Detection of Distinct Distributions of Acetaminophen and Acetaminophen-Cysteine in Kidneys up to 10 µm Resolution and Identification of a Novel Acetaminophen Metabolite Using an AP-MALDI Imaging Mass Microscope.

Drug distribution studies in tissue are crucial for understanding the pharmacokinetics and potential toxicity of drugs. Recently, matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) has gained attention for drug distribution studies due to its high sensitivity, label-free nature, and ability to distinguish between parent drugs, their metabolites, and endogenous molecules. Despite these advantages, achieving high spatial resolution in drug imaging is challenging. Importantly, many drugs and metabolites are rarely detectable by conventional vacuum MALDI-MSI because of their poor ionization efficiency. It has been reported that acetaminophen (APAP) and one of its major metabolites, APAP-Cysteine (APAP-CYS), cannot be detected by vacuum MALDI-MSI without derivatization. In this context, we showed the distribution of both APAP and APAP-CYS in kidneys at high spatial resolution (25 and 10 µm) by employing an atmospheric pressure-MALDI imaging mass microscope without derivatization. APAP was highly accumulated in the renal pelvis 1 h after drug administration, while APAP-CYS exhibited characteristic distributions in the outer medulla and renal pelvis at both 30 min and 1 h after administration. Interestingly, cluster-like distributions of APAP and APAP-CYS were observed in the renal pelvis at 10 µm spatial resolution. Additionally, a novel APAP metabolite, tentatively coined as APAP-butyl sulfate (APAP-BS), was identified in the kidney, brain, and liver by combining MSI and tandem MSI. For the first time, our study revealed differential distributions of APAP, APAP-CYS (in kidneys), and APAP-BS (in kidney, brain, and liver) and is believed to enhance the understanding of the pharmacokinetics and potential nephrotoxicity of this drug.

The concerted elevation of conjugation reactions is associated with the aggravation of acetaminophen toxicity in Akr1a-knockout mice with an ascorbate insufficiency.

AIMS: Acetaminophen (APAP) is a relatively safe analgesic drug, but overdosing can cause acute liver failure. Ingested APAP is detoxified by metabolic conversion through conjugation reactions with glucuronate, sulfate, or glutathione (GSH). The consumption of GSH through conjugation as well as mitochondrial dysfunction is considered to be responsible for the increased susceptibility to APAP-induced hepatotoxicity. Compared to wild-type (WT) mice, Akr1a-knockout (KO) mice are vulnerable to developing hepatotoxicity due to the fact that ascorbate synthesis is attenuated. We used such KO mice to investigate how these conjugation reactions are involved in the hepatotoxicity caused by an overdose of APAP under ascorbate-deficient conditions. MAIN METHODS: APAP (400 mg/kg) was intraperitoneally administered to WT mice and KO mice. In addition to histological and blood biochemical analyses, metabolites in the liver, blood plasma, and urine were measured at several time points by liquid chromatography-mass spectrometry. KEY FINDINGS: Liver damage occurred earlier in the KO mice than in the WT mice. The levels of APAP-Cys, a final metabolite of GSH-conjugated APAP, as well as glucuronidated APAP and sulfated APAP were all higher in the KO mice compared to the WT mice. Treatment of the APAP-administered KO mice with N-acetylcysteine or supplementation of ascorbate suppressed the conjugation reactions at 6 h after APAP had been administrated, which mitigated the degree of liver damage. SIGNIFICANCE: An ascorbate deficiency coordinately stimulates conjugation reactions of APAP, which, combined with the mitochondrial damage caused by APAP metabolites, collectively results in the aggravation of the acute liver failure.

Decreased plasma acetaminophen glucuronide/acetaminophen concentration ratio warns the onset of acetaminophen-induced liver injury.

