Low Doses Of Acetaminophen Research Articles

Acetaminophen influences musculoskeletal signaling but not adaptations to endurance exercise training.

Acetaminophen (ACE) is a widely used analgesic and antipyretic drug with various applications, from pain relief to fever reduction. Recent studies have reported equivocal effects of habitual ACE intake on exercise performance, muscle growth, and risks to bone health. Thus, this study aimed to assess the impact of a 6-week, low-dose ACE regimen on muscle and bone adaptations in exercising and non-exercising rats. Nine-week-old Wistar rats (n = 40) were randomized to an exercise or control (no exercise) condition with ACE or without (placebo). For the exercise condition, rats ran 5 days per week for 6 weeks at a 5% incline for 2 min at 15 cm/s, 2 min at 20 cm/s, and 26 min at 25 cm/s. A human equivalent dose of ACE was administered (379 mg/kg body weight) in drinking water and adjusted each week based on body weight. Food, water intake, and body weight were measured daily. At the beginning of week 6, animals in the exercise group completed a maximal treadmill test. At the end of week 6, rats were euthanized, and muscle cross-sectional area (CSA), fiber type, and signaling pathways were measured. Additionally, three-point bending and microcomputer tomography were measured in the femur. Follow-up experiments in human primary muscle cells were used to explore supra-physiological effects of ACE. Data were analyzed using a two-way ANOVA for treatment (ACE or placebo) and condition (exercise or non-exercise) for all animal outcomes. Data for cell culture experiments were analyzed via ANOVA. If omnibus significance was found in either ANOVA, a post hoc analysis was completed, and a Tukey's adjustment was used. ACE did not alter body weight, water intake, food intake, or treadmill performance (p > .05). There was a treatment-by-condition effect for Young's Modulus where placebo exercise was significantly lower than placebo control (p < .05). There was no treatment by condition effects for microCT measures, muscle CSA, fiber type, or mRNA expression. Phosphorylated-AMPK was significantly increased with exercise (p < .05) and this was attenuated with ACE treatment. Furthermore, phospho-4EBP1 was depressed in the exercise group compared to the control (p < .05) and increased in the ACE control and ACE exercise group compared to placebo exercise (p < .05). A low dose of ACE did not influence chronic musculoskeletal adaptations in exercising rodents but acutely attenuated AMPK phosphorylation and 4EBP1 dephosphorylation post-exercise.

Acetaminophen impairs ferroptosis in the hippocampus of septic mice by regulating glutathione peroxidase 4 and ferroptosis suppressor protein 1 pathways.

Neuronal ferroptosis is a major cause of cognitive impairment and mortality in patients with sepsis-associated encephalopathy (SAE). A low dose of acetaminophen (APAP) in septic mice can prevent ferroptosis in the hippocampal tissue; however, the underlying mechanism is unknown. This study aimed to investigate the mechanism by which APAP reduces ferroptosis in the hippocampal tissues of septic mice. A mouse model of SAE was established, and the ferroptosis pathway inhibitors RSL3 and iFSP1+RSL3 were used in addition to APAP for the interventions, respectively. The 7-day survival rate of the mice was recorded, and cognitive function was examined using the Morris water maze test. Hematoxylin and eosin staining was performed to observe hippocampal tissue damage. Hippocampal iron and malondialdehyde (MDA) were measured using chemical colorimetric methods. Immunofluorescence was used to detect the reactive oxygen species (ROS) content in hippocampal tissues. RSL3 reversed the efficacy of APAP on improving cognitive dysfunction in septic mice but did not obviously reverse the survival rate of mice enhanced by APAP. RSL3 aggravated APAP-induced hippocampal tissue damage in mice attenuated by APAP. RSL3 inhibited glutathione peroxidase 4 (GPX4) expression and increased ferroptosis suppressor protein 1 (FSP1) and 4-hydroxy-2-nonenal (4-HNE) expression. RSL3 also reversed the effects of APAP in reducing iron, MDA, and ROS levels in the hippocampal tissues of septic mice. iFSP1+RSL3 further reversed the effect of APAP on ameliorating cognitive dysfunction in septic mice and successfully reversed the survival rate of mice enhanced by APAP. iFSP1+RSL3 aggravated APAP-induced cerebral hippocampal damage. iFSP1+RSL3 inhibited both GPX4 and FSP1, further reversing the effect of APAP on the reduction in iron, 4-HNE, ROS, and MDA levels in the cerebral hippocampus of mice with sepsis. These data suggest that APAP inhibits ferroptosis in the cerebral hippocampus of septic mice through the GPX4 and FSP1 pathways.

