Investigation on modulation of human P-gp by multiple doses of Radix Astragali extract granules using fexofenadine as a phenotyping probe

HDI Highlighter, The First Intelligent Tool to Screen the Literature on Herb-Drug Interactions

Herbal food supplements are commonly used and can be an important part of patient self-care. Like all other bio-active and therapeutic products, they have a benefit/risk balance. These products are not without adverse effects and potentially interact with other therapies. Educating patients and providing information for health professionals about the risk of herb-drug interactions is key. One of the purposes of the biomedical literature is to inform prescribers. Scientific literature accessible on databases such as PubMed is dense and careful reading is time consuming. We propose a reading aid tool named "HDI highlighter" to help readers to find key information in clinical studies and case reports describing herb-drug interactions. It uses natural language processing algorithms (artificial intelligence) with a pharmaceutical focus. Semantic relation extraction for herb-drug interactions from the biomedical literature are overexpressed using keywords. We have tested it to review 120 published articles over the last 10 years. In these articles, we have shown that case reports often involved long-term or semi-long-term treatments such as cancer or human immunodeficiency virus therapies, antiepileptic drugs, or central nervous system drugs. Similarly, these classes of drugs are more extensively targeted by clinical studies. Herb-drug interactions described in case reports are identified in medicinal, recreational, and alimentary uses. They also usually lack a rigorous description of the herb(s) involved. Typically, clinical studies provide a complete description of protocols and dosages, with a few exceptions explained by patients' needs. Clinical studies on herbs are nevertheless conducted on a limited number of patients. All these limitations make the interpretation of herb-drug interactions complicated, but the HDI highlighter provides a quick overview of the herb-drug interaction literature.

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

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

Effects of breviscapine and C3435T MDR1 gene polymorphism on the pharmacokinetics of fexofenadine, a P-glycoprotein substrate, in healthy volunteers

Breviscapine (BRE) is usually used for long-term use in patients with cardiovascular diseases such as coronary heart disease, angina pectoris, and cerebral thrombosis. It is possible to combine it with P-glycoprotein (P-gp) substrates in clinic. At present, little is known about whether the simultaneous use of BRE affects the disposal of P-gp substrates. The aim of this study was to evaluate the effect of BRE on the pharmacokinetics of fexofenadine (FEX), a P-gp probe substrate and its associations with the MDR1 C3435T genetic polymorphism in healthy volunteers. In this randomised, open-label, placebo-controlled, two-phase crossover clinical study, drug interactions were evaluated in healthy volunteers. FEX was used as a phenotypic probe for P-gp. In each phase, 18 volunteers were given daily doses of 120 mg (40 mg, three times a day) of BRE tablet or a placebo for 14 days. On day 15, a single oral dose of 120 mg FEX hydrochloride was given orally. Blood samples were collected at predefined time intervals, and plasma levels of FEX were determined by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The pharmacokinetic parameters were calculated by non-compartmental method, and bioequivalence was evaluated. Results showed that BRE pretreatment did not significantly affect the pharmacokinetics of FEX. The peak maximum plasma concentration (C _max) and the area under the plasma concentration-time curve from zero to infinity (AUC_inf) mean value of FEX with BRE and placebo-treated groups were 699 ng/mL vs. 710 ng/mL and 2972.5 ng⋅h/mL vs. 3460.5 ng⋅h/mL, respectively. The geometric mean ratios (90% confidence intervals) for FEX C _max and AUC_inf were within the pre-specified range of 0.8-1.25, indicating that FEX in the two pretreatment phases were bioequivalent. Pharmacokinetic parameters of FEX showed no statistically significant difference between MDR1 C3435T CC, CT and TT genotype, revealing that BRE and MDR1 C3435T gene polymorphisms did not affect the pharmacokinetics of FEX in healthy volunteers.

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

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

Herb-Drug Interactions of Commonly Used Chinese Medicinal Herbs

With more and more popular use of traditional herbal medicines, in particular Chinese herbal medicines, herb-drug interactions have become a more and more important safety issue in the clinical applications of the conventional drugs. Researches in this area are increasing very rapidly. Herb-drug interactions are complicated due to the fact that multiple chemical components are involved, and these compounds may possess diverse pharmacological activities. Interactions can be in both pharmacokinetics and pharmacodynamics. Abundant studies focused on pharmacokinetic interactions of herbs and drugs. Herbs may affect the behavior of the concomitantly used drugs by changing their absorption, distribution, metabolism, and excretion. Studies on pharmacodynamics interactions of herbs and drugs are still very limited. Herb-drug interactions are potentially causing changes in drug levels and drug activities and leading to either therapeutic failure or toxicities. Sometime it can be fatal. The exposures to drugs, lacking of knowledge in the potential adverse herb-drug interactions, will put big risk to patients' safety in medical services. On the contrary, some interactions may be therapeutically beneficial. It may be used to help develop new therapeutic strategies in the future. This chapter is trying to review the development in the area of herb-drug interactions based on the recently published research findings. Information on the potential interactions among the commonly used Chinese medicinal herbs and conventional drugs is summarized in this chapter.

