Clinical pharmacokinetics of paracetamol

Caffeine, but not paracetamol (acetaminophen), enhances muscular endurance, strength, and power

BACKGROUND

Caffeine is one of the most popular ergogenic aids consumed by athletes. Caffeine's ergogenic effect has been generally explained by its ability to bind to adenosine receptors, thus modulating pain and reducing perceived exertion. Another pharmacological agent that may improve performance due to its analgesic proprieties is paracetamol. This study aimed to explore the effects of caffeine, paracetamol, and caffeine + paracetamol consumption on muscular endurance, strength, power, anaerobic endurance, and jumping performance.

METHODS

In this randomized, crossover, double-blind study, 29 resistance-trained participants (11 men and 18 women) ingested either a placebo, caffeine (3 mg/kg), paracetamol (1500 mg) or caffeine + paracetamol 45 min before the testing sessions. The testing sessions included performing the bench press exercise with 75% of one-repetition maximum to momentary muscular failure, isokinetic knee extension and flexion at angular velocities of 60°/sec and 180°/sec, Wingate, and countermovement jump (CMJ) tests.

RESULTS

Compared to placebo, isolated caffeine ingestion increased the number of repetitions performed in the bench press (p = 0.005; d = 0.42). Compared to placebo, isolated caffeine ingestion and/or caffeine + paracetamol consumption was ergogenic for strength (torque), muscular endurance (total work), or power in the isokinetic assessment, particularly at slower angular velocities (p = 0.027 to 0.002; d = 0.16 to 0.26). No significant differences between the conditions were observed for outcomes related to the Wingate and CMJ tests.

CONCLUSION

This study provided novel evidence into the effectiveness of caffeine, paracetamol, and their combination on exercise performance. We found improvements in muscular endurance, strength, or power only when caffeine was consumed in isolation, or in combination with paracetamol. Isolated paracetamol consumption did not improve performance for any of the analyzed outcomes, thus calling into question its ergogenic potential.

Synthesis and Reactivity of Masked Organic Sulfates

Nature offers a variety of structurally unique, sulfated endobiotics including sulfated glycosaminoglycans, sulfated tyrosine peptides, sulfated steroids/bile acids/catecholamines. Sulfated molecules display a large number of biological activities including antithrombotic, antimicrobial, anticancer, anti-inflammatory, and others, which arise from modulation of intracellular signaling and enhanced in vivo retention of certain hormones. These characteristics position sulfated molecules very favorably as drug-like agents. However, few have reached the clinic. Major hurdles exist in realizing sulfated molecules as drugs. This state-of-the-art has been transformed through recent works on the development of sulfate masking technologies for both alkyl (sulfated carbohydrates, sulfated steroids) and aryl (sTyr-bearing peptides/proteins, sulfated flavonoids) sulfates. This review compiles the literature on different strategies implemented for different types of sulfate groups. Starting from early efforts in protection of sulfate groups to the design of newer SuFEx, trichloroethyl, and gem-dimethyl-based protection technologies, this review presents the evolution and application of concepts in realizing highly diverse, sulfated molecules as candidate drugs and/or prodrugs. Overall, the newer strategies for sulfate masking and demasking are likely to greatly enhance the design and development of sulfated molecules as non-toxic drugs of the future.

Increased Postoperative Opioid Consumption in the Presence of Coadministration of 5-Hydroxytryptamine Type 3 Antagonists with Acetaminophen: A Hospital Registry Study

BACKGROUND

Acetaminophen and 5-hydroxytryptamine type 3 (5-HT3) receptor antagonists are administered as standard prophylaxes for postoperative pain, nausea, and vomiting. Preclinical studies, however, suggest that 5-HT3 antagonists may compromise acetaminophen's analgesic effect. This hospital registry study investigates whether 5-HT3 antagonists mitigate the analgesic effect of prophylactic acetaminophen in a perioperative setting.

METHODS

This study included 55,016 adult patients undergoing general anesthesia for ambulatory procedures at a tertiary healthcare center in Massachusetts from 2015 to 2022. Using binary exposure variables and a comprehensive selection of preplanned patient- and procedure-related covariates for confounder control, the authors investigated whether intraoperative 5-HT3 antagonists affected the association between pre- or intraoperative acetaminophen and postoperative opioid consumption, gauged by opioid dose in milligram oral morphine equivalents (OME) administered in the postanesthesia care unit. A multivariable, zero-inflated negative binomial regression model was applied.

RESULTS

A total of 3,166 patients (5.8%) received only acetaminophen, 15,438 (28.1%) only 5-HT3 antagonists, 31,850 (57.9%) both drugs, and 4,562 (8.3%) neither drug. The median postanesthesia care unit opioid dose was 7.5 mg OME (interquartile range, 7.5 to 14.3 mg OME) among 16,640 of 55,016 (30.2%) patients who received opioids, and the mean opioid dose was 3.2 mg OME across all patients (maximum cumulative dose, 20.4 mg OME). Acetaminophen administration was associated with a -5.5% (95% CI, -9.6 to -1.4%; P = 0.009; adjusted absolute difference, -0.19 mg OME; 95% CI, -0.33 to -0.05; P = 0.009) reduction in opioid consumption among patients who did not receive a 5-HT3 antagonist, while there was no effect in patients who received a 5-HT3 antagonist (adjusted absolute difference, 0.00 mg OME; 95% CI, -0.06 to 0.05; P = 0.93; P for interaction = 0.013).

CONCLUSIONS

A dose-dependent association of pre- or intraoperative acetaminophen with decreased postoperative opioid consumption was not observed when 5-HT3 antagonists were coadministered, suggesting that physicians might consider reserving 5-HT3 antagonists as rescue medication for postoperative nausea or vomiting when acetaminophen is administered for pain prophylaxis.

EDITOR’S PERSPECTIVE

Evaluation of the mechanism of action of paracetamol, drotaverine, and peppermint oil and their effects in combination with hyoscine butylbromide on colonic motility: human ex-vivo study

Introduction

Drotaverine, paracetamol, and peppermint oil are often prescribed for the treatment of gastrointestinal spasm and pain. This study aimed to evaluate the effect of these drugs alone and combined with the well-known antispasmodic hyoscine butylbromide on the human colon.

Methods

Colon samples were obtained from macroscopically normal regions of 68 patients undergoing surgery and studied in muscle bath. Drotaverine, paracetamol, and peppermint oil were tested alone and in combination with hyoscine butylbromide on (1) spontaneous contractility induced by isometric stretch (in the presence of 1 µM tetrodotoxin) and (2) contractility induced by 10-5 M carbachol and after (3) electrical field stimulation-induced selective stimulation of excitatory (in the presence of 1 mM Nω-nitro-L-arginine and 10 µM MRS2179) and (4) inhibitory (under non-adrenergic, non-cholinergic conditions) pathways. (5) Drotaverine alone was also tested on cAMP-dependent pathway activated by forskolin.

Results

Compared with the vehicle, drotaverine and paracetamol (10-9-10-5 M) did not modify spontaneous contractions, carbachol-induced contractions, and responses attributed to selective activation of excitatory pathways. The addition of hyoscine butylbromide (10-7-10-5 M), concentration-dependently reduced myogenic contractions and carbachol- and electrical field stimulation-induced contractile responses. The association of paracetamol (10-4 M) and hyoscine butylbromide (10-7-10-5 M) was not different from hyoscine butylbromide alone (10-7-10-5 M). At higher concentrations (10-3M-3*10-3 M), paracetamol decreased myogenic and carbachol-induced contractions. The adenylate cyclase activator, forskolin, concentration-dependently reduced contractility, leading to smooth muscle relaxation. The effect of forskolin 10-7 M was concentration-dependently enhanced by drotaverine (10-6M-10-5M).

Discussion

Peppermint oil reduced myogenic activity and carbachol- and electrical field stimulation-induced contractions. The association of hyoscine butylbromide and peppermint oil was synergistic since the interaction index measured with the isobologram was lower than 1. No effect was seen on the neural-mediated inhibitory responses with any of the drugs studied although peppermint oil reduced the subsequent off-contraction. Drotaverine and hyoscine butylbromide have a complementary effect on human colon motility as one stimulates the cAMP inhibitory pathway and the other inhibits the excitatory pathway. Peppermint oil is synergic with hyoscine butylbromide suggesting that a combination therapy may be more effective in treating patients. In contrast, at therapeutic concentrations, paracetamol does not modify colonic contractility, suggesting that the association of paracetamol and hyoscine butylbromide has independent analgesic and antispasmodic properties.

Pain Reduction of Ibuprofen Sodium Dihydrate Alone and in Combination with Acetaminophen in an Untreated Endodontic Pain Model: A Randomized, Double-blind Investigation

INTRODUCTION

Most pain studies have been based on a postsurgical, third molar model using ibuprofen (IBU)/acetaminophen (APAP). Studies have found quicker onset of pain relief with a newer formulation of IBU - ibuprofen sodium dihydrate (ISD). The purpose of this study was to compare pain reduction of ISD/APAP to ISD in an acute endodontic pain model of untreated patients experiencing moderate to severe pain with symptomatic apical periodontitis.

METHODS AND MATERIALS

In this double-blind randomized study, 64 adult emergency patients in acute moderate to severe pain, a pulpal diagnosis of symptomatic irreversible pulpitis or necrosis, and symptomatic apical periodontitis participated. Each patient randomly received either one dose of 768 mg ISD/1000 mg APAP or one dose of 768 mg ISD. Pain intensity scores were recorded every 15 minutes over 240 minutes using the Heft-Parker VAS along with time to first sign of pain relief, time to meaningful pain relief, and time to 50% pain relief also recorded. The data were analyzed statistically.

