Series: current issues in mutagenesis and carcinogenesis, No. 65. The genotoxicity and carcinogenicity of paracetamol: a regulatory (re)view

Causal Effects and Immune Cell Mediators of Prescription Analgesic Use and Risk of Liver Cancer and Precancerosis in European Population: A Mendelian Randomization Study

Diverse clinical observations and basic studies have been conducted to explore the implications of analgesic medications in liver diseases. However, the direct causal relationship between prescription analgesic use (PAU) and the risk of liver cancer and precancerosis remains unclear. Thus, we aimed to reveal the conceivable causal effect of PAU on liver cancer and precancerosis, with immune cells as mediating factors. Two-sample Mendelian randomization (MR) analyses were performed to ascertain the causality of PAU on liver cancer and precancerosis. Sensitivity analysis approaches were employed to assess the heterogeneity and pleiotropy of results. Our findings revealed a causal correlation between different PAUs and the risk of liver cancer and alcoholic liver disease (ALD). Specifically, salicylic acid derivatives (SADs) and anilide medications were found to have a protective effect on liver cancer. And non-steroidal anti-inflammatory drugs (NSAIDs) and anilide medications showed a causal impact on ALD. Finally, mediation analyses found that anilide medications influence liver cancer through different immune cell phenotypes. Our research provides new genetic evidence for the causal impact of PAU on liver cancer and precancerosis, with the mediating role of immune cells demonstrated, offering a valuable foundation for researching analgesic medications in liver cancer and precancerosis treatment.

Comments on "DNA-binding activities of compounds acting as enzyme inhibitors, ion channel blockers and receptor binders."

I read with interest the article "DNA-binding activities of compounds acting as enzyme inhibitors, ion channel blockers and receptor binders" recently published in Chemico-Biological Interactions. The authors suggested that acetaminophen, one of the most used drugs worldwide, alkylates DNA at therapeutic doses and is genotoxic. Given the implications of this statements for public health, it is important for the reader to hear a different perspective that is based on the entire literature on this subject. Everything considered, there is no credible evidence that acetaminophen is a genotoxic hazard or a carcinogen at therapeutic doses.

Effects of paracetamol on the polychaete Hediste diversicolor: occurrence of oxidative stress, cyclooxygenase inhibition and behavioural alterations

Pharmaceuticals are significant environmental stressors, since they are utilized around the world; they are usually released in to the aquatic system without adequate treatment and several non-target species can be harmed because of their intrinsic properties. Paracetamol is one of the most widely prescribed analgesics in human medical care. Consequently, this compound is systematically reported to occur in the wild, where it may exert toxic effects on non-target species, which are mostly uncharacterized so far. The objective of the present work was to assess the acute (control, 5, 25, 125, 625 and 3125 μg/L) and chronic (control, 5, 10, 20, 40 and 80 μg/L) effects of paracetamol on behavioural endpoints, as well as on selected oxidative stress biomarkers [superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GRed)] and the anti-inflammatory activity biomarker cyclooxygenase (COX), in the polychaete Hediste diversicolor (Annelida: Polychaeta). Exposure to paracetamol caused effects on behavioural traits, with increased burrowing time (96 h) and hypoactivity (28 days). In addition, exposure to paracetamol resulted also in significant increases of SOD activity, but only for intermediate levels of exposure, but for both acute and chronic exposures. Both forms of GPx had their activities significantly increased, especially after chronic exposure. Acutely exposed organisms had their GRed significantly decreased, while chronically exposed worms had their GRed activity augmented only for the lowest tested concentrations. Effects were also observed in terms of COX activity, showing that paracetamol absorption occurred and caused an inhibition of COX activity in both exposure regimes. It is possible to conclude that the exposure to concentrations of paracetamol close to the ones in the environment may be deleterious to marine ecosystems, endangering marine life by changing their overall redox balance, and the biochemical control of inflammatory intermediaries. Behaviour was also modified and the burrowing capacity was adversely affected. This set of effects clearly demonstrate that paracetamol exposure, under realistic conditions, it not exempt of adverse effects on marine invertebrates, such as polychaetes.

Paracetamol Intake and Hematologic Malignancies: A Meta-Analysis of Observational Studies

Hematologic malignancies cause more than half a million deaths every year worldwide. Analgesics were suggested as chemopreventive agents for several cancers but so far, results from individual studies about the relationship between paracetamol (acetaminophen) use and hematologic malignancies are conflicting. Therefore, we decided to perform a systematic review and meta-analysis. We retrieved studies published in any language by systematically searching Medline, Embase, Conference Proceedings Citation Index, Open Access Theses and Dissertations, and the five regional bibliographic databases of the World Health Organization until December 2020. Pooled odds ratios (OR) and their 95% confidence intervals (CI) were calculated according to the inverse of their variances. We performed separate analyses by histologic type. We also evaluated publication bias and assessed quality. A total of 17 study units met our inclusion criteria. The results show an association of hematologic malignancies with any paracetamol intake (OR 1.49, 95% CI 1.23-1.80) and with high paracetamol intake (OR 1.77, 95% CI 1.45-2.16). By subtype, risk was higher for multiple myeloma (OR 2.13, 95% CI 1.54-2.94) for any use and OR 3.16, 95% CI 1.96-5.10 for high intake, while risk was lower and non-significant for non-Hodgkin lymphoma. This meta-analysis provides evidence that paracetamol intake may be associated with hematologic malignancies and suggests that a dose-response effect is plausible. These results are unlikely to be due to publication bias or low quality of studies. Future research should focus on assessing the dose-response relationship.

A comprehensive weight of evidence assessment of published acetaminophen genotoxicity data: Implications for its carcinogenic hazard potential

In 2019, the California Office of Environmental Health Hazard Assessment initiated a review of the carcinogenic hazard potential of acetaminophen, including an assessment of its genotoxicity. The objective of this analysis was to inform this review process with a weight-of-evidence assessment of more than 65 acetaminophen genetic toxicology studies that are of widely varying quality and conformance to accepted standards and relevance to humans. In these studies, acetaminophen showed no evidence of induction of point or gene mutations in bacterial and mammalian cell systems or in in vivo studies. In reliable, well-controlled test systems, clastogenic effects were only observed in unstable, p53-deficient cell systems or at toxic and/or excessively high concentrations that adversely affect cellular processes (e.g., mitochondrial respiration) and cause cytotoxicity. Across the studies, there was no clear evidence that acetaminophen causes DNA damage in the absence of toxicity. In well-controlled clinical studies, there was no meaningful evidence of chromosomal damage. Based on this weight-of-evidence assessment, acetaminophen overwhelmingly produces negative results (i.e., is not a genotoxic hazard) in reliable, robust high-weight studies. Its mode of action produces cytotoxic effects before it can induce the stable, genetic damage that would be indicative of a genotoxic or carcinogenic hazard.

The association between non-steroidal anti-inflammatory drugs (NSAIDs) and myelodysplastic syndromes in the Adults in Minnesota with Myelodysplastic Syndromes (AIMMS) Study

Myelodysplastic syndromes (MDS) are a heterogeneous group of blood disorders. Non-steroidal anti-inflammatory drugs (NSAIDs) are associated with a chemopreventive effect in some cancers. We evaluated associations between NSAID use and MDS in a population-based case-control study. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Secondary analyses stratified by sex and MDS subtype were also conducted.The analysis included 399 MDS cases and 698 controls. No significant associations between MDS and use of aspirin (OR = 0.87, 95% CI 0.67-1.14), ibuprofen (OR = 0.91, 95% CI 0.64-1.30), acetaminophen (OR = 1.29, 95% CI 0.90-1.84) or NSAIDs overall (OR = 0.92, 95% CI 0.68-1.23) were observed. No significant associations were observed in models stratified by sex or MDS subtype; however, the direction of the effect between NSAID use and MDS varied by MDS subtype. Our results do not support an association between NSAID use and MDS overall.