Acetaminophen (APAP)-induced liver injury (AILI) is the most common cause of acute liver failure. Although the mechanisms that trigger AILI are well known, it is less understood how to halt AILI progression and facilitate liver recovery. Therefore, it is necessary to understand the pathophysiology of APAP hepatotoxicity in patients and to examine predictive/preventive markers. In a clinical study, we had a case in which aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels increased in a patient with a low ratio of APAP glucuronide concentration (AP-G)/APAP plasma concentration. Then a reverse translational study was conducted for clarifying this clinical question. The relationship between plasma AP-G/APAP concentration ratio and the levels of AST and ALT was examined by in vivo and in vitro experiments. In in vivo experiments, 10-week-old rats showed lower UGT activity, lower AP-G/APAP concentration ratios, and higher AST and ALT levels than 5-week-old rats. This suggests an inverse correlation between the AP-G/APAP concentration ratio and the AST, ALT levels in APAP-treated rats. Furthermore, as a result of the in vitro experiment, it was confirmed that the cell viability decreased when the AP-G/APAP concentration ratio in the culture medium decreased. Since the decrease in the plasma AP-G/APAP concentration ratio appears earlier than the increase of AST and ALT levels, the ratio might be a presymptomatic marker of AILI. When APAP is used for a long time, it is recommended to perform therapeutic drug monitoring of the AP-G/APAP concentration ratio, which is a predictive/preventive marker of AILI.

Short-Term High-Fat Diet Alters Acetaminophen Metabolism in Healthy Individuals.

BACKGROUND: Acetaminophen is metabolized through a nontoxic sulfation and glucuronidation pathway and toxic oxidation pathway (via CYP2E1 and CYP1A2). A short-term high-fat diet induces alterations in the steatotic liver and may alter hepatic drug enzyme activity. In the case of acetaminophen, these alterations may result in an increased risk of hepatotoxicity. Therefore, this study was conducted to assess the effect of a 3-day hypercaloric high-fat diet on the plasma levels of acetaminophen metabolites. METHODS: Nine healthy subjects participated in this randomized, crossover intervention study. The subjects consumed a regular diet or a regular diet supplemented with 500 mL of cream (1700 kcal) for 3 days and then fasted overnight. After ingesting 1000-mg acetaminophen, the plasma concentration of acetaminophen (APAP) and its metabolites [acetaminophen glucuronide, acetaminophen sulfate, 3-cysteinyl-acetaminophen, and 3-(N-acetyl-L-cystein-S-yl)-acetaminophen, and 3-methoxy-acetaminophen] were measured. RESULTS: The 3-day high-fat diet increased the extrapolated area under the concentration-time curve from 0 to infinity (area under the curve 0-inf ) of APAP-Cys by approximately 20% ( P = 0.02) and that from 0 to 8 hours (area under the curve 0-8 ) of APAP-Cys-NAC by approximately 39% ( P = 0.01). The 3-day high-fat diet did not alter the pharmacokinetic parameters of the parent compound acetaminophen and other metabolites. CONCLUSIONS: A short-term, hypercaloric, high-fat diet increases the plasma levels of the APAP metabolites formed by the oxidation pathway, which may increase the risk of hepatotoxicity.

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 (Vd). 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.

The effect of nutritional status on the pharmacokinetic profile of acetaminophen.

Nutritional imbalance (low protein / high fat) is a public health problem affecting many people in developing and developed nations. Such an imbalance will influence pathophysiological homeostasis in individuals and thereby considerably impact drug pharmacokinetics. It was reported that short-term fasting increases acetaminophen exposure in healthy subjects, whereas no effect was observed after a high-fat diet. These findings suggest the necessity of considering nutritional status when assessing the risk of acetaminophen-induced hepatotoxicity. Additionally, the role of nutrition status on the pharmacokinetic profile of acetaminophen (APAP) at toxic doses is either scanty or not available. With this background, we aimed to compare the effects of nutrition status on the pharmacokinetic profile of APAP at a toxic dose in three different dietary regimens like - Normal diet (ND), Low protein diet (LPD), and High-fat diet (HFD). Balb/C female mice were divided into three groups after weaning, and for the next 15 weeks, they were fed with their respective diets (ND, LPD, and HFD). After that, mice were dosed with APAP (300 mg/kg p.o), and blood sampling was done at different time intervals and centrifuged at 3000 rpm for 5 min to collect plasma samples. Plasma samples were analyzed using the HPLC method. Data analysis was done by Non-compartment analysis using Phoenix WinNonlin 8.3 software. LPD group shows higher values of Cmax, tmax, t1/2, and AUC0-4, AUC0-x values than ND and HFD groups. Both Cmax and AUC follow the pattern of drug exposure where LPD > ND > HFD. In conclusion, nutrition in the diet alters APAP pharmacokinetic profile at a toxic dose in three different diet regimes. Further study on CYP450 concentration and activity is essential to understand the pharmacokinetics difference between these dietary regimens.