RESULTS

Both ISD and ISD/APAP groups showed a progressive decrease in pain from baseline to 120 minutes after medication administration. Afterward, a relative plateau was seen in the patients' pain. There was no difference in the VAS scores between the ISD and ISD/APAP at any given time point, time to first sign of pain relief, time to meaningful pain relief, and time to 50% pain relief.

CONCLUSIONS

The addition of APAP to ISD for pain control in an untreated endodontic pain model did not differ significantly from ISD alone.

The Insidious Enemy of the Liver: The Situation in Childhood Acetaminophen Poisoning and Early N-AC Treatment

METHODS

This study was designed as a cross-sectional, observational, retrospective study. The variables of the study were paracetamol overdose, demographic information, poisoning mechanisms, clinical, laboratory findings, and clinical progression of the cases. The cases compared in whom treatment was initiated within the first 8 hours after poisoning and those in whom it was not. χ 2 , t test, and logistic regression analyses were conducted at appropriate facilities.

RESULTS

Three hundred forty-eight cases were included in the study. N-AC treatment was initiated within the first 8 hours after poisoning in 322 cases (92.5%), and 26 cases received N-AC treatment after 8 hours after poisoning. Liver toxicity developed in 6 cases (1.7%), and indications for liver transplantation were met in 36 cases (10.3%). Among the 26 cases for which treatment was not initiated within the first 8 hours, 18 cases (69.2%) had indications for liver transplantation ( P < 0.01). It was found that N-AC within the first 8 hours reduced the risk by 43 times ( P = 0.02) and being older than 6 years, being admitted to the intensive care unit, and having alanine aminotransferase values above 1000 U/L increased the risk significantly ( P = 0.009, P = 0.005, P < 0.001). When a receiver operating characteristic curve was plotted for the 4th-hour blood acetaminophen level to predict liver transplantation, a value of 684.5 μg/mL emerged with 89% sensitivity and 93% specificity (area under the curve, 0.951).

CONCLUSIONS

As a result, this study demonstrates the protective effect of early-initiated N-AC therapy on liver toxicity in pediatric acetaminophen poisoning cases. It also highlights a significant impact of gastrointestinal decontamination methods.

Rapid identification of potential nonsteroidal anti-inflammatory drug overdose-induced liver toxicity and prediction of follow-up exposure: Integrating bioanalytical and population pharmacokinetic assay

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most frequently used drugs that can cause liver toxicity. The aim of this study was to integrate bioanalytical and population pharmacokinetic (PopPK) assay to rapidly screen and quantify the concentrations of NSAIDs in plasma and monitor clinical safety. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous quantification of acetaminophen (APAP), flurbiprofen (FLB), aspirin (ASP), and ibuprofen (IBP), four commonly used NSAIDs. The PopPK model of the signature toxicant was analyzed based on the published literature. The LC-MS/MS method was successfully validated and applied to determine NSAID concentrations in patient plasma samples. APAP, ASP, and IBP data were best fitted using a one-compartment model, and FLB data were best fitted using a two-compartment model. Bootstrapping and visual predictive checks suggested that a robust and reliable pharmacokinetic model was developed. A fast, simple, and sensitive LC-MS/MS method was developed and validated for determining APAP, FLB, ASP, and IBP in human plasma. Combined with the PopPK model, this method was applied to rapidly analyze the concentrations of NSAIDs in clinical samples from patients presenting to the emergency department with acute liver dysfunction and monitored NSAIDs clinical safety.

Construction of An Oral Bioavailability Prediction Model Based on Machine Learning for Evaluating Molecular Modifications

OBJECTIVE

This study aims to explore the impact of ADME on the Oral Bioavailability (OB) of drugs and to construct a machine learning model for OB prediction. The model is then applied to predict the OB of modified berberine and atenolol molecules to obtain structures with higher OB.

METHODS

Initially, a drug OB database was established, and corresponding ADME characteristics were obtained. The relationship between ADME and OB was analyzed using machine learning, with Morgan fingerprints serving as molecular descriptors. Compounds from the database were input into Random Forest, XGBoost, CatBoost, and LightGBM machine learning models to train the OB 7prediction model and evaluate its performance. Subsequently, berberine and atenolol were modified using Chemdraw software with ten different substituents for mono-substitution, and chlorine atoms for a full range of double substitutions. The modified molecular structures were converted into the same format as the training set for OB prediction. The predicted OB values of the modified structures of berberine and atenolol were compared.

RESULTS

An OB database of 386 drugs was obtained. It was found that smaller molecular weight and a higher number of rotatable bonds (ten or less) could potentially lead to higher OB. The four machine learning models were evaluated using MSE, R2 score, MAE, and MFE as metrics, with Random Forest performing the best. The models' predictions for the test set were particularly accurate when OB ranged from 30% to 90%. After mono-substitution and double substitution of berberine and atenolol, the OB of both drugs was significantly improved.

CONCLUSIONS

This study found that some ADME properties of molecules do not have an absolute impact on OB. The database played a decisive role in the process of the machine learning OB prediction model, and the performance of the model was evaluated based on predictions within a range of strong generalization ability. In most cases, mono-substitution and double substitution were beneficial for enhancing the OB of berberine and atenolol. In summary, this study successfully constructed a machine learning regression prediction model that can accurately predict drug OB, which can guide drug design to achieve higher OB to some extent.

Pharmacokinetic profile of oral and subcutaneous administration of paracetamol in the koala (Phascolarctos cinereus) and prediction of its analgesic efficacy

The pharmacokinetic profile of paracetamol in koalas is described when administered orally at 15 mg/kg; followed by the same dose, administered every 12 hours (hrs), repeated five times. After the initial oral administration, the median (range) maximal plasma concentration (Cmax), the time Cmax was reached (Tmax) and elimination half-life (t1/2) were 16.93 μg/mL (13.66 to 20.25 μg/mL); 4 hrs (4 to 8 hrs) and 5.54 hrs (4.66 to 7.67 hrs), respectively. When paracetamol was administered orally at 15 mg/mL every 12 hrs, the trough total plasma concentration range remained comparable to the therapeutic range in humans i.e. 4 to 20 μg/mL that is known to provide some analgesia. However, there is a smaller proportion of free drug (i.e. not bound to plasma proteins; and the active form) available in koala plasma (approximately 40% unbound) compared to human plasma (approximately 80% unbound). Consequently, even when there are similar total drug plasma concentrations in both koala and human plasma, the therapeutic efficacy may be reduced in koalas compared to humans. The initial oral dose and subsequent twice daily doses resulted in no obvious adverse effects in any koala. Haematology, plasma electrolyte and biochemical analyte values remained within their reference ranges eight hrs after the last dose but there was a significant change in alanine transaminase (ALT) levels (an increase), and in total protein (a decrease) (both p = 0.03). A dose of 15 mg/kg was also administered as a subcutaneous injection, diluted 50:50 with saline, to two koalas. As the oral formulation and the subcutaneous administration resulted in comparable absorption, the study focused on the oral profile. Based on these results there is an argument to recommend a slight increase in the oral paracetamol dose for the koala, however further investigation is required to confirm whether repeated administration of a slightly higher dose may be associated with more severe or additional significant changes in haematology, electrolytes or biochemical analytes. However, a preferable recommendation would be to administer this dosage of paracetamol in combination with another analgesic such as tramadol, as a subcutaneous injection, to improve efficacy.

Natural Products That Protect Against Acetaminophen Hepatotoxicity: A Call for Increased Rigor in Preclinical Studies of Dietary Supplements

Acetaminophen (APAP) overdose is one of the most common causes of acute liver injury. The current standard-of-care treatment for APAP hepatotoxicity, N-acetyl-l-cysteine, is highly effective when administered early after overdose, but loses efficacy in later-presenting patients. As a result, there is interest in the identification of new treatments for APAP overdose patients. Natural products are a promising source of new treatments because many are purported to have hepatoprotective effects. In fact, a great deal of research has been done to identify natural products that can protect against APAP-induced liver injury. However, serious concerns have been raised about the rigor and human relevance of these studies. Here, we systematically reviewed the APAP-natural product literature from 2013 to 2023 to determine the veracity of these concerns and the scope of the potential problem. The results substantiate the concerns that have been previously raised and point to concrete steps that can be taken to improve APAP-natural product research.

Evaluation of pain intensity with prostaglandin E2 biomarker and visual analog scale during initiation of orthodontic treatment: A prospective study

OBJECTIVES

The aim of this study was to assess subjectively and objectively, at which timepoint the patient undergoing fixed orthodontic treatment will have maximum pain during the initiation of orthodontic treatment.

MATERIALS AND METHOD

A total of 22 patients (21 ± 2.7 years, [15 female and 7 male]) requiring extraction of maxillary first premolar participated in the study. Following bonding, an initial archwire of 0.016" NiTi was placed with a distal force of 100 g applied to the canines. The concentration of prostaglandin E2 (PGE2) in the gingival crevicular fluid was assessed at four time points: 1 hour before (T0); 24 hours (T1); 48 hours (T2); 72 hours (T3) after initial archwire placement. The pain intensity was recorded with visual analog scale.

RESULTS

The concentration of PGE2 increased from T0 to T1. The highest concentration was observed at T2 following which there was a mild decline at T3. Statistically significant difference in the PGE2 concentration was observed between T0 to T1 and T1 to T2. The visual analogue scale (VAS) scores increased from T0 to T1. The highest score was observed at T2 followed by a decline at T3. A statistically significant difference in the VAS score was noted between T0 to T1 and T2 to T3. On correlating PGE2 and VAS score, a weak negative correlation was noted between T0 to T1 and no correlation was noted between T1 to T2 and T2 to T3.

