Multidrug and toxin extrusion protein 1-mediated interaction of metformin and Scutellariae radix in rats

A comprehensive review on pharmacokinetic mechanism of herb-herb/drug interactions in Chinese herbal formula

Oral administration of Chinese Herbal Medicine (CHM) faces various challenges in reaching the target organs including absorption and conversion in the gastrointestinal tract, hepatic metabolism via the portal vein, and eventual systemic circulation. During this process, factors such as gut microbes, physical or chemical barriers, metabolic enzymes, and transporters play crucial roles. Particularly, interactions between different herbs in CHM have been observed both in vitro and in vivo. In vitro, interactions typically manifest as detectable physical or chemical changes, such as facilitating solubilization or producing precipitates when decoctions of multiple herbs are administered. In vivo, such interactions cause alterations in the ADME (absorption, distribution, metabolism, and excretion) profile on metabolic enzymes or transporters in the body, leading to competition, antagonism, inhibition, or activation. These interactions ultimately contribute to differences in the therapeutic and pharmacological effects of multi-herb formulas in CHM. Over the past two thousand years, China has cultivated profound expertise and solid theoretical frameworks over the scientific use of herbs. The combination of multiple herbs in one decoction has been frequently employed to synergistically enhance therapeutic efficacy or mitigate toxic and side effects in clinical settings. Additionally combining herbs with increased toxicity or decreased effect is also regarded as a remedy, a practice that should be approached with caution according to Traditional Chinese Medicine (TCM) physicians. Such historical records and practices serve as a foundation for predicting favorable multi-herb combinations and their potential risks. However, systematic data that are available to support the clinical practice and the exploration of novel herbal formulas remain limited. Therefore, this review aims to summarize the pharmacokinetic interactions and mechanisms of herb-herb or herb-drug combinations from existing works, and to offer guidance as well as evidence for optimizing CHM and developing new medicines with CHM characteristics.

No Interference of H9 Extract on Trastuzumab Pharmacokinetics in Their Combinations

Trastuzumab is used to treat breast cancer patients overexpressing human epidermal growth factor receptor 2, but resistance and toxicity limit its uses, leading to attention to trastuzumab combinations. Recently, the synergistic effect of trastuzumab and H9 extract (H9) combination against breast cancer has been reported. Because drug exposure determines its efficacy and toxicity, the question of whether H9 changes trastuzumab exposure in the body has been raised. Therefore, this study aimed to characterize trastuzumab pharmacokinetics and elucidate the effect of H9 on trastuzumab pharmacokinetics at a combination dose that shows synergism in mice. As a result, trastuzumab showed linear pharmacokinetics after its intravenous administration from 1 to 10 mg/kg. In the combination of trastuzumab and H9, single and 2-week treatments of oral H9 (500 mg/kg) did not influence trastuzumab pharmacokinetics. In the multiple-combination treatments of trastuzumab and H9 showing their synergistic effect (3 weeks of trastuzumab with 2 weeks of H9), the pharmacokinetic profile of trastuzumab was comparable to that of 3 weeks of trastuzumab alone. In tissue distribution, the tissue to plasma ratios of trastuzumab below 1.0 indicated its limited distributions within the tissues, and these patterns were unaffected by H9. These results suggest that the systemic and local exposures of trastuzumab are unchanged by single and multiple-combination treatments of H9.

Potential herb‒drug interactions between anti-COVID-19 drugs and traditional Chinese medicine

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread worldwide. Effective treatments against COVID-19 remain urgently in need although vaccination significantly reduces the incidence, hospitalization, and mortality. At present, antiviral drugs including Nirmatrelvir/Ritonavir (PaxlovidTM), Remdesivir, and Molnupiravir have been authorized to treat COVID-19 and become more globally available. On the other hand, traditional Chinese medicine (TCM) has been used for the treatment of epidemic diseases for a long history. Currently, various TCM formulae against COVID-19 such as Qingfei Paidu decoction, Xuanfei Baidu granule, Huashi Baidu granule, Jinhua Qinggan granule, Lianhua Qingwen capsule, and Xuebijing injection have been widely used in clinical practice in China, which may cause potential herb-drug interactions (HDIs) in patients under treatment with antiviral drugs and affect the efficacy and safety of medicines. However, information on potential HDIs between the above anti-COVID-19 drugs and TCM formulae is lacking, and thus this work seeks to summarize and highlight potential HDIs between antiviral drugs and TCM formulae against COVID-19, and especially pharmacokinetic HDIs mediated by metabolizing enzymes and/or transporters. These well-characterized HDIs could provide useful information on clinical concomitant medicine use to maximize clinical outcomes and minimize adverse and toxic effects.

