate as capsule materials.

METHODS

The optimal preparation technology of chitosan-alginate tanshinone self-microemulsifying sustained-release microcapsules was determined by using the orthogonal design experiment and single-factor analysis. The drug loading and entrapment rate were used as evaluation indexes to assess the quality of the drug, and the in vitro release rate was used to evaluate the drug release performance.

RESULTS

The best technology of chitosan-alginate tanshinone self-microemulsifying sustained-release microcapsules is as follows: the concentration of alginate is 1.5%, the ratio of tanshinone self-microemulsion volume to alginate volume to chitosan mass is 1:1:0.5 (ml: ml: g), and the best concentration of calcium chloride is 2.0%. To prepare the microcapsules using this technology, the drug loading will be 0.046%, the entrapment rate will be 80.23%, and the 24-hour in vitro cumulative release rate will be 97.4%.

CONCLUSION

The release of the microcapsules conforms to the Higuchi equation and the first-order drug release model and has a good sustained-release performance.

High Doses of Δ9-Tetrahydrocannabinol Might Impair Irinotecan Chemotherapy: A Review of Potentially Harmful Interactions

This review proposes the hypothesis that the effectiveness of irinotecan chemotherapy might be impaired by high doses of concomitantly administered Δ⁹-tetrahydrocannabinol (THC). The most important features shared by irinotecan and THC, which might represent sources of potentially harmful interactions are: first-pass hepatic metabolism mediated by cytochrome P450 (CYP) enzyme CYP3A4; glucuronidation mediated by uridine diphosphate glycosyltransferase (UGT) enzymes, isoforms 1A1 and 1A9; transport of parent compounds and their metabolites via canalicular ATP-binding cassette (ABC) transporters ABCB1 and ABCG2; enterohepatic recirculation of both parent compounds, which leads to an extended duration of their pharmacological effects; possible competition for binding to albumin; butyrylcholinesterase (BChE) inhibition by THC, which might impair the conversion of parent irinotecan into the SN-38 metabolite; mutual effects on mitochondrial dysfunction and induction of oxidative stress; potentiation of hepatotoxicity; potentiation of genotoxicity and cytogenetic effects leading to genome instability; possible neurotoxicity; and effects on bilirubin. The controversies associated with the use of highly concentrated THC preparations with irinotecan chemotherapy are also discussed. Despite all of the limitations, the body of evidence provided here could be considered relevant for human-risk assessments and calls for concern in cases when irinotecan chemotherapy is accompanied by preparations rich in THC.

Potential Adverse Drug Events with Tetrahydrocannabinol (THC) Due to Drug-Drug Interactions

Tetrahydrocannabinol (THC) is the primary psychoactive ingredient in cannabis. While the safety of THC and cannabis has been extrapolated from millennia of recreational use, medical marijuana programs have increased exposure among medically complex individuals with comorbid conditions and many co-prescribed medications. Thus, THC should be recognized as a pharmacologically complex compound with potential for drug–drug interactions and adverse drug events. This review summarizes potential adverse drug events related to THC when combined with other medications. Metabolic drug–drug interactions are primarily due to THC conversion by CYP3A4 and CYP2C9, which can be impacted by several common medications. Further, CYP2C9 polymorphisms are highly prevalent in certain racial groups (up to 35% in Caucasians) and increase the bioavailability of THC. THC also has broad interactions with drug-metabolizing enzymes and can enhance adverse effects of other medications. Pharmacodynamic interactions include neurological effects, impact on the cardiovascular system, and risk of infection. General clinical recommendations for THC use include starting with low doses and titrating to desired effects. However, many interactions may be unavoidable, dose-limiting, or a barrier to THC-based therapy. Future work and research must establish sufficient data resources to capture medical marijuana use for such studies. Meanwhile, clinicians should balance the potential risks of THC and cannabis and the lack of strong evidence of efficacy in many conditions with patient desires for alternative therapy.

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.

Natural Health Product-Drug Interaction Causality Assessment in Pediatric Adverse Event Reports Associated with Attention-Deficit/Hyperactivity Disorder Medication

Background: Some pediatric patients with attention-deficit/hyperactivity disorder (ADHD) use natural health products (NHPs) such as herbal remedies. Although herbal remedies are generally considered to be safe when they are used appropriately, they may contain active components that can interact with medications being used concurrently, with potential for NHP-drug interactions leading to adverse events. Objectives: The objectives of this study were (1) to identify adverse event reports (AERs) involving commonly used herbal remedies and ADHD prescription medicines in children and adolescents; (2) to evaluate the quality of collected AERs; and (3) to assess whether NHP-drug interactions can be causally linked to reported adverse events. Methods: We systematically searched the FDAble database (FDAble.com) for herbal remedies commonly used by patients (4-18 years old) also taking ADHD drugs from 1997 to 2015. We assessed the completeness of the AERs and used three causality assessment tools modified for NHPs (Naranjo Adverse Drug Reaction Probability Scale, HORN Drug Interaction Probability Scale, and World Health Organization Uppsala Monitoring Centre Scale). Results: Of the 23 identified AERs involving both an herbal remedy and an ADHD prescription medication, most involved multiple (>3) substances with inadequate detail to assess multiple potential interactions. Following data extraction and evaluation of completeness, five AERs involving only one herbal remedy and one ADHD medication were evaluated for causality. An NHP-drug interaction was assessed to be probable in one case and to be possible in another. Both these reports involved a methylphenidate formulation and St. John's wort. Conclusions: Eighteen of the 23 identified AERs involving both an herbal remedy and an ADHD drug also involved other multiple ingredient products. The reporting quality was poor for the five AERs examined. Further research is needed to study the interaction between St. John's wort and methylphenidate.

Catalytic Hydrolysis Mechanism of Cocaine by Human Carboxylesterase 1: An Orthoester Intermediate Slows Down the Reaction

Human carboxylesterase 1 (hCES1) is a major carboxylesterase in the human body and plays important roles in the metabolism of a wide variety of substances, including lipids and drugs, and therefore is attracting more and more attention from areas including lipid metabolism, pharmacokinetics, drug–drug interactions, and prodrug activation. In this work, we studied the catalytic hydrolysis mechanism of hCES1 by the quantum mechanics computation method, using cocaine as a model substrate. Our results support the four-step theory of the esterase catalytic hydrolysis mechanism, in which both the acylation stage and the deacylation stage include two transition states and a tetrahedral intermediate. The roles and cooperation of the catalytic triad, S221, H468, and E354, were also analyzed in this study. Moreover, orthoester intermediates were found in hCES1-catalyzed cocaine hydrolysis reaction, which significantly elevate the free energy barrier and slow down the reaction. Based on this finding, we propose that hCES1 substrates with β-aminocarboxylester structure might form orthoester intermediates in hCES1-catalyzed hydrolysis, and therefore prolong their in vivo half-life. Thus, this study helps to clarify the catalytic mechanism of hCES1 and elucidates important details of its catalytic process, and furthermore, provides important insights into the metabolism of hCES1 substrates and drug designing.