CONCLUSION

The patients experience maximum pain between 24 hours (T1) and 48 hours (T2) following initial archwire placement. The highest concentration of PGE2 and VAS score was observed at 48 hours (T2).

Searching for gene-gene interactions through variance quantitative trait loci of 29 continuous Taiwan Biobank phenotypes

Introduction: After the era of genome-wide association studies (GWAS), thousands of genetic variants have been identified to exhibit main effects on human phenotypes. The next critical issue would be to explore the interplay between genes, the so-called "gene-gene interactions" (GxG) or epistasis. An exhaustive search for all single-nucleotide polymorphism (SNP) pairs is not recommended because this will induce a harsh penalty of multiple testing. Limiting the search of epistasis on SNPs reported by previous GWAS may miss essential interactions between SNPs without significant marginal effects. Moreover, most methods are computationally intensive and can be challenging to implement genome-wide. Methods: I here searched for GxG through variance quantitative trait loci (vQTLs) of 29 continuous Taiwan Biobank (TWB) phenotypes. A discovery cohort of 86,536 and a replication cohort of 25,460 TWB individuals were analyzed, respectively. Results: A total of 18 nearly independent vQTLs with linkage disequilibrium measure r 2 < 0.01 were identified and replicated from nine phenotypes. 15 significant GxG were found with p-values <1.1E-5 (in the discovery cohort) and false discovery rates <2% (in the replication cohort). Among these 15 GxG, 11 were detected for blood traits including red blood cells, hemoglobin, and hematocrit; 2 for total bilirubin; 1 for fasting glucose; and 1 for total cholesterol (TCHO). All GxG were observed for gene pairs on the same chromosome, except for the APOA5 (chromosome 11)-TOMM40 (chromosome 19) interaction for TCHO. Discussion: This study provided a computationally feasible way to search for GxG genome-wide and applied this approach to 29 phenotypes.

Exposure to Paracetamol in Early Pregnancy and the Risk of Developing Cerebral Palsy: A Case-Control Study Using Serum Samples

OBJECTIVE

To investigate whether maternal paracetamol use in early pregnancy is associated with cerebral palsy (CP) in offspring.

STUDY DESIGN

We conducted a registry and biobank-based case-control study with mother-child pairs. We identified CP cases (n = 322) born between 1995 and 2014 from a nationwide CP-registry. Randomly selected controls (n = 343) and extra preterm controls (n = 258) were obtained from a birth registry. For each mother, a single serum sample from early pregnancy (gestation weeks 10-14) was retrieved from a biobank and analyzed for serum concentrations of paracetamol, categorized into unexposed (<1 ng/ml), mildly exposed (1-100 ng/ml), and highly exposed (>100 ng/ml), and in quartiles. Analyses were performed using logistic regression and adjusted for potential confounders. Separate analyses were conducted including only those children born preterm and only those born term.

RESULTS

Of the 923 participants, 36.8% were unexposed, 53.2% mildly exposed, and 10% highly exposed to paracetamol. Overall, prenatal exposure to paracetamol was not associated with CP. Sensitivity and subgroup analyses showed no clear associations between paracetamol and CP across strata of term/preterm birth as well as subtypes of CP.

CONCLUSIONS

The present study does not support an association between intrauterine exposure to paracetamol in early pregnancy and the risk of CP. However, it is important to stress that the exposure estimate is based on a single serum sample.

Acetaminophen treatment in children and adults with spinal muscular atrophy: a lower tolerance and higher risk of hepatotoxicity

Acute liver failure has been reported sporadically in patients with spinal muscular atrophy (SMA) and other neuromuscular disorders with low skeletal muscle mass receiving recommended dosages of acetaminophen. It is suggested that low skeletal muscle mass may add to the risk of toxicity. We aimed to describe the pharmacokinetics and safety of acetaminophen in patients with SMA. We analyzed acetaminophen metabolites and liver biomarkers in plasma from SMA patients and healthy controls (HC) every hour for six or eight hours on day 1 and day 3 of treatment with therapeutic doses of acetaminophen. Twelve patients with SMA (six adults and six children) and 11 HC participated in the study. Adult patients with SMA had significantly lower clearance of acetaminophen compared to HC (14.1 L/h vs. 21.5 L/h). Formation clearance of acetaminophen metabolites, glucuronide, sulfate, and oxidative metabolites were two-fold lower in the patients compared to HC. The liver transaminases and microRNAs increased nine-fold in one adult SMA patient after two days of treatment. The other patients and HC did not develop abnormal liver biomarkers. In this study, patients with SMA had lower clearance and slower metabolism of acetaminophen, and one patient developed liver involvement. We recommend giving 15 mg/kg/dose to SMA adults (with a maximum of 4000 mg/day) and monitoring standard liver biomarkers 48 h after first-time treatment of acetaminophen.

Impact of Prenatal Acetaminophen Exposure for Hippocampal Development Disorder on Mice

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used as analgesic agents. They have been detected in various environmental matrices. The degradation of environmental contaminants and the long-term adverse effects have become a major public concern. Prenatal exposure to acetaminophen can cause damage to the developing hippocampus. However, the molecular mechanisms behind hippocampal damage following prenatal acetaminophen exposure (PAcE) remain unclear. The present study shows an increased risk of adverse neurodevelopmental outcomes in offspring following exposure to acetaminophen during pregnancy on mice. The results revealed that different doses, timings, and duration of exposure to acetaminophen during pregnancy were associated with dose-dependent changes in the hippocampus of the offspring. Furthermore, exposure to high doses, multiple-treatment courses, and late pregnancy induced pathological changes, such as wrinkling and vacuolation, inhibited hippocampal proliferation and increased apoptosis. In addition, PAcE significantly decreased the expression of genes related to synaptic development in fetal hippocampal neurons and hippocampal astrocyte and microglia were also damaged to varying degrees. The significant reduction either in SOX2, an essential gene in regulating neural progenitor cell proliferation, and reduction of genes related to the SOX2/Notch pathway may suggest that the role of SOX2/Notch pathway in impaired hippocampal development in the offspring due to PAcE. In general, PAcE at high doses, multiple-treatment courses, and mid- and late gestation were associated with neurodevelopmental toxicity to the offspring.

Predicting Volume of Distribution in Neonates: Performance of Physiologically Based Pharmacokinetic Modelling

The volume of distribution at steady state (Vss) in neonates is still often estimated through isometric scaling from adult values, disregarding developmental changes beyond body weight. This study aimed to compare the accuracy of two physiologically based pharmacokinetic (PBPK) Vss prediction methods in neonates (Poulin & Theil with Berezhkovskiy correction (P&T+) and Rodgers & Rowland (R&R)) with isometrical scaling. PBPK models were developed for 24 drugs using in-vitro and in-silico data. Simulations were done in Simcyp (V22) using predefined populations. Clinical data from 86 studies in neonates (including preterms) were used for comparison, and accuracy was assessed using (absolute) average fold errors ((A)AFEs). Isometric scaling resulted in underestimated Vss values in neonates (AFE: 0.61), and both PBPK methods reduced the magnitude of underprediction (AFE: 0.82-0.83). The P&T+ method demonstrated superior overall accuracy compared to isometric scaling (AAFE of 1.68 and 1.77, respectively), while the R&R method exhibited lower overall accuracy (AAFE: 2.03). Drug characteristics (LogP and ionization type) and inclusion of preterm neonates did not significantly impact the magnitude of error associated with isometric scaling or PBPK modeling. These results highlight both the limitations and the applicability of PBPK methods for the prediction of Vss in the absence of clinical data.

Acute Liver Failure After Administration of Acetaminophen at the Recommended Daily Dose in an Adult: A Case Report

Acetaminophen may cause liver damage in a dose-dependent way: we experienced a case where an intravenous injection of 3 g/day of acetaminophen, which is less than the recommended maximum dose, was thought to have caused acute liver failure in a 73-year-old female. Four courses of postoperative adjuvant chemotherapy were given, without liver damage until the third course. After the administration of the fourth course, the patient experienced nausea and vomiting. She was admitted to the hospital with a diagnosis of enteritis a week later. At the time of admission, there was no liver impairment. For abdominal pain caused by enteritis, acetaminophen was administered intravenously over two days, totaling 4,000 mg. On the third day, acute liver failure developed, and N-acetylcysteine was administered. There was no improvement after the introduction of treatment; hence, 1,000 mg/day of steroid pulse therapy was administered. The patient's liver function started to improve, and she was discharged from the hospital two weeks later. This case suggests that the amount of acetaminophen used per unit of body weight may be unintentionally greater for adults with a small physique; thus, physicians should provide sufficient monitoring to discover side effects early and ensure there is appropriate use.

Revamping Biopharmaceutics-Pharmacokinetics with Scientific and Regulatory Implications for Oral Drug Absorption

PURPOSE

The Wagner-Nelson and Loo-Riegelman methods developed in the 1960s and used since for the construction of percent of drug absorbed as a function of time as well as in in vitro in vivo correlations are re-considered in the light of the physiologically sound Finite Absorption Time (F.A.T.) concept developed recently.

METHODS

The classical equations for the percentage of drug absorption as a function of time were modified by taking into account the termination of drug absorption at F.A.T., replacing the parameters associated with the assumption of infinite drug absorption.