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

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

Is it appropriate regarding patient preference to take Myrtol standardized enteric-coated soft capsules after a meal rather than at fasted state? A food-drug pharmacokinetic interaction study in healthy Chinese volunteers

BACKGROUND

According to prescribing information for Myrtol standardized enteric-coated soft capsules, the medicine should be taken on an empty stomach. Some patients may experience stomach discomfort after oral administration in fasted state and would prefer to take the medicine after a meal. However, there is no literature addressing the effect of meal on absorption of this drug; therefore, it is desirable to explore the feasibility of taking the capsule after a meal from pharmacokinetic perspective.

METHODS

A gas chromatography coupled with triple quadruples mass spectrometry assay was established and validated for determining plasma concentrations of eucalyptol, a target component of Myrtol standardized capsules. A self-control clinical study was carried out in healthy male volunteers in fasted and fed states after a single oral dose of 300 mg capsules. Comparison of pharmacokinetic parameters in the two phases and bioequivalence evaluation were performed.

RESULTS

The specificity, sensitivity, accuracy, and precision of the assay satisfied the requirements for biopharmaceutical analysis. Pharmacokinetic parameters of eucalyptol (fasted vs fed) were as follows: maximal plasma concentrations (Cmax) (167.60±114.69 vs 518.89±314.47 ng·mL-1), time of maximum concentration (Tmax) (3.7±1.1 vs 4.8±0.7 h), elimination half-life (T1/2) (3.2±1.4 vs 2.6±0.7 h), area under the plasma concentration-time curve (AUC0-t) (584.91±369.90 vs 1,271.61±605.82 ng·h·mL-1), and AUC0-∞ (690.36±467.26 vs 1,458.02±720.21 ng·h·mL-1). There was statistically significant difference in Cmax, AUC0-t, and AUC0-∞ between the two dosing methods (P<0.05). Pharmacokinetic parameters of eucalyptol given in fasted state in Chinese were comparable to those in Germany population. The 90% confidence intervals for the ratio of Cmax (18.4%~64.7%), AUC0-t (28.9%~68.5%), and AUC0-∞ (31.1%~68.4%) values for the test (fasted) and reference (fed) were beyond the Food and Drug Administration's acceptable range of 80%~125%. In addition, significant difference was obtained in Tmax (P<0.05).

CONCLUSION

Compared with dosing at fasted state, taking Myrtol standardized capsules after a meal achieves a delayed absorption rate and an increased absorption extent. The two dosing methods were not bioequivalent in this small study and, thus, not interchangeable. Patient preference and pharmacokinetic food-drug interaction issue should be balanced. Further clinical study is necessary to explore the clinical outcome of oral administration of Myrtol standardized capsules after or with meal.

Pharmacogenomics and herb-drug interactions: merge of future and tradition

The worldwide using of herb products and the increasing potential herb-drug interaction issue has raised enthusiasm on discovering the underlying mechanisms. Previous review indicated that the interactions may be mediated by metabolism enzymes and transporters in pharmacokinetic pathways. On the other hand, an increasing number of studies found that genetic variations showed some influence on herb-drug interaction effects whereas these genetic factors did not draw much attention in history. We highlight that pharmacogenomics may involve the pharmacokinetic or pharmacodynamic pathways to affect herb-drug interaction. We are here to make an updated review focused on some common herb-drug interactions in association with genetic variations, with the aim to help safe use of herbal medicines in different individuals in the clinic.

Effects of danshen ethanol extract on the pharmacokinetics of fexofenadine in healthy volunteers

This study investigated the effect of multidose administration of danshen ethanol extract on fexofenadine pharmacokinetics in healthy volunteers. A sequential, open-label, two-period pharmacokinetic interaction design was used. 12 healthy male volunteers received a single oral dose of fexofenadine (60 mg) followed by danshen ethanol extract (1 g orally, three times a day) for 10 days, after which they received 1 g of the danshen extract with fexofenadine (60 mg) on the last day. The plasma concentrations of fexofenadine was measured by LC-MS/MS. After 10 days of the danshen extract administration, the mean AUC and C_max⁡ of the fexofenadine was decreased by 37.2% and 27.4% compared with the control, respectively. The mean clearance of fexofenadine was increased by 104.9%. The in vitro study showed that tanshinone IIA and cryptotanshinone could induce MDR1 mRNA. This study showed that multidose administration of danshen ethanol extract could increase oral clearance of fexofenadine. The increased oral clearance of fexofenadine is attributable to induction of intestinal P-glycoprotein.