N-acetylcysteine amide (NACA) is the amide derivative of N-acetylcysteine (NAC) that is rapidly converted to NAC after systemic administration. It has emerged as a promising thiol antioxidant for multiple indications; however, the pharmacokinetic property is yet unclear due to lack of an accurate quantification method. The present investigation aimed to develop an analytical method for simultaneous quantification of NACA and NAC in plasma. A new reagent (2-(methylsulfonyl)-5-phenyl-1,3,4-oxadiazole, MPOZ) was introduced for thiol stabilization during sample processing and storage. Further, we utilized tris (2-carboxyethyl) phosphine (TCEP) to reduce the oxidized forms of NACA and NAC. After derivatization, NACA-MPOZ and NAC-MPOZ were quantified using liquid chromatography-mass spectrometry (LC-MS). The new method was validated and found to have high specificity, linearity, accuracy, precision, and recovery for the quantification of NACA and NAC in plasma. Furthermore, the formed derivatives of NACA and NAC were stable for 48 h under different conditions. The method was utilized in pharmacokinetic study which showed that the bioavailability of NACA is significantly higher than NAC (67% and 15%, respectively). The pharmacokinetic of NACA obeyed a two-compartment open model. The glutathione (GSH)-replenishing capacity was found to be three to four-fold higher after the administration of NACA compared to that observed after the administration of NAC. In conclusion, the present method is simple, robust and reproducible, and can be utilized in both experimental and clinical studies. NACA might be considered as a prodrug for NAC. Furthermore, this is the first report describing the pharmacokinetics and bioavailability of NACA in mouse.

中文翻译：

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使用新的分析方法，N-乙酰半胱氨酸酰胺及其主要代谢产物在小鼠体内的药代动力学概况。

N-乙酰半胱氨酸酰胺（NACA）是N-乙酰半胱氨酸（NAC）的酰胺衍生物，在全身给药后迅速转化为NAC。它已成为一种有前景的硫醇抗氧化剂，可用于多种适应症。然而，由于缺乏准确的定量方法，其药代动力学性质尚不清楚。本研究旨在开发一种同时定量血浆中NACA和NAC的分析方法。引入了一种新试剂（2-（甲基磺酰基）-5-苯基-1,3,4-恶二唑，MPOZ），用于在样品处理和存储过程中稳定硫醇。此外，我们利用三（2-羧乙基）膦（TCEP）还原了NACA和NAC的氧化形式。衍生化后，使用液相色谱-质谱法（LC-MS）对NACA-MPOZ和NAC-MPOZ进行定量。经过验证，该新方法具有定量，线性，准确性，精密度和回收率高的特点，可用于血浆中NACA和NAC的定量分析。此外，所形成的NACA和NAC的衍生物在不同条件下稳定48小时。该方法用于药代动力学研究，结果表明NACA的生物利用度显着高于NAC（分别为67％和15％）。NACA的药代动力学服从两室开放模型。发现与施用NAC后观察到的相比，补充NACA后补充谷胱甘肽（GSH）的能力高三至四倍。总之，本方法简单，稳健且可重现，可用于实验和临床研究。NACA可能被视为NAC的前药。此外，