Evaluation of potential herb-drug interactions based on the effect of Suxiao Jiuxin Pill on CYP450 enzymes and transporters

Abstract

Ethnopharmacology relevance

Suxiao jiuxin pill (SJP) is a Chinese medical drug with anti-inflammatory, anti-apoptotic, and vasodilatory function. It is widely used in combination with other drugs for the treatment of coronary heart disease (CHD) and angina. Nevertheless, the effect of SJP on Cytochrome P450 (CYP450) enzymes and transporters’ activity related to drug metabolism is rarely studied.

Objective

The aim of this study was to investigate the effect of SJP on the activity of drug-metabolizing enzyme CYP450 and transporters.

Materials and methods

Human primary hepatocytes were used in present study. Probe substrates of CYP450 enzymes were incubated in human liver microsomes (HLMs) with and without SJP while IC₅₀ values were calculated. The inhibitory effect of SJP on the activity of CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6 and 3A4 was evaluated. The inducing effect of SJP on the activity of CYP1A2, 2B6 and 3A4 was accessed. The inhibition of SJP on human OATP1B1 was investigated through cell-based assay. The inhibition of SJP on human MDR1 and BCRP was also estimated by means of the vesicles assay.

Results

The results showed that the SJP under the concentration of 1000 μg/mL could inhibit the activity of CYP1A2, 2B6, 2C19, and 3A4, with IC₅₀ values of 189.7, 308.2, 331.2 and 805.7 μg/mL, respectively. There was no inhibitory effect found in the other 3 liver drug enzyme subtypes. In addition, SJP showed no induction effect on CYP1A2, 2B6 and 3A4, however it had a significant inhibitory effect on human-derived OATP1B1 at the concentration of 100 and 1000 μg/mL, with the IC₅₀ value of 21.9 μg/mL. Simultaneously, the SJP inhibited BCRP at high concentration of 1000 μg/mL but did not affect human MDR1.

Conclusions

Based on these research results above, it is suggested that the SJP can affect some of the CYP450 enzymes and transporters' activity. When used in combination with related conventional drugs, potential herb-drug interactions should be considered.

Introduction

Clinically, it is very common to combine multiple drugs for a better efficacy, especially when treating the elderly patients with cardiovascular and cerebrovascular diseases. Drug combination increases the incidence of drug interactions which potentially impacts the therapeutic effect, and also leads to more adverse events. Previous studies have shown that 15%–19% of adverse reactions were caused by drug interactions (Pirmohamed et al., 2004), among which the interaction of the drug metabolic stage plays the main role, accounting for about 40% of pharmacokinetic interactions (Sun and Miao, 2012).

Metabolic drug interaction refers to the interaction in the metabolic link that occurs when two or more drugs are administered simultaneously or sequentially. The liver is the main site of drug metabolism that mainly includes the oxidation, reduction, and hydrolysis reactions involved in the Cytochrome P450 (CYP450) enzyme system in stage I and the binding reactions of glucuronidation, sulfation, and acetylation in stage II (Krishna and Klotz, 1994). Among which, the oxidation reaction of stage I has a leading role in drug metabolism (Krishna and Klotz, 1994). CYP450 enzymes are a large family of supergenes composed of many isoenzymes highly produced in the liver, which play a decisive role in the biotransformation of a large number of drugs with different structures (Yan and Caldwell, 2001). The drug absorption, distribution, metabolism, and excretion are very complicated processes. In addition to the liver's metabolic transformation, membrane transporters can actively transport drugs in and out of the cells, balance the concentration of drugs in cells, and show great potential in changing drug metabolism (DeGorter et al., 2012).

With the increasing use of traditional Chinese medicines (TCM), TCM and conventional drugs have been widely used to prevent and treat cardiovascular diseases, such as hypertension, coronary heart disease (CHD) and heart failure. Therefore, the interactions between TCM and conventional drugs has recently gained increasing interest among the research community (Li and Xu, 2013). However, many researches on herb-drug interactions have focused on single herb or monomer, such as salvianolic acid B is the major components of Salvia miltiorrhiza (Danshen), which can obviously speed up the metabolism of losartan by inducing the activity of CYP3A4/CYP2C9 and expression (Wang et al., 2016). The TCM Ginkgo biloba extract has been employed for a variety of medicinal purposes, including improving the peripheral and cerebral circulation for the treatment of vascular disorders and enhancing the blood flow to the brain for ameliorating Alzheimer's disease (McKenna et al., 2001). The high dose of Ginkgo biloba extract significantly increased the maximum blood concentration (C_max) and the area under the curve (AUC_0-∞) of the clopidogrel active metabolite, compared with rats without Ginkgo biloba extract (Deng et al., 2016). However, TCM compounds are more widely used than single herb or monomer. While it is still a challenge to study the metabolic interaction between TCM compounds and other drugs due to the complexity of these compounds' composition.

Suxiao jiuxin pill (SJP) is composed of Rhizome Ligusticum Chuanxiong (Chuanxiong, Ligusticum chuanxiong Hort.) and Borneolum Syntheticum (Bingpian). Chemical studies have revealed that the 36 components of SJP include 6 phenolic acids (such as ferulic acid and vanillic acid), 28 phthalides (such as ligustilide and senkyunolide A), ligustrazine and Borneolum Syntheticum were identified through UPLC-Q/TOF-MS (Lei et al., 2018). At the same time, we determined 8 components in SJP which reflected in the supplemental materials, and the specific situation of main components of SJP is presented in Table 1. It is the first pure traditional Chinese medicine dropping pill in the Pharmacopoeia of the People's Republic of China (Wu et al., 2019). It has been clinically used in China for over 40 years. Previous studies have shown that SJP has anti-inflammatory, anti-apoptotic, and vasodilatory properties (Bai et al., 2014; Lei et al., 2019; Li et al., 2018). It is used to control the acute attack of angina pectoris by reducing the frequency of angina pectoris attack and improving patients' cardiac function with acute coronary syndrome after percutaneous coronary intervention (PCI) (Ren et al., 2018; Shen et al., 2020). SJP is commonly applied in combination with other drugs such as aspirin, nitroglycerin, metoprolol, and statins. Meta-analysis has shown that this combination can reduce nitroglycerin in patients with CHD and may further improve the symptoms of angina pectoris compared to SJP alone (Duan et al., 2008). Clinically, the herb-drug interactions is often ignored. There is a relative lack of understanding of potential drug interactions in combination with Western medicine, including SJP, which may affect the medication's effectiveness and safety.

In this study, to provide a theoretical basis for the clinical safe and effective combination of SJP and other conventional drugs. We provided the incubation system of human liver microsomes (HLMs), human primary hepatocytes, and transporter vesicles in vitro in accordance with the guidance for industry drug interaction studies from the FDA (U.S. Department of Health and Human Services., Food and Drug Administration., Center for Drug Evaluation and Research CDER, 2017b). Evaluate the inhibitory effect of SJP on 7 liver drug enzymes (CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4) and 3 transporters [multidrug resistance proteins1 (MDR1), breast cancer resistance protein (BCRP), and organic anion transporting polypeptide 1B1 (OATP1B1)] involved in drug metabolism, and the induction effect on 3 liver drug enzymes (CYP1A2, 2B6, and 3A4).