Metabolic syndrome-induced tubulointerstitial injury: Role of oxidative stress and preventive effects of acetaminophen

The prevalence of metabolic syndrome persistently increases and affects over 30% of U.S. adults. To study how metabolic syndrome may induce tubulointerstitial injury and whether acetaminophen has renal-protective properties, 4-week-old obese Zucker rats were randomly assigned into three groups, control (OC), vehicle dimethyl sulfoxide (OV), and acetaminophen treatment (30mg/kg/day for 26 weeks), and lean Zucker rats served as healthy controls. Significant tubulointerstitial injuries were observed in both OC and OV animals, evidenced by increased tubular cell death, tubular atrophy/dilation, inflammatory cell infiltration, and fibrosis. These tubulointerstitial alterations were significantly reduced by treatment with a chronic but low dose of acetaminophen, which acted to diminish NADPH oxidase isoforms Nox2 and Nox4 and decrease tubulointerstitial oxidative stress (reduced tissue superoxide and macromolecular oxidation). Decreased oxidative stress by acetaminophen was paralleled by the reduction of tubular proapoptotic signaling (diminished Bax/Bcl-2 ratio and caspase 3 activation) and the alleviation of tubular epithelial-to-mesenchymal transition (decreased transforming growth factor β, connective tissue growth factor, α-smooth muscle actin, and laminin). These data suggest that increased oxidative stress plays a critical role in mediating metabolic syndrome-induced tubulointerstitial injury and provide the first evidence suggesting that acetaminophen may be of therapeutic benefit for the prevention of tubulointerstitial injury.

Age-related decrease in cerebrovascular-derived neuroprotective proteins: Effect of acetaminophen

As the population ages, the need for effective methods to maintain brain function in older adults is increasingly pressing. Vascular disease and neurodegenerative disorders commonly co-occur in older persons. Cerebrovascular products contribute to the neuronal milieu and have important consequences for neuronal viability. In this regard vascular derived neuroprotective proteins, Such as vascular endothelial growth factor (VEGF), pigment epithelium-derived factor (PEDF), and pituitary adenylate cyclase activating peptide (PACAP) are important for maintaining neuronal viability, especially in the face of injury and disease. The objective of this study is to measure and compare levels of VEGF, PEDF and PACAP released from isolated brain microvessels of Fischer 344 rats at 6, 12, 18, and 24months of age. Addition of acetaminophen to isolated brain microvessels is employed to determine whether this drug affects vascular expression of these neuroprotective proteins. Experiments on cultured brain endothelial cells are performed to explore the mechanisms/mediators that regulate the effect of acetaminophen on endothelial cells. The data indicate cerebrovascular expression of VEGF, PEDF and PACAP significantly decreases with age. The age-associated decrease in VEGF and PEDF is ameliorated by addition of acetaminophen to isolated brain microvessels. Also, release of VEGF, PEDF, and PACAP from cultured brain endothelial cells decreases with exposure to the oxidant stressor menadione. Acetaminophen treatment upregulates VEGF, PEDF and PACAP in brain endothelial cells exposed to oxidative stress. The effect of acetaminophen on cultured endothelial cells is in part inhibited by the selective thrombin inhibitor hirudin. The results of this study suggest that acetaminophen may be a useful agent for preserving cerebrovascular function. If a low dose of acetaminophen can counteract the decrease in vascular-derived neurotrophic factors evoked by age and oxidative stress, this drug might be useful for improving brain function in the elderly.