RESULTS

Mathematical analysis using the relevant Physiologically Based Pharmacokinetic Finite Time (PBFTK) models assuming one- or two-compartment drug disposition, revealed that the modified %absorbed versus time curves are of bilinear type with an ascending limb intersecting the horizontal line at F.A.T. A computer-based methodology is described for the estimation of F.A.T. from experimental data. More than one linear ascending limb is found when more than one absorption phase is operating. Experimental data were analyzed and the estimates for F.A.T were found to be similar to those derived from nonlinear regression analysis using PBFTPK models.

CONCLUSION

These results place an end to the routinely reported exponential %absorbed versus time curves prevailing in biopharmaceutics-pharmacokinetics since their inception in the'60 s. These findings point to the use of the F.A.T. concept in drug absorption research and regulatory guidelines such as deconvolution techniques for the assessment of drug input rate, stochastic mean absorption time calculations, population analyses, in vitro in vivo correlations and bioequivalence guidelines.

Trigger point dry needling increases masseter muscle oxygenation in patients with temporomandibular disorder

BACKGROUND

Temporomandibular disorder (TMD) is an umbrella term encompassing various clinical complaints involving the temporomandibular joints, masticatory muscles, and/or associated orofacial structures. Myogenous TMDs are the most frequent cause of chronic orofacial pain. Musculoskeletal pain is commonly associated with myofascial trigger points (MTPs), for which dry needling (DN) is a routine treatment.

OBJECTIVE

To investigate muscle oxygenation and pain immediately after DN application on an MTP in the masseter muscle of patients with myogenous TMDs.

METHODOLOGY

Masseter muscle oxygen tissue saturation indices (TSI%) were assessed by near-infrared spectroscopy (NIRS) pre- and post-interventions by a randomized, controlled, double-blind, crossover DN/Sham clinical trial (primary outcome). Pain was investigated by the visual analog scale (VAS). In total, 32 individuals aged from 18 to 37 years who were diagnosed with myogenous TMD and myofascial trigger points in their masseter muscles participated in this study. Relative deltas for the studied variables were calculated. Data normality was tested using the Shapiro-Wilk test. According to their distribution, data were analyzed by two-way ANOVA and the Student's t-, and Mann-Whitney tests. Statistical analyses were performed using Prism® 5.0 (GraphPad, USA).

RESULTS

We found a significant difference (2,108% vs. 0,142%) between masseter muscle TSI% deltas after the DN and Sham interventions, respectively (n=24). We only evaluated women since men refused to follow NIRS procedures. Pain increased immediately after DN (n=32, 8 men), in comparison to Sham delta VAS.

CONCLUSION

These findings show an increase in tissue oxygen saturation in the evaluated sample immediately after the DN intervention on the MTP of patients' masseter muscle. Pain may have increased immediately after DN due to the needling procedure.

Analgesic effect of oral paracetamol 1000 mg/ibuprofen 400 mg, paracetamol 1000 mg/codeine 60 mg, paracetamol 1000 mg/ibuprofen 400 mg/codeine 60 mg, or placebo on acute postoperative pain: a single-dose, randomized, and double-blind study

PURPOSE

Combining analgesics with different mechanisms of action may increase the analgesic efficacy. The multidimensional pharmacodynamic profiles of ibuprofen 400 mg/paracetamol 1000 mg, ibuprofen 400 mg/paracetamol 1000 mg/codeine 60 mg, and paracetamol 1000 mg/codeine 60 mg and placebo were compared.

METHODS

A randomized, double-blind, placebo-controlled, parallel-group, single-centre, outpatient, and single-dose study used 200 patients of both sexes and homogenous ethnicity after third molar surgery (mean age 24 years, range 19-30 years). Primary outcome was sum pain intensity over 6 h (SPI). Secondary outcomes were time to analgesic onset, duration of analgesia, time to rescue drug intake, number of patients taking rescue drug, sum pain intensity difference (SPID), maximum pain intensity difference, time to maximum pain intensity difference, number needed to treat, prevent remedication and harm values, adverse effects, and patient-reported outcome measure (PROM).

RESULTS

Analgesia following ibuprofen and paracetamol combination with or without codeine was comparable. Both were better than paracetamol combined with codeine. Secondary variables supported this finding. Post hoc analysis of SPI and SPID revealed a sex/drug interaction trend in the codeine-containing groups where females experienced less analgesia. PROM showed a significant sex/drug interaction in the paracetamol and codeine group, but not in the other codeine-containing group. Especially females reported known and mild side effects in the codeine-containing groups.

CONCLUSION

Codeine added to ibuprofen/paracetamol does not seem to add analgesia in a sex-mixed study population. Sex may be a confounding factor when testing weak opioid analgesics such as codeine. PROM seems to be more sensitive than traditional outcome measures.

TRIAL REGISTRATION

ClinicalTrials.gov June 2009 NCT00921700.

Protective Effect of Water-Soluble Acacetin Prodrug on APAP-Induced Acute Liver Injury Is Associated with Upregulation of PPARγ and Alleviation of ER Stress

A water-soluble acacetin prodrug has been synthesized and reported by our group previously. Acetaminophen (APAP) overdose is a leading cause of acute liver injury. We found that subcutaneous injection of acacetin prodrug (5, 10, 20 mg/kg) decreased serum ALT, AST, and ALP, corrected the abnormal MDA and GSH in liver, and improved intrahepatic hemorrhage and destruction of liver structures in APAP (300 mg/kg)-treated mice. Molecular mechanism analysis revealed that the expressions of endoplasmic reticulum (ER) stress markers ATF6, CHOP, and p-PERK, apoptosis-related protein BAX, and cleaved caspase 3 were decreased by acacetin in a dose-dependent manner in vivo and in vitro. Moreover, via the acacetin-upregulated peroxisome-proliferator-activated receptor gamma (PPARγ) of HepG2 cells and liver, the suppressive effect of acacetin on ER stress and apoptosis was abolished by PPARγ inhibitor (GW9662) or PPARγ-siRNA. Molecular docking revealed that acacetin can bind to three active pockets of PPARγ, mainly by hydrogen bond. Our results provide novel evidence that acacetin prodrug exhibits significant protective effect against APAP-induced liver injury by targeting PPARγ, thereby suppressing ER stress and hepatocyte apoptosis. Acacetin prodrug is likely a promising new drug candidate for treating patients with acute liver injury induced by APAP.

Titanate nanotubes as an efficient oral detoxifying agent against drug overdose: application in rat acetaminophen poisoning

Voluntary drug intoxication is mainly due to drug overdose or the interaction of several drugs. Coma and its associated complications such as hypoventilation, aspiration pneumopathy, and heart rhythm disorders are the main hallmarks of drug intoxication. Conventional detoxification treatments, including gastric lavage or vomiting, administration of ipecac or activated charcoal (CH), and the use of antidotes, have proven to be inefficient and are generally associated with severe adverse effects. To overcome these limitations, titanate nanotubes (TiNTs) are proposed as an efficient emerging detoxifying agent because of their tubular shape and high adsorption capacity. In the present study, the detoxifying ability of TiNTs was evaluated on paracetamol (PR)-intoxicated rats. Results indicate that the loading ability of PR into TiNTs (70%) was significantly higher than that recorded for CH (38.6%). In simulated intestinal medium, TiNTs showed a controlled drug release of less than 10% after 72 h of incubation. In PR-intoxicated rats, TiNTs treatment resulted in a 64% decrease of PR after 4 h of poisoning versus 40% for CH. Concomitantly, TiNTs efficiently reduced PR absorption by 90% after 24 h of poisoning, attenuated the elevated levels of biochemical markers (i.e., alanine aminotransferase, aspartate aminotransferase, creatinine, and TNF-α) and mitigated oxidative stress by increasing the activity of superoxide dismutase and reducing the oxidized glutathione/total glutathione ratio, suggesting a histoprotective effect of TiNTs against paracetamol-induced toxicity in rats. In addition to their safety and high stability in the entire gastro-intestinal tract, biodistribution analysis revealed that TiNTs exhibited low intestinal absorption owing to their large cluster size of compact aggregate nanomaterials across the intestinal villi hindering the absorption of paracetamol. Collectively, these data provide a new and promising solution for in vivo detoxification. TiNTs are expected to have great potential for the treatment of voluntary and accidental intoxication in emergency care.

Provider-directed analgesia for dental pain

INTRODUCTION

Extraction of impacted molar teeth is a common procedure performed by oral surgeons and general dentists, with postoperative pain being a significant adverse event post-surgery. If mismanaged, pain can lead to complications that impact oral and systemic health. The current scourge of the opioid epidemic has ushered in a new era of provider-directed analgesic (PDA) therapy in dentistry.

AREAS COVERED

This article provides an in-depth review on the major pharmacological and therapeutic properties of established and alternative analgesics used to manage dental pain.

EXPERT OPINION

Substantial evidence-based literature shows combination of a non-steroidal anti-inflammatory drug (NSAID; e.g. ibuprofen) and acetaminophen provides superior pain relief than single-agent or combination opioid regimens. However, there are clinical scenarios (e.g. severe pain) when short-course opioid prescription is appropriate in select patients, in which a 2-3-day treatment duration is typically sufficient. Alternative agents (e.g. caffeine, gabapentin, phytotherapies), typically in combination with established agents, can mitigate postoperative dental pain. Some evidence suggests preemptive therapies (e.g. corticosteroids, NSAIDs) reduce amounts of postsurgical analgesic consumption and might lessen opioid prescription burden. In summary, this comprehensive review provides an opportune update on the evolving landscape of pharmacotherapy for acute postsurgical dental pain, informing best practices for PDA in the dental setting.