Mechanism of dasabuvir inhibition of acetaminophen glucuronidation.

OBJECTIVES: Acetaminophen (APAP) (paracetamol) is a widely used non-prescription drug for pain relief and antipyretic effects. The clearance of APAP is mainly through phase-2 biotransformation catalysed by UDP-glucuronosyl transferases (UGT). Dasabuvir is an anti-hepatitis C drug reported to inhibit several UGT isoforms. The study evaluated the in-vitro inhibitory capacity of dasabuvir versus APAP glucuronidation. METHODS: Procedures included human liver microsomal incubations with APAP and isoform-selective probe substrates. KEY FINDINGS: Dasabuvir inhibited APAP metabolism by a reversible, mixed-type (competitive and non-competitive) partial inhibition, with an inhibition constant Ki = 3.4 µM. The index constant 'a' was 6.7, indicating the relative contribution of competitive and non-competitive inhibition. The enzyme-inhibitor complex was still able to catalyse the reaction by 12% of the control capacity. Dasabuvir produced strong partial inhibition effect of UGT1A1 and UGT1A9 and relatively complete inhibition of UGT1A6. CONCLUSIONS: Consistent with previous reports, dasabuvir inhibits the activity of 3 UGT isoforms associated with APAP metabolism. In-vitro to in-vivo scaling by 2 different approaches showed identical results, predicting an increased AUC of APAP by a factor of 1.3-fold with coadministration of dasabuvir. Until the findings are confirmed in clinical drug interaction studies, APAP dosage should not exceed 3 g per day in dasabuvir-treated patients to avoid potentially hepatotoxic APAP exposures.

Confectionery Xylitol Gum-Containing Tablets for Medical Application and the Sintering Effect on Gum Tablets.

Confectionery ingredients are expected to enhance the medication adherence of pediatric patients taking bitter-tasting drugs when adequate pediatric medicines are not available in practical settings. Gum is a familiar confectionery, and several drug-loaded gums are on the market as medicated chewing gums. In this study, medical gum tablets composed of confectionery xylitol gum and a drug (ibuprofen or acetaminophen) were prepared and evaluated for the purpose of potential hospital applications. The effect of the sintering process, a heating treatment, on the physical properties of the solid materials was also examined. The sintering process markedly improved the hardness of the gum tablets. The sintering temperature and time affected the hardness of both ibuprofen- and acetaminophen-loaded gum tablets, whereas heat treatment around the melting point of ibuprofen or xylitol and longer heat treatment resulted in failure of the preparation or a reduction in hardness. The sintered gum tablets exhibited a delayed drug release profile in artificial saliva after an in vitro chewing test. The current results provide basic and useful information about the preparation of gum-containing tablets in future clinical settings.

Drug-Polymer Interactions in Acetaminophen/Hydroxypropylmethylcellulose Acetyl Succinate Amorphous Solid Dispersions Revealed by Multidimensional Multinuclear Solid-State NMR Spectroscopy.

The bioavailability of insoluble crystalline active pharmaceutical ingredients (APIs) can be enhanced by formulation as amorphous solid dispersions (ASDs). One of the key factors of ASD stabilization is the formation of drug-polymer interactions at the molecular level. Here, we used a range of multidimensional and multinuclear nuclear magnetic resonance (NMR) experiments to identify these interactions in amorphous acetaminophen (paracetamol)/hydroxypropylmethylcellulose acetyl succinate (HPMC-AS) ASDs at various drug loadings. At low drug loading (<20 wt %), we showed that 1H-13C through-space heteronuclear correlation experiments identify proximity between aromatic protons in acetaminophen with cellulose backbone protons in HPMC-AS. We also show that 14N-1H heteronuclear multiple quantum coherence (HMQC) experiments are a powerful approach in probing spatial interactions in amorphous materials and establish the presence of hydrogen bonds (H-bond) between the amide nitrogen of acetaminophen with the cellulose ring methyl protons in these ASDs. In contrast, at higher drug loading (40 wt %), no acetaminophen/HPMC-AS spatial proximity was identified and domains of recrystallization of amorphous acetaminophen into its crystalline form I, the most thermodynamically stable polymorph, and form II are identified. These results provide atomic scale understanding of the interactions in the acetaminophen/HPMC-AS ASD occurring via H-bond interactions.