Gene interaction network analysis suggests differences between high and low doses of acetaminophen

Bayesian networks for quantifying linkages between genes were applied to detect differences in gene expression interaction networks between multiple doses of acetaminophen at multiple time points. Seventeen (17) genes were selected from the gene expression profiles from livers of rats orally exposed to 50, 150 and 1500 mg/kg acetaminophen (APAP) at 6, 24 and 48 h after exposure using a variety of statistical and bioinformatics approaches. The selected genes are related to three biological categories: apoptosis, oxidative stress and other. Gene interaction networks between all 17 genes were identified for the nine dose-time observation points by the TAO-Gen algorithm. Using k-means clustering analysis, the estimated nine networks could be clustered into two consensus networks, the first consisting of the low and middle dose groups, and the second consisting of the high dose. The analysis suggests that the networks could be segregated by doses and were consistent in structure over time of observation within grouped doses. The consensus networks were quantified to calculate the probability distribution for the strength of the linkage between genes connected in the networks. The quantifying analysis showed that, at lower doses, the genes related to the oxidative stress signaling pathway did not interact with the apoptosis-related genes. In contrast, the high-dose network demonstrated significant interactions between the oxidative stress genes and the apoptosis genes and also demonstrated a different network between genes in the oxidative stress pathway. The approaches shown here could provide predictive information to understand high- versus low-dose mechanisms of toxicity.

Effects of molybdate and pentachlorophenol on the sulfation of acetaminophen

Pentachlorophenol (PCP) is an inhibitor of phenol-sulfotransferases and has been used to ascertain the role of sulfation in toxicology. Recently, molybdate has been shown to inhibit the sulfation of various chemicals by decreasing hepatic concentrations of the cosubstrate, 3′-phosphoadenosine 5′-phosphosulfate (PAPS). The purpose of this study was to compare the effectiveness of these two chemicals in inhibiting the sulfation of various doses of acetaminophen (AA) in the rat. PCP (40 μmol/kg) decreased the 2-h combined biliary and urinary excretion of AA-sulfate by 78, 83, 84, and 47% of the 0.1, 0.3, 1, and 3 mmol/kg doses of AA, respectively. Molybdate (7.5 mmol/kg) decreased the sulfation of these same doses of AA by 50, 65, 62, and 81%, respectively. These data indicate that PCP is more effective in decreasing the sulfation of low than high doses of AA, which may result from less AA, at lower doses, to compete with PCP for sulfotransferases. Conversely, molybdate is more effective in decreasing sulfation of high rather than low doses of AA because molybdate decreases sulfate availability and decreases PAPS synthesis. More PAPS is required for the sulfation of high than low doses of AA. Therefore, PCP inhibits sulfation more effectively at low doses of AA when sulfation is limited by sulfotransferases, and molybdate inhibits sulfation more effectively at high doses of AA when sulfation is limited by PAPS.

. . . and Preventing Liver Damage

Even low doses of over-the-counter ibuprofen can cause liver damage in patients with hepatitis C, according to a recent study. As a result, patients with the joint pain that often accompanies the disease should take low doses of acetaminophen instead.

Effect of acetaminophen and of low intermittent doses of diazepam on prevention of recurrences of febrile seizures

