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The metabolism study of radiolabeled drugs plays an important role in the development of new drugs. It provides information on drug absorption, metabolism, tissue distribution and excretion, and plays an irreplaceable role in the metabolite safety evaluation and mass balance of new drugs. The new guidance draft on clinical trials of radiolabeled drugs recently released by the US FDA puts forward higher standards and has been widely concerned by the industry. In recent years, in the research and development of new drugs in China, 14C labeled drugs have been used to carry out clinical metabolism studies, which has overcome key technical bottlenecks and accumulated experience. This paper summarizes the above research progress, analyzes the existing problems, and preliminarily looks forward to the future technological development and application.
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Rocuronium bromide is an acetylcholine N2 receptor antagonist, which can be used as an auxiliary drug for general anesthesia. It has been reported that rocuronium has two possible metabolic pathways: N-dealkylation and O-deacetylation, which are mainly taken up by liver and excreted by bile in the form of primary drugs. In this paper, the metabolites of rocuronium in human bile were detected by UHPLC-QE-orbitrap-MS, thirteen metabolites were detected, including eleven phase I metabolites and two phase II metabolites, eleven of which had not been previously reported. At the same time, HEK293 cells overexpressing transporter were used to explore the transmembrane transport mechanism of rocuronium, the results showed that rocuronium was the substrate of MATE1, OCT1, OATP1B1 and OATP1B3. The above research results enrich the metabolic pathway of rocuronium in vivo, and put forward the possible transport mechanism of liver uptake and bile excretion, which can better guide the accurate and safe clinical drug application. The collection of human bile samples in this study was approved by the ethics committee of Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine (Approval Number: 2019-775-130-01).
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FGF21-164 is a fusion protein obtained by structural modification and coupling of endogenous FGF21. It is a candidate drug used in the treatment of glucose and lipid metabolic disorders caused by obesity. In this study, the candidate peptide mass spectrometry information of the protein hydrolyzed by trypsin was predicted by Skyline software and verified by high resolution mass spectrometry. The specific surrogate peptide (YLYTDDAQQTEAHLEIR) with the best mass response was selected after optimizing ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Under ESI positive ion mode, the parent ion m/z 689.3 with 3 charge and the product ion m/z 738.4 with single charge can be monitored. After dilution by PBS, the serum samples were denatured under 60 ℃ and alkylated to reduce the matrix effect, then incubated with trypsin at 37 ℃ for 2 h, to obtain the surrogate peptide. The chromatographic separation was carried out on an EclipsePlus C18 column (2.1 mm×50 mm, 1.8 μm) using aqueous solution containing 0.1% formic acid (phase A) and acetonitrile solution containing 0.1% formic acid (phase B). Finally, the concentration of FGF21-164 fusion protein in mouse serum was quantitatively analyzed by external standard method by monitoring the above ion pairs using triple quadrupole mass spectrometer. This method showed a good linearity in the range of 2.50-500 μg·mL-1 (r = 0.998 8), and was successfully applied to the pharmacokinetic study of FGF21-164 fusion protein in mice. This experiment was approved by the Experimental Animal Ethics Committee of Shanghai Institute of Materia Medica, Chinese Academy of Sciences (batch number: 20180004040450). Compared with the endogenous FGF21, the t1/2 of FGF21-164 fusion protein was prolonged from 0.5 h to 2.6 h, which is expected to prolong the therapeutic efficacy of this protein.
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ZSP1601, a novel pan-phosphodiesterase inhibitor is in development for the treatment of nonalcoholic steatohepatitis. A physiologically-based pharmacokinetic (PBPK) model was developed to predict the pharmacokinetics of ZSP1601 in human. The PBPK model following intravenous and oral dose of ZSP1601 in rats and dogs was firstly built using preclinical in vitro and in vivo data. The PBPK model in human was then built based on models in animal. The in vitro-in vivo extrapolation (IVIVE) method and some allometric scaling methods were used to predict the clearance in human, respectively. The PBPK models using IVIVE and allometry of unbound CL plus the rule of exponents methods predicted the pharmacokinetics of ZSP1601 in healthy Chinese subjects successfully. The predicted parameters Cmax and AUC following single oral dose administration were within 0.5-2 folds of the observed data. The model was optimized and the final model was used to predict the pharmacokinetics of ZSP1601 in North European Caucasian, Geriatrics, Obese and Morbidly Obese, respectively. Animal studies were approved by the Animal Management and Use Committee of Suzhou AppTec Inc., and the approved No. is SZ20140916.
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Liquid chromatography-tandem mass spectrometry (LC-MS) is a promising alternative or complementary method for traditional ligand-binding assays (LBA) in antibody drug bioanalysis. However, issues related to method development, sample preparation, sensitivity and quantitative accuracy need to be addressed. This paper reviews progress in bioanalysis of antibody drugs by LC-MS methods, introduces the principle of the LC-MS method for the analysis of antibody drugs, and describes the challenges faced in quantitative antibody analysis by the LC-MS method. New strategies that can be used to deal with these challenges include: selection of surrogate peptides, purification and enrichment of samples, improvement in enzymatic digest efficiency, enrichment of peptides, and use of low rate LC. We review the application of LC-MS technology in the biological analysis of antibody drugs and discuss the prospect of using the LC-MS method for the analysis of antibody drugs.