Pharmaceutical treatment of osteoarthritis

OBJECTIVE

To review the current state of pharmaceutical treatment recommendations for the management of osteoarthritis.

METHOD

A narrative review was drafted to describe treatment guidelines, mechanism of action, pharmacokinetics, and toxicity for nine classes of pharmaceuticals: 1) oral nonsteroidal anti-inflammatory drugs (NSAIDs), 2) topical NSAIDs, 3) COX-2 inhibitors, 4) duloxetine, 5) intra-articular corticosteroids, 6) intra-articular hyaluronic acid, 7) acetaminophen (paracetamol), 8) tramadol, and 9) capsaicin.

RESULTS

In general, oral and topical NSAIDs, including COX-2 inhibitors, are strongly recommended first-line treatments for osteoarthritis due to their ability to improve pain and function but are associated with increased risks in patients with certain comorbidities (e.g., heightened cardiovascular risks). Intra-articular corticosteroid injections are generally recommended for osteoarthritis management and have relatively minor adverse effects. Other treatments, such as capsaicin, tramadol, and acetaminophen, are more controversial, and many updated guidelines offer differing recommendations.

CONCLUSION

The pharmaceutical management of osteoarthritis is a constantly evolving field. Promising treatments are emerging, and medicines that were once considered conventional (e.g., acetaminophen) are gradually becoming less acceptable based on concerns with efficacy and safety. Clinicians need to consider the latest evidence and recommendations to make an informed decision with their patients about how to optimize treatment plans for patients with knee, hip, polyarticular, or hand osteoarthritis.

Gut inflammation and adaptive immunity amplify acetaminophen toxicity in bowel and liver

BACKGROUND AND AIM

Prevention of liver failure arising from accidental or deliberate paracetamol (acetaminophen [APAP]) overdose remains a vexed health problem despite well-publicized guidelines for its early detection and treatment. It is recognized that the gut may aggravate liver pathology, via the gut-liver axis. The main aim of this study was to assess the role of the colon in APAP-induced liver toxicity.

METHODS

Liver necrosis and colitis were studied following sublethal doses of APAP administered intraperitoneally to C57Bl/6 wild-type (WT) mice, as well as to C57Bl/6 Winnie mice, which develop a spontaneous colitis caused by a SNP in Muc2, and WT mice with acute DSS-induced colitis. Repeated APAP exposure was studied in WT and Rag1 ko mice that lack mature T and B lymphocytes.

RESULTS

APAP overdose resulted in significant colonic injury in WT mice (P < 0.05), which resolved by 24 h. Underlying colitis was not associated with liver necrosis, but colitis exacerbated APAP-induced liver injury and extended APAP-colonic injury. Prior APAP exposure exacerbated both APAP-liver and APAP-colonic injury more so in WT than Rag1 ko mice. APAP impaired barrier function with increased intestinal permeability and associated bacterial translocation to the liver and spleen in mice with the Winnie phenotype.

CONCLUSIONS

This study identifies novel roles for APAP in causing colitis, the amplification of APAP-liver toxicity where there is underlying colitis, and involvement of immune memory in APAP-toxicity. The latter could be key for decoding the poorly understood but important clinical entity of chronic APAP liver failure.

Generation & characterization of expandable human liver sinusoidal endothelial cells and their application to assess hepatotoxicity in an advanced in vitro liver model

Liver sinusoidal endothelial cells (LSECs) are highly specialized endothelial cells forming the hepatic sinusoidal wall. Besides their high endocytic potential, LSECs have been demonstrated to markedly contribute to liver homeostasis and immunity, and may partially explain unexpected hepatotoxicity of drug candidates. However, their use for in vitro investigations is compromised by poor cell yields and a limited proliferation capacity. Here, we report the transient expansion of primary human LSECs from three donors by lentiviral transduction. Transduced ("upcyte®") LSECs were able to undergo at least 25 additional population doublings (PDs) before growth arrest due to senescence. Expanded upcyte® LSECs maintained several characteristics of primary LSECs, including expression of surface markers such as MMR and LYVE-1 as well as rapid uptake of acetylated LDL and ovalbumin. We further investigated the suitability of expanded upcyte® LSECs and proliferating upcyte® hepatocytes for detecting acetaminophen toxicity at millimolar concentrations (0, 0.5, 1, 2, 5, 10 mM) in static 2D cultures and a microphysiological 3D model. upcyte® LSECs exhibited a higher sensitivity to acetaminophen-induced toxicity compared to upcyte® hepatocytes in 2D culture, however, culturing upcyte® LSECs together with upcyte® hepatocytes in a co-culture reduced APAP-induced toxicity compared to 2D monocultures. A perfused Dynamic42 3D model was more sensitive to acetaminophen than the 2D co-culture model. Cytotoxicity in the 3D model was evident by decreased cellular viability, elevated LDH release, reduced nuclei counts and impaired cell morphology. Taken together, our data demonstrate that transient expansion of LSECs represents a suitable method for generation of large quantities of cells while maintaining many characteristics of primary cells and responsiveness to acetaminophen.

Large paracetamol overdose-Higher dose acetylcysteine is required

Paracetamol poisoning continues to be a worldwide problem and, despite the availability of an effective antidote, acetylcysteine (NAC), the optimal way to use this antidote, particularly following very large doses of paracetamol, has not been established. Recent case series have shown an increased toxicity from high doses of paracetamol, even in those receiving prompt NAC therapy, particularly in patients above the 300 mg/L nomogram treatment line. Clinical trial evidence supporting shorter NAC dosing now allows the possibility for intensifying treatment without the risk of very high rates of ADRs. New biomarkers also show the possibility of early identification of patients at risk of liver injury who might also benefit from increased intensity treatment. This article discusses these data and proposes a logical therapy for increasing NAC dosing which now requires clinical trial testing.

Acetaminophen pharmacokinetics in infants and children with congenital heart disease

BACKGROUND

Acetaminophen is routinely used for perioperative analgesia in children undergoing major surgical procedures. There are few estimates of acetaminophen pharmacokinetic parameters in children with congenital heart disease, especially those with cyanotic heart disease.

AIMS

The current study prospectively investigated differences in acetaminophen pharmacokinetics following surgery using cardiopulmonary bypass in children with cyanotic and acyanotic congenital heart disease.

METHODS

Children (2-6 years, 9-23 kg) presenting for median sternotomy for Fontan palliation (cyanotic patients) or two ventricle surgical repair (acyanotic patients) were eligible for inclusion. A single intravenous dose of acetaminophen (15 mg/kg) was administered at the start of sternal closure after separation from cardiopulmonary bypass. The time-course of acetaminophen concentrations were described using non-linear mixed effects models. One and two-compartment disposition models with first-order elimination were tested. Pharmacokinetic parameter estimates were scaled using allometry and standardized to a 70 kg person.

RESULTS

There were 208 acetaminophen concentrations assayed from 30 children, 15 with cyanotic, and 15 with acyanotic heart disease. A 2-compartment model best described acetaminophen PK. Parameter estimates (population parameter variability, PPV%; 95% confidence interval, CI) were clearance CL 15.3 L.h-1.70 kg-1 (22.2%; 13.8-16.7), intercompartment clearance Q 45.4 L.h-1.70 kg-1 (22.4%; 25.2-61.9), central volume of distribution V1 33.5 L.70 kg-1 (23.2%; 25.9-38.8), peripheral volume of distribution V2 32.1 L.70 kg^-1 (21.7%; 25.9-38.8). Neither clearance nor volume parameters differed between cyanotic and acyanotic patients.

CONCLUSIONS

Acetaminophen pharmacokinetics were characterized using a 2-compartment model with first-order elimination following cardiac bypass surgery in children. Population pharmacokinetic parameter estimates were similar to other studies in children. No differences were detected between patients with cyanotic and acyanotic heart disease.

Comparative assessment of chewing sugar-free gum and conventional analgesic drugs in alleviating self-reported pain associated with fixed orthodontic appliances: A systematic review and meta-analysis

OBJECTIVE

To compare the effect of chewing sugar-free gum towards alleviating self-reported orthodontic treatment (OT) pain compared with conventional analgesic drugs (CADs).

SEARCH SOURCES

An unrestricted search of indexed databases and manual searching was performed up to September 2021.

DATA SELECTION

Randomised controlled trials (RCTs) comparing the impact of chewing gum and CADs on relieving self-reported orthodontic pain were included.

DATA EXTRACTION

Data screening, extraction and risk of bias (RoB) assessment were performed by two authors. Meta-analyses were performed using a random-effects model. The quality of available evidence was assessed using the Grades of Recommendation, Assessment, Development and Evaluation approach.

RESULTS

Nine RCTs were included. Eight RCTs used the Visual Analogue Scale for self-reported pain assessment, while one RCT used the Numeric Rating Scale. Five RCTs had a high RoB and four RCTs had a moderate RoB. Power analysis for sample size estimation was performed in six RCTs. Separate meta-analyses were performed by pooling quantitative data from five RCTs that compared self-reported orthodontic pain between chewing gum and ibuprofen groups for the following timepoints: baseline; immediately; 2 hours; 6 hours; bedtime; 24 hours; 2 days; 3 days; 5 days; and 7 days after the placement of orthodontic appliances. None of the timepoints individually indicated a difference in self-reported pain scores between chewing sugar-free gum and ibuprofen groups. The overall level of evidence was very low.

CONCLUSION

Chewing sugar-free gum is a potentially useful alternative to CADs towards pain alleviation during fixed OT.

