正-丁苯酞在大鼠和人体内、外代谢产物的初步鉴定及与肝CYP450同工酶的相互作用

目的：对正-丁苯酞（n-Butylphthalide，NBP）进行系统的药物代谢和与药酶相互作用的研究。方法：采用稳定同位素示踪和LC-MS／MS相结合的技术，研究NBP在大鼠、人体外和体内的代谢产物，利用体外肝微粒体法配合体内实验鉴定了参与NBP代谢的CYP450同工酶类型，探讨其与CYP450主要同工酶之间的代谢性相互作用。结果：初步鉴定了NBP在人体外肝微粒体孵育液、尿液和血浆中的9种I相代谢产物及相关Ⅱ相结合产物，新发现NBP在大鼠体外肝微粒体孵育液、尿液和粪便中的7种I相代谢产物。大鼠和人体参与NBP代谢的主要CYP450同工酶是CYP2E、3A和2C；发现NBP在大鼠和人体内各产物的生成均由多个同工酶催化完成，同一种同工酶也参与了多个NBP产物的生成，但参与各个产物生成的同工酶的种类和比例略有不同。当大鼠体外NBP浓度达到50μM时对CYP2C有一定抑制作用，达到200μM时对CYP1A、2C和2D有一定抑制作用；人体外NBP浓度达到15μM时对CYP2C19有一定抑制作用；大鼠NBP灌胃给药160mg·kg-1（连续5日）和静脉给药20mg·kg-1（连续4日）对肝脏CYP450主要同工酶不存在具有临床意义的诱导和抑制效应。结论：本研究较全面地获得了NBP在大鼠和人体内的代谢途径信息，为安全、合理用药、预测药物代谢性相互作用，以及新药的进一步开发提供了有价值的参考依据。

Current progress in the treatment of chronic hepatitis C

Over the last decade, the standard of care for the treat- ment of chronic hepatitis C has been the combination of pegylated-interferon-alfa （PEG-IFN） and ribavirin （RBV） which results in sustained virological response （SVR） rates of 75%-85% in patients with genotypes 2 or 3 but only of 40%-50% in patients with genotype 1. Cur- rently, there are rapid and continuous developments of numerous new agents against hepatitis C virus （HCV）, which are the focus of this review. Boceprevir and tela- previr, two first-generation NS3/4A HCV protease inhibi- tors, have been recently licensed in several countries around the world to be used in combination with PEG- IFN and RBV for the treatment of genotype 1 patients. Boceprevir or telaprevir based triple regimens, com- pared with the PEG-IFN/RBV combination, improve the SVR rates by 25%-31% in treatment-naTve genotype 1 patients, by 40%-64% in prior relapsers, by 33%-45% in prior partial responders and by 24%-28% in prior null responders. At the same time, the application of response-guided treatment algorithms according to the on-treatment virological response results in shortening of the total therapy duration to only 24 wk in 45%-55% of treatment-na＇ive patients. There are, however, several challenges with the use of the new triple combinations in genotype 1 patients, such as the need for immediate results of HCV RNA testing using sensitive quantitative assays, new and more frequent adverse events （anemia and dysgeusia for boceprevir; pruritus, rash and anemia for telaprevir）, new drug interactions and increasing dif- ficulties in compliance. Moreover, the SVR rates are still poor in very difficult to treat subgroups of genotype 1 patients, such as null responders with cirrhosis, while there is no benefit for patients who cannot tolerate PEG- IFN/RBV or who are infected with non-1 HCV genotype. Many newer anti-HCV agents of different classes and numerous combinations are currently under evaluation with encouraging results. Preliminary data suggest that the treatment of chronic HCV patients with well toler- ated combinations of oral agents without PEG-IFN is feasible and may lead to a universal HCV cure over the next 5-10 years.

Carboxylesterases mediated herb-drug interactions:a systematic review

Esterases participate in the metabolism of^10%of the clinical drugs that contain ester or amide bonds,but the esterases mediated drug/herb-drug interactions(DDIs or HDIs)have not been reviewed in depth.Carboxylesterases(CEs),the most abundant esterases expressed in the metabolic organ of mammals,play a pivotal role in hydrolysis of a variety of endogenous and xenobiotic esters.In the human body,two predominant carboxylesterases including hCE1 and hCE2 have been identified and extensively studied over the past decade.These two enzymes have been found with hydrolytic activity towards a variety of endogenous esters and ester-containing drugs.Recent studies have demonstrated that strong inhibition on hCEs may slow down the hydrolysis of CEs substrates,which may affect their pharmacokinetic properties and thus trigger potential DDIs or HDIs.Over the past decade,many herbal extracts and herbal constitutes have been found with strong inhibitory effects against CEs,and their potential risks on herb-drug interactions(HDIs)have also attracted much attention.This review focused on recent progress in hCEs mediated herb-drug interactions.The roles of hCEs in drug metabolism,the inhibitory capacities and inhibition mechanism of a variety of herbal extract and herbal constitutes against hCEs have been well summarized.Furthermore,the challenges and future perspectives in this field are highlighted by the authors.All information and knowledge presented in this review will be very helpful for the pharmacologists to deeper understand the metabolic interactions between herbal constituents and hCEs,as well as for clinical clinicians to reasonable use herbal medicines for alleviating hCEs-associated drug toxicity or avoiding the occurrence of clinically relevant hCEs-mediated HDIs.

Herb-drug enzyme-mediated interactions and the associated experimental methods： a review

OBJECTIVE: To review the interactions between herbs and widely used drugs and summarize the associated experimental methods.METHODS: Definite herb-drug interactions were obtained by searching Pub Med, other large overseas databases and summarizing new researches from China. We summarize some methods to assess the interaction between herbs and drugs involving microsomal, cell culture and animal experiments, and clinical trials, classifying this method as single ingredient herbs, crude herb extracts, andherbal formulae.RESULTS: Many herbs interact with drugs through a complex cytochrome P450 and/or P-glycoprotein mechanism. Herb-induced enzyme inhibition and/or induction may result in enhanced and / or decreased plasma, tissue, urine and bile drug concentrations, leading to a change in a drug's pharmacokinetic parameters and resulting in the improper treatment of patients and potentially severe side effects. Use of an appropriate method for comprehensively assessing herb-drug interactions can minimize clinical risks. Different methods were used by researchers to assess the pharmacological changes of drugs in vivo and in vitro and the mechanisms of the interactions from microsomal, cell culture and animal experiments, and clinical trials are discussed in this review.CONCLUSION: Co-medication with herbs can result in changes in pharmacological effects of many drugs. This review describes the assessment of single-ingredient herbs, crude herb extracts, and herbal formulae. When choosing a research method to investigate herb-drug interactions, the properties of the drugs and herbs should be considered.