Comparison of Oral Loading Dose to Intravenous Acetaminophen in Children for Analgesia After Tonsillectomy and Adenoidectomy: A Randomized Clinical Trial.

BACKGROUND: Acetaminophen is a frequently used adjunct analgesic in pediatric patients undergoing tonsillectomy and adenoidectomy. We compared opioid administration following preoperative intravenous (IV) or oral acetaminophen in addition to a standard multimodal regimen to test the hypothesis that 1 loading dose approach would provide superior opioid sparing effects among pediatric surgical patients undergoing tonsillectomy and adenoidectomy. METHODS: This single-center, double-blind, double-dummy prospective randomized study was conducted in patients ages 3 to 15 years undergoing tonsillectomy and adenoidectomy with or without myringotomy and tube placement between September 2017 and July 2019. Subjects received 1 dose of either oral acetaminophen 30 mg/kg with IV placebo (oral group) or IV acetaminophen 15 mg/kg with oral placebo (IV group). Acetaminophen plasma levels were measured at 2 timepoints to evaluate safety and determine plasma levels attained by each dosing regimen. Intraoperative opioid administration and postoperative analgesia were standardized. Standardized postoperative multimodal analgesia included opioid if needed to control pain assessed by standardized validated pediatric pain scales. The primary outcome measure was total opioid administration in the first 24 hours after surgery. Continuous data were not normally distributed and were analyzed using the Wilcoxon rank sum test and the Hodges-Lehman estimator of the median difference. Clinical significance was defined as a 100 µg/kg IV morphine equivalents per day difference. RESULTS: Sixty-six subjects were randomized into and completed the study (29 women, 37 men; age 5.9 ± 3.0 years; percentile weight for age 49.5 ± 30.2; no differences between groups). There was no opioid dose difference between oral (median 147.6; interquartile range [IQR], 119.6-193.0 µg/kg) and IV groups (median 125.4; IQR, 102.8-150.9 µg/kg; median difference 21.3; 95% confidence interval [CI] -2.5 to 44.2 µg/kg IV morphine equivalents; P = .13). No acetaminophen levels exceeded the predefined safety threshold (40 mg/L). No difference was found in the percentage of patients with severe pain: 50.0% oral group, 47.2% IV group; relative risk of severe pain in IV 0.94; 95% CI, 0.57-1.6; P = .82. Postoperative plasma acetaminophen levels were higher in oral (22; IQR, 16-28 mg/L) than IV (20; IQR, 17-22 mg/L) group (median difference 7.0; 4.0-8.0 mg/L; P = .0001). CONCLUSIONS: Opioid-sparing effects did not differ following an oral or standard IV acetaminophen loading dose with no identified acetaminophen toxicity in pediatric patients undergoing tonsillectomy and adenoidectomy who received standardized multimodal postoperative analgesia. An oral loading dose may provide more consistent serum acetaminophen levels at lower cost compared to a standard IV dose.

Pharmacokinetics of Intravenous Paracetamol (Acetaminophen) and Ductus Arteriosus Closure After Premature Birth.

In preterm infants, a high risk of hemodynamically significant patent ductus arteriosus (PDA) exists and its persistence is associated with an increased risk of severe morbidity. Current pharmacological options include ibuprofen or indomethacin. However, treatment by indomethacin or ibuprofen of a large PDA was shown to reduce early pulmonary hemorrhage and later medical treatment but had no effect on neonatal death or morbidity. Early prophylactic treatment of ductus arteriosus by paracetamol seems to be an attractive opportunity to reduce life-threatening morbidity. However, there are currently no data regarding the pharmacokinetics (PK) and pharmacodynamics of paracetamol in preterm neonates in this potential new indication. In this study, we aimed to develop a population PK model for paracetamol and investigate the relationship between paracetamol exposure levels and time to contraction of the ductus. Data were modeled using Monolix software. A one-compartment model adequately described the paracetamol concentration-time course. A Weibull model adequately described the time to contraction of the ductus. Our results suggest that the dosage used in this study (i.e., first day 42.5 mg/kg, then 30 mg/kg/day) allows for reaching the maximum inhibition response from paracetamol regarding the time to close the ductus. However, this study pointed out a lower effect of paracetamol on extremely preterm neonates (below 27 weeks). Therefore, a dose-finding study focusing specifically on extremely preterm neonates with treatment efficacy and toxicity is strongly needed.

