A reliable method of liquid chromatography for the quantification of acetaminophen and identification of its toxic metabolite N-acetyl-p-benzoquinoneimine for application in pediatric studies

The aim of the present study was to develop a simple, selective and reliable method to quantify acetaminophen and its toxic metabolite N‐acetyl‐p‐benzoquinoneimine (NAPQI) for pediatric studies using 100 µL plasma samples, by reverse‐phase HPLC and UV detection. The assay was performed using a C₁₈ column and an isocratic elution with water–methanol–formic acid (70:30:0.15; v/v/v) as mobile phase. Linearity of the method was assayed in the range of 1–30 µg/mL for acetaminophen and 10–200 µg/mL for NAPQI, with a correlation coefficient r = 0.999 for both compounds, and inter‐ and intra‐day coefficients of variation of less than 13%. Several commonly co‐administered drugs were analyzed for selectivity and no interference with the determinations was observed. The detection and quantification limits for acetaminophen and NAPQI were 0.1 and 1 µg/mL, and 0.1 and 10 µg/mL respectively. The present method can be used to monitor acetaminophen levels using 100 µL plasma samples, which may be helpful when very small samples need to be analyzed, as in pharmacokinetics determination or drug monitoring in plasma in children. This assay is also able to detect the NAPQI for drug monitoring in patients diagnosed with acetaminophen intoxication. Copyright © 2010 John Wiley & Sons, Ltd.     

Simultaneous Spectrofluorimetric Determination of Paracetamol and Caffeine in Pharmaceutical Preparations in Solid‐Phase Using Partial Least Squares Multivariate Calibration

Abstract

Partial least‐squares algorithm (PLS)‐1 was used for the solid‐phase spectrofluorimetric determination of paracetamol (PA) and caffeine (CF) in pharmaceutical formulations. In despite of the closely overlapping spectral bands, the method allows the simultaneous quantification and sample preparation prior to analysis is not required. The calibration set consisted of 96 samples with 100–400 mg/g^?1 PA plus 10–65 mg/g^?1 CF; another set of 25 samples was used for external validation. Agreement between predicted and experimental concentrations was fair (r=0.993 and 0.964 for PA and CF models). Prediction performance was evaluated in terms of the coefficient of variability (CV), relative predictive determination (RPD), and ratio error range (RER). The PLS‐1 model was used for the determination of PA and CF in pharmaceutical formulations.     

Resolution of Ternary and Quaternary Mixtures of Drugs in Pharmaceutical Preparations by Use of Spectrophotometric Data in Conjunction with PLS-1 and PLS-2 Data Processing Methods

Abstract

Two variants of partial least-squares methodology (PLS-1 and PLS-2) have been used for the analysis of ternary and quaternary mixtures of acetaminophen-acetylsalicylic acid-codeine and caffeine, respectively. This methodology permits the simultaneous quantification of the aforementioned drugs even with closely overlapping spectral bands without any separation step. The concentration ranges are 4.0–12.0, 0.2–1.0 and 4.0–12.0 μg·ml^?1 for acetaminophen-acetylsalicylic acid-codeine and 10.0–20.0, 6.0–16.0, 1.0–5.0 and 0.2–1.0 μg·ml^?1 for acetaminophen-acetylsalicylic acid-caffeine and codeine, respectively. A systematic study of the experimental data by applying an exhaustive statistical analysis to demostrate the validity of the proposed methods is presented. The results of the determination of these drugs in pharmaceutical preparations are also presented. The analytical results were quite good in all cases.     

多波长分光光度法测定对乙酰氨基酚合成过程中三组分含量

探讨了在ＨＣＬ体系中用双波长等吸收点分光光度法及系数倍率法同时测定对乙酰氨基酚合成过程中对硝基酚，对氧基酚和对乙酰氨酚三组分含量的可行性，对硝基酚的最大吸收为３１８ｎｍ，线性范围为０－３０ｍｇ／Ｌ；对乙酰基酚的测定波长为２４０ｎｍ，参比波长为３５８ｎｍ；对氨基酚的测定波长为２４０ｎｍ，３５８ｎｍ，３６１ｎｍ。     

Inclusion of Nonopiate Analgesic Drugs in Cyclodextrins. II. X-ray Structure of a 1 : 1 β-Cyclodextrin – Acetaminophen Complex

Single crystals of a 1 : 1 complex between-cyclodextrin (-CD) and the analgesicacetaminophen (paracetamol) have been prepared and themode of inclusion of the drug has been determined fromX-ray data collected at 293 K. Complexcharacterization by UV and thermogravimetric analysesyielded the composition-(CDacetaminophen13.3H₂O. The complex crystallizes in the space group C2 with a =19.207(7), b = 24.48(1), c =15.700(4)Å, = 109.52(2)° and Z = 4complex units in the crystal unit cell. The hostmolecules form dimeric motifs withC₂ crystallographic symmetry which pack in thechannel mode. Guest molecules residing in the hostdimer are disordered, each acetaminophen moleculebeing statistically distributed over two sites withequal occupancy. In each case, the guest hydroxylgroup is located at the host primary face while theacetamide residue lies at the dimer interface. TwoC₂-related water molecules are trapped inside thehost cavity, being hydrogen bonded to theC₂-related carbonyl groups of one of thedisordered guest conformers. Structural features ofthe complex are discussed with reference to recentspectroscopic and other studies aimed at elucidatingthe nature of the interaction between acetaminophenand -CD.     

