Paracetamol: new vistas of an old drug

Estimates of Paracetamol Poisoning in Brazil: Analysis of Official Records From 1990s to 2020

Objective: To assess the cases of paracetamol poisoning in Brazil.

METHODS

Analysis of official records of deaths between 1996 and 2019 from the Brazil Mortality Information System (SIM), admissions between 2008 and 2020 from the Hospital Information System (SIH), and cases of poisoning between 2017 and 2020 in health services, reported to the Brazilian Notifiable Diseases Surveillance System (SINAN). In SIM and SIH, records with ICD-10 were included: F55, T39, X40, X60, and Y10. In SINAN, commercial products containing paracetamol were identified. Records were stratified by age, sex, and intentionality. Mean and standard error were calculated for each stratum based on the annual data, by federation unit. Poisoning reports by 1,000,000 inhabitants were calculated from each state and compared to the national average.

RESULTS

In total, 492 deaths, 5,666 hospital admissions, and 17,031 cases of paracetamol poisoning were recorded in the period. Deaths occurred mostly among adults (71.3% ± 3.0) and in suicide attempts (37.3% ± 2.7). Hospital admissions were more frequent in adults (69.7% ± 1.4), women (57.1% ± 2.5), and unintentional poisoning (80.2% ± 4.2). Poisoning reports was more also frequent among adults (71.4% ± 1.2), women (74.2% ± 0.6), and due to accidents (79.6% ± 1.8). The South and Southeast regions of the country presented the highest frequencies in all outcomes, above the national average.

CONCLUSION

Paracetamol exposure is a concern for preventable poisonings, hospital admissions and deaths. More accurate data about paracetamol poisoning are required to support surveillance actions and the development of mechanisms to reduce poisoning, particularly related to adults, women and suicide attempts.

Paracetamol-Induced Hypothermia in Rodents: A Review on Pharmacodynamics

Paracetamol can induce hypothermia in humans and rodents. The study’s aim is to review the mechanisms of paracetamol-induced hypothermia in rodents or the results issued from in vitro studies on the same species’ tissues (in doses that do not produce hepatic impairment) using the latest developments published in scientific journals over the last 15 years. Available human studies are also analysed. An extensive search in PubMed databases exploring the hypothermic response to paracetamol was conducted. 4669 articles about paracetamol’s effects on body temperature in mice or rats were found. After applying additional filters, 20 articles were selected for review, with 9 of them presented in tabular forms. The analysis of these articles found that the hypothermic effect of paracetamol is due to the inhibition of a cyclooxygenase-1 variant, is potentiated by endothelin receptor antagonists, and can be mediated through GABAA receptors and possibly through transient receptor potential cation channel subfamily A member 1 via N-acetyl-p-benzoquinone imine in the central nervous system. Human studies confirm the in vivo and in vitro experiments in rodents regarding the presence of a hypothermic effect after high, non-toxic doses of paracetamol. Further research is required to understand the mechanisms behind paracetamol’s hypothermic effect in humans.

Paracetamol (Acetaminophen) and its Effect on the Developing Mouse Brain

Paracetamol, or acetaminophen (AAP), is the most commonly used analgesic during pregnancy and early life. While therapeutic doses of AAP are considered harmless during these periods, recent findings in both humans and rodents suggest a link between developmental exposure to AAP and behavioral consequences later in life. The aim of this study is to evaluate the impact of neonatal exposure to clinically relevant doses of AAP on adult spontaneous behavior, habituation, memory, learning, and cognitive flexibility later in life using a mouse model. Markers of oxidative stress, axon outgrowth, and glutamatergic transmission were also investigated in the hippocampus during the first 24 h after exposure. In addition, potential long-term effects on synaptic density in the hippocampus have been investigated. In a home cage setting, mice neonatally exposed to AAP (30 + 30 mg/kg, 4 h apart) on postnatal day 10 displayed altered spontaneous behavior and changed habituation patterns later in life compared to controls. These mice also displayed reduced memory, learning and cognitive flexibility compared to control animals in the Morris water maze. An increase of markers for oxidative stress was observed in the hippocampus 6 h after AAP exposure. As AAP is the first choice treatment for pain and/or fever during pregnancy and early life, these results may be of great importance for risk assessment. Here we show that AAP can have persistent negative effects on brain development and suggest that AAP, despite the relatively low doses, is capable to induce acute oxidative stress in the hippocampus.

The Effect of Acetaminophen on Running Economy and Performance in Collegiate Distance Runners

Acetaminophen (ACT) may decrease perception of pain during exercise, which could allow runners to improve running economy (RE) and performance. The aim of this study was to determine the effects of ACT on RE and 3 km time trial (TT) performance in collegiate distance runners. A randomized, double blind, crossover study was employed in which 11 track athletes (9M/2F; age: 18.8 ± 0.6 years; VO₂ max: 60.6 ± 7.7 mL/kg/min) completed three intervention sessions. Participants ingested either nothing (baseline, BSL), three gelatin capsules (placebo, PLA), or three 500 mg ACT caplets (ACT). One hour after ingestion, participants completed a graded exercise test consisting of 4 × 5 min steady-state stages at ~55–75% of VO₂ max followed by a 3 km TT. There was no influence of ACT on RE in any stage. Similarly, ACT did not favorably modify 3 km TT performance [mean ± SD: BSL = 613 ± 71 s; PLA = 617 ± 70 s; ACT = 618 ± 70 s; p = 0.076]. The results indicate that ACT does not improve RE or TT performance in collegiate runners at the 3 km distance. Those wanting to utilize ACT for performance must understand that ACT’s benefits have yet to be significant amongst well-trained runners. Future studies should examine the effects of ACT on well-trained runners over longer trial distances and under more controlled conditions with appropriate medical oversight.