Urinary paracetamol (4-acetaminophenol) and its isomer 2-acetaminophenol of Chinese pregnant women: Exposure characteristics and association with oxidative stress biomarkers

N-Acetyl-4-aminophenol (NA4AP, paracetamol/acetaminophen), a widely used pharmaceutical, is ubiquitous in urine samples of general population, raising concern about human health risks; oxidative stress is considered to be a mechanism for its toxicities. N-Acetyl-2-aminophenol (NA2AP) is an isomer of NA4AP; until now, few studies characterized exposure characteristics of NA4AP and NA2AP in pregnant women. In this work, NA4AP and NA2AP concentrations in urine samples (n = 2124) collected at three different trimesters were measured to examine their internal body burden among Chinese pregnant women (n = 708) and their associations with three oxidative stress biomarkers (OSBs, 8-OHG, 8-OHdG, and HNE-MA). NA4AP was detected in 100% of the urine samples (median concentration: 7.96 ng/mL); NA2AP was detected in 94.9% of them (median: 3.05 ng/mL). The intraclass correlation coefficients of their concentrations across three trimesters were poor (<0.4); correlations of NA4AP and NA2AP were weak (r: 0.15-0.23). Pregnant women who had higher household income or urine samples provided in summer (vs. winter) had higher concentrations of NA4AP. Pregnant women who had a college degree or above (vs. less than a high school education) had higher concentrations of NA2AP but urine samples provided in summer (vs. winter) had lower concentrations of NA2AP. The 95th percentile estimated daily intake of NA4AP (2,331 ng/kg-bw/d) based on averaged concentrations of the three trimesters was 40 times lower than the cRfD for NA4AP (2.33 vs. 93 μg/kg-bw/d). Urinary concentrations of NA4AP and NA2AP were associated with higher levels of the selected OSBs. For example, an interquartile range increase in NA4AP was associated with a 26.5% (95% CI: 23.6-29.6%) increase in 8-OHG, a 27.5% (95% CI: 23.8-31.3%) increase in 8-OHdG, and a 33.4% (95% CI: 24.7-42.7%) increase in HNE-MA (p < 0.05). This is the first study to measure their concentrations repeatedly over three trimesters, examine their exposure characteristics, and reveal their associations with the selected OSBs in pregnant women. Further studies are needed to identify non-intentional exposure sources of NA4AP, NA2AP, and another isomer of them (i.e., N-acetyl-3-aminophenol), as well as more health risks related to their exposure.

Paeoniflorin Protects against Acetaminophen-Induced Liver Injury in Mice via JNK Signaling Pathway

BACKGROUND

Drug-induced liver injury (DILI), represented by acetaminophen (APAP), is a common cause of acute liver failure in clinics. Paeoniflorin (PF) has been proven to demonstrate a significant hepatoprotective effect. However, it is still unclear whether it can be a potential agent against hepatotoxicity induced by APAP. This study aimed to explore the preventive and therapeutic effects and mechanisms of PF on APAP-induced liver injury.

METHODS

Different doses of PF (50, 100, and 200 mg/kg) were given to C57BL/6 male mice for five consecutive days. After 12 h of APAP (250 mg/kg i.p.) treatment, blood and liver tissues were collected and isolated for detection.

RESULTS

The results showed that the therapeutic effects of PF on APAP mice were presented in the downregulation of the content of serum indices and significantly improved hepatic tissue edema and inflammatory infiltration. Meanwhile, PF reduces the level of the mitochondrial metabolic enzyme. Ulteriorly, it was found that PF has a downregulating effect on the apoptotic reaction and could inhibit the protein expression of CYP2E1/JNK signaling, which in turn reduces the damage of APAP.

CONCLUSION

Our findings showed that PF acted as a protective agent against APAP-induced hepatotoxicity by inhibiting JNK-related signals, suggesting a novel insight into treating APAP-induced liver injury.

Oxidative stress mediates end-organ damage in a novel model of acetaminophen-toxicity in Drosophila

Acetaminophen is the most common cause of acute drug-induced liver injury in the United States. However, research into the mechanisms of acetaminophen toxicity and the development of novel therapeutics is hampered by the lack of robust, reproducible, and cost-effective model systems. Herein, we characterize a novel Drosophila-based model of acetaminophen toxicity. We demonstrate that acetaminophen treatment of Drosophila results in similar pathophysiologic alterations as those observed in mammalian systems, including a robust production of reactive oxygen species, depletion of glutathione, and dose-dependent mortality. Moreover, these effects are concentrated in the Drosophila fat body, an organ analogous to the mammalian liver. Utilizing this system, we interrogated the influence of environmental factors on acetaminophen toxicity which has proven difficult in vertebrate models due to cost and inter-individual variability. We find that both increasing age and microbial depletion sensitize Drosophila to acetaminophen toxicity. These environmental influences both alter oxidative stress response pathways in metazoans. Indeed, genetic and pharmacologic manipulations of the antioxidant response modify acetaminophen toxicity in our model. Taken together, these data demonstrate the feasibility of Drosophila for the study of acetaminophen toxicity, bringing with it an ease of genetic and microbiome manipulation, high-throughput screening, and availability of transgenic animals.

Desorption Electrospray Ionization Mass Spectrometry Imaging Allows Spatial Localization of Changes in Acetaminophen Metabolism in the Liver after Intervention with 4-Methylpyrazole

Acetaminophen (APAP) overdose is the most common cause of acute liver failure in the US, and hepatotoxicity is initiated by a reactive metabolite which induces characteristic centrilobular necrosis. The only clinically available antidote is N-acetylcysteine, which has limited efficacy, and we have identified 4-methylpyrazole (4MP, Fomepizole) as a strong alternate therapeutic option, protecting against generation and downstream effects of the cytotoxic reactive metabolite in the clinically relevant C57BL/6J mouse model and in humans. However, despite the regionally restricted necrosis after APAP, our earlier studies on APAP metabolites in biofluids or whole tissue homogenate lack the spatial information needed to understand region-specific consequences of reactive metabolite formation after APAP overdose. Thus, to gain insight into the regional variation in APAP metabolism and study the influence of 4MP, we established a desorption electrospray ionization mass spectrometry imaging (DESI-MSI) platform for generation of ion images for APAP and its metabolites under ambient air, without chemical labeling or a prior coating of tissue which reduces chemical interference and perturbation of small molecule tissue localization. The spatial intensity and distribution of both oxidative and nonoxidative APAP metabolites were determined from mouse liver sections after a range of APAP overdoses. Importantly, exclusive differential signal intensities in metabolite abundance were noted in the tissue microenvironment, and 4MP treatment substantially influenced this topographical distribution.

Acetaminophen toxicity and overdose: current understanding and future directions for NAC dosing regimens

INTRODUCTION

Although N-acetyl-cysteine (NAC) has long been used for the treatment of acetaminophen poisoning/overdose, the optimal NAC dosing regimen for varying patterns or severity of the poisoning/overdose is still unknown.

AREAS COVERED

Relevant literature was searched for in the MEDLINE (from 1964 until August 31^st, 2022), SCOPUS (from 2004 until August 31^st, 2022) and GOOGLE SCHOLAR (from 2004 until August 31^st, 2022) databases, without restriction in terms of publication date. The inclusion criteria were: original clinical studies reporting results, and studies investigating efficacy and safety of NAC dosing regimens in case(s) of overdose or poisoning with acetaminophen.

EXPERT OPINION

For a more effective treatment of acetaminophen poisoning in the future, it will be crucial to advance the technology of measuring acetaminophen, its metabolites and NAC in the serum, preferably with the point-of-care technique, so that in real time it can be continuously assessed whether it is necessary to administer NAC, and further to increase the dose of NAC and extend the duration of its administration, or not.

Characterization and Quantification of Oxidized High Mobility Group Box 1 Proteoforms Secreted from Hepatocytes by Toxic Levels of Acetaminophen

The high mobility group box 1 (HMGB1), which is released during acute acetaminophen (APAP) overdose, is thought to mediate a subsequent immune response, particularly hepatic infiltration of macrophages. The redox behavior of HMGB1 and the proteoforms of HMGB1 present in oxidative environments has been the subject of a number of confusing and contradictory studies. Therefore, a stable isotope dilution two-dimensional nanoultrahigh-performance liquid chromatography parallel reaction monitoring/high-resolution mass spectrometry method was developed in order to characterize and quantify oxidative modifications to the cysteine (Cys) residues (Cys-23, Cys-45, and Cys-106) that are present in HMGB1. Disulfide linkages were determined using carbamidoethyl derivatization before and after reduction as well as by direct analysis of disulfide cross-linked peptides. A stable isotope labeled form of HMGB1 was used as an internal standard to correct for sample to sample differences in immunoaffinity precipitation, derivatization, and electrospray ionization. Four discrete HMGB1 proteoforms were found to be released from a hepatocarcinoma cell model of APAP overdose after 24 h. Fully reduced HMGB1 with all three Cys-residues in their free thiol state accounted for 18% of the secreted HMGB1. The proteoform with disulfide between Cys-23 and Cys-45 accounted for 24% of the HMGB1. No evidence was obtained for a disulfide cross-link between Cys-106 and the other two Cys-residues. However, 45% of the HMGB1 formed a cross-link with unidentified intracellular proteins via an intermolecular disulfide bond, and 12% was present as the terminally oxidized cysteic acid. Surprisingly, there was no evidence for the formation of HMGB1 disulfides with GSH or other low molecular weight thiols. Secreted plasma HMGB1 Cys-23/Cys45 disulfide proteoform together with the Cys-106/protein disulfide proteoforms could potentially serve as early biomarkers of hepatoxicity after APAP overdose as well as biomarkers of drug-induced liver injury.