Electrochemical Behavior and Ultrasensitive,Simple and Effective Voltammetric Determination of Acetaminophen Using Modified Glassy Carbon Electrode Based on 4-Hydroxyquinoline-3-carboxylic Acid

An electrochemical oxidation of acetaminophen (ACOP) has been successfully performed by using glassy carbon electrode covered with 4-hydroxyquinoline-3-carboxylic acid (4HQ3CA) to reinforce electrode's feature. To characterize the modified electrode (4HQ3CA/GC), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and Fourier transform infrared spectroscopy (FT-IR) techniques were used. The finding optimum conditions (supporting electrolyte, pH) and the electrochemical determination studies were performed with differential pulse voltammetry (DPV). It was decided that the supporting electrolyte medium suitable for ACOP determination was Britton-Robinson (BR) buffer and the effect of pH change on the oxidation peak of ACOP in this media was investigated. The effect of changing scan rate on the oxidation peak of ACOP was examined and this study showed that the oxidation process of ACOP on the 4HQ3CA/GC modified electrode surface was diffusion and adsorption controlled process. A wide concentration range from 0.0025 μM to 141 μM with a limit of detection (LOD) of 5.98×10⁻¹⁰ M (3 s/m) was obtained. This prepared sensor was carried out for the determination of ACOP in pharmaceutical sample.     

Hepatoprotective effect of chiisanoside against acetaminophen-induced acute liver injury in mice

This study was designed to investigate the hepatoprotective effect of chiisanoside (CSS) and its possible mechanisms on acetaminophen (APAP)-induced acute liver damage in mice. The serum activities of alanine transaminase (ALT), aspartate transaminase (AST), tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and the hepatic levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA) were determined using the commercially available assay kits. The hepatic mRNA levels were measured by RT-PCR. The hepatic protein expressions of nuclear factor-kappa B (NF-κB), MAPK and their phosphorylated isoforms were evaluated by western blot assays. The results indicated that CSS (240 mg/kg) exhibited the hepatoprotective effects by inhibiting oxidative stress and inflammation on APAP-induced acute liver injury. Furthermore, the anti-inflammatory activity of CSS is largely related to the regulation of the NF-κB and MAPKs signaling pathways. These findings suggested that CSS possessed hepatoprotective effect against APAP-induced hepatotoxicity in mice.     

Preparation and Optimization of PEGylated Nano Graphene Oxide-Based Delivery System for Drugs with Different Molecular Structures Using Design of Experiment (DoE)

Graphene oxide (GO), due to its 2D planar structure and favorable physical and chemical properties, has been used in different fields including drug delivery. This study aimed to investigate the impact of different process parameters on the average size of drug-loaded PEGylated nano graphene oxide (NGO-PEG) particles using design of experiment (DoE) and the loading of drugs with different molecular structures on an NGO-PEG-based delivery system. GO was prepared from graphite, processed using a sonication method, and functionalized using PEG 6000. Acetaminophen (AMP), diclofenac (DIC), and methotrexate (MTX) were loaded onto NGO-PEG particles. Drug-loaded NGO-PEG was then characterized using dynamic light scattering (DLS), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), XRD. The DLS data showed that the drug-loaded NGO-PEG suspensions were in the size range of 200 nm–1.3 µm. The sonication time and the stirring rate were found to be the major process parameters which affected the average size of the drug-loaded NGO-PEG. FTIR, DSC, XRD, and SEM demonstrated that the functionalization or coating of the NGO occurred through physical interaction using PEG 6000. Methotrexate (MTX), with the highest number of aromatic rings, showed the highest loading efficiency of 95.6% compared to drugs with fewer aromatic rings (diclofenac (DIC) 70.5% and acetaminophen (AMP) 65.5%). This study suggests that GO-based nano delivery systems can be used to deliver drugs with multiple aromatic rings with a low water solubility and targeted delivery (e.g., cancer).     

高效液相色谱用蒸发光散射检测器检定方法研究

论述了用胆固醇/甲醇溶液、对乙酰氨基酚/甲醇溶液、咖啡因/甲醇溶液检定蒸发光散射检测器,并且在相同实验条件下进行了3种溶液的性能对比,选取其中性能较好的溶液作为目标溶液进行长期考察,为以后将ELSD纳入液相色谱仪检定规程做准备。