N-(4-Meth-oxy-2-nitro-phen-yl)acetamide

In the title compound, C9H10N2O4, the three substituents vary in the degree of lack of planarity with the central phenyl ring. The meth-oxy group is nearest to being coplanar, with a C-C-O-C torsion angle of 6.1 (5)°. The nitro group is less coplanar, with a 12.8 (5)° twist about the C-N bond and the acetamido group is considerably less coplanar with the central ring, having a 25.4 (5)° twist about the C-N bond to the ring. The NH group forms an intra-molecular N-H⋯O hydrogen bond to a nitro-group O atom.

Therapeutic Potential of Cannabis, Cannabidiol, and Cannabinoid-Based Pharmaceuticals

<b><i>Background:</i></b> There is a growing interest in the use of cannabis (and its extracts), as well as CBD oil (hemp extracts containing cannabidiol), for therapeutic purposes. While there is reason to believe that cannabinoids may be efficacious for a number of different diseases and syndromes, there exist limited objective data supporting the use of crude materials (CBD oil, cannabis extracts, and/or cannabis itself). <b><i>Summary:</i></b> In the present review, we examined data for pure cannabinoid compounds (dronabinol, nabilone, and CBD), as well as partially purified medicinal cannabis extracts (nabiximols), to provide guidance on the potential therapeutic uses of high-THC cannabis and CBD oil. In general, data support a role for cannabis/cannabinoids in pain, seizure disorders, appetite stimulation, muscle spasticity, and treatment of nausea/vomiting. Given the biological activities of the cannabinoids, there may be utility in treatment of central nervous system disorders (such as neurodegenerative diseases, PTSD, and addiction) or for the treatment of cancer. However, those data are much less compelling. <b><i>Key Message:</i></b> On balance, there are reasons to support the potential use of medical cannabis and cannabis extract (Δ⁹-THC-dominant or CBD-dominant), but much more careful research is required.

Doping in Racing Pigeons (Columba livia domestica): A Review and Actual Situation in Belgium, a Leading Country in This Field

Pigeon racing is a sport in which trained homing pigeons (Columba livia domestica) are released between 60 and 1200 km from their loft and then have to return home as quickly as possible. The first race was held in 1818 in Belgium and since then, Belgium has led the world in pigeon breeding. Unfortunately, as in other sports, doping has become a major issue and doping controls have been implemented. This review provides information about pigeon racing, rules from the Royal Federation Colombophile of Belgium, and laws applicable in Belgium as doping control issues cannot be understood without including them as part of pigeon racing. The main pharmacological data concerning corticoids, non-steroidal anti-inflammatory drugs, anabolic steroids, pain relievers and narcotic analgesics, bronchodilators and β-agonists, drugs acting on the central nervous system and other performance-enhancing drugs, in addition to methods relevant to doping in pigeons are presented. Moreover, the chosen matrix and analytical methods are described.

Nonopioid analgesics for analgesia in critically ill patients: Friends, enemies, or collaborators

Patients in intensive care units (ICUs) experience pain, which they describe as a significant cause of stress during treatment. It can progress to chronic pain and significantly affect the quality of life. Opioids have long been the backbone of ICU pain therapy. The consequences of their long-term use are known today, such as prolonged ICU stay and mechanical ventilation, resulting in increased treatment costs. Additionally, abstinence syndrome is a consequence of abrupt opioid withdrawal. Also, there is a risk of tolerance and hyperalgesia after prolonged opioid use. Globally, opioid dependence after hospital opioid treatment is alarming, although there is still a lack of data on its incidence after ICU. Multimodal analgesia enables comfort to the patient, opioid-sparing, and avoidance of side effects of non-opioid analgesics. Nonsteroidal anti-inflammatory drugs (NSAIDs) are a broad group of drugs recommended with paracetamol to treat mild to moderate acute postoperative pain. Although often prescribed by intensivists, their use in treating painful conditions in ICU is controversial due to the possible consequences on the organs of critically ill patients. Due to the inhibition of cyclooxygenases, NSAIDs indirectly cause vasoconstriction of the renal arteries and arterioles, leading to kidney damage. NSAIDs inhibit platelet aggregation and may predispose to bleeding. Analgesia of a critically ill patient is a important part of their treatment, however it can be challenging in certain patients. Numerous combinations of pharmacological and non-pharmacological approaches can be adapted to the patient's current characteristics.