Assessment of the biochemical pathways for acetaminophen toxicity: Implications for its carcinogenic hazard potential

In 2019 California's Office of Environmental Health Hazard Assessment (OEHHA) initiated a review of the carcinogenic hazard potential of acetaminophen. In parallel with this review, herein we evaluated the mechanistic data related to the steps and timing of cellular events following therapeutic recommended (≤4 g/day) and higher doses of acetaminophen that may cause hepatotoxicity to evaluate whether these changes indicate that acetaminophen is a carcinogenic hazard. At therapeutic recommended doses, acetaminophen forms limited amounts of N-acetyl-p-benzoquinone-imine (NAPQI) without adverse cellular effects. Following overdoses of acetaminophen, there is potential for more extensive formation of NAPQI and depletion of glutathione, which may result in mitochondrial dysfunction and DNA damage, but only at doses that result in cell death - thus making it implausible for acetaminophen to induce the kind of stable, genetic damage in the nucleus indicative of a genotoxic or carcinogenic hazard in humans. The collective data demonstrate a lack of a plausible mechanism related to carcinogenicity and are consistent with rodent cancer bioassays, epidemiological results reviewed in companion manuscripts in this issue, as well as conclusions of multiple international health authorities.

Effect of hydro-methanol stem bark extract of Burkea africana on erythrocyte osmotic fragility and haematological parameters in acetaminophen-poisoned rats

Background

Burkea africana is a widely used medicinal plant in folkloric medicine in many developing countries of the world. It is useful in the treatment of various ailments including hepatitis, jaundice, diarrhea, stomach aches, abscesses, oedema, epilepsy, bloody diarrhea, gonorrhea, syphilis, toothaches and poisoning. Nevertheless, there are little or no scientific evidence to substantiate this medicinal claim by traditional healers. Burkea africana stem bark was therefore, investigated for its protective or stabilizing effect on erythrocyte membrane in acetaminophen-treated rats. B. africana stem bark was extracted using 80% methanol. Erythrocyte stabilizing effect was studied using erythrocyte osmotic fragility (EOF) test. Thirty (30) male rats were randomly assigned into five (5) groups of six (6) rats each. Groups 1 and 2 served as normal control and negative control (acetaminophen-treated group) respectively. Groups 3, 4 and 5 were pretreated with methanol stem bark extract of Burkea africana (MSBEBA) at doses of 200, 400 and 600 mg/kg body weight respectively once daily for seven (7) days. Blood samples were collected from the animals in all the groups on the 8 day for evaluation of packed cell volume, haemoglobin, red blood cell, white blood cell counts, and differential white blood cell count as well as erythrocyte osmotic fragility.

Results

The erythrocyte osmotic fragility test showed that there was a significantly (p < 0.05) low percentage hemolysis in the groups pre-treated with the extract when compared with the negative control. The percentage hemolysis was least at 600 mg/kg body weight of the extract. There was also a significant (p < 0.05) increase in the packed cell volume, haemoglobin, red blood cell count at all the doses of the extract used. Neutrophils were significantly (p < 0.05) decreased while lymphocytes were significantly increased in the groups administered MSBEBA 400 and 600 mg/kg body weight.

Conclusion

Methanol stem bark extract of Burkea africana had protective effect on the red blood cells and also improved haematological parameters. This indicates that Burkea africana may be useful in the treatment of disease conditions that results in hemolytic anemia by stabilizing red erythrocyte membranes and enhancing erythropoiesis.

Testing of acetaminophen in support of the international multilaboratory in vivo rat Pig-a assay validation trial

Acetaminophen, a nonmutagenic compound as previously concluded from bacteria, in vitro mammalian cell, and in vivo transgenic rat assays, presented a good profile as a nonmutagenic reference compound for use in the international multilaboratory Pig-a assay validation. Acetaminophen was administered at 250, 500, 1,000, and 2,000 mg·kg-1 ·day-1 to male Sprague Dawley rats once daily in 3 studies (3 days, 2 weeks, and 1 month with a 1-month recovery group). The 3-Day and 1-Month Studies included assessments of the micronucleus endpoint in peripheral blood erythrocytes and the comet endpoint in liver cells and peripheral blood cells in addition to the Pig-a assay; appropriate positive controls were included for each assay. Within these studies, potential toxicity of acetaminophen was evaluated and confirmed by inclusion of liver damage biomarkers and histopathology. Blood was sampled pre-treatment and at multiple time points up to Day 57. Pig-a mutant frequencies were determined in total red blood cells (RBCs) and reticulocytes (RETs) as CD59-negative RBC and CD59-negative RET frequencies, respectively. No increases in DNA damage as indicated through Pig-a, micronucleus, or comet endpoints were seen in treated rats. All positive controls responded as appropriate. Data from this series of studies demonstrate that acetaminophen is not mutagenic in the rat Pig-a model. These data are consistent with multiple studies in other nonclinical models, which have shown that acetaminophen is not mutagenic. At 1,000 mg·kg-1 ·day-1 , Cmax values of acetaminophen on Day 28 were 153,600 ng/ml and 131,500 ng/ml after single and repeat dosing, respectively, which were multiples over that of clinical therapeutic exposures (2.6-6.1 fold for single doses of 4,000 mg and 1,000 mg, respectively, and 11.5 fold for multiple dose of 4,000 mg) (FDA 2002). Data generated were of high quality and valid for contribution to the international multilaboratory validation of the in vivo Rat Pig-a Mutation Assay.

Inhibitory activity of black mulberry (Morus nigra) extract against testicular, liver and kidney toxicity induced by paracetamol in mice

Black mulberry (Morus nigra) leaves is broadly used in traditional medicine worldwide. However, there are no scientific reports regarding testicular protection, hepato-and nephroprotective activities of M. nigra leaves. The present investigation was assessed the protective mechanism by which methanol extract from M. nigra leaves suppressed the damaging effects induced by paracetamol (APAP) in different mouse tissues. Male mice were orally given APAP (500 mg/kg) with or without M. nigra extract (150, 300, and 500 mg/kg) for four consecutive days. The results showed that crude extract possessed potent antioxidant activity (EC₅₀ = 42.97 µg extract/mL) due to the presence of a high amount of polyphenol and flavonoid compounds. Gallic acid, chlorogenic acid, catechin, and rutin were isolated from the n-butanol fraction of M. nigra extract. Unexpectedly, oral administration of APAP did not induce chromosomal aberrations in mouse bone marrow; however, it produced damaging effects on testis, liver, and kidney tissues. Interestingly, M. nigra extract suppressed APAP-induced genotoxicity by lowering meiotic chromosomal aberrations in spermatocytes, morphological sperm abnormalities, and % DNA damage in comet tail in the liver and kidney tissues. The altered levels of glutathione S transferase activity, lipid peroxidation, liver, and kidney functions were significantly reversed when M. nigra was given to APAP group. The restoring of the histo-architectural distortions and decreasing over-expression of p53 protein as determined by immunohistochemistry in the liver, kidney, and testis sections were strengthened the protective activity of M. nigra extract. Conclusion, the bioactive components in the leaves of black mulberry appear to be a good candidate for genetic protection, treatment of oxidative stress-induced organotoxicity.

Development of Electrochemical Sensor Based on Carbonaceal and Metal Phthalocyanines Materials for Determination of Ethinyl Estradiol

This work describes the development of an electrochemical sensor that was used in the determination of ethinyl estradiol (EE) in pharmaceutical formulations, river water, and milk using the square wave voltammetry technique. Studies were carried out using different carbonaceous materials (multiwalled carbon nanotubes, reduced graphene oxide Reduced graphene oxide, graphite) and different metallic phthalocyanines (cobalt, iron and manganese). Based on these studies it was possible to obtain the best system for the construction of the sensor. The device was obtained by the chemical modification of a glassy carbon electrode (GCE) with multiwalled carbon nanotubes (MWCNTs) and cobalt phthalocyanine (CoPc). The materials were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Under conditions previously optimized for the proposed method, an analytical curve was constructed, presenting linearity in a range of 2.50–90.0 μmol L−1 (R = 0.990), with detection limit of 2.20 μmol L−1 and quantification of 2.50 μmol L−1. The validation of the methodology for the determination of EE using GCE-MWCNTs-CoPc was performed, being accurate, precise, stable and sensitive. The recovery of ethinyl estradiol in the sample of pharmaceutical formulation was 103.93%, in the samples of river water ranged from 92.75% to 96.47%, and in the milk sample was from 88.00% to 96.20%. Thus, the proposed method presented a viable alternative for the determination of ethinyl estradiol in the quality control of pharmaceutical and food formulations as well as in environmental control.