Change of metformin concentrations in the liver as a pharmacological target site of metformin after long-term combined treatment with ginseng berry extract

Metformin as an oral glucose-lowering drug is used to treat type 2 diabetic mellitus. Considering the relatively high incidence of cardiovascular complications and other metabolic diseases in diabetic mellitus patients, a combination of metformin plus herbal supplements is a preferrable way to improve the therapeutic outcomes of metformin. Ginseng berry, the fruit of Panax ginseng Meyer, has investigated as a candidate in metformin combination mainly due to its anti-hyperglycemic, anti-hyperlipidemic, anti-obesity, anti-hepatic steatosis and anti-inflammatory effects. Moreover, the pharmacokinetic interaction of metformin via OCTs and MATEs leads to changes in the efficacy and/or toxicity of metformin. Thus, we assessed how ginseng berry extract (GB) affects metformin pharmacokinetics in mice, specially focusing on the effect of the treatment period (i.e., 1-day and 28-day) of GB on metformin pharmacokinetics. In 1-day and 28-day co-treatment of metformin and GB, GB did not affect renal excretion as a main elimination route of metformin and GB therefore did not change the systemic exposure of metformin. Interestingly, 28-day co-treatment of GB increased metformin concentration in the livers (i.e., 37.3, 59.3% and 60.9% increases versus 1-day metformin, 1-day metformin plus GB and 28-day metformin groups, respectively). This was probably due to the increased metformin uptake via OCT1 and decreased metformin biliary excretion via MATE1 in the livers. These results suggest that co-treatment of GB for 28 days (i.e., long-term combined treatment of GB) enhanced metformin concentration in the liver as a pharmacological target tissue of metformin. However, GB showed a negligible impact on the systemic exposure of metformin in relation to its toxicity (i.e., renal and plasma concentrations of metformin).

Rutaecarpine enhances the anti-diabetic activity and hepatic distribution of metformin via up-regulation of Oct1 in diabetic rats

Diabetes mellitus is a chronic metabolic disorder with multiple complications, patients who receive metformin may have a simultaneous intake of herbal medicine containing rutaecarpine due to cardiovascular protection and hypolipidemic effects of rutaecarpine. There might be drug interactions between metformin and rutaecarpine. This study aimed to investigate the effects of rutaecarpine on the pharmacodynamics and pharmacokinetics of metformin in diabetic rats.The diabetic rat model was induced with high-fat diet and low dose streptozotocin. Metformin with or without rutaecarpine was administered by oral gavage for 42 days. Pharmacodynamics and pharmacokinetics parameters were evaluated.The pharmacodynamics results revealed that co-administration of rutaecarpine with metformin resulted in a remarkable reduction of serum glucose and lipid profiles in diabetic rats compared to metformin treated alone. The pharmacokinetics results showed that co-treatments of rutaecarpine with metformin did not affect the systemic exposure and renal distribution of metformin, but increased metformin concentration in liver. Furthermore, rutaecarpine increased Oct1-mediated metformin uptake into hepatocytes by upregulation of Oct1 expression in the liver.The above data indicate that rutaecarpine enhanced the anti-diabetic effect of metformin, which may be associated with the increased hepatic distribution of metformin through up-regulation of Oct1 in response to rutaecarpine.

Drug-herb interactions between Scutellaria baicalensis and pharmaceutical drugs: Insights from experimental studies, mechanistic actions to clinical applications