Influence of general anaesthesia on the intravenous acetaminophen pharmacokinetics in Beagle dogs.

OBJECTIVE: To determine if general anaesthesia influences the intravenous (IV) pharmacokinetics (PK) of acetaminophen in dogs. STUDY DESIGN: Prospective, crossover, randomized experimental study. ANIMALS: A group of nine healthy Beagle dogs. METHODS: Acetaminophen PK were determined in conscious and anaesthetized dogs on two separate occasions. Blood samples were collected before, and at 5, 10, 15, 30, 45, 60 and 90 minutes and 2, 3, 4, 6, 8, 12 and 24 hours after 20 mg kg-1 IV acetaminophen administration. Haematocrit, total proteins, albumin, alanine aminotransferase, aspartate aminotransferase, urea and creatinine were determined at baseline and 24 hours after acetaminophen. The anaesthetized group underwent general anaesthesia (90 minutes) for dental cleaning. After the administration of dexmedetomidine (3 µg kg-1) intramuscularly, anaesthesia was induced with propofol (2-3 mg kg-1) IV, followed by acetaminophen administration. Anaesthesia was maintained with isoflurane in 50% oxygen (Fe'Iso 1.3-1.5%). Dogs were mechanically ventilated. Plasma concentrations were analysed with high-performance liquid chromatography. PK analysis was undertaken using compartmental modelling. A Wilcoxon test was used to compare PK data between groups, and clinical laboratory values between groups, and before versus 24 hours after acetaminophen administration. Data are presented as median and range (p < 0.05). RESULTS: A two-compartmental model best described time-concentration profiles of acetaminophen. No significant differences were found for volume of distribution values 1.41 (0.94-3.65) and 1.72 (0.89-2.60) L kg-1, clearance values 1.52 (0.71-2.30) and 1.60 (0.91-1.78) L kg-1 hour-1 or terminal elimination half-life values 2.45 (1.45-8.71) and 3.57 (1.96-6.35) hours between conscious and anaesthetized dogs, respectively. Clinical laboratory variables were within normal range. No adverse effects were recorded. CONCLUSIONS AND CLINICAL RELEVANCE: IV acetaminophen PK in healthy Beagle dogs were unaffected by general anaesthesia under the study conditions. Further studies are necessary to evaluate the PK in different clinical contexts.

Evaluation of Physiologically Based Pharmacokinetic Models to Predict the Absorption of BCS Class I Drugs in Different Pediatric Age Groups.

Age-related changes in many parameters affecting drug absorption remain poorly characterized. The objective of this study was to apply physiologically based pharmacokinetic (PBPK) models in pediatric patients to investigate the absorption and pharmacokinetics of 4 drugs belonging to the Biopharmaceutics Classification System (BCS) class I administered as oral liquid formulations. Pediatric PBPK models built with PK-Sim/MoBi were used to predict the pharmacokinetics of acetaminophen, emtricitabine, theophylline, and zolpidem in different pediatric populations. The model performance for predicting drug absorption and pharmacokinetics was assessed by comparing the predicted absorption profile with the deconvoluted dose fraction absorbed over time and predicted with observed plasma concentration-time profiles. Sensitivity analyses were performed to analyze the effects of changes in relevant input parameters on the model output. Overall, most pharmacokinetic parameters were predicted within a 2-fold error range. The absorption profiles were generally reasonably predicted, but relatively large differences were observed for acetaminophen. Sensitivity analyses showed that the predicted absorption profile was most sensitive to changes in the gastric emptying time (GET) and the specific intestinal permeability. The drug's solubility played only a minor role. These findings confirm that gastric emptying time, more than intestinal permeability or solubility, is a key factor affecting BCS class I drug absorption in children. As gastric emptying time is prolonged in the fed state, a better understanding of the interplay between food intake and gastric emptying time in children is needed, especially in the very young in whom the (semi)fed condition is the prevailing prandial state, and hence prolonged gastric emptying time seems more plausible than the fasting state.