Effects of commonly used therapeutic drugs, paracetamol, and acetylsalicylic acid, on key physiological traits of the sea snail Gibbula umbilicalis

Over time, the consumption of pharmaceutical drugs has highly augmented, directly contributing for an increase of the discharges of these substances into sewage water due to excretion, and their direct release to the environment, with or without adequate treatment. Considering that part of the sewage water is dumped into rivers and seas, this is the major source of contamination of the aquatic environment. Paracetamol and acetylsalicylic acid are among the most worldwide consumed pharmaceutical drugs, frequently found in wastewater discharges and consequently in the aquatic environment in considerable amounts, posing ecotoxicity concerns especially towards aquatic non-target species. Thus, it is important to study the ecotoxicological implications that these drugs might pose to organisms from aquatic environments. The objective of this study was to assess the toxic effects of these two compounds on key biochemical features (antioxidant defenses and damage, metabolism, and cholinergic neurotoxicity) of the marine snail species Gibbula umbilicalis after an acute (96 h) exposure, simulating pulses of contamination. In order to understand the effects that those drugs have on this species, the biochemical biomarkers analyzed were the activities of catalase (CAT), glutathione-S-transferases (GSTs), cholinesterases (ChEs), and the levels of lipid peroxidation (TBARS). After acute exposure to paracetamol, catalase activity decreased significantly in organisms exposed to both highest concentrations; no significant alterations were observed for glutathione-S-transferases activity; TBARS concentration decreased significantly in organisms exposed to the intermediate and both highest concentrations, and cholinesterase activity increased significantly in animals exposed to the lowest concentration. However, after acute exposure to acetylsalicylic acid, catalase activity increased significantly; no significant alterations were observed for glutathione-S-transferases activity, and TBARS concentrations and cholinesterase activity increased. This set of data shows that G. umbilicalis is highly responsive to the presence of the tested drugs, and may thus be a promising species to serve as test organism in future marine ecotoxicological testing. The adoption of this species may broaden the offer of highly ecologically representative test organisms to be included in biomonitoring projects of the coastal and marine environment. Furthermore, it is possible to suggest that both drugs may pose significant deleterious effects of pro-oxidative origin to the physiology of the selected species, with potential adverse ecological consequences, even after short periods of exposure. The absence of neurotoxicity showed that despite being able to trigger antioxidant mechanisms, both drugs did not affect neurotransmission.

In vivo genotoxicity testing strategies: Report from the 7th International workshop on genotoxicity testing (IWGT)

The working group reached complete or majority agreement on many issues. Results from TGR and in vivo comet assays for 91 chemicals showed they have similar ability to detect in vivo genotoxicity per se with bacterial mutagens and Ames-positive carcinogens. TGR and comet assay results were not significantly different when compared with IARC Group 1, 2 A, and unclassified carcinogens. There were significantly more comet assay positive responses for Group 2B chemicals, and for IARC classified and unclassified carcinogens combined, which may be expected since mutation is a sub-set of genotoxicity. A liver comet assay combined with the bone marrow/blood micronucleus (MNviv) test would detect in vivo genotoxins that do not exhibit tissue-specific or site-of-contact effects, and is appropriate for routine in vivo genotoxicity testing. Generally for orally administered substances, a comet assay at only one site-of-contact GI tract tissue (stomach or duodenum/jejunum) is required. In MNviv tests, evidence of target tissue exposure can be obtained in a number of different ways, as recommended by ICH S2(R1) and EFSA (Hardy et al., 2017). Except for special cases the i.p. route is inappropriate for in vivo testing; for risk evaluations more weight should be given to data from a physiologically relevant administration route. The liver MN test is sufficiently validated for the development of an OECD guideline. However, the impact of dosing animals >6 weeks of age needs to be evaluated. The GI tract MN test shows promise but needs more validation for an OECD guideline. The Pig-a assay detects systemically available mutagens and is a valuable follow-up to in vitro positive results. A new freeze-thaw protocol provides more flexibility. Mutant reticulocyte and erythrocyte frequencies should both be determined. Preliminary data are available for the Pig-a assay in male rat germ cells which require validation including germ cell DNA mutation origin.

Cytotoxic effects of Benzodioxane, Naphthalene diimide, Porphyrin and Acetamol derivatives on HeLa cells

Objectives:

To synthesize novel compounds belonging to Benzodioxane, Naphthalene diimide, Aminophenol derivatives and Porphyrin classes and test their potential anticancer properties.

Methods:

Several compounds were synthesized and their molecular identity was confirmed using nuclear magnetic resonance. Potential anticancer properties were determined using cytopathogenicity assays and growth inhibition assays using cervical cancer cells (HeLa). Cells were incubated with different concentrations of compounds belonging to Benzodioxane, Naphthalene diimide, Aminophenol derivatives and Porphyrins and effects were determined. HeLa cells cytopathogenicity was determined by measuring lactate dehydrogenase release using cytotoxicity detection assay. Growth inhibition assays were performed by incubating 50% semi-confluent HeLa cells with Benzodioxane, Naphthalene diimide, Aminophenol derivatives and Porphyrin compounds and HeLa cell proliferation was observed. Growth inhibition and host cell death were compared in the presence and absence of drugs.

Results:

Cytopathogenicity assays showed that the selected compounds were cytotoxic against HeLa cells, killing up to 90% of cells. Growth inhibition assays exhibited 100% growth inhibition. These effects are likely via oxidative stress, production of reactive oxygen species, changes in cytosolic and intracellular calcium/adenine nucleotide homeostasis, inhibition of ribonucleotide reductase/cyclooxygenase and/or glutathione depletion.

Conclusions:

Benzodioxane, Naphthalene diimide, Aminophenol derivatives and Porphyrins exhibited potent anticancer properties. These findings are promising and should pave the way in the rationale development of anticancer drugs. Using different cancer cell lines, future studies will determine their potential as anti-tumour agents as well as their precise molecular mode of action.

Hypersensitivity of mouse embryonic fibroblast cells defective for DNA polymerases η, ι and κ to various genotoxic compounds: Its potential for application in chemical genotoxic screening

Genotoxic agents cause modifications of genomic DNA, such as alkylation, oxidation, bulky adduct formation, and strand breaks, which potentially induce mutations and changes to the structure or number of genes. Majority of point mutations are generated during error-prone bypass of modified nucleotides (translesion DNA synthesis, TLS); however, when TLS fails, replication forks stalled at lesions eventually result in more lethal effects, formation of double-stranded breaks (DSBs). Here we compared sensitivities to various compounds among mouse embryonic fibroblasts derived from wild-type and knock-out mice lacking one of the three Y-family TLS DNA polymerases (Polη, Polι, and Polκ) or all of them (TKO). The compounds tested in this study include genotoxins such as methyl methanesulfonate (MMS) and nongenotoxins such as ammonium chloride. We found that TKO cells exhibited the highest sensitivities to most of the tested genotoxins, but not to the non-genotoxins. In order to quantitatively evaluate the hypersensitivity of TKO cells to different chemicals, we calculated ratios of half-maximal inhibitory concentration for WT and TKO cells. The ratios for 9 out of 10 genotoxins ranged from 2.29 to 5.73, while those for 5 nongenotoxins ranged from 0.81 to 1.63. Additionally, the two markers for DNA damage, ubiquitylated proliferating cell nuclear antigen and γ-H2AX after MMS treatment, were accumulated in TKO cells more greatly than in WT cells. Furthermore, following MMS treatment, TKO cells exhibited increased frequency of sister chromatid exchange compared with WT cells. These results indicated that the hypersensitivity of TKO cells to genotoxins resulted from replication fork stalling and subsequent DNA double-strand breaks, thus demonstrating that TKO cells should be useful for evaluating chemical genotoxicity.