Transplacental transfer of acetaminophen in pregnant rats

Acetaminophen is among the most widely used analgesics; however, the proportion and mechanism of transplacental transfer of unbound acetaminophen with actual pharmacological activity remain unknown. Our hypothesis is that acetaminophen gradually penetrates the blood-placenta barrier to reach the fetus. A multiple microdialysis coupled to liquid chromatography with photodiode array detection method was developed to monitor acetaminophen levels in the maternal blood, placenta, fetus, and amniotic fluid of a pregnant rat and investigate this hypothesis. The pharmacokinetic data indicates that acetaminophen exhibits a nonlinear behavior in the maternal blood within the dosage regimen of 100 and 300 mg/kg. In addition, acetaminophen penetrates the placenta, fetus, and amniotic fluid during treatment. The transplacental transfer ratio represented by the area under the concentration curve (AUC) ratio for the conceptus (the collective term for the fetus, placenta, and amniotic fluid) and maternal blood (AUC_tissue/AUC_blood) was approximately 11-23 % after acetaminophen (100 and 300 mg/kg) administration. However, the transporter of multidrug resistance-associated protein (MRP) inhibitor MK-571 did not significantly change the transplacental transfer ratio. This basic study provides constructive information for the clinical application of acetaminophen in pregnant women.

Pharmacogenetic profiling and individualised therapy in the treatment of degenerative spinal conditions

Patients presenting with degenerative spinal changes are often poor surgical candidates due to associated co-morbidities, frailty, or sarcopenia. Additionally, surgeries of a degenerative spine can prove difficult due to the distortion of normal surgical anatomy. Therefore, many patients are managed conservatively with a variety of modalities, including over-the-counter and prescription medications. Nevertheless, several patients do not experience adequate relief from pain with analgesic medications, precipitating multiple hospital visits, and usage of resources. As a result, back pain is regarded as a major economic burden, with total costs of associated treatment exceeding $100 billion annually. Pharmacogenetics is a relatively novel method of evaluating an individual's response to analgesic medications, through analysis of germline polymorphisms. It entails obtaining a genetic sample, often via buccal swab or peripheral blood sample, and genetic analysis achieved through either polymerase chain reaction +/- Sanger sequencing, microassays, restriction length fragment polymorphism analysis, or genetic library preparation and next generation sequencing. The potential efficacy of pharmacogenetic analysis has been highlighted across several specialities to date. However, a paucity of evidence exists regarding spine surgery populations. Nevertheless, regular prospective pharmacogenetic analysis may ultimately prove beneficial when concerning degenerative spinal cohorts due to aforementioned surgical and economic considerations. The purpose of this narrative review is to outline how metaboliser profile variants affect the pharmacokinetics of specific analgesia used to treat back pain, and to discuss the current potential and limitations of employing regular pharmacogenetic analysis for spine surgery populations with degenerative conditions.

Interaction of the Emerging Mycotoxins Beauvericin, Cyclopiazonic Acid, and Sterigmatocystin with Human Serum Albumin

Beauvericin (BEA), cyclopiazonic acid (CPA), and sterigmatocystin (STC) are emerging mycotoxins. They appear as contaminants in food and animal feed, leading to economic losses and health risks. Human serum albumin (HSA) forms stable complexes with certain mycotoxins, including ochratoxins, alternariol, citrinin, and zearalenone. HSA binding can influence the toxicokinetics of xenobiotics, and albumin can also be considered and applied as a relatively cheap affinity protein. Therefore, we examined the potential interactions of BEA, CPA, and STC with HSA employing fluorescence spectroscopy, ultracentrifugation, ultrafiltration, and molecular modeling. Spectroscopic and ultracentrifugation studies demonstrated the formation of low-affinity BEA–HSA (K_a ≈ 10³ L/mol) and moderately strong CPA–HSA and STC–HSA complexes (K_a ≈ 10⁴ L/mol). In ultrafiltration experiments, CPA slightly displaced each site marker (warfarin, naproxen, and camptothecin) tested, while BEA and STC did not affect significantly the albumin binding of these drugs. Modeling studies suggest that CPA occupies Sudlow’s site I, while STC binds to the Heme site (FA1) on HSA. Considering the interactions of CPA with the site markers, the CPA–HSA interaction may have toxicological importance.

Unraveling the effect of intra- and intercellular processes on acetaminophen-induced liver injury

In high dosages, acetaminophen (APAP) can cause severe liver damage, but susceptibility to liver failure varies across individuals and is influenced by factors such as health status. Because APAP-induced liver injury and recovery is regulated by an intricate system of intra- and extracellular molecular signaling, we here aim to quantify the importance of specific modules in determining the outcome after an APAP insult and of potential targets for therapies that mitigate adversity. For this purpose, we integrated hepatocellular acetaminophen metabolism, DNA damage response induction and cell fate into a multiscale mechanistic liver lobule model which involves various cell types, such as hepatocytes, residential Kupffer cells and macrophages. Our model simulations show that zonal differences in metabolism and detoxification efficiency are essential determinants of necrotic damage. Moreover, the extent of senescence, which is regulated by intracellular processes and triggered by extracellular signaling, influences the potential to recover. In silico therapies at early and late time points after APAP insult indicated that prevention of necrotic damage is most beneficial for recovery, whereas interference with regulation of senescence promotes regeneration in a less pronounced way.

Synthesis of calcium carbonate-quince bio-composite for programmed and on-demand drug release of paracetamol at target site: a green chemistry approach

In this study, an inorganic-organic composite system was developed through biomineralization of calcium carbonate in the quince-seed mucilage-based hydrogel. Drug-polymer interactions were studied by FTIR, DSC, XRD and SEM analysis. The water absorption capacity was calculated by swelling index. Drug release was determined at various pH. Several in vitro kinetic models were applied to observe drug release behaviour. Studies of drug-polymer interactions and particle flow characteristics of the developed composite material have shown that there is good compatibility between drug and the excipients. The XRD and SEM results confirmed calcite polymorphs in the developed composite material. Thermograms showed that the developed composite material was heat stable. A restricted drug release was observed in an acidic medium (pH 1.2). A controlled drug release was depicted from the developed system at pH 6.8. The drug release mechanism of Super Case II was suggested. The developed system was considered to be an effective drug carrier for colon targeted oral delivery of non-steroidal anti-inflammatory drugs (NSAIDs) to avoid gastric irritation and risk of ulceration.

Graphical abstract

An illustration of extraction of quince hydrogel and development of calcium carbonate-quince (CaCO3-Q) composite system; QSM = Quince seed mucilage.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00289-022-04400-1.

Voltammetric determination of acetaminophen in pharmaceutical preparations and human urine using glassy carbon paste electrode modified with reduced graphene oxide

A completely new direct voltammetric method has been developed for determination of acetaminophen (APAP), known as popular analgesic drug. The present electroanalytical method is based on anodic oxidation of APAP at the glassy carbon paste electrode modified with reduced graphene oxide (RGO). Key experimental conditions were studied, resulting in a set of optimal conditions: acetate buffer (pH 5.0) as working medium electrolyte, content of RGO, parameters of squarewave voltammetry including the potential step of 5 mV, potential amplitude of 50 mV, and frequency of 40 Hz. If peak area is used for evaluation, a linear range from 1.2 × 10^–6 to 2.2 × 10^–4 mol L⁻¹ characterized by determination coefficient of 0.9971, limits of quantification and detection, 9.3 × 10^–7 mol L⁻¹ and 3.1 × 10^–7 mol L⁻¹, respectively, will be obtained. Under validation, the precision was described by relative standard deviation of 2.9% for the model sample analysis. Finally, the developed voltammetric method was compared with a reference high-performance liquid chromatography method in the analysis of commercially available pharmaceutical preparation and human urine collected from five healthy volunteers.

Activation of the eIF2α-ATF4 Pathway by Chronic Paracetamol Treatment Is Prevented by Dietary Supplementation with Cysteine

Chronic treatment with acetaminophen (APAP) induces cysteine (Cys) and glutathione (GSH) deficiency which leads to adverse metabolic effects including muscle atrophy. Mammalian cells respond to essential amino acid deprivation through the phosphorylation of the eukaryotic translation initiation factor 2α (eIF2α). Phosphorylated eIF2α leads to the recruitment of activating transcription factor 4 (ATF4) to specific CCAAT/enhancer-binding protein-ATF response element (CARE) located in the promoters of target genes. Our purpose was to study the activation of the eIF2α-ATF4 pathway in response to APAP-induced Cys deficiency, as well as the potential contribution of the eIF2α kinase GCN2 and the effect of dietary supplementation with Cys. Our results showed that chronic treatment with APAP activated both GCN2 and PERK eIF2α kinases and downstream target genes in the liver. Activation of the eIF2α-ATF4 pathway in skeletal muscle was accompanied by muscle atrophy even in the absence of GCN2. The dietary supplementation with cysteine reversed APAP-induced decreases in plasma-free Cys, liver GSH, muscle mass, and muscle GSH. Our new findings demonstrate that dietary Cys supplementation also reversed the APAP-induced activation of GCN2 and PERK and downstream ATF4-target genes in the liver.