Hydroxysafflor yellows alleviate thrombosis and acetaminophen-induced toxicity in vivo by enhancing blood circulation and poison excretion.

BACKGROUND: Hydroxysafflor yellow A (HSYA) from the flower of Carthamus tinctorius (Safflower) has been reported to have various pharmacological effects. However, little is known about the bioactivities of other chemical constituents in Safflower and the relationship between enhancement of blood circulation and hepatoprotection by HSYA. PURPOSE: The present research was to evaluate the antithrombotic and hepatoprotective activities of HSYA and C, examine their mechanisms of actions, including influence on the excretion velocity of acetaminophen, and the relationship between the antithrombotic, hepatoprotective, and other bioactivities. METHODS: The hepatoprotective activities were examined by acetaminophen (APAP)-induced zebrafish toxicity and carbon tetrachloride (CCl4)-induced mouse liver injury. The concentrations of APAP in zebrafish and APAP that was excreted to the culture media were quantified by UHPLC-MS. The anti-thrombosis effect of HSYA and C were examined by the phenylhydrazine (PHZ)-induced zebrafish thrombosis. RESULTS: HSYA and HSYC showed robust protection on APAP-induced toxicity and PHZ-induced thrombosis. The hepatoprotective effects of HSYA and C were more potent than that of the positive control, acetylcysteine (61.7% and 58.0%, respectively, vs. 56.9% at 100 µM) and their antithrombosis effects were more robust than aspirin (95.1% and 86.2% vs. 52.7% at 100 µM). HSYA and C enhanced blood circulation, rescued APAP-treated zebrafish from morphological abnormalities, and mitigated APAP-induced toxicity in liver development in liver-specific RFP-expressing transgenic zebrafish. HSYC attenuated CCl4-induced mouse liver injury and regulated the levels of HIF-1α, iNOS, TNF-α, α-SMA, and NFκB in liver tissues. HSYA was also protective in a dual thrombotic and liver toxicity zebrafish model. By UHPLC-MS, HSYA accelerated the excretion of APAP. CONCLUSION: HSYA and C are the bioactive constituents of Safflower that are responsible for the herbal drug's traditional use in promoting blood circulation to remove blood stasis. Safflower and its chalcone constituents may protect from damage due to exogenous or disease-induced endogenous toxins by enhancing the excretion velocity of toxins.

A metabolomic analysis of thiol response for standard and modified N-acetyl cysteine treatment regimens in patients with acetaminophen overdose.

N-acetylcysteine (NAC) is an antidote to prevent acetaminophen (paracetamol-APAP)-induced acute liver injury (ALI). The 3-bag licensed 20.25 h standard regimen, and a 12 h modified regimen, are used to treat APAP overdose. This study evaluated the redox thiol response and APAP metabolites, in patients with a single APAP overdose treated with either the 20.25 h standard or 12 h modified regimen. We used liquid chromatography tandem mass spectrometry to quantify clinically important oxidative stress biomarkers and APAP metabolites in plasma samples from 45 patients who participated in a randomized controlled trial (SNAP trial). We investigated the time course response of plasma metabolites at predose, 12 h, and 20.25 h post-start of NAC infusion. The results showed that the 12 h modified regimen resulted in a significant elevation of plasma NAC and cysteine concentrations at 12 h post-infusion. We found no significant alteration in the metabolism of APAP, mitochondrial, amino acids, and other thiol biomarkers with the two regimens. We examined APAP and purine metabolism in overdose patients who developed ALI. We showed the major APAP-metabolites and xanthine were significantly higher in patients with ALI. These biomarkers correlated well with alanine aminotransferase activity at admission. Receiver operating characteristic analysis showed that at admission, plasma APAP-metabolites and xanthine concentrations were predictive for ALI. In conclusion, a significantly higher redox thiol response with the modified NAC regimen at 12 h postdose suggests this regimen may produce greater antioxidant efficacy. At baseline, plasma APAP and purine metabolites may be useful biomarkers for early prediction of APAP-induced ALI.

Acetaminophen and tramadol hydrochloride-loaded soft gelatin capsule: preparation, dissolution and pharmacokinetics in beagle dogs.