Toxicological effects of paracetamol on the clam Ruditapes philippinarum: exposure vs recovery

Exposure of wild organisms to anthropogenic substances never follows a definite time-course and pulsed events can often determine biological responses to such chemicals, confounding the interpretation of toxicological data. This is the case of specific chemicals such as pharmaceutical drugs, which are commonly released by sewage systems into sensitive areas, including estuaries. The presence and amount of these chemicals in the wild can be modulated by events such as dilution due to heavy rain, floods, or by varying patterns of domestic water use (daily vs. seasonal). The present study aimed to obtain additional data about the toxicity of paracetamol towards the marine clam species Ruditapes philippinarum, following realistic modes of exposure. Thus, the toxicity assessment was made after an acute exposure to different concentrations of paracetamol, followed by a recovery period. The adopted toxicological endpoints included energy-related parameters (glycogen content, GLY; protein content, PROT; electron transport system activity, ETS), activity of antioxidant and biotransformation enzymes (superoxide dismutase, SOD; glutathione peroxidase, GPx; Glutathione-S-transferases, GSTs), levels of reduced glutathione (GSH), neurotoxicity (cholinesterases activity, ChEs), and indicators of oxidative damage (lipid peroxidation, LPO). The here obtained results showed an increase in SOD and GPx activities after exposure. In organisms exposed to the highest concentration tested it was also possible to observe a significant increase in GSTs activity. However, these alterations in the antioxidant defence system were not able to prevent the occurrence of oxidative stress in exposed organisms. Furthermore, exposure to paracetamol induced neurotoxicity in clams, with a concentration-dependent ChEs inhibition along the exposure concentrations. Exposure to paracetamol also led to an increase of GLY content which resulted from metabolic activity depression along the increasing exposure gradient. In recovering organisms the activities of SOD, GPx and GSTs decreased back towards control values presenting lower values than the ones observed in organisms after acute exposure to paracetamol. No LPO was registered in organisms after the recovery period. In addition, after recovery, clams showed no signs of neurotoxicity, with ChEs activities in previously exposed organisms similar to control clams. After recovery clams seemed to re-establish their metabolic capacity, especially evidenced in clams previously exposed to the highest paracetamol concentration as demonstrated by the increase of ETS activity up to control values. Furthermore, the decrease of GLY content after recovery may indicate that clams increased their metabolic activity and started to use their energetic reserves to re-establish their oxidative status. This set of data shows that an acute exposure to paracetamol can exert deleterious effects that may compromise specific biochemical pathways in sensitive aquatic species, such as R. philippinarum, but organisms can re-establish their biochemical status to control levels after a recovery period.

Paracetamol causes endocrine disruption and hepatotoxicity in male fish Rhamdia quelen after subchronic exposure

Paracetamol is one of the most widely sold non-prescription drugs. This study aimed to evaluate the effects of the paracetamol on reproductive, biochemical, genetic, histopathological and hematogical biomarkers by waterborne exposure. Male fish of Rhamdia quelen were exposed to environmental concentrations of paracetamol (0, 0.25, 2.5μg/L) in a semi-static bioassay for 21days. Hemoglobin and hematocrit were reduced upon exposure to 0.25μg/L of paracetamol. Leukocytes and thrombocytes increased after paracetamol exposure. Paracetamol reduced testosterone levels in all exposed groups and increased estradiol levels at higher concentration. Serotonin and dopamine levels increased at exposure to 0.25μg/L. Paracetamol also caused protein carbonyls and increased SOD activity in fish exposed to 2.5μg/L and in addition led to an inhibition of EROD and GST activities in both concentrations. Hepatic genotoxicity occurred at the 0.25μg/L concentration. Hepatic tissues of exposed fish showed mild blood congestion and leucocytes infiltration. The results showed that paracetamol disrupted the hypothalamic-pituitary-gonadal axis, changed hematological parameters and caused hepatotoxicity in Rhamdia quelen. The findings suggest that this drug merits attention relative to its potential endocrine disrupter effect and hepatotoxicity, even at concentrations found in the aquatic environment.

Use of acetaminophen in relation to the occurrence of cancer: a review of epidemiologic studies

Acetaminophen has several pharmacologic properties that suggest it could be carcinogenic in human beings. A number of epidemiologic studies have been conducted to examine whether use of acetaminophen actually predisposes to the occurrence of one or more forms of cancer. There are inherent limitations to many of these studies, including the inaccurate identification of users and nonusers of acetaminophen, relatively short follow-up for cancer incidence, and the potential for confounding by indication. The present manuscript reviews the results of epidemiologic studies of acetaminophen use in relation to cancer incidence published through the end of 2015. The limitations of the underlying studies notwithstanding, some interim conclusions can be reached. For all but several forms of cancer, there is no suggestion that persons who have taken acetaminophen are at altered risk, even persons who have consumed a large quantity of the drug or those who have taken it for an extended duration. While in some studies the incidence of renal cell carcinoma has been observed to be increased among acetaminophen users, several other studies have failed to observe any such association; the reason for the discrepant findings is unclear. Some of the small number of studies that have presented data on the incidence of lymphoma, leukemia, and plasma cell disorders have found the risk to be modestly higher in users than nonusers of acetaminophen, but the results of other studies of these malignancies will be needed to gauge the possible role of publication bias as the basis for the positive results.

Associations of NSAID and paracetamol use with risk of primary liver cancer in the Clinical Practice Research Datalink

Liver cancer incidence has been rising rapidly in Western countries. Nonsteroidal anti-inflammatory drugs (NSAIDs) and paracetamol are widely-used analgesics that may modulate the risk of liver cancer, but population-based evidence is limited. We conducted a case-control study (1195 primary liver cancer cases and 4640 matched controls) within the United Kingdom's Clinical Practice Research Datalink to examine the association between the use of prescription NSAIDs and paracetamol and development of liver cancer. Multivariable-adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression. Overall, ever-use of NSAIDs was not associated with risk of liver cancer (aOR=1.05, 95% CI=0.88-1.24), regardless of recency and intensity of use. Use of paracetamol was associated with a slightly increased risk of liver cancer (aOR=1.18, 95% CI=1.00-1.39), particularly among individuals with body mass index<25kg/m(2) (aOR=1.56, 95% CI=1.17-2.09). Our results suggest that NSAID use was not associated with liver cancer risk in this population. Ever-use of paracetamol may be associated with slightly higher liver cancer risk, but results should be interpreted cautiously due to methodological limitations. Given that paracetamol is a widely-used analgesic, further examination of its relationship with liver cancer is warranted.

Application of the TGx-28.65 transcriptomic biomarker to classify genotoxic and non-genotoxic chemicals in human TK6 cells in the presence of rat liver S9

In vitro transcriptional signatures that predict toxicities can facilitate chemical screening. We previously developed a transcriptomic biomarker (known as TGx-28.65) for classifying agents as genotoxic (DNA damaging) and non-genotoxic in human lymphoblastoid TK6 cells. Because TK6 cells do not express cytochrome P450s, we confirmed accurate classification by the biomarker in cells co-exposed to 1% 5,6 benzoflavone/phenobarbital-induced rat liver S9 for metabolic activation. However, chemicals may require different types of S9 for activation. Here we investigated the response of TK6 cells to higher percentages of Aroclor-, benzoflavone/phenobarbital-, or ethanol-induced rat liver S9 to expand TGx-28.65 biomarker applicability. Transcriptional profiles were derived 3 to 4 hr following a 4 hr co-exposure of TK6 cells to test chemicals and S9. Preliminary studies established that 10% Aroclor- and 5% ethanol-induced S9 alone did not induce the TGx-28.65 biomarker genes. Seven genotoxic and two non-genotoxic chemicals (and concurrent solvent and positive controls) were then tested with one of the S9s (selected based on cell survival and micronucleus induction). Relative survival and micronucleus frequency was assessed by flow cytometry in cells 20 hr post-exposure. Genotoxic/non-genotoxic chemicals were accurately classified using the different S9s. One technical replicate of cells co-treated with dexamethasone and 10% Aroclor-induced S9 was falsely classified as genotoxic, suggesting caution in using high S9 concentrations. Even low concentrations of genotoxic chemicals (those not causing cytotoxicity) were correctly classified, demonstrating that TGx-28.65 is a sensitive biomarker of genotoxicity. A meta-analysis of datasets from 13 chemicals supports that different S9s can be used in TK6 cells, without impairing classification using the TGx-28.65 biomarker.

