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

Brij 35 inhibited the CYP2E1-mediated metabolism and P-gp mediated transport of paracetamol in rats and in vitro models: amelioration of paracetamol toxicity

The harmful by-product of paracetamol is known as N-Acetyl-p-benzoquinoneimine, (NAPQI). When paracetamol is given at therapeutic dosages or in excess, it undergoes Phase I metabolism in the liver via Cytochrome P-450 2E1 (CYP2E1), and then it produces NAPQI. Previous studies reported that a nonionic surfactant known as Brij 35 (Polyoxyethylene lauryl ether) has been shown to be an effective inhibitor of CYP2E1 and P-glycoprotein (P-gp). Hence, this in vitro and in vivo investigation set out to assess Brij 35 impact on paracetamol CYP2E1-mediated metabolism. For the in vitro investigation, isolated rat hepatocytes were used. Male Wistar rats were used for in vivo studies. There were 30 rats in total, with six individuals each group distributed among the five groups. The first group animals received 0.5% sodium carboxy methyl cellulose (control group); the second group animals treated with 300 mg/kg of paracetamol; the third group animals treated with Brij 35 (5 mg/kg) along with 300 mg/kg of paracetamol; the fourth group animals treated with 10 mg/kg of Brij 35 along with 300 mg/kg of paracetamol, and the fifth group animals treated with 20 mg/kg of Brij 35 along with 300 mg/kg of paracetamol for consecutive 21 days. The current study found that paracetamol plasma concentrations were much higher and NAPQI plasma concentrations were much lower when Brij 35 was co-administered may be due to inhibition of CYP2E1-mediated metabolism and P-gp-mediated intestinal transport of paracetamol. Brij 35 also reduced the increased hepatic and renal markers with significant hepatoprotective and nephroprotective changes in the histopathological investigation.

Two chromatographic methods for analyzing paracetamol in spiked human plasma with its toxic metabolite, N-acetyl parabenzoquinone imine and its antidote, N-acetyl-L-cysteine

Acetaminophen, also known as paracetamol (APAP), is a highly utilized pharmaceutical agent on a global scale, particularly in the field of pediatrics. Regrettably, an overdose of APAP, resulting from the predominant oxidation, has the potential to trigger acute liver injury. The study's goal was to find an easy, accurate, and selective way to measure APAP, N-acetyl para benzoquinone imine (NAPQI) (an APAP metabolite that is harmful), and N-acetyl-L-cysteine (NAC) (an antidote). Two different chromatographic methods were used. The HPTLC method, which used silica gel 60 F254 as a stationary phase and a developing liquid made up of methanol, ethyl acetate, and glacial acetic acid (8:2:0.2, v/v/v) and a UV detection at 254 nm. The HPLC method was developed using a mobile phase consisting of water, methanol, and formic acid in a proportion of (70:30:0.15, v/v/v). The stationary phase used in the approach was a C18 column. Analytes quantification was established utilizing a UV detector operating at a wavelength of 254 nm. The present methods make it possible to measure the amount of APAP in plasma samples. When it comes to pharmacokinetics or medication levels in children's plasma, for example, this may be also very helpful. The current methods can quantify NAPQI, which is helpful in figuring out drug concentrations in individuals with APAP intoxication diagnoses. Additionally, the current approaches can estimate NAC as an antidote; as a result, this study is a complete study because it can analyse drug, toxic metabolite, and antidote in one analytical run. Using the innovative blue applicability grade index software, which measures the practicality of procedures, both methodologies were compared with a reported methods. Additionally, the achievement of the eco-friendliness profile of the designed procedures was assessed. Both techniques passed the ICH validation tests.

