No abstract

Acetaminophen (APAP) is a widely used analgesic and antipyretic drug. It is mainly metabolized by phase 1 and 2 reactions in the liver, and thus it could be involved in many drug-drug interactions. Therefore, the study of APAP metabolism is important in toxicological and pharmacokinetic studies. The objective of this study was to develop a rapid and sensitive method for the determination of APAP and its six metabolites in rat plasma for the pharmacokinetic studies. APAP and its metabolites were separated through a Capcell Pak MGII C(18) column and quantitated with a 16 min run in a triple-quadruple mass spectrometer. The mobile phases were composed of 0.1% formic acid in either 95% water or 95% acetonitrile and analysis was performed twice in positive and negative modes. Validations such as accuracy, precision, recovery, matrix effect and stability were found to be within acceptance criteria of validation guidelines, indicating that the assay was applicable to the determination of the plasma concentrations of drug and its six metabolites. In conclusion, we developed an LC-MS/MS method for the quantitative analysis of APAP and its six metabolites in rat plasma, and this method appears to be useful for pharmacokinetic/toxicokinetic studies of APAP and its metabolites in rats.

The identification of biomarkers for the early detection of acute kidney injury (AKI) is clinically important. Acute kidney injury (AKI) in critically ill patients is closely associated with increased morbidity and mortality. Conventional biomarkers, such as serum creatinine (SCr) and blood urea nitrogen (BUN), are frequently used to diagnose AKI. However, these biomarkers increase only after significant structural damage has occurred. Recent efforts have focused on identification and validation of new noninvasive biomarkers for the early detection of AKI, prior to extensive structural damage. Furthermore, AKI biomarkers can provide valuable insight into the molecular mechanisms of this complex and heterogeneous disease. Our previous study suggested that pyruvate kinase M2 (PKM2), which is excreted in the urine, is a sensitive biomarker for nephrotoxicity. To appropriately and optimally utilize PKM2 as a biomarker for AKI requires its complete characterization. This review highlights the major studies that have addressed the diagnostic and prognostic predictive power of biomarkers for AKI and assesses the potential usage of PKM2 as an early biomarker for AKI. We summarize the current state of knowledge regarding the role of biomarkers and the molecular and cellular mechanisms of AKI. This review will elucidate the biological basis of specific biomarkers that will contribute to improving the early detection and diagnosis of AKI.

To evaluate the metabolic interaction between host and gut microflora on drug metabolism, pseudo germ-free rats were prepared with an antibiotics cocktail to change their gut conditions. The usefulness of the pseudo germ-free model was evaluated for observing the DMPK of acetaminophen (APAP). Pseudo germ-free rats were prepared by orally administering antibiotic cocktails consisting of bacitracin, streptomycin and neomycin, and then APAP was orally administered to control and pseudo germ-free rats. The plasma concentration of APAP and its six metabolites were quantified using a validated LC-MS/MS method. A non-compartment model estimated the pharmacokinetic parameters of APAP and its metabolites, and the ratios of the area under curve (AUC; AUC(metabolite) /AUC(APAP) ) were also observed to evaluate the change of APAP metabolism. The AUCs of APAP and APAP-Glth (glutathione) were higher and the AUC(APAP-Sul) /AUC(APAP) (metabolic efficiency of sulfate conjugation) was lower in pseudo germ-free rats than those in the control rats. The decrease in metabolic efficiency of sulphate conjugation could result from the reduction of the sulphate supply, causing an increase of the AUC of APAP and APAP-Glth. The activities of gut microflora can affect the state of hepatic sulphate for drug conjugation, indirectly leading to characteristic APAP metabolism. These results indicate that gut microflora may play an important role in the pharmacokinetics and metabolism of APAP. Thus, the metabolic interaction between host and gut microflora should be considered upon drug administration and pseudo germ-free rats prepared in the present study can be competent for investigating the metabolic interaction between host and gut microflora on drug metabolism.