Acetaminophen Has Lipid Composition-Dependent Membrane Interactivity That Could Be Related to Nephrotoxicity but Not to Analgesic Activity and Hepatotoxicity

OBJECTIVE

Although acetaminophen is one of the most widely used over-the-counter drugs, the mechanisms by which this classical drug exerts analgesic, hepatotoxic, and nephrotoxic effects remain unclear. We hypothesized that acetaminophen might act on cellular membranes of nerves, liver, and kidneys. In order to verify this hypothesis, we studied the interactivity of acetaminophen with biomimetic lipid bilayer membranes by comparing with structurally related phenacetin.

METHODS

Liposomal membranes (unilamellar vesicles suspended in the buffer of pH 7.4) were prepared with phospholipids and cholesterol to mimic the membrane lipid composition of neuronal cells, hepatocytes, and nephrocytes. They were subjected to reactions with acetaminophen and phenacetin at clinically relevant concentrations, followed by measuring fluorescence polarization to determine their membrane interactivity to modify membrane fluidity.

RESULTS

Acetaminophen and phenacetin interacted with neuro-mimetic and hepato-mimetic membranes to increase membrane fluidity at 10-100 μM. Both drugs were more effective in fluidizing hepato-mimetic membranes than neuro-mimetic membranes. Although the relative membrane-interacting potency was phenacetin >> acetaminophen in neuro-mimetic and hepato-mimetic membranes, such membrane effects conflicted with their relative analgesic and hepatotoxic effects. Acetaminophen and phenacetin strongly interacted with nephro-mimetic membranes to increase membrane fluidity at 2-100 μM and 0.1-100 μM, respectively. Phenacetin interacted significantly with nephro-mimetic membranes at lower concentrations (<2 μM) than acetaminophen, which was consistent with their relative nephrotoxic effects.

CONCLUSION

In comparison with phenacetin, lipid composition-dependent membrane interactivity of acetaminophen could be related to nephrotoxicity but not to analgesic activity and hepatotoxicity.

Oral acetaminophen-induced spinal 5-hydroxytriyptamine release produces analgesic effects in the rat formalin test

The mechanism by which acetaminophen produces its analgesic effects is not fully understood. One possible mechanism is the activation of the spinal 5-hydroxytryptamine (5-HT) receptor, although direct evidence of spinal 5-HT release has not yet been reported. N-arachidonoylphenolamine (AM404), a metabolite of acetaminophen, is believed to be the key substance that contributes to the analgesic effects of acetaminophen. In this study, we examined whether acetaminophen and AM404 induce spinal 5-HT release and the mechanism through which spinal 5-HT receptor activation exerts analgesic effects in a rat formalin test in an inflammatory pain model. Spinal 5-HT release was examined by intrathecal microdialysis in conscious and freely moving rats. Acetaminophen was administered orally, and AM404 was administered intracerebroventricularly. In rat formalin tests, oral acetaminophen and intracerebroventricular AM404 induced significant spinal 5-HT release and produced analgesic effects. The analgesic effect of oral acetaminophen was partially antagonized by intrathecal administration of WAY100135 (a 5-HT_1A receptor antagonist) and SB269970 (a 5-HT₇ receptor antagonist). In contrast, the analgesic effect of intracerebroventricular AM404 was completely antagonized by WAY100135, while SB269970 had no effect. Our data suggest that while oral acetaminophen and intracerebroventricular AM404 activate the spinal 5-HT system, the role of the spinal 5-HT system activated by oral acetaminophen differs from that activated by intracerebroventricular AM404.

Fast determination of paracetamol and its hydrolytic degradation product p-aminophenol by capillary and microchip electrophoresis with contactless conductivity detection

Paracetamol (PAC) is one of the most extensively used analgesics and antipyretic drugs to treat mild and moderate pain. P-aminophenol (PAP), the main hydrolytic degradation product of PAC, can be found in environmental water. Recently, capillary electrophoresis (CE) has been developed for the detection of a wide variety of chemical substances. The purpose of this study is to develop a simple and fast method for the detection and separation of PAC and its main hydrolysis product PAP, using CE and microchip electrophoresis (ME) with capacitively coupled contactless conductivity detection (C⁴ D). The determination of these compounds using ME with C⁴ D is being reported for the first time. The separation was run for all analytes using a background electrolyte (BGE) (20 Mm β-alanine, pH 11) containing 14% (v/v) methanol. The RSDs obtained for migration time were less than 0.05%, and RSDs obtained for peak area were less than 3%. The detection limits (S/N = 3) that were achieved ranged from 0.3 to 0.6 mg/L without sample preconcentration. The presented method showed rapid analysis time (less than 1 min), high efficiency and precision, low cost, and a significant decrease in the consumption of reagents. The microchip system has proved to be an excellent analytical technique for fast and reliable environmental applications. This article is protected by copyright. All rights reserved.