Effect of Chronic Kidney Disease on Hepatic Clearance of Drugs in Rats

The pharmacokinetics of some hepatically cleared drugs have been reported to fluctuate in patients with renal impairment, but the definitive factors have not been clarified. We compared the pharmacokinetics of some drugs with different hepatic elimination processes in a chronic kidney disease (CKD) rat model, to optimize their administration during kidney injury. We chose indocyanine green (ICG), midazolam (MDZ), and acetaminophen (APAP) as reference drugs to determine changes in hepatic clearance pathways in presence of CKD. Drugs were intravenously administered via the jugular vein to the CKD model rats, previously established by adenine administration, and then, blood, bile, and urine samples were collected. The plasma concentration of ICG, which is eliminated into the bile without biotransformation, increased; and its total body clearance (CL_tot) significantly decreased in the CKD group compared to the control group. Moreover, the plasma concentrations of MDZ and APAP, metabolized in the liver by CYP3A and Ugt1a6 enzymes, respectively, were higher in the CKD group than in the control group. The biliary clearances of APAP and its derivative APAP-glucuronide increased in the CKD group, whereas their renal clearances were markedly decreased with respect to those in the control group. Altogether, plasma concentrations of some hepatically eliminated drugs increased in the CKD rat model, but depending on their pharmacokinetic characteristics. This study provides useful information for optimizing the administration of some hepatically cleared drugs in CKD patients.

The feasibility and safety in using acetaminophen with fentanyl for pain control after liver resection with regards to liver function: A prospective single-center pilot study in Japan

INTRODUCTION

Acetaminophen has been widely used as an analgesic agent after various types of surgery. However, acetaminophen may sometimes induce severe liver dysfunction, which can occasionally lead to the need for liver transplantation. The aim of this study was to assess the feasibility and efficacy of administering acetaminophen to patients after liver resection (LR).

PATIENTS AND METHODS

The prospective study included 50 patients who underwent the following procedures: partial LR (n = 21) and more than one section LR (n = 29). Pain control was provided with continuous intravenous fentanyl and acetaminophen every 6 hours (within 2 days). We analyzed the liver function and blood concentration of acetaminophen at 1 and 3 days after LR using high performance liquid chromatography (HPLC), and investigated the results of partial and more than one section LR, and also examined the degree of liver fibrosis.

RESULTS

The alanine transaminase level on postoperative days 1, 5, and 7 and total bilirubin on postoperative days 1 to 5 after LR in patients with more than one section LR was significantly higher than the levels in patients with partial resection. No patients developed liver failure. The blood concentration of acetaminophen by HPLC was significantly elevated in patients with resection of more than one section in comparison to the partial resection group.

CONCLUSION

The safety of acetaminophen was evaluated in Japanese patients who underwent different types of LR with different degrees of liver fibrosis.

Simultaneous Determination of Schisandrin and Promethazine with Its Metabolite in Rat Plasma by HPLC-MS/MS and Its Application to a Pharmacokinetic Study

This study aimed to develop a selective, simple, and sensitive HPLC-MS/MS method for the simultaneous determination of schisandrin and promethazine (PMZ) with its metabolite in rat plasma, which was further used for a pharmacokinetic herb-drug interaction study. HPLC-MS/MS analyses were performed on an Agilent Technologies 1290 LC and a 6410 triple quadrupole mass spectrometer. The following parameters, the lower limit of quantification (LLOQ), calibration curve, accuracy, precision, stability, matrix effect, and recovery, were validated. The linear range of the developed method for PMZ, its metabolite promethazine sulfoxide (PMZSO), and schisandrin in rat plasma was 0.5-200 ng/mL (R 2 > 0.995), with an LLOQ of 0.5 ng/mL, which completely met the determination requirements of biosamples. The intra- and interday precision (RSD, %) was below 13.31% (below 16.67% for the LLOQ) in various plasma, whose accuracy (bias, %) was from -8.52% to 11.40%, which were both within an acceptable range. This method was successfully applied to a pharmacokinetic herb-drug interaction study after oral administration of PMZ with or without S. chinensis water extract. The results demonstrated that coadministration with the S. chinensis water extract might affect the pharmacokinetic behaviors of PMZ. In turn, when taken together with PMZ, the pharmacokinetic parameters of schisandrin, the main active component of S. chinensis, were also affected. The method established in the current study was selective, simple, sensitive, and widely available with good linearity, high accuracy and precision, and a stable sample preparation process. Moreover, this analytical method provides a significant approach for the investigation of herb-drug interaction between S. chinensis and PMZ. The potential pharmacokinetic herb-drug interaction of PMZ- and schisandrin-containing preparations should be noted.