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Based on Chinese clinical guidance for COVID-19 pneumonia diagnosis and treatment (7th edition), the metabolism and pharmacokinetics of drugs used in clinical treatment of COVID-19 were reviewed. The antiviral drugs include remdesivir, chloroquine/hydroxychloroquine, lopinavir/ritonavir, favipiravir, arbidol, baicalin, baicalein and forsythin. Among them, the metabolism and pharmacokinetics of arbidol, baicalin and forsythin are the research results of the author's laboratory. This article aims to provide reference for the efficacy evaluation and rational drug use of COVID-19.
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Nifedipine, a calcium channel antagonist, is metabolized mainly by CYP3A4 to dehydronifedipine. A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to simultaneously determine nifedipine and dehydronifedipine in human plasma using d6-nifedipine/d6-dehydronifedipine as internal standards. After extraction from the plasma by protein precipitation, the analytes and internal standard were separated on a Hypersil Gold C18 (50 mm×2.1 mm, 1.9 μm). The mobile phase consisted of methanol and 5 mmol·L-1ammonium acetate aqueous solution (0.1% formic acid). Positive electrospray ionization was performed using multiple reaction monitoring (MRM) with transitions of m/z 347.3→254.1 for nifedipine, m/z 345.2→283.9 for dehydronifedipine, m/z 353.3→257.1 for d6-nifedipine, m/z 351.2→286.9 for d6-dehydronifedipine. The method had a linear calibration curves over the concentrations of 0.10-80.0 ng·mL-1 for nifedipine and 0.050-40.0 ng·mL-1 for dehydronifedipine. The validated LC-MS/MS method has been successfully used study pharmacokinetic interactions of apatinib (CYP3A4 inhibitor) and nifedipine (CYP3A4 substrate) in human. This clinical trial was approved by the society of ethics and conducted in the first hospital of China medical university.
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Covalent tyrosine kinase inhibitors (TKIs) can inhibit the signaling pathway of tumor cells by covalent binding with cysteine residues of target proteins, which has the advantages of high potency, extended duration of action and overcoming drug resistance. In this article, we will review the metabolism and pharmacokinetics of some covalent TKIs. Currently, the covalent TKIs approved by US food and drug administration (FDA) are afatinib, neratinib, dacomitinib, osimertinib, ibrutinib and acalabrutinib. Pyrotinib have been approved by National Medical Products Administration (NMPA) to reach the market recently. Covalent TKIs can covalently bind with plasma proteins, especially human serum albumin, thus effected the pharmacokinetics of these drugs.
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The purpose of current study is to investigate the metabolic profile of a triptolide derivative (5R)-5-hydroxytriptolide in vitro. (5R)-5-Hydroxytriptolide was incubated with the hepatocytes of human, monkey, dog, rat or mouse, respectively. Compared with inactivated hepatocytes, four metabolites were identified in hepatocytes from all five species: oxidative ring-opening metabolite (M1), glutathione-conjugating metabolite (M2), and monooxidative combined with glutathione-conjugating metabolites (M3-1 and M3-2), respectively. In human or rat liver microsomes, seven metabolites of (5R)-5-hydroxytriptolide were found, dehydrogenated metabolite (M4) and monooxidative metabolites (M5-1–M5-6), respectively. Reference standards for the metabolites were obtained either through chemical semisynthesis or biotransformation through rat primary hepatocytes. The structures of five metabolites were confirmed, which were 12,13-epoxy ring-opening metabolite M1, 12-glutathione-conjugating metabolite M2, (16S)-, (2R)- and (19R)-monohydroxylated metabolites M5-1, M5-4, and M5-5, respectively. In vitro activity assay revealed that only (2R)-hydroxylated metabolite exhibited weak immunosuppressive activity with less than one-tenth the activity of its parent drug, and a significant decrease in toxicity was observed. It is suggested that (5R)-5-hydroxytriptolide might undergo metabolic inactivation and detoxification in vivo.
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An LC-MS/MS method was developed for the simultaneous determination of fosaprepitant and aprepitant in human plasma, and applied to a pharmacokinetic study of 150 mg fosaprepitant dimeglumine injection to 12 Chinese healthy volunteers. The analytes and internal standards were extracted from plasma by protein precipitation with acetonitrile and separated on a Cortex C18+ (50 mm×2.1 mm, 2.7 μm) column using a gradient elution procedure. Mass spectrometry was performed in negative MRM mode, and parent-to-produce transitions were as follows:m/z 613.1→78.9 for fosaprepitant, m/z 617.0→78.9 for d4-fosaprepitant, m/z 533.2→275.1 for aprepitant and m/z 537.2→279.1 for d4-aprepitant. Plasma sample was basified to stabilize fosaprepitant. The standard curves were demonstrated to be liner in the range of 15.0 to 6 000 ng·mL-1 for fosaprepitant and 10.0 to 4 000 ng·mL-1 for aprepitant. The intra-day precisions and inter-day precisions and accuracy were within the acceptable limits for all concentrations.