Anti-Inflammatory and Anti-Oxidative Effects of AM404 in IL-1β-Stimulated SK-N-SH Neuroblastoma Cells

An emerging number of studies address the involvement of neuroinflammation and oxidative stress in the pathophysiology of central nervous system (CNS) disorders such as depression, schizophrenia, anxiety, and neurodegenerative diseases. Different cytokines and molecules, such as prostaglandin (PG) E₂, are associated with neuroinflammatory processes. The active acetaminophen metabolite AM404 has been shown to prevent inflammation and neuroinflammation in primary microglia and organotypic hippocampal slice cultures. However, its effects on pathophysiological conditions in the CNS and especially on neurons are still poorly understood. In this study, we therefore evaluated the effects of AM404 and acetaminophen on the arachidonic acid cascade and oxidative stress induced by interleukin (IL)-1β in human SK-N-SH neuronal cells. We observed that AM404 and acetaminophen significantly and concentration-dependent inhibited IL-1β-induced release of PGE₂, independent of cyclooxygenases (COX)-1 and COX-2 enzymatic activity as well as COX-2 mRNA and protein levels in SK-N-SH-cells. The reduction of IL-1β-induced PGE₂-release by AM404 and acetaminophen treatment might be mediated by the 8-iso-PGF_2α pathway since IL-1β-induced synthesis of this free radical marker is dose-dependently reduced by both compounds, respectively. Therefore, understanding of the potential therapeutic properties of AM404 in neuroinflammation and oxidative stress might lead to future treatment options of different neurological disorders.

Systematic review of the impact of cannabinoids on neurobehavioral outcomes in preclinical models of traumatic and nontraumatic spinal cord injury

STUDY DESIGN

Systematic review.

OBJECTIVES

To evaluate the impact of cannabinoids on neurobehavioral outcomes in preclinical models of nontraumatic and traumatic spinal cord injury (SCI), with the aim of determining suitability for clinical trials involving SCI patients.

METHODS

A systematic search was performed in MEDLINE and Embase databases, following registration with PROPSERO (CRD42019149671). Studies evaluating the impact of cannabinoids (agonists or antagonists) on neurobehavioral outcomes in preclinical models of nontraumatic and traumatic SCI were included. Data extracted from relevant studies, included sample characteristics, injury model, neurobehavioural outcomes assessed and study results. PRISMA guidelines were followed and the SYRCLE checklist was used to assess risk of bias.

RESULTS

The search returned 8714 studies, 19 of which met our inclusion criteria. Sample sizes ranged from 23 to 390 animals. WIN 55,212-2 (n = 6) and AM 630 (n = 8) were the most used cannabinoid receptor agonist and antagonist respectively. Acute SCI models included traumatic injury (n = 16), ischaemia/reperfusion injury (n = 2), spinal cord cryoinjury (n = 1) and spinal cord ischaemia (n = 1). Assessment tools used assessed locomotor function, pain and anxiety. Cannabinoid receptor agonists resulted in statistically significant improvement in locomotor function in 9 out of 10 studies and pain outcomes in 6 out of 6 studies.

CONCLUSION

Modulation of the endo-cannabinoid system has demonstrated significant improvement in both pain and locomotor function in pre-clinical SCI models; however, the risk of bias is unclear in all studies. These results may help to contextualise future translational clinical trials investigating whether cannabinoids can improve pain and locomotor function in SCI patients.

Management of Osteoarthritis: Expert Opinion on NSAIDs

Osteoarthritis (OA) is a leading cause of disability among older adults worldwide. Treatment aims are to alleviate inflammatory pain and improve physical function through non-pharmacological and pharmacological interventions. Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended as first-line therapy. However, selection is challenged by patient age, comorbidities and polypharmacy, and by the drug's benefit/risk balance, all of which together influence the risk of cardiovascular (CV), gastrointestinal (GI) and renal adverse events (AEs). While the efficacy profile of the various NSAIDs is delineated, the differences in their safety profile are not straightforward. This narrative review provides practical indications by a multidisciplinary Italian expert panel for general practitioners and specialists managing OA patients with chronic inflammatory pain; the goal is to maximize therapy efficacy while reducing untoward effects caused by inappropriate NSAID use. The discussion on the best approach to NSAIDs spanned the following topics: (1) patient evaluation: investigate pain origin, duration and components together with possible risk factors for CV, GI and renal AEs; (2) non-pharmacological interventions: the physiatrist provides a person-centered, holistic approach accounting for all patient aspects; (3) pharmacological interventions: patient profile and drugs' pharmacological properties affect NSAID selection, which drugs to be used in combination or to be avoided, formulation and therapy duration; (4) the pharmacologist's, general practitioner's and pain therapist's points of view; (5) NSAID safety: the individual baseline risk and the drug's safety profile are major determinants of CV, GI and renal risk; consider possible drug-drug interactions; (6) periodical re-evaluation of treatment response and adherence, using scales to assess pain and function.

Intrauterine and Lactational Exposure to Paracetamol: Cardiometabolic Evaluation in Adult Female and Male Offspring

ABSTRACT

Paracetamol (PAR) is the most common over-the-counter drug recommended by physicians for treatment of pain and fever during gestation. This drug is not teratogenic, being considered safe for fetus; however, PAR crosses the blood-placental barrier. Considering that, the present study aimed to evaluate the vascular and metabolic safety of PAR exposure during intrauterine and neonatal development in adult male and female-exposed offspring. Wistar female rats were gavaged, with PAR (350 mg/kg/d), from gestational day 6-21 or from gestational day 6 until postnatal day 21. Control dams received water by gavage at the same periods. The male and female offspring were evaluated at adulthood (80 days of life). The thoracic aorta reactivity to acetylcholine, sodium nitroprusside, and phenylephrine was evaluated in male and female adult offspring. It was observed that aortic relaxation was similar between the PAR and control offspring. In addition, the contraction to phenylephrine was similar between the groups. Further, the insulin sensitivity, adipose tissue deposition and blood pressure were not different between PAR and control adult offspring. These results suggest that the protocol of PAR exposure used in the present study did not program vascular and metabolic alterations that would contribute to the development of cardiometabolic diseases in adult life, being safe for the exposed offspring.