Evaluation of mRNA expression of drug-metabolizing enzymes in acetaminophen-induced hepatotoxicity using a three-dimensional hepatocyte culture system

1. The expression and activity of drug-metabolizing enzymes are known to affect the pharmacokinetics of drugs metabolized in the liver. Here, we assessed the effect of acetaminophen (APAP)-induced hepatotoxicity on the mRNA expression of drug-metabolizing enzymes and elucidated the underlying mechanism using three-dimensional (3D) cultures of HepG2 cells.2. 3D culture cells enabled us to establish an in vitro model of APAP-induced hepatotoxicity which showed the increase in N-acetyl-p-benzoquinone imine production, reactive oxygen species (ROS) generation and cellular injury.3. In this 3D culture model, APAP treatment significantly increased the mRNA expression of drug-metabolizing enzymes (cytochrome P450 [CYP]3A4, CYP2E1 and UDP-glucuronosyltransferase 1A6) and their nuclear receptors (pregnane X receptor and constitutive androstane receptor) compared with untreated cells. Treatment with N-acetylcysteine, a therapeutic agent for APAP-induced hepatotoxicity, suppressed these increases. In addition, the mRNA expression of drug-metabolizing enzymes and nuclear receptors were elevated depending on the concentration of H₂O₂, one of ROS involved in the development of APAP-induced hepatotoxicity. The mRNA expression of nuclear receptors increased before that of drug-metabolizing enzymes.4. In conclusion, ROS may induce the mRNA expression of nuclear receptors and promote the transcription of drug-metabolizing enzymes in the in vitro model of APAP-induced hepatotoxicity.

Ibuprofen for Pain Control in Children: New Value for an Old Molecule

BACKGROUND

Acute pain is one of the major complaints reported in pediatric emergency departments and general wards. Recently, both the US Food and Drug Administration and European Medicine Agency emitted some warnings regarding the use of opioids, including codeine, in children.

OBJECTIVE

The aims of this study were summarizing the main pharmacological aspects of ibuprofen, discussing the current evidence about the use of ibuprofen in different and specific clinical settings, and providing a comparison with acetaminophen and/or codeine, according to available studies.

STUDY DESIGN AND METHODS

Studies evaluating ibuprofen for the management of acute pain in children were extracted from the PubMed and MEDLINE database within the period ranging from 1985 through 2017. After discussing safety of ibuprofen and its concomitant use with acetaminophen, the specific indications for the clinical practice were considered.

RESULTS

Ibuprofen resulted to be more effective than acetaminophen, and comparable to the combination acetaminophen-codeine, for the control of acute pain related to musculoskeletal pain. Moreover, similar results have been reported also in the management of toothache and inflammatory diseases of the oral cavity and pharynx. Ibuprofen resulted to be useful as a first approach to episodic headache. Finally, the role of ibuprofen in the management of postoperative pain and, particularly, after tonsillectomy and/or adenoidectomy has been reconsidered recently.

CONCLUSIONS

Ibuprofen resulted to be the most studied nonsteroidal anti-inflammatory drug in the management of acute pain in children; in general, it showed a good safety profile and provided evidence of effectiveness, despite some differences according to the specific clinical context.

Glucosamine-paracetamol spray-dried solid dispersions with maximized intrinsic dissolution rate, bioavailability and decreased levels of in vivo toxic metabolites

Purpose

This study is aimed at preparing and testing physicochemical, pharmacokinetic and levels of toxic metabolites of paracetamol and glucosamine solid dispersions intended for multiple deliveries via the parenteral or per oral route.

Methods

Solid dispersions were prepared using the spray drying technique at different molar ratios of paracetamol and glucosamine. Characterization of the solid dispersions was carried out using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), equilibrium solubility and intrinsic dissolution rate. In vivo pharmacokinetics and toxic metabolites of the prepared dispersions were evaluated and compared to those of pure drugs and physical mixtures.