Chromatography as Method for Analytical Confirmation of Paracetamol in Postmortem Material Together with Psychoactive Substances

Introduction:

Paracetamol (Acetaminophen) in addition to aspirin is the most commonly used analgesic and antipyretic medication by millions of patients worldwide. It is an example that paracetamol as medicine that in the world is provided without a doctor’s prescription, can lead to death. Today paracetamol became an integral part of a heroin mixture and is very popular at the street market. The main reason for this is that it can be obtained without a prescription, it is cheap, and by most people well tolerated without side effects. It is probably used for “cutting” the pure heroin, as it says in the jargon, and in that manner from small amount of pure drug is obtained greater amount, which is then sold on the street. The goal is to identify presence of paracetamol, by analytical method of gas chromatography mass spectrometer (GC-MS) in postmortem material together with psychoactive substances.

Material and methods:

For chemical-toxicological analysis is used biological material collected trough autopsy of 20 deceased people, suspected to have died due to psychoactive substance overdose. All received samples are stored at -20 ° C until analysis at our laboratory. From processed 47 samples that were analyzed in the period from 2014 to 2015, 19 are blood samples, urine 19, 3 samples of stomach contents, and 6 samples of bile content. Deceased were middle-aged, of which only 7 were female. The tested samples were processed according to two methods of extraction. Extraction by XAD-2 resin, and the extraction by the method of salting out with sodium tungstate. Extracts of the samples were then dissolved in chloroform and continued analysis at the analytical instrument. Identification of the paracetamol presence, in the test biological samples is demonstrated by the technique of gas chromatography with mass spectometry (hereinafter referred to as GC-MS). The technique of GC-MS is a selective, sensitive and reliable, and is therefore considered a “gold standard” for determining the drug, and the drug substance. Used GC-MS instrument was an Agilent 7890A with helium as the carrier gas.

Results:

The analysis of blood samples, urine, bile and stomach contents, obtained after the autopsy of deceased persons, by using gas chromatography with mass spectrometry, in analytical manner confirmed the fact that paracetamol is a very common component of psychoactive substances poisoning. In our assay of samples we detected psychoactive substances (heroin, codeine, morphine, sertraline, diazepam), and almost all were found in the combination with paracetamol, indicating the poor quality of illicit drugs sold on the market.

Discussion:

Paracetamol (Acetaminophen) is a very common component in mixtures of street drugs. Such mixtures almost anyone can afford, but the very quality of these drugs has become extremely low, because it does not sell the pure substance, but is mixed with various medications. According to research Pantazia et al. the heroin mixture proportion of the heroin is very small so a lot of that mixture has only 3% of heroin, a large number of cases can be only 1% of pure heroin. Most of the time it replaces caffeine and paracetamol. According to the Risser et al. reason why acetaminophen component is present in these mixtures is because it can be purchased without a prescription, it is cheap, well tolerated by most people and shows no side effects.

Conclusion:

When we talk about illegal drugs, we must emphasize the fact that there is no quality control, or the composition of the drug. The composition of the drug purchased on the black market is still unknown to potential user. While reaching the final drug users it pass through many hands, and at each step something is added to increase earnings. Most often present additives or impurities in narcotic drugs that are added are caffeine, ephedrine, acetaminophen, acetylsalicylic acid (aspirin) and additives such as powders, cement and chalk.

Single crystal XRD, vibrational and quantum chemical calculation of pharmaceutical drug paracetamol: A new synthesis form

The common house hold pharmaceutical drug, paracetamol (PAR), has been synthesized from 4-chloroaniline as a first ever report. After the synthesis, good quality single crystals were obtained for slow evaporation technique under the room temperature. The crystal and molecular structures were re-determined by the single crystal X-ray diffraction. The vibrational spectral measurements were carried out using FT-IR and FT-Raman spectroscopy in the range of 4000-400 cm(-1). The single crystal X-ray studies shows that the drug crystallized in the monoclinic system polymorph (Form-I). The crystal packing is dominated by N-H⋯O and O-H⋯O classical hydrogen bonds. The ac diagonal of the unit cell features two chain C(7) and C(9) motifs running in the opposite directions. These two chain motifs are cross-linked to each other to form a ring R4(4)(22) motif and a chain C2(2)(6) motif which is running along the a-axis of the unit cell. Along with the classical hydrogen bonds, the methyl group forms a weak C-H⋯O interactions in the crystal packing. It offers the support for molecular assembly especially in the hydrophilic regions. Further, the strength of the hydrogen bonds are studied the shifting of vibrational bands. Geometrical optimizations of the drug molecule were done by the Density Functional Theory (DFT) using the B3LYP function and Hartree-Fock (HF) level with 6-311++G(d,p) basis set. The optimized molecular geometry and computed vibrational spectra are compared with experimental results which show significant agreement. The factor group analysis of the molecule was carried out by the various molecular symmetry, site and factor group species using the standard correlation method. The Natural Bond Orbital (NBO) analysis was carried out to interpret hyperconjugative interaction and intramolecular charge transfer (ICT). The chemical softness, chemical hardness, electro-negativity, chemical potential and electrophilicity index of the molecule were found out first time by HOMO-LUMO plot. The frontier orbitals shows lower band gap values signify the possible biological/pharmaceutical activity of the molecule. The thermodynamical properties are also obtained from the calculated frequencies of the optimized structures.

Quantitative LC-MS/MS determination of flupirtine, its N-acetylated and two mercapturic acid derivatives in man

The non-opiate analgesic drug flupirtine was shown in vitro to undergo hydrolysis followed by N-acetylation to form D13223, glucuronidation and conjugation with glutathione to form the stable mercapturic acid derivatives M-424 and M-466. To quantify flupirtine and its metabolites in samples obtained in a clinical study in healthy subjects selected on their genotype of NAT2, UGT1A1 and GSTP1, two LC-MS/MS methods were developed. The validation range for flupirtine and D-13223 in serum was 0.5-500 ng/ml. For urine and feces, the validation ranges for flupirtine and D-13223 were 20-5000 ng/ml and 5.0-5000 ng/ml, respectively. M-424 and M-466 could be quantified in urine between 5.0 and 5000 ng/ml. Free flupirtine and D-13223 were separated from serum, urine and feces with liquid-liquid extraction. For flupirtine and D-13223, the chromatography was performed on a XTerra C18 column isocratically with a mobile phase consisting of ammonium formate buffer (pH 3.5mM) and acetonitrile (50:50; v/v), for M-466 and M-424 a Synergi(®) Fusion-RP column was used and a linear gradient method with water/HCOOH (pH 3) and acetonitrile. The mass spectrometer operated both with electro spray ionization in positive multiple reaction monitoring mode. The developed methods fulfilled the current FDA criteria on bioanalytical method validation for accuracy (error: -16.9 to 11.2%), precision (1.2-13.4%), recovery, stability and matrix effects over the observed analytical range. Thus, the methods were suitable to quantify flupirtine absorption and metabolic disposition in man after single intravenous and oral dosing (100mg) and repeated oral administration (400mg once daily).

Preparation, spectroscopic, thermal, antihepatotoxicity, hematological parameters and liver antioxidant capacity characterizations of Cd(II), Hg(II), and Pb(II) mononuclear complexes of paracetamol anti-inflammatory drug

Keeping in view that some metal complexes are found to be more potent than their parent drugs, therefore, our present paper aimed to synthesized Cd(II), Hg(II) and Pb(II) complexes of paracetamol (Para) anti-inflammatory drug. Paracetamol complexes with general formula [M(Para)2(H2O)2]·nH2O have been synthesized and characterized on the basis of elemental analysis, conductivity, IR and thermal (TG/DTG), (1)H NMR, electronic spectral studies. The conductivity data of these complexes have non-electrolytic nature. Comparative antimicrobial (bacteria and fungi) behaviors and molecular weights of paracetamol with their complexes have been studied. In vivo the antihepatotoxicity effect and some liver function parameters levels (serum total protein, ALT, AST, and LDH) were measured. Hematological parameters and liver antioxidant capacities of both Para and their complexes were performed. The Cd(2+)+Para complex was recorded amelioration of antioxidant capacities in liver homogenates compared to other Para complexes treated groups.