Electrochemical determination of acetaminophen at a carbon electrode modified in the presence of β-cyclodextrin: role of the activated glassy carbon and the electropolymerised β-cyclodextrin

Acetaminophen is a well-known drug commonly used to provide pain relief, but it can also lead to acute liver failure at high concentrations. Therefore, there is considerable interest in monitoring its concentrations. Sensitive and selective acetaminophen electrochemical sensors were designed by cycling a glassy carbon electrode (GCE) to high potentials in the presence of β-CD in a phosphate electrolyte, or by simply activating the GCE electrode in the phosphate solution. Using cyclic voltammetry, adsorption-like voltammograms were recorded. The acetaminophen oxidation product, N-acetyl benzoquinone imine, was protected from hydrolysis, and this was attributed to the adsorption of acetaminophen at the modified GCE. The rate constants for the oxidation of acetaminophen were estimated as 4.3 × 10–3 cm2 s–1 and 3.4 × 10–3 cm2 s–1 for the β-CD-modified and -activated electrodes, respectively. Using differential pulse voltammetry, the limit of detection was calculated as 9.7 × 10–8 M with a linear concentration range extending from 0.1 to 80 μM. Furthermore, good selectivity was achieved in the presence of caffeine, ascorbic acid and aspirin, enabling the determination of acetaminophen in a commercial tablet. Similar electrochemical data were obtained for both the β-CD-modified and activated GCE surfaces, suggesting that the enhanced detection of acetaminophen is connected mainly to the activation and oxidation of the GCE. Using SEM, EDX and FTIR, no evidence was obtained to indicate that the β-CD was electropolymerised at the GCE.

Long-term exposure of marine mussels to paracetamol: is time a healer or a killer?

Pharmaceuticals pose a major threat to the marine environment, and several studies have recently described their negative effects on marine organisms. Pharmaceutical compounds are constantly being released into aquatic ecosystems, and chronic exposure, even at low concentrations, may have a major impact on marine organisms. The purpose of the present study is to evaluate the biological changes induced by one of the most widely used pharmaceuticals-paracetamol-in the blue mussel Mytilus edulis, after a long-term exposure at environmentally relevant concentrations. We present our data alongside and in comparison with results from a previous short-term exposure, to demonstrate the significance of exposure period on the effects of paracetamol in adult blue mussels. After 24 days of laboratory exposure, seven potential target genes were selected to examine toxicological effects in mussels' gonads and possible disruptive effects on reproductive processes. The results show the modulation of some important reproduction-related genes: estrogen receptor-2 (ER2), vitelline envelope zona pellucida domain-9 (V9), and vitellogenin (VTG). Variations in mRNA expression of four other genes involved in apoptosis (HSP70, CASP8, BCL2, and FAS) are also highlighted. Histopathological alterations caused by paracetamol, together with neutral red retention time response in mussels' hemocytes, are presented herein. Overall, this study highlights the exacerbated effects of low concentration of paracetamol after chronic exposure, similar to the damage induced by higher concentrations in a short exposure scenario, thus emphasizing the importance of length of exposure period when studying the effects of this substance. Additionally, this study also discusses the potential of paracetamol to inflict several major changes in the reproductive system of mussels and thus possibly affect the survival of populations.

Physiologically based pharmacokinetic modelling of acetaminophen in preterm neonates-The impact of metabolising enzyme ontogeny and reduced cardiac output

In preterm neonates, physiologically based pharmacokinetic (PBPK) models are suited for studying the effects of maturational and non-maturational factors on the pharmacokinetics of drugs with complex age-dependent metabolic pathways like acetaminophen (APAP). The aim of this study was to determine the impact of drug metabolising enzymes ontogeny on the pharmacokinetics of APAP in preterm neonates and to study the effect of reduced cardiac output (CO) on its PK using PBPK modelling. A PBPK model for APAP was first developed and validated in adults and then scaled to paediatric age groups to account for the effect of enzyme ontogeny. In preterm neonates, CO was reduced by 10%, 20%, and 30% to determine how this might affect APAP PK in preterm neonates. In all age groups, the predicted concentration-time profiles of APAP were within 5th and 95th percentile of the clinically observed concentration-time profiles and the predicted Cmax and AUC were within 2-folds of the reported parameters in clinical studies. Sulfation accounted for most of APAP metabolism in children, with the highest contribution of 68% in preterm neonates. A reduction in CO by up to 30% did not significantly alter the clearance of APAP in preterm neonates. The model successfully incorporated the ontogeny of drug metabolising enzymes involved in APAP metabolism and adequately predicted the PK of APAP in preterm neonates. A reduction in hepatic perfusion as a result of up to 30% reduction in CO has no effect on the PK of APAP in preterm neonates.