See commentary, “Prevention of recurrent febrile seizures”Acetaminophen and low doses of diazepam were evaluated for the prevention of recurrences of febrile seizures in a placebo-controlled, double-blind trial. Children after their first febrile seizure were assigned to receive either one dose of rectally administered diazepam, and then, after 6 hours, oral doses of 0.2 mg/kg three times a day for the first 2 days if the fever stayed greater than 38.5° C, or a placebo similarly during forthcoming febrile episodes. In addition, each febrile episode was randomly assigned to be treated with acetaminophen or the placebo. Thus four groups were examined for 2 years: patients receiving two kinds of placebo, patients receiving diazepam and a placebo, patients receiving acetaminophen and a placebo, and patients receiving both diazepam and acetaminophen. Of a total of 180 patients (102 boys), 161 were followed for the 2-year period and 157 were seen at the last outpatient examination: 80 in the diazepam group and 77 in the placebo group. The final analysis of the efficacy of the drugs was made on the basis of the data from 153 patients who had had at least one febrile episode during follow-up. There were 641 fever events during this period, and 38 children (21.1%) had 55 recurrences of febrile seizures. Acetaminophen had no effect on the recurrence rate. Seizures recurred at least once in 21 patients (28.4%) receiving diazepam and 17 (21.5%) receiving a placebo (p = 0.4138, log-rank test). The combination of antipyretic agents with anticonvulsant medication did not reduce the recurrence of febrile seizures. Our results show that low doses of acetaminophen or diazepam or both are ineffective for preventing febrile seizures. (J PEDIATR 1995;126:991-5)

Acute hepatic and renal toxicity from low doses of acetaminophen in the absence of alcohol abuse or malnutrition: Evidence for increased susceptibility to drug toxicity due to cardiopulmonary and renal insufficiency

A 67-yr-old man with chronic cardiopulmonary disease exhibited severe hepatic and moderately severe renal injury after short-term ingestion of therapeutic doses of acetaminophen (1 to 3 gm/day for 3 days). Drug metabolism and other studies, performed 5 mo after recovery from the acute insult, indicated that the patient had decreased rates of hepatic metabolism of acetaminophen to its primary, nontoxic metabolites and decreased kidney function that was compromised further by acetaminophen ingestion. He also had abnormally low concentrations of hepatic and plasma reduced glutathione. Alcohol abuse and malnutrition could not be implicated in the pathogenesis of injury; rather it appeared that advancing age with chronic renal, cardiac and pulmonary insufficiency contributed to acetaminophen toxicity in this patient. (HEPATOLOGY 1994;19:1141–1148.)

Acute hepatic and renal toxicity from low doses of acetaminophen in the absence of alcohol abuse or malnutrition: Evidence for increased susceptibility to drug toxicity due to cardiopulmonary and renal insufficiency

A 67-yr-old man with chronic cardiopulmonary disease exhibited severe hepatic and moderately severe renal injury after short-term ingestion of therapeutic doses of acetaminophen (1 to 3 gm/day for 3 days). Drug metabolism and other studies, performed 5 mo after recovery from the acute insult, indicated that the patient had decreased rates of hepatic metabolism of acetaminophen to its primary, nontoxic metabolites and decreased kidney function that was compromised further by acetaminophen ingestion. He also had abnormally low concentrations of hepatic and plasma reduced glutathione. Alcohol abuse and malnutrition could not be implicated in the pathogenesis of injury; rather it appeared that advancing age with chronic renal, cardiac and pulmonary insufficiency contributed to acetaminophen toxicity in this patient.

A case of prolonged liver injury caused by low dose of acetaminophen

A case of prolonged liver injury caused by low dose of acetaminophen

Effects of sulfur-amino acid-deficient diets on acetaminophen metabolism and hepatotoxicity in rats