Results

Instant water solubility and more than 7-fold increase in dissolution rate led to significantly high plasma drug concentration (>6.5-fold) compared to paracetamol alone. More than 2-fold increase in area under the curve from 0 to 24 h from the dispersions was noticed on the third day of oral dosing to animals. Lower number and concentration followed by the complete disappearance of toxic pathway metabolites were observed on second and third days of dosing with solid dispersions and physical mixtures, respectively.

Conclusions

The spray-dried dispersions support safer and more effective delivery of multiple doses of paracetamol, leading to an acceleration of its analgesic actions. Synergism between the analgesic actions of paracetamol and joint protective actions of glucosamine in this combination is expected to facilitate effective treatment of persistent pain-related illnesses such as osteoarthritis.

A reliable LC-MS/MS method for the quantification of N-acetyl-p-benzoquinoneimine, acetaminophen glutathione and acetaminophen glucuronide in mouse plasma, liver and kidney: Method validation and application to a pharmacokinetic study

A rapid, specific, and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated to simultaneously quantify N-acetyl-p-benzoquinoneimine (NAPQI), acetaminophen-glutathione (acetaminophen-glut) and acetaminophen-glucuronide (acetaminophen-gluc) in mouse plasma, liver and kidney homogenates. Analytes were eluted by a binary gradient mobile phase composed of water (phase A) and methanol containing 0.1% formic acid (phase B) at a flow rate of 0.3 mL/min, which was performed on a CAPCELL PAK C₁₈ MG II column. It took 3.2 min to detect three analytes in a single run. Quantification was carried out in positive mode combined with multiple reaction monitoring. The validation of the LC-MS/MS method consisted of specificity, linearity, precision, accuracy, protein precipitation recovery, matrix effect, dilution integrity and stability. The plasma and tissue homogenate calibration curves were linear over concentration ranges of 0.050-5.00, 0.050-5.00 and 0.100-40.0 μg/mL, with a lower limit of quantification of 0.050, 0.050, and 0.100 μg/mL for NAPQI, acetaminophen-glut and acetaminophen-gluc, respectively. The intra- and inter-run precision values were within 12.47% for NAPQI, 12.11% for acetaminophen-glut and 11.86% for acetaminophen-gluc at their lower limit of quantitation levels. The samples were stable under all tested conditions. This method was successfully applied to study the pharmacokinetics of NAPQI, acetaminophen-glut and acetaminophen-gluc in ICR mice following oral administration of 200 mg/kg of acetaminophen suspension.

Novel approach for evaluating pharmaceuticals toxicity using Daphnia model: analysis of the mode of cytochrome P450-generated metabolite action after acetaminophen exposure

Because of its widespread use, the pharmaceutical acetaminophen (APAP) is frequently detected in aquatic environments. APAP can have serious physiological effects, such as reduced reproduction, low growth rates, and abnormal behavior, in aquatic organisms. However, the methods available for evaluation of the aquatic toxicity of APAP are of limited usefulness. The present study aimed to develop reliable and sensitive markers for evaluation of APAP toxicity using Daphnia as a model organism. We focused on N-acetyl-p-benzoquinoneimine (NAPQI) production from APAP via cytochrome P450 metabolism because NAPQI causes APAP toxicity. Daphnia magna were exposed to APAP (0, 50, or 100 mg/L for 12 h or 24 h), and the total metabolites were extracted and analyzed for NAPQI. Direct detection of NAPQI was difficult because of its high reactivity, and its peak was close to that for APAP. Therefore, we tried to identify molecular and biochemical indicators associated with NAPQI generation, elimination, and its interactions with macromolecules. We identified changes in CYP370A13 gene expression, glutathione depletion, inhibition of thioredoxin reductase activity, and production of reactive oxygen species as indicators of D. magna exposure to APAP. These indicators could be used to develop sensitive and accurate techniques to evaluate the environmental toxicity of APAP.

Extended stability of intravenous acetaminophen in syringes and opened vials

PURPOSE

The stability of i.v. acetaminophen beyond the manufacturer-recommended usage limit of six hours for opened vials was evaluated.