Paracetamol: A Review of Guideline Recommendations

Musculoskeletal pain conditions are age-related, leading contributors to chronic pain and pain-related disability, which are expected to rise with the rapid global population aging. Current medical treatments provide only partial relief. Furthermore, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids are effective in young and otherwise healthy individuals but are often contraindicated in elderly and frail patients. As a result of its favorable safety and tolerability record, paracetamol has long been the most common drug for treating pain. Strikingly, recent reports questioned its therapeutic value and safety. This review aims to present guideline recommendations. Paracetamol has been assessed in different conditions and demonstrated therapeutic efficacy on both acute and chronic pain. It is active as a single agent and is additive or synergistic with NSAIDs and opioids, improving their efficacy and safety. However, a lack of significant efficacy and hepatic toxicity have also been reported. Fast dissolving formulations of paracetamol provide superior and more extended pain relief that is similar to intravenous paracetamol. A dose reduction is recommended in patients with liver disease or malnourished. Genotyping may improve efficacy and safety. Within the current trend toward the minimization of opioid analgesia, it is consistently included in multimodal, non-opioid, or opioid-sparing therapies. Paracetamol is being recommended by guidelines as a first or second-line drug for acute pain and chronic pain, especially for patients with limited therapeutic options and for the elderly.

Endocannabinoids Regulate Stem Cells of the Apical Papilla via a Cannabinoid Receptor and TRPV1-Independent Mechanism

INTRODUCTION

Endogenous cannabinoids (endocannabinoids [eCBs]) have been shown to have a multitude of functions including neurotransmission and immune modulatory effects. This study aimed to evaluate if stem cells of the apical papilla (SCAP) express the receptors and enzymes of the endocannabinoid system (ECS) and whether eCBs regulate their proliferation and mineralization potential.

METHODS

Gene expression of the main components of the ECS and transient receptor potential vanilloid 1 (TRPV1) was evaluated in SCAP cultures. SCAP were treated with 2 concentrations of eCBs and/or capsazepine, a TRPV1 antagonist. SCAP viability was evaluated after 1, 4, and 7 days. Osteogenic differentiation was assessed after 14 days, and the gene expression of mineralization markers was assessed after 7 days.

RESULTS

The enzymes of ECS and TRPV1 but not the cannabinoid receptors (cannabinoid receptors 1 and 2) were expressed in SCAP. Anandamide, 2-arachidonoylglycerol, and N-arachidonoylphenolamine (AM-404) reduced SCAP viability in all experimental periods at the highest concentration compared with the group with no treatment. Anandamide and AM-404 did not inhibit SCAP differentiation potential, but 2-arachidonoylglycerol at the highest concentration did. SCAP treated with AM-404 presented a down-regulation in gene expression of alkaline phosphatase (ALP), dentin matrix protein 1 (DMP-1), and dentin sialophosphoprotein (DSPP) compared with the proliferation medium group but not with control group.

CONCLUSIONS

SCAP expressed the genes of the main components of ECS and TRPV1, and eCBs can affect SCAP viability, mineralization, and gene expression.

Fibromyalgia in Older Individuals

Fibromyalgia (FM) is a condition of chronic widespread pain (CWP) that can occur throughout the life cycle and is likely underrecognized in older patients. FM is associated with considerable suffering and reduction in quality of life and may occur as a unique condition, but in older patients is most likely to be associated with another medical illness. Understood mechanistically to be a sensitization of the nervous system, recently identified as nociplastic pain, FM is accepted as a valid medical illness that requires a positive diagnosis and directed treatments. The cornerstone of treatments for FM are nonpharmacologic interventions, with the understanding that medications provide only modest benefit for most patients, and with particular concern about adverse effects in older patients. If FM is not recognized, treatments may be misdirected to the other medical condition, with failure to address FM symptoms, leading to overall poor outcome. In contrast, new complaints in older patients should not immediately be attributed to FM, and physicians should be vigilant to ensure that onset of a new illness is not ignored. As FM is most often a lifelong condition, patients should be encouraged to identify their own personal strategies that can attenuate symptoms, especially when symptoms flare. Continued life participation should be the outcome goal.

Quality assessment of nine paracetamol 500 mg tablet brands marketed in Saudi Arabia

Objective

To evaluate in-vitro quality of paracetamol 500 mg tablet brands marketed in Saudi Arabia.

Results

Two reference (R1 and R2) and seven generic (G1-G7) brands were commercially available. Four brands were single-drug, containing paracetamol only (R1, G1-G3) and five contained additional active ingredients (R2, G4-G7). All brands were immediate-release. Weight variation (n = 20, range as percent difference from mean), active substance content (n = 20, mean (SD) as percent difference from label), breaking force (n = 10, mean (SD)), and friability (n = 20, as percent weight loss) ranged from 97 to 102%, 96.1% (2.9%) to 99.8% (1.1%), 9.9 (0.4) to 21.0 (0.9) kg, and 0.017% to 0.809%, respectively. Disintegration (water medium) time (n = 6, minute: second) ranged from 02:35–03:09 to 12:49–13:10. Dissolution (phosphate buffer, pH 5.8) profile showed a mean release at 30 min of 87% to 97% of label content, with seven brands passing stage-1 (≥ 85% for each of 6 test units) and two passing stage-2 (mean of 12 test units ≥ 85%) criteria. Despite statistically significant differences between R1 and R2 and some of their corresponding generic brands in active substance content, breaking force, and amount dissolved at 30 min, all nine brands met the pre-specified quality standards.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05672-y.