Biochemical effects of acetaminophen in aquatic species: edible clams Venerupis decussata and Venerupis philippinarum

Acetaminophen (paracetamol) is one of the most used pharmaceutical drugs, due to its antipyretic and analgesic properties that turn it into a primary choice in varied pathologies and conditions. However, and despite its massive use, acetaminophen is not exempt of adverse effects, especially when administered in over dosage, which are related to the formation of toxic metabolites by oxidative pathways. It is thus possible to observe that toxicity caused by acetaminophen is usually mediated by reactive oxygen species and can result in multiple effects, ranging from protein denaturation to lipid peroxidation and DNA damage. The occurrence of acetaminophen has been reported in the aquatic environment, being important to address the potential exertion of toxic effects on nontarget environmentally exposed organisms. The present study intended to characterize the effects of acute acetaminophen exposure on physiological traits (antioxidant defense, oxidative damage) of two species of bivalves, namely, the edible clams Venerupis decussata and Venerupis philippinarum. Results showed a significant increase in all oxidative stress biomarkers, evidencing the bioactivation of acetaminophen into a deleterious prooxidant, triggering the onset of deleterious effects. Furthermore, strong interspecific differences were observed among responses of the two tested species, which was a major issue due to intrinsic ecological implications when one considers that both species share the same habitat.

A transcriptomics-based in vitro assay for predicting chemical genotoxicity in vivo

The lack of accurate in vitro assays for predicting in vivo toxicity of chemicals together with new legislations demanding replacement and reduction of animal testing has triggered the development of alternative methods. This study aimed at developing a transcriptomics-based in vitro prediction assay for in vivo genotoxicity. Transcriptomics changes induced in the human liver cell line HepG2 by 34 compounds after treatment for 12, 24, and 48 h were used for the selection of gene-sets that are capable of discriminating between in vivo genotoxins (GTX) and in vivo nongenotoxins (NGTX). By combining transcriptomics with publicly available results for these chemicals from standard in vitro genotoxicity studies, we developed several prediction models. These models were validated by using an additional set of 28 chemicals. The best prediction was achieved after stratification of chemicals according to results from the Ames bacterial gene mutation assay prior to transcriptomics evaluation after 24h of treatment. A total of 33 genes were selected for discriminating GTX from NGTX for Ames-positive chemicals and 22 for Ames-negative chemicals. Overall, this method resulted in 89% accuracy and 91% specificity, thereby clearly outperforming the standard in vitro test battery. Transcription factor network analysis revealed HNF3a, HNF4a, HNF6, androgen receptor, and SP1 as main factors regulating the expression of classifiers for Ames-positive chemicals. Thus, the classical bacterial gene mutation assay in combination with in vitro transcriptomics in HepG2 is proposed as an upgraded in vitro approach for predicting in vivo genotoxicity of chemicals holding a great promise for reducing animal experimentations on genotoxicity.

Formation and characterization of covalent guanosine adducts with electrochemistry-liquid chromatography-mass spectrometry

Chemicals can interact with the genetic material giving rise to the formation of covalent adducts. These alterations can lead to adverse consequences, including cancer, reproductive impairment, development anomalies, or genetic diseases. In search for an assay allowing identification of hazardous compounds that might form covalent adducts with nucleic acids, electrochemistry (EC)/liquid chromatography (LC)/mass spectrometry (MS) is presented. EC/LC/MS is a purely instrumental approach. EC is used for oxidative activation, LC for the fractionation of the reaction mixture, and MS for the detection and characterization of the reaction products. To test the system capabilities, we investigated the formation of covalent adducts produced by guanosine and acetaminophen (APAP). Electrochemical activation of mixtures of guanosine and APAP gave rise to the formation of four isomers of (guanosine + APAP-2H). Mass voltammograms as well as dose–response-curves were used to obtain insights in the mechanism of adduct formation. These experiments revealed that a mechanism involving radical intermediates is favored. The initial step of adduct formation is the conversion of both APAP and guanosine into radicals via one-electron–one-proton reactions. Among different competing reaction pathways, the generated radical intermediates undergo intermolecular reactions to form covalent adducts between guanosine and APAP.

Hepatoprotective activity of Andrographis paniculata and Swertia chirayita

Andrographis paniculata (Family: Acanthaceae) and Swertia chirayita (Family: Gentianaceae) are two controversial medicinal plants used as Kiriyattu, having similar therapeutic action and are used as a hepatoprotective and hepatostimulative agent. A. paniculata grows in southern parts of India and S. chirayita in the Himalayan region. The present work concerns on the ability of the extracts of these plants to offer protection against acute hepatotoxicity induced by paracetamol (150 mg/kg) in Swiss albino mice. Oral administration of A. paniculata or S. chirayita extract (100-200mg/kg) offered a significant dose dependent protection against paracetamol induced hepatotoxicity as assessed in terms of biochemical and histopathological parameters. The paracetamol induced elevated levels of serum marker enzymes such as serum glutamate pyruvate transaminase (GPT), serum glutamate oxaloacetate transaminase (GOT), alkaline phosphatase (ALP), and bilirubin in peripheral blood serum and distorted hepatic tissue architecture along with increased levels of lipid peroxides (LPO) and reduction of superoxide dismutase (SOD), catalase, reduced glutathione (GSH) and glutathione peroxidase (GPx) in liver tissue. Administration of the plant extracts after paracetamol insult restored the levels of these parameters to control (untreated) levels. Thus the present study revealed that the extracts of A. paniculata or S. chirayita offered protection against hepatotoxicity induced by paracetamol.

Nonsteroidal anti-inflammatory drug and acetaminophen use and risk of adult myeloid leukemia

BACKGROUND

Little is known about the causes of adult leukemia. A few small studies have reported a reduced risk associated with regular use of nonsteroidal anti-inflammatory drugs (NSAID).

METHODS

In a population-based case-control study, we evaluated analgesic use among 670 newly diagnosed myeloid leukemia cases [including 420 acute myeloid leukemias (AML) and 186 chronic myeloid leukemias (CML)] and 701 controls aged 20 to 79 years. Prior use of aspirin, ibuprofen, acetaminophen, other NSAIDs, and COX-2 inhibitors was assessed and included frequency, duration, and quantity. ORs and 95% CIs were calculated using unconditional logistic regression adjusting for potential confounders.

RESULTS

Regular/extra strength aspirin use was inversely associated with myeloid leukemia in women (OR = 0.59, 95% CI = 0.37-0.93) but not in men (OR = 0.85, 95% CI = 0.58-1.24). In contrast, acetaminophen use was associated with an increased risk of myeloid leukemia in women only (OR = 1.60, 95% CI = 1.04-2.47). These relationships were stronger with increasing dose and duration. When stratified by leukemia type, aspirin use was inversely associated with AML and CML in women. No significant overall associations were found with ibuprofen or COX-2 inhibitors for either sex; however, a decreased risk was observed with other anti-inflammatory analgesic use for women with AML or CML (OR = 0.47, 95% CI = 0.22-0.99; OR = 0.31, 95% CI = 0.10-0.92, respectively).

CONCLUSIONS

Our results provide additional support for the chemopreventive benefits of NSAIDs, at least in women. Because leukemia ranks fifth in person-years of life lost due to malignancy, further investigation is warranted.

IMPACT

NSAIDs may reduce, whereas acetaminophen may increase, myeloid leukemia risk in women.