Paracetamol perturbs neuronal arborization and disrupts the cytoskeletal proteins SPTBN1 and TUBB3 in both human and chicken in vitro models

Epidemiological studies have linked long-term/high-dose usage of paracetamol (N-acetyl-para-aminophenol, APAP) during pregnancy to adverse neuropsychiatric outcomes, primarily attention-deficit hyperactive disorder (ADHD), in the offspring. Though variable, ADHD has been associated with phenotypic alterations characterized by reductions in grey matter densities and aberrations in structural connectivity, effects which are thought to originate in neurodevelopment. We used embryonic chicken cerebellar granule neurons (CGNs) and neuronally differentiating human NTERA2 cells (NT2Ns) to investigate the in vitro effects of APAP on cell viability, migration, neuritogenesis, and the intracellular levels of various proteins involved in neurodevelopment as well as in the maintenance of the structure and function of neurites. Exposure to APAP ranging from 100 to 1600 μM yielded concentration- and time-dependent reductions in cell viability and levels of neurite arborization, as well as reductions in the levels of the cytoskeletal protein β2-spectrin, with the highest APAP concentration resulting in between 50 and 75% reductions in the aforementioned metrics over the course of 72 h. Exposure to APAP also reduced migration in the NT2Ns but not CGNs. Moreover, we found concentration- and time-dependent increases in punctate aggregation of the cytoskeletal protein β3-tubulin following exposure to APAP in both cell model systems, with the highest APAP concentration approximately doubling the number of aggregates over 72-120 h. Our findings demonstrate that APAP negatively perturbs neurite arborization degree, with concurrent reductions in the protein levels of β2-spectrin and disruption of the integrity of β3-tubulin, both proteins of which play important roles in neuronal structure and function.

Use of temperature changes and pro-inflammatory biomarkers to diagnose bacterial infections in patients with severe cerebral trauma

Background: In patients undergoing neurosurgeries, inflammation and infection are strongly related; however, inflammation can be present without infection. Midregional proadrenomedullin (MR-proADM) is a relatively new sepsis biomarker that is rarely used clinically. Recently, the concept of DiffTemp was introduced, that is, a >1°C rise from individual normal temperature accompanied by malaise, as a more accurate definition of temperature assessed as fever. The aim of the present study was to examine the importance of C-reactive protein (CRP), white blood cells, procalcitonin, and MR-proADM levels and DiffTemp.Methods: This prospective, comparative study had a quantitative approach. Forty-two patients, aged >18 years and presenting with severe cerebral trauma were included from a neurosurgery intensive care unit. The outcome variable was infection; group 0, no infection (n=11); group 1, suspected infection (n=15); and, group 2, confirmed infection (n=16). Group assignments were performed using biomarkers, medical records, bacterial cultures, and International Classification of Diseases-10, and by the clinical assessment of criteria for nosocomial infections by a neurosurgeon.Results: On comparing groups 1 and 2, MR-proADM and DiffTemp were associated with a higher risk of confirmed infection (odds ratio, 5.41 and 17.14, respectively). Additionally, DiffTemp had a 90.9% specificity in patients with no infection and a 93.8% sensitivity in patients with confirmed infections. CRP and procalcitonin levels were not associated with an increased risk of confirmed infection.Conclusion: Increased levels of MR-proADM were associated with a higher risk of confirmed infection. DiffTemp was associated with a higher risk of having a confirmed infection.

Genetic and pharmacologic proteasome augmentation ameliorates Alzheimer's-like pathology in mouse and fly APP overexpression models

The proteasome has key roles in neuronal proteostasis, including the removal of misfolded and oxidized proteins, presynaptic protein turnover, and synaptic efficacy and plasticity. Proteasome dysfunction is a prominent feature of Alzheimer's disease (AD). We show that prevention of proteasome dysfunction by genetic manipulation delays mortality, cell death, and cognitive deficits in fly and cell culture AD models. We developed a transgenic mouse with neuronal-specific proteasome overexpression that, when crossed with an AD mouse model, showed reduced mortality and cognitive deficits. To establish translational relevance, we developed a set of TAT-based proteasome-activating peptidomimetics that stably penetrated the blood-brain barrier and enhanced 20S/26S proteasome activity. These agonists protected against cell death, cognitive decline, and mortality in cell culture, fly, and mouse AD models. The protective effects of proteasome overexpression appear to be driven, at least in part, by the proteasome's increased turnover of the amyloid precursor protein along with the prevention of overall proteostatic dysfunction.

A green approach to the analysis of co-administered ampicillin/sulbactam and paracetamol in human urine

The novelty of this work is the simultaneous analysis of sulbactam (SUL), ampicillin (AMP), and paracetamol (PARA) in human urine samples, using the environmentally benign RP-HPLC method. A C18 column was used in chromatographic separation using potassium dihydrogen phosphate (10 mmol L^-1, pH 5)/ethanol (90 %, V/V) as the mobile phase; flow rate was 1.00 mL min^-1. UV detection at 220 nm was used for quantification. The proposed method showed good linearity in the concentration ranges of 2.20-250.00 μg mL^-1 for SUL, 2.50-250.00 μg mL^-1 for PARA, and 14.50-250.00 μg mL^-1 for AMP. Direct injection of urine samples with no prior extraction was performed. This method was found successful in moving towards greener studies of drugs' urinary excretion, by decreasing hazardous solvent consumption and waste. Moreover, the method was applied to investigate the urinary excretion of the drugs and possible interaction between ampicillin and paracetamol.

4'-Nitrobiphenyl thioglucoside as the Smallest, fluorescent photosensitizer with cancer targeting ligand

We have previously developed a glucose-linked biphenyl photosensitizer that can pass through glucose transporters, aiming for cancer-selective photodynamic therapy (PDT). Its small size (MW: 435) will allow oral administration and a fast clearance avoiding photosensitivity. However, its fluorescence efficiency was quite low, causing difficulty in monitoring cellular uptake. We thus synthesized a series of monosaccharide-linked biphenyl derivatives with a sulfur atom replacing an oxygen atom, in search of a photosensitizer with a brighter fluorescence. Among them, 4'-nitrobiphenyl thioglucoside showed a fluorescence emission extending to near infra-red region with a strength three times greater than that of the previous compound. This compound was found to have a higher ¹O₂-producing efficiency (Φ_Δ: 0.75) than the previous compound (Φ_Δ: 0.65). The thioglucoside indicated a significant photodamaging effect (IC₅₀: 250 μM) against cancer cells. Although the galactose and mannose analogs exerted similar photodamaging effects, they were moderately toxic in the dark at a concentration of 300 μM. The thioglucoside and thiomannoside were at least partially uptaken through glucose transporters as demonstrated by inhibition with cytochalasin B, whereas no inhibition was observed for the galactoside. The behavior of d-glucose toward the cellular uptakes of these photosensitizers was bipolar: inhibitory at a low concentration and recovery or acceleratory at a higher concentration. These results indicate that 4'-nitrobiphenyl thioglucoside is the smallest (MW: 393) cancer-targeting photosensitizer with a trackable fluorescence property.

Population Pharmacokinetic Modelling of Acetaminophen and Ibuprofen: the Influence of Body Composition, Formulation and Feeding in Healthy Adult Volunteers

BACKGROUND AND OBJECTIVE

Combined acetaminophen and ibuprofen are common antipyretic and analgesic drugs. Formulation and feeding affect drug absorption. Drug clearance has a nonlinear relationship with total body weight. The covariate effect of fat mass on acetaminophen and ibuprofen pharmacokinetics remains unexplored. This study sought to quantify acetaminophen and ibuprofen pharmacokinetics with intravenous, tablet, sachet and oral suspension formulations in fed and fasted states.

METHODS

Pooled time-concentration data for acetaminophen and ibuprofen were available from fasting and fed healthy adults. Data from intravenous, tablet, sachet and suspension formulations were analysed using nonlinear mixed-effects models. Body composition was considered as a covariate on clearances and volumes of distribution (V_d). Size metrics investigated were total body weight, fat and fat-free mass. Theory-based allometry was used to scale pharmacokinetic parameters to a 70 kg individual. A factor on absorption half-life and lag time quantified delays due to feeding for oral formulations. Pharmacokinetic-pharmacodynamic simulations were used to explore the time courses of pain response for acetaminophen and ibuprofen for each formulation.

RESULTS

Pooled data included 116 individuals (18-49 years, 49-116 kg) with 6095 acetaminophen and 6046 ibuprofen concentrations available for analysis. A two-compartment pharmacokinetic model with first-order elimination described disposition for both drugs. Normal fat mass was the best covariate to describe acetaminophen clearance (CL), with a factor for fat contribution (FFATCL) of 0.816. Acetaminophen volume of distribution was described using total body weight. Normal fat mass was the best covariate to describe ibuprofen clearance (FFATCL = 0.863) and volume of distribution: (FFATV = 0.718). Clearance and central volume of distribution were 24.0 L/h/70 kg and 43.5 L/h/70 kg for acetaminophen. Ibuprofen clearance and central volume of distribution were 3.79 L/h/70 kg and 10.5 L/h/70 kg. Bioavailability and absorption half-life were 86% and 12 min for acetaminophen and 94% and 27 min for ibuprofen. Absorption lag times were 5.3 min and 6.7 min for acetaminophen and ibuprofen, respectively. Feeding increased both absorption half-life and absorption lag time when compared to the tablet formulation under fasting conditions. Feeding had the most pronounced effect on the lag time associated with tablet formulation for both drugs. Time to a pain score reduction of 2 points (visual analogue score, 0-10) differed by only 5-10 min across all formulations for acetaminophen and ibuprofen.

CONCLUSION

Fat mass was an important covariate to describe acetaminophen and ibuprofen pharmacokinetics. The absorption half-lives of acetaminophen and ibuprofen were increased in fed states. The delay in absorption, quantified by a lag time, was protracted for both drugs.