Cysteine is required for the synthesis of cosubstrates for two pathways of acetaminophen metabolism: 3′-phosphoadenosine-5′-phosphosulfate (PAPS) for sulfation and glutathione (GSH) for detoxification of the reactive metabolite ( N-acetyl- p-benzoquinoneimine, NAPQI). Dietary deficiency of cysteine may reduce hepatic production of PAPS and GSH and thereby reduce metabolism of the drug (by sulfation and detoxification of NAPQI) and hence lead to potentiation of acetaminophen liver injury. Conversely, limitation of sulfur-containing amino acids could result in depression of protein synthesis and hepatic cytochrome P450 levels, and hence in decreased reactive metabolite formation and decreased liver injury. To determine whether the potentiating effects exceed the protective effects, rats were fed isocaloric AIN-76 liquid diets containing various levels of methionine as the sole source of sulfur in the diet for 3 weeks prior to administration of acetaminophen. Sulfur deficiency was assessed by measuring urinary inorganic sulfate levels. Sulfur-deficient diets retarded growth but did not affect nitrogen balance. Sulfur-deficient animals had lower basal levels of hepatic GSH. Pharmacokinetic studies revealed that at low doses of acetaminophen (20 mg/kg), animals fed sulfur-deficient diets metabolized the drug more slowly due to a markedly reduced sulfation capacity, whereas at the high dose of acetaminophen (400 mg/kg), rats that were fed sulfur-deficient diets had a higher clearance of the drug than rats that were fed the complete diet. The increase in clearance was due largely to an enhanced glucuronidation capacity and an enhanced P450-dependent oxidation as indicated by mercapturate formation. Histologic studies revealed that rats fed sulfur-deficient diets showed increases in both incidence and severity of acetaminophen hepatic necrosis. Thus, the potentiating effects exceeded the protective effects. These observations raise the possibility that nutritional inadequacy of sulfur-containing amino acids which could occur during protein malnutrition may similarly enhance susceptibility to acetaminophen liver injury in humans.

Effect of cobalt protoporphyrin on hepatic drug-metabolizing enzymes: Specificity for cytochrome P-450

Cobaltic protoporphyrin IX (cobalt protoporphyrin) is known to cause an extensive and long-lasting depletion of hepatic cytochrome P-450 in rats, and it has been used to evaluate the role of hepatic cytochrome P-450 in xenobiotic metabolism and toxicity. To examine the specificity of cobalt protoporphyrin for hepatic cytochrome P-450, cobalt protoporphyrin was administered to rats and hamsters, and its effects on cytochrome P-450-dependent and non-P-450-dependent phase I and phase II metabolism were determined. Cobalt protoporphyrin pretreatment depleted hepatic cytochrome P-450 in both species and lowered their V max values for the hepatic microsomal metabolism of ethylmorphine, aminopyrine, ethoxyresorufin and ethoxycoumarin, without change in their K m values. In the rat, cobalt protoporphyrin treatment lowered both the V max, and the K m for microsomal metabolism of aniline. In vivo hepatic cytochrome P-450-dependent metabolism, as measured by antipyrine clearance, was decreased in both species. UDP-Glucuronyltransferase, phenolsulfotransferase and glutathione- S-transferase were unaffected, as was hepatic glutathione. Modest effects of cobalt protoporphyrin were seen on the hepatic microsomal flavoprotein mixed-function oxidase (hamster only), cytochrome P-450 reductase, cytochrome b 5, (rat only), UDPGA (rat only), and glycogen, and on blood glucose (rat). In in vivo studies with hamsters given a low dose of acetaminophen, cobalt protoporphyrin suppressed the apparent rate constants for the cytochrome P-450-dependent pathways of acetaminophen metabolism but had no effect on acetaminophen glucuronidation and sulfation. Polyacrylamide gel electrophoresis analysis indicated that cobalt protoporphyrin markedly reduced the levels of the cytochrome P-450 holoenzyme but did not alter either the content or profile of the cytochrome P-450 apoenzyme. Collectively, the data indicate that cobalt protoporphyrin shows relatively high selectivity for the hepatic cytochrome P-450 system, and support the use of this compound as a tool for resolution of the role of hepatic cytochrome P-450 in xenobiotic metabolism and toxicity.

Renal Tubular Necrosis and Liver Damage

A 40-year-old woman developed renal tubular necrosis and liver injury following ingestion of acetaminophen 1 g 12 days after halothane anesthesia. The possibility of a synergistic association between halothane and acetaminophen, and of probable hepatic and renal damage occurring after a low dose of acetaminophen, as well as the possibility of renal tubular necrosis induced by halothane are discussed.