Long-term use of acetaminophen, aspirin, and other nonsteroidal anti-inflammatory drugs and risk of hematologic malignancies: results from the prospective Vitamins and Lifestyle (VITAL) study

PURPOSE

Among previous studies examining the associations of over-the-counter analgesics or nonsteroidal anti-inflammatory drugs (NSAIDs) and incident hematologic malignancies, results were inconsistent for NSAIDs but suggested an increased risk with acetaminophen (paracetamol). Herein, we used a large prospective cohort study to examine these associations.

PATIENTS AND METHODS

In total, 64,839 men and women age 50 to 76 years were recruited from 2000 to 2002 to the Vitamins and Lifestyle (VITAL) study. Incident hematologic malignancies (n = 577) were identified through December 2008 by linkage to the Surveillance, Epidemiology and End Results cancer registry. Hazard ratios (HRs) associated with use of analgesics for total incident hematologic malignancies and cancer subcategories were estimated by Cox proportional hazards models. Models were adjusted for age, sex, race/ethnicity, education, smoking, self-rated health, arthritis, chronic musculoskeletal pain, migraines, headaches, fatigue, and family history of leukemia/lymphoma.

RESULTS

After adjustment, there was an increased risk of incident hematologic malignancies associated with high use (≥ 4 days/week for ≥ 4 years) of acetaminophen (HR, 1.84; 95% CI, 1.35 to 2.50 for high use; P trend = .004). This association was seen for myeloid neoplasms (HR, 2.26; 95% CI, 1.24 to 4.12), non-Hodgkin's lymphomas (HR, 1.81; 95% CI, 1.12 to 2.93), and plasma cell disorders (HR, 2.42; 95% CI, 1.08 to 5.41), but not chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL; HR, 0.84; 95% CI, 0.31 to 2.28). By comparison, there was no association with risk of incident hematologic malignancies for increasing use of aspirin, nonaspirin NSAIDs, or ibuprofen.

CONCLUSION

High use of acetaminophen was associated with an almost two-fold increased risk of incident hematologic malignancies other than CLL/SLL. Neither aspirin nor nonaspirin NSAIDs are likely useful for prevention of hematologic malignancies.

Follow-up actions from positive results of in vitro genetic toxicity testing

Appropriate follow-up actions and decisions are needed when evaluating and interpreting clear positive results obtained in the in vitro assays used in the initial genotoxicity screening battery (i.e., the battery of tests generally required by regulatory authorities) to assist in overall risk-based decision making concerning the potential effects of human exposure to the agent under test. Over the past few years, the International Life Sciences Institute (ILSI) Health and Environmental Sciences Institute (HESI) Project Committee on the Relevance and Follow-up of Positive Results in In Vitro Genetic Toxicity (IVGT) Testing developed a decision process flow chart to be applied in case of clear positive results in vitro. It provides for a variety of different possibilities and allows flexibility in choosing follow-up action(s), depending on the results obtained in the initial battery of assays and available information. The intent of the Review Subgroup was not to provide a prescriptive testing strategy, but rather to reinforce the concept of weighing the totality of the evidence. The Review Subgroup of the IVGT committee highlighted the importance of properly analyzing the existing data, and considering potential confounding factors (e.g., possible interactions with the test systems, presence of impurities, irrelevant metabolism), and chemical modes of action when analyzing and interpreting positive results in the in vitro genotoxicity assays and determining appropriate follow-up testing. The Review Subgroup also examined the characteristics, strengths, and limitations of each of the existing in vitro and in vivo genotoxicity assays to determine their usefulness in any follow-up testing.

Pentadecapeptide BPC 157 and its effects on a NSAID toxicity model: diclofenac-induced gastrointestinal, liver, and encephalopathy lesions

AIMS

We attempted to fully antagonize the extensive toxicity caused by NSAIDs (using diclofenac as a prototype).

MAIN METHODS

Herein, we used the stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV, MW 1419), an anti-ulcer peptide shown to be efficient in inflammatory bowel disease clinical trials (PL 14736) and various wound treatments with no toxicity reported. This peptide was given to antagonize combined gastrointestinal, liver, and brain toxicity induced by diclofenac (12.5mg/kg intraperitoneally, once daily for 3 days) in rats.

KEY FINDINGS

Already considered a drug that can reverse the toxic side effects of NSAIDs, BPC 157 (10 μg/kg, 10 ng/kg) was strongly effective throughout the entire experiment when given (i) intraperitoneally immediately after diclofenac or (ii) per-orally in drinking water (0.16 μg/mL, 0.16 ng/mL). Without BPC 157 treatment, at 3h following the last diclofenac challenge, we encountered a complex deleterious circuit of diclofenac toxicity characterized by severe gastric, intestinal and liver lesions, increased bilirubin, aspartate transaminase (AST), alanine transaminase (ALT) serum values, increased liver weight, prolonged sedation/unconsciousness (after any diclofenac challenge) and finally hepatic encephalopathy (brain edema particularly located in the cerebral cortex and cerebellum, more in white than in gray matter, damaged red neurons, particularly in the cerebral cortex and cerebellar nuclei, Purkinje cells and less commonly in the hippocampal neurons).

SIGNIFICANCE

The very extensive antagonization of diclofenac toxicity achieved with BPC 157 (μg-/ng-regimen, intraperitoneally, per-orally) may encourage its further use as a therapy to counteract diclofenac- and other NSAID-induced toxicity.

Successful drug development despite adverse preclinical findings part 2: examples

To illustrate the process of addressing adverse preclinical findings (APFs) as outlined in the first part of this review, a number of cases with unexpected APF in toxicity studies with drug candidates is discussed in this second part. The emphasis is on risk characterization, especially regarding the mode of action (MoA), and risk evaluation regarding relevance for man. While severe APFs such as retinal toxicity may turn out to be of little human relevance, minor findings particularly in early toxicity studies, such as vasculitis, may later pose a real problem. Rodents are imperfect models for endocrine APFs, non-rodents for human cardiac effects. Liver and kidney toxicities are frequent, but they can often be monitored in man and do not necessarily result in early termination of drug candidates. Novel findings such as the unusual lesions in the gastrointestinal tract and the bones presented in this review can be difficult to explain. It will be shown that well known issues such as phospholipidosis and carcinogenicity by agonists of peroxisome proliferator-activated receptors (PPAR) need to be evaluated on a case-by-case basis. The latter is of particular interest because the new PPAR α and dual α/γ agonists resulted in a change of the safety paradigm established with the older PPAR α agonists. General toxicologists and pathologists need some understanding of the principles of genotoxicity and reproductive toxicity testing. Both types of preclinical toxicities are major APF and clinical monitoring is difficult, generally leading to permanent use restrictions.

Electrochemical simulation of oxidation processes involving nucleic acids monitored with electrospray ionization-mass spectrometry

Oxidation is commonly involved in the alteration of nucleic acids giving rise to diverse effects including mutation, cell death, malignancy, and aging. We demonstrate that electrochemistry represents an efficient and fast method to mimic oxidative modification of nucleic acids occurring in biological systems. Oxidation reactions were performed in a thin-layer cell employing a conductive diamond electrode as the working electrode and were monitored with electrospray ionization-mass spectrometry. Mass voltammograms were acquired for guanosine, adenosine, cytidine, and uridine. The observed oxidation potentials increased in the order guanosine << adenosine < cytidine < uridine. Oxidation products of guanosine were characterized using high-resolution (tandem) mass spectrometry performed with a quadrupole-quadrupole time-of-flight instrument. On the basis of these experiments, it was concluded that the initial electrode reaction involves a one-electron, one-proton step to give a free radical. The primary oxidation product represents the starting point for a number of follow-up reactions, including guanosine dimerization as well as further oxidation to 8-hydroxyguanosine. Similar results were obtained for guanosine monophosphate and the corresponding dinucleotide. Furthermore, the guanosine radical was identified as an important intermediate for the formation of a covalent adduct with acetaminophen. This observation sheds new light on the mechanism of adduct formation as it demonstrates that oxidative activation of both the nucleobase and the adduct-forming agent is necessary to observe a detectable amount of adduct species.