Linear and nonlinear investigations for the adsorption of paracetamol and metformin from water on acid-treated clay

Natural clays are considered a safe, low-cost, and sound sorbent for some pharmaceutical and body care products from water. Metformin (MF) and paracetamol (PA) are of the most consumable drugs worldwide. A portion of natural clay was treated with distilled water, and another part was treated with hydrochloric acid. The water-treated clay (WTC) and the acid-treated clay (ATC) were characterized by scanning electron microscopy-energy dispersive spectroscopy, X-ray diffraction, Fourier transforms infrared spectroscopy, and nitrogen adsorption isotherm. Batch experiments were employed to investigate the influence of contact time and solution parameters on the adsorption of PA and MF on WTC and ATC. 30 min attained the equilibrium for all sorbent-sorbate systems. Both sorbents fitted the pseudo-second-order kinetic model with a preference to the nonlinear fitting, and the mechanism of adsorption partially fitted the liquid-film diffusion model. The PA and MF adsorption on WTC and ATC fitted the Freundlich model in preference to nonlinear fitting. The adsorption of pollutants on both sorbents was spontaneous, exothermic, and physisorption in nature. Even at low concentrations, both WTC and ATC showed efficiency above 80% in removing PA and MF from tab water, groundwater, and Red seawater. These findings nominated natural clay as an alternative to the costly nanomaterials as sorbents for removing pharmaceutical contaminants from water.

Striatal TRPV1 activation by acetaminophen ameliorates dopamine D2 receptor antagonist-induced orofacial dyskinesia

Antipsychotics often cause tardive dyskinesia, an adverse symptom of involuntary hyperkinetic movements. Analysis of the US Food and Drug Administration Adverse Event Reporting System and JMDC insurance claims revealed that acetaminophen prevented the dyskinesia induced by dopamine D₂ receptor antagonists. In vivo experiments further showed that a 21-day treatment with haloperidol increased the number of vacuous chewing movements (VCMs) in rats, an effect that was inhibited by oral acetaminophen treatment or intracerebroventricular injection of N-(4-hydroxyphenyl)-arachidonylamide (AM404), an acetaminophen metabolite that acts as an activator of the transient receptor potential vanilloid 1 (TRPV1). In mice, haloperidol-induced VCMs were also mitigated by treatment with AM404 applied to the dorsal striatum, an effect not seen in TRPV1-deficient mice. Acetaminophen prevented the haloperidol-induced decrease in the number of c-Fos⁺preproenkephalin⁺ striatal neurons in wild-type mice but not in TRPV1-deficient mice. Finally, chemogenetic stimulation of indirect pathway medium spiny neurons in the dorsal striatum decreased haloperidol-induced VCMs. These results suggest that acetaminophen activates the indirect pathway neurons by activating TRPV1 channels via AM404.

Current State of Analgesia and Sedation in the Pediatric Intensive Care Unit

Critically ill pediatric patients often require complex medical procedures as well as invasive testing and monitoring which tend to be painful and anxiety-provoking, necessitating the provision of analgesia and sedation to reduce stress response. Achieving the optimal combination of adequate analgesia and appropriate sedation can be quite challenging in a patient population with a wide spectrum of ages, sizes, and developmental stages. The added complexities of critical illness in the pediatric population such as evolving pathophysiology, impaired organ function, as well as altered pharmacodynamics and pharmacokinetics must be considered. Undersedation leaves patients at risk of physical and psychological stress which may have significant long term consequences. Oversedation, on the other hand, leaves the patient at risk of needing prolonged respiratory, specifically mechanical ventilator, support, prolonged ICU stay and hospital admission, and higher risk of untoward effects of analgosedative agents. Both undersedation and oversedation put critically ill pediatric patients at high risk of developing PICU-acquired complications (PACs) like delirium, withdrawal syndrome, neuromuscular atrophy and weakness, post-traumatic stress disorder, and poor rehabilitation. Optimal analgesia and sedation is dependent on continuous patient assessment with appropriately validated tools that help guide the titration of analgosedative agents to effect. Bundled interventions that emphasize minimizing benzodiazepines, screening for delirium frequently, avoiding physical and chemical restraints thereby allowing for greater mobility, and promoting adequate and proper sleep will disrupt the PICU culture of immobility and reduce the incidence of PACs.