Whilst the popular use of herbal medicine globally, it poses challenges in managing potential drug-herb interaction. There are two folds of the drug-herb interaction, a beneficial interaction that may improve therapeutic outcome and minimise the toxicity of drug desirably; by contrast, negative interaction may evoke unwanted clinical consequences, especially with drugs of narrow therapeutic index. Scutellaria baicalensis Georgi is one of the most popular medicinal plants used in Asian countries. It has been widely used for treating various diseases and conditions such as cancer, diabetes, inflammation, and oxidative stress. Studies on its extract and bioactive compounds have shown pharmacodynamic and pharmacokinetic interactions with a wide range of pharmaceutical drugs as evidenced by plenty of in vitro, in vivo and clinical studies. Notably, S. baicalensis and its bioactives including baicalein, baicalin and wogonin exhibited synergistic interactions with many pharmaceutical drugs to enhance their efficacy, reduce toxicity or overcome drug resistance to combat complex diseases such as cancer, diabetes and infectious diseases. On the other hand, S. baicalensis and its bioactives also affected the pharmacokinetic profile of many drugs in absorption, distribution, metabolism and elimination via the regulatory actions of the efflux pumps and cytochrome P450 enzymes. This review provides comprehensive references of the observed pharmacodynamic and pharmacokinetic drug interactions of Scutellaria baicalensis and its bioactives. We have elucidated the interaction with detailed mechanistic actions, identified the knowledge gaps for future research and potential clinical implications. Such knowledge is important for the practice of both conventional and complementary medicines, and it is essential to ensure the safe use of related herbal medicines. The review may be of great interest to practitioners, consumers, clinicians who require comprehensive information on the possible drug interactions with S. baicalensis and its bioactives.

Combined effects of Scutellaria baicalensis with metformin on glucose tolerance of patients with type 2 diabetes via gut microbiota modulation

Metformin is a widely prescribed antidiabetic agent, whereas Scutellaria baicalensis (SB) is a commonly used medicinal herb for treatment of type 2 diabetes (T2D). Gut microbiota is involved in pathophysiology of metabolic diseases including T2D, and intestinal microbiota may be one of the important therapeutic targets for the ailment. This study was conducted to investigate the effects of SB combined with metformin on treatment of T2D while evaluating changes in the gut microbiota composition. Patients with T2D were randomized into control and treatment groups. Subjects who had already been prescribed metformin were allotted to additional SB (3.52 g/day) group or placebo group. The initial treatment session was 8 wk, and after washout period for 4 wk they were crossed over to the opposite treatment for another 8 wk. The influence of SB and placebo on the intestinal microbiota was analyzed by MiSeq system based on 16S rRNA gene. Glucose tolerance was lower in the SB group than the placebo group. Similarly, the relative RNA expression of TNF-α was significantly reduced after SB treatment. SB treatment influenced the gut microbiota, especially Lactobacillus and Akkermansia, which showed remarkable increases after SB treatment. Some subjects showed high liver enzyme levels after SB treatment, and their microbiota composition at baseline differed with subjects whose liver enzymes were not affected. We also predicted that selenocompound metabolism was increased and naphthalene degradation was decreased after SB treatment. These results suggest that SB with metformin treatment may improve the glucose tolerance and inflammation and influence the gut microbiota community in T2D.

Lonicera japonica extract increases metformin distribution in the liver without change of systemic exposed metformin in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Flower and flower bud of Lonicera japonica, Lonicerae Flos, have been popularly used as medicinal plant for the treatment of clearing heat and thirst, thereby improving diabetic or diabetic associated symptoms (thirst and poor eyesight).

AIM OF THE STUDY

Organic cation transporters (OCTs) and multi-drug and toxin extrusion proteins (MATEs) are known to play important roles in metformin transport in the liver and kidneys. Thus, there might be interactions between Lonicerae Flos and metformin via OCTs and MATEs. Also treatment period has been issued in transporter-mediated drug interactions. The objective of this study was to determine the effect of Lonicerae Flos ethanol extract (LJ) on metformin pharmacokinetics and its glucose lowering activity in different treatment periods.

MATERIALS AND METHODS

Effect of LJ on metformin uptake was evaluated in vitro HEK-293 cells expressing human OCTs or MATEs. Treatment period-dependent impact of LJ on systemic exposure and hepatic distribution of metformin as well as its glucose tolerance activity were assessed in in vivo rats.

RESULTS

LJ substantially inhibited MATE1-mediated metformin uptake in vitro. In evaluating treatment period effects of LJ and metformin, 1-, 7-, and 28-day co-treatments of LJ with metformin did not change systemic exposure of metformin compared to those in metformin alone. Whereas, 28-day co-treatment of LJ with metformin increased metformin concentration in liver as a pharmacological target site of metformin. It could be due to the reduced MATE1-mediated metformin efflux from hepatocytes to bile by MATE1 inhibition in liver. Glucose tolerance activity was also enhanced by 28-day co-treatment of LJ and metformin compared to metformin alone.

CONCLUSIONS

In 28-day co-treatment of LJ and metformin, LJ increased metformin concentration in liver and improved glucose tolerance activity without systemic exposure change of metformin, suggesting the importance to consider treatment period effect and both systemic exposure and tissue distribution in drug interactions.