The objective of this study was to develop a novel acetaminophen and tramadol hydrochloride-loaded soft capsule (ATSC) with enhanced bioavailability of tramadol. The ATSC was manufactured in a pilot-scale batch size with the capsule contents composed of tramadol, acetaminophen, PEG 400 and Capmul MCM at a weight ratio of 37.5:325:177.5:30. Moreover, its dissolution, stability and pharmacokinetics in beagle dogs were carried out compared to commercial tablet. The dissolved amounts of acetaminophen from the ATSC and commercial tablet were not significantly different. However, compared to the latter, the former had significantly higher dissolution rate of tramadol at the initial times. In beagle dogs, the ATSC provided no significant difference in plasma concentrations and AUC of acetaminophen than did the commercial tablet; however, it significantly improved those of tramadol compared to the other, indicating the enhanced oral bioavailability of tramadol. Compared to the commercial tablet, the ATSC had a larger AUC value for tramadol (55.27 ± 11.06 vs. 92.62 ± 21.52 h·ng/ml). In the accelerated long-term stability, the ATSC offered higher than 96% drug content of acetaminophen and tramadol, suggesting that it was stable for at least six months. Therefore, this ATSC would be a recommendable candidate with enhanced oral bioavailability and excellent stability.

Controlled release evaluation of paracetamol loaded amine functionalized mesoporous silica KCC1 compared to microcrystalline cellulose based tablets.

In the pharmaceutical manufacturing, drug release behavior development is remained as one of the main challenges to improve the drug effectiveness. Recently, more focus has been done on using mesoporous silica materials as drug carriers for prolonged and superior control of drug release in human body. In this study, release behavior of paracetamol is developed using drug-loaded KCC-1-NH2 mesoporous silica, based on direct compaction method for preparation of tablets. The purpose of this study is to investigate the utilizing of pure KCC-1 mesoporous silica (KCC-1) and amino functionalized KCC-1 (KCC-1-NH2) as drug carriers in oral solid dosage formulations compared to common excipient, microcrystalline cellulose (MCC), to improve the control of drug release rate by manipulating surface chemistry of the carrier. Different formulations of KCC-1 and KCC-NH2 are designed to investigate the effect of functionalized mesoporous silica as carrier on drug controlled-release rate. The results displayed the remarkable effect of KCC-1-NH2 on drug controlled-release in comparison with the formulation containing pure KCC-1 and formulation including MCC as reference materials. The pure KCC-1 and KCC-1-NH2 are characterized using different evaluation methods such as FTIR, SEM, TEM and N2 adsorption analysis.

Study of the pharmacokinetics of various drugs under conditions of antiorthostatic hypokinesia and the pharmacokinetics of acetaminophen under long-term spaceflight conditions.

OBJECTIVES: To study the pharmacokinetics and relative bioavailability of drugs of different chemical structure and pharmacological action under conditions simulating the effects of some factors of spaceflight, as well as the peculiarities of the pharmacokinetics of acetaminophen under long-term spaceflight conditions. METHODS: The pharmacokinetics of verapamil (n=8), propranolol (n=8), etacizine (n=9), furosemide (n=6), and acetaminophen (n=7) in healthy volunteers after a single oral administration under normal conditions (background) and under antiorthostatic hypokinesia (ANOH), the pharmacokinetics of acetaminophen in spaceflight members under normal ground conditions (background) (n=8) and under prolonged spaceflight conditions (SF) (n=5) were studied. RESULTS: The stay of volunteers under antiorthostatic hypokinesia had different effects on the pharmacokinetics and bioavailability of drugs: Compared to background, there was a decreasing trend in Vz for verapamil (-54 Δ%), furosemide (-20 Δ%), propranolol (-8 Δ%), and acetaminophen (-9 Δ%), but a statistically significant increase in Vz was found for etacizine (+39 Δ%); there was an increasing trend in Clt for propranolol (+13 Δ%) and acetaminophen (+16 Δ%), and a decreasing trend in Clt for etacizine, verapamil, and furosemide (-22, -23 and -9 Δ% respectively) in ANOH. The relative bioavailability of etacizine, verapamil, and furosemide in ANOH increased compared to background (+40, +23 and +13 Δ%, respectively), propranolol and acetaminophen decreased (-5 and -12 Δ% accordingly). The relative rate of absorption of etacizine and furosemide in ANOH decreased (-19 and -20 Δ%, respectively) while that of verapamil, propranolol, and acetaminophen increased (+42, +58 and +26 Δ%, respectively). A statistically significant decrease in AUC0-∞ (-57 Δ%), Cmax (-53 Δ%), relative bioavailability of acetaminophen (-52 Δ%) and a sharp increase in Clt (+147 Δ%), Tmax (+131 Δ%) as well as a trend towards a significant decrease in T1/2 (-53 Δ%), MRT (-36 Δ%) and a moderate increase in Vz (+24 Δ%) were found under control compared to background. Unidirectional changes in AUC0-∞, Clt, T1/2, MRT and relative bioavailability of acetaminophen, which are more pronounced in SF and opposite dynamics for Cmax, Tmax, Vz were found in ANOH and SP compared to background studies. CONCLUSIONS: The data obtained allow recommending the studied drugs for rational pharmacotherapy in the possible development of cardiovascular disease in manned spaceflight.