Chronic kidney disease and cancer: a troubling connection

Chronic kidney disease (CKD) and cancer are connected in a number of ways in both directions: cancer can cause CKD either directly or indirectly through the adverse effects of therapies; CKD may, conversely, be a risk factor for cancer; and both may be associated because they share common risk factors, often toxins. In this review, we briefly address the issue of paraneoplastic nephropathies as well as that of toxin-related cancers and CKD, including analgesic and aristolochic acid nephropathies. We then focus on the links between the various stages of CKD and cancer incidence, and critically examine major epidemiologic surveys in the field. Compared with the general population, kidney transplant recipients have a threefold to fourfold increase in overall cancer risk, and relative risks higher than 3 for about 20 specific tumors, most, but not all, of which are known or suspected to be caused by viral agents. After dialysis, cancer risk increases 10% to 80% according to studies, with relative risks significantly higher than in the general population, for about 10 cancer sites. There is emerging evidence for an excess risk of cancer in patients in early CKD stages.

Synthesis and pharmacological evaluation of N-phenyl-acetamide sulfonamides designed as novel non-hepatotoxic analgesic candidates

In this paper we report the design, synthesis and pharmacological evaluation of a series of N-phenyl-acetamide sulfonamide derivatives (5a-g), planned by structural modification on the prototype paracetamol (1). In this series (5a-g), compound LASSBio-1300 (5e; ID(50)=5.81 micromol/kg) stands out as a new non-hepatotoxic analgesic drug candidate. The increase of area, volume and electrostatic potential of paracetamol's analogues seems to be beneficial to the analgesic activity. Unlike paracetamol (1) and the other analogues (5a, 5d-g), compounds 5b and 5c presented an important anti-hypernociceptive activity associated to inflammatory pain.

Genotoxic Activities of Aniline and its Metabolites and Their Relationship to the Carcinogenicity of Aniline in the Spleen of Rats

Aniline (in the form of its hydrochloride) has been shown to induce a rather rare spectrum of tumors in the spleen of Fischer 344 rats. The dose levels necessary for this carcinogenic activity were in a range where also massive effects on the blood and non-neoplastic splenotoxicity as a consequence of methemoglobinemia were to be observed. This review aimed at clarifying if aniline itself or one of its metabolites has a genotoxic potential which would explain the occurrence of the spleen tumors in rats as a result of a primary genetic activity. The database for aniline and its metabolites is extremely heterogeneous. With validated assays it ranges from a few limited Ames tests (o- and m-hydroxyacetanilide, phenylhydroxylamine, nitrosobenzene) to a broad range of studies covering all genetic endpoints partly with several studies of the same or different test systems (aniline, p-aminophenol, p-hydroxyacetanilide). This makes a direct comparison rather difficult. In addition, a varying number of results with as yet not validated systems are available for aniline and its metabolites. Most results, especially those with validated and well performed/documented studies, did not indicate a potential of aniline to induce gene mutations. In five different mouse lymphoma tests, where colony sizing was performed only in one test, aniline was positive. If this indicates a peculiar feature of a point mutagenic potential or does represent a part of the clastogenic activity for which there is evidence in vitro as well as in vivo remains to be investigated. There is little evidence for a DNA damaging potential of aniline. The clastogenic activity in vivo is confined to dose levels, which are close to lethality essentially due to hematotoxic effects. The quantitatively most important metabolites for experimental animals as well as for humans (p-aminophenol, p-hydroxyacetanilide) seem to have a potential for inducing chromosomal damage in vitro and, at relatively high dose levels, also in vivo. This could be the explanation for the clastogenic effects that have been observed after high doses/concentrations with aniline. They do not induce gene mutations and there is little evidence for a DNA damaging potential. None of these metabolites revealed a splenotoxic potential comparable to that of aniline in studies with repeated or long-term administration to rats. The genotoxicity database on those metabolites with a demonstrated and marked splenotoxic potential, i.e. phenylhydroxylamine, nitrosobenzene, is unfortunately very limited and does not allow to exclude with certainty primary genotoxic events in the development of spleen tumors. But quite a number of considerations by analogy from other investigations support the conclusion that the effects in the spleen do not develop on a primary genotoxic basis. The weight of evidences suggests that the carcinogenic effects in the spleen of rats are the endstage of a chronic high-dose damage of the blood leading to a massive overload of the spleen with iron, which causes chronic oxidative stress. This conclusion, based essentially on pathomorphological observations, and analogy considerations thereof by previous authors, is herewith reconfirmed under consideration of the more recently reported studies on the genotoxicity of aniline and its metabolites, on biochemical measurements indicating oxidative stress, and on the metabolism of aniline. It is concluded that there is no relationship between the damage to the chromosomes at high, toxic doses of aniline and its major metabolites p-aminophenol/p-hydroxyacetanilide and the aniline-induced spleen tumors in the rat.

[Notion of threshold in mutagenesis: implications for mutagenic and carcinogenic risk assessment]

During years, it has been widely admitted in the scientific community that there was no threshold in mutagenesis: a compound was or not a mutagen. The meaning of such a proposition was that a risk existed at all exposure level, because, at least theoretically, one molecule is sufficient to cause the formation of a DNA adduct which is able to induce a mutation. However, works carried out in the last few years have shown that in the case of some specific mechanisms of mutagenesis, a threshold could be demonstrated essentially in the case of compounds that do not react directly with DNA. Several types of thresholds exist, and the simple statistical threshold is not sufficient in terms of risk assessment. A biological threshold that is consistent with a mechanism of action of the mutagen should be established. Amongst these mechanisms, we can mention some mechanism with a demonstrated threshold: effects of aneugens, effects of topoisomerases inhibitors, effects of DNA polymerases inhibitors, effects of compounds with a different metabolism at high doses compared to low doses. On the contrary, for some mechanisms, the demonstration of the mechanism is suspected, but not totally demonstrated. It is the case of compounds which induce nucleotides pool imbalance or compounds which are DNA repair inhibitors. In some cases, when a redundancy exists in the repair of damages, like oxidative DNA damage, a threshold is suspected. Some authors even recently proposed the possibility of a threshold in the case of alkylating agents. The majority of mutagenic thresholds were demonstrated in vitro, however some mechanisms were demonstrated in vivo, for example in the case of micronucleus induction by hypo or hyperthermia in rodents bone marrow. The use of threshold in risk assessment requires the use of the most sensitive endpoint for example, non disjunction in the case of aneugens, confusing factors like apoptosis should be eliminated and species sensitivities should be taken into account. A very important point to consider is to demonstrate that the mechanism with threshold was really thee only one involved in the mutagenic effect. The demonstration of such thresholds is of particular interest for human risk assessment in the case of mutagens and of genotoxic carcinogens.

Hepatoprotective and antioxidant effects of Cuscuta chinensis against acetaminophen-induced hepatotoxicity in rats

Tu-Si-Zi, the seeds of Cuscuta chinensis Lam. (Convolvulaceae), is a traditional Chinese medicine that is commonly used to nourish and improve the liver and kidney conditions in China and other Asian countries. As oxidative stress promotes the development of acetaminophen (APAP)-induced hepatotoxicity, the aim of the present study was to evaluate and compare the hepatoprotective effect and antioxidant activities of the aqueous and ethanolic extracts of C chinensis on APAP-induced hepatotoxicity in rats. The C chinensis ethanolic extract at an oral dose of both 125 and 250mg/kg showed a significant hepatoprotective effect relatively to the same extent (P<0.05) by reducing levels of glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), and alkaline phosphatase (ALP). In addition, the same ethanolic extract prevented the hepatotoxicity induced by APAP-intoxicated treatment as observed when assessing the liver histopathology. Regarding the antioxidant activity, C chinensis ethanolic extract exhibited a significant effect (P<0.05) by increasing levels of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), and by reducing malondialdehyde (MDA) levels. In contrast, the same doses of the aqueous extract of C chinensis did not present any hepatoprotective effect as seen in the ethanolic extract, and resulted in further liver deterioration. In conclusion, these data suggest that the ethanolic extract of Cuscuta chinensis can prevent hepatic injuries from APAP-induced hepatotoxicity in rats and this is likely mediated through its antioxidant activities.