METHODS

Intravenous acetaminophen (10 mg/mL) was obtained. Three identical samples of 100 mg (10 mL in a 10-mL syringe), 250 mg (25 mL in a 30-mL syringe), 500 mg (50 mL in a 60-mL syringe), 250 mg (25 mL in the original vial), and 900 mg (90 mL in original vial) were prepared. A 0.5-mL volume of each sample was withdrawn, diluted with mobile phase to an expected concentration of 50 μg/mL, and assayed in duplicate using high-performance liquid chromatography immediately after preparation and at 24, 48, 72, and 84 hours. The samples were visually inspected for any change in color, and pH was assessed at each time of analysis. The stability of the solutions was determined by calculating the percentage of the initial acetaminophen concentration remaining at each test hour. Stability was defined as the retention of at least 90% of the initial acetaminophen concentration.

RESULTS

At least 99% of the initial concentration of acetaminophen remained in the original vials and polypropylene syringes throughout the 84-hour study period. There were no detectable changes in color, pH, visible microbial growth, or visible drug precipitation.

CONCLUSION

Intravenous acetaminophen (10 mg/mL) was physically and chemically stable in a range of volumes for up to 84 hours in the opened vials and in polypropylene syringes at room temperature.

Reconstruction of the abdominal vagus nerve using sural nerve grafts in canine models

Background

Recently, vagus nerve preservation or reconstruction of vagus has received increasing attention. The present study aimed to investigate the feasibility of reconstructing the severed vagal trunk using an autologous sural nerve graft.

Methods

Ten adult Beagle dogs were randomly assigned to two groups of five, the nerve grafting group (TG) and the vagal resection group (VG). The gastric secretion and emptying functions in both groups were assessed using Hollander insulin and acetaminophen tests before surgery and three months after surgery. All dogs underwent laparotomy under general anesthesia. In TG group, latency and conduction velocity of the action potential in a vagal trunk were measured, and then nerves of 4 cm long were cut from the abdominal anterior and posterior vagal trunks. Two segments of autologous sural nerve were collected for performing end-to-end anastomoses with the cut ends of vagal trunk (8–0 nylon suture, 3 sutures for each anastomosis). Dogs in VG group only underwent partial resections of the anterior and posterior vagal trunks. Laparotomy was performed in dogs of TG group, and latency and conduction velocity of the action potential in their vagal trunks were measured. The grafted nerve segment was removed, and stained with anti-neurofilament protein and toluidine blue.

Results

Latency of the action potential in the vagal trunk was longer after surgery than before surgery in TG group, while the conduction velocity was lower after surgery. The gastric secretion and emptying functions were weaker after surgery in dogs of both groups, but in TG group they were significantly better than in VG group. Anti-neurofilament protein staining and toluidine blue staining showed there were nerve fibers crossing the anastomosis of the vagus and sural nerves in dogs of TG group.

Conclusion

Reconstruction of the vagus nerve using the sural nerve is technically feasible.

Effect of metoclopramide on the excretion rate of paracetamol using HPLC-DAD

A simple, precise, accurate and robust high-performance liquid chromatography assay was developed and validated for the simultaneous analysis of metoclopramide and paracetamol in human urine. The drugs were isolated from urine samples by solid-phase extraction using C8 cartridges, then analyzed on a C18 reversed-phase column using a mixture of aqueous phase (water containing 0.2% TEA adjusted to pH 3 using ortho-phosphoric acid) and methanol in a ratio of 80:20 (v/v). The method was found to be linear for both drugs in a concentration range of 0.5 to 160 µg/mL using a concentration of 10 µg/mL of internal standard (theophylline) in urine samples (r > 0.999). The accuracy of the method was higher than 91.73% (percentage of the grand mean of recoveries) and the precision was lower than 3.4% (overall percentage of relative standard deviation) for both metoclopramide and paracetamol. The method was applied to the determination of the drugs in urine samples obtained from male volunteers, following the administration of two formulations, one containing paracetamol alone (Paracetamol(®)) and the other containing a mixture of paracetamol and metoclopramide (Migracicid(®)). Determination of the drugs was conducted and the effect of increasing the rate of absorption, consequently increasing the mean urinary excretion of paracetamol due to the presence of metoclopramide in the pharmaceutical formulation, was recorded.