Orostachys japonicus ameliorates acetaminophen-induced acute liver injury in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Orostachys japonicus A. Berger (O. japonicus), referred to as Wa-song in Korea is a traditional and herbal medicine. Even though it has been traditionally used to treat inflammation- and toxicity-related diseases, the effects of ethanol extract of O. japonicus (OJE) on acetaminophen (N-acetyl-p-aminophenol, APAP) overdose-induced hepatotoxicity have not been determined yet. AIM OF THE STUDY: The present study was aimed to investigate the effects of OJE against APAP-induced acute liver injury (ALI) and explore the underlying mechanisms. MATERIALS AND METHODS: Mice were treated orally with OJE (50, 100, or 200 mg/kg) for seven days before APAP (300 mg/kg) injection. After 12 h of APAP treatment, serum and liver tissues were collected. An in vitro system using primary hepatocytes was also applied in this study. RESULTS: Pretreatment with OJE, especially at a dose of 200 mg/kg, reduced APAP overdose-induced ALI in mice, as evidenced by decreased serum alanine/aspartate aminotransferase levels, histopathological damage, and inflammation. Consistently, OJE pretreatment reduced the gene transcription of cytochrome P450 (CYP) 3A11 and CYP1A2 in livers of mice injected with or without APAP, at least in part, via inactivation of nuclear receptor pregnane X receptor (PXR). Furthermore, the role of PXR in mediating the OJE regulation of CYPs was confirmed in primary hepatocytes, which showed that OJE pretreatment inhibited PXR activity and APAP hepatotoxicity enhanced by pregnenolone 16α-carbonitrile, a mouse agonist of PXR. Besides, the antioxidative activity provided by OJE, involving increases in hepatic glutathione (GSH) content and decreases in malondialdehyde levels, has been shown to exert hepatoprotective effects in normal and injured livers. Moreover, APAP-activated c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) in mice liver were indirectly inhibited by pretreatment with OJE. CONCLUSIONS: Taken together, our findings showed that OJE attenuated APAP-induced ALI by decreasing APAP-metabolizing enzymes via inactivation of PXR and the restoration of hepatic GSH content. Therefore, OJE could be a promising hepatoprotective agent.

Pharmacokinetics of acetaminophen after intravenous and oral administration in fasted and fed Labrador Retriever dogs.

Acetaminophen (paracetamol) is used in dogs to manage fever and mild pain. The aim of this study was to assess the pharmacokinetics of acetaminophen in both fed and fasted Labrador Retrievers after a single intravenous and oral administration (20 mg/kg). Six healthy dogs underwent three treatments in a randomized block study (a, n = 2; b, n = 2; c, n = 2). In phase one, group a received acetaminophen intravenously, group b and c orally after being fasted and fed, respectively. In phase two and three, groups were swapped, and the experiment was repeated. At the end of the trial, each dog received the same treatment. Acetaminophen plasma concentrations were detected using a validated HPLC-UV method. The pharmacokinetic analysis was performed using a noncompartmental model. Clearance, volume at steady state and half-life of acetaminophen in Labrador Retrievers were 0.42 L/kg hr, 0.87 L/kg and 1.35 hr, respectively. No significant statistical differences were found between fasted and fed dogs regarding maximum plasma concentration, time at maximum concentration and bioavailability as measured by the AUC. Feeding does not significantly affect the acetaminophen oral pharmacokinetics.