Effect of Intravenous Acetaminophen on Mean Arterial Blood Pressure: A Post Hoc Analysis of the EFfect of Intravenous ACetaminophen on PosToperative HypOxemia After Abdominal SurgeRy Trial

BACKGROUND

Acetaminophen is commonly used as part of multimodal analgesia for acute pain. The intravenous formulation offers a more predictable bioavailability compared to oral and rectal acetaminophen. There have been reports of hypotension with intravenous acetaminophen attributable to centrally mediated and vasodilatory effects. We tested the hypothesis that in adults having abdominal surgery the use of intravenous acetaminophen versus placebo for postoperative pain management is associated with a decrease in mean arterial pressure (MAP) after its administration.

METHODS

This is a substudy of eFfect of intravenous ACetaminophen on posToperative hypOxemia after abdominal surgeRy (FACTOR) trial (NCT02156154). FACTOR trial randomly assigned adults undergoing abdominal surgery to either 1 g of acetaminophen or placebo every 6 hours during the first postoperative 48 hours. Continuous monitoring of blood pressure was obtained by noninvasive ViSi Mobile device (Sotera Wireless, Inc, San Diego, CA) at 15-second intervals during initial 48 hours postoperatively. We excluded patients without continuous monitoring data available. The primary outcome was the MAP difference between MAP 5 minutes before study drug administration (baseline) and MAP 30 minutes poststudy drug administration initiation. We used a linear mixed effects model to assess the treatment effect on MAP change. The secondary outcome was MAP area under baseline (AUB) during the 30 minutes after treatment. In a sensitivity analysis of change in MAP from predrug to postdrug administration, we instead used postdrug MAP as the outcome adjusting for the baseline MAP in the model.

RESULTS

Among 358 patients analyzed, 182 received acetaminophen and 176 placebo. The mean (standard deviation [SD]) of average MAP change was -0.75 (5.9) mm Hg for the treatment and 0.32 (6.3) mm Hg for the placebo. Acetaminophen was found to decrease the MAP from baseline more than placebo after drug administration. The estimated difference in mean change of MAP was -1.03 (95% confidence interval [CI] -1.60 to -0.47) mm Hg; P < .001. The sensitivity analysis showed postoperative MAP in the acetaminophen group was 1.33 (95% CI, 0.76-1.90) mm Hg lower than in the placebo group (P < .001). The median of MAP AUB was 33 [Q1 = 3.3, Q3 = 109] mm Hg × minutes for the treatment and 23 [1.6, 79] mm Hg × minutes for the placebo. Acetaminophen was found to increase the AUB with an estimated median difference of 15 (95% CI, 5-25) mm Hg × minutes (P = .003).

CONCLUSIONS

Intravenous acetaminophen decreases MAP after its administration. However, this decrease does not appear to be clinically meaningful. Clinicians should not refrain to use intravenous acetaminophen for acute pain management because of worries of hypotension.

The anti-tumour activity of DNA methylation inhibitor 5-aza-2'-deoxycytidine is enhanced by the common analgesic paracetamol through induction of oxidative stress

The DNA demethylating agent 5-aza-2'-deoxycytidine (DAC, decitabine) has anti-cancer therapeutic potential, but its clinical efficacy is hindered by DNA damage-related side effects and its use in solid tumours is debated. Here we describe how paracetamol augments the effects of DAC on cancer cell proliferation and differentiation, without enhancing DNA damage. Firstly, DAC specifically upregulates cyclooxygenase-2-prostaglandin E2 pathway, inadvertently providing cancer cells with survival potential, while the addition of paracetamol offsets this effect. Secondly, in the presence of paracetamol, DAC treatment leads to glutathione depletion and finally to accumulation of ROS and/or mitochondrial superoxide, both of which have the potential to restrict tumour growth. The benefits of combined treatment are demonstrated here in head and neck squamous cell carcinoma (HNSCC) and acute myeloid leukaemia cell lines, further corroborated in a HNSCC xenograft mouse model and through mining of publicly available DAC and paracetamol responses. The sensitizing effect of paracetamol supplementation is specific to DAC but not its analogue 5-azacitidine. In summary, the addition of paracetamol could allow for DAC dose reduction, widening its clinical usability and providing a strong rationale for consideration in cancer therapy.

A Systematic Review of Clinical Studies on the Effect of Psychoactive Cannabinoids in Psychiatric Conditions in Alzheimer Dementia

BACKGROUND

The systematic reviews and meta-analyses performed until now did not provide the adequate picture of actual knowledge in the field of neuropsychiatric symptoms treatment using psychotropic cannabinoids in patients with Alzheimer disease (AD).

THE STUDY QUESTION

Which is the level of evidence, from quantitative and qualitative point of view, concerning the efficacy and safety of the treatment with psychotropic cannabinoids of neuropsychiatric symptoms in AD?

STUDY DESIGN

PubMed, EMBASE, Cochrane Database of Systematic Reviews, Google Scholar Data, and Clinicaltrials.gov were searched for randomized clinical trials with cannabinoids in Alzheimer dementia agitation and aggression.

MEASURES AND OUTCOMES

The rationale, the objectives, and the methods used for searching the trials have been established according to PRISMA Criteria 2009.

RESULTS

The total number of patients in the 9 publications evaluated in this study, which included data from 6 clinical trials, was 422 patients-treatments, where treatment was a psychoactive cannabinoid or placebo, some of them obtained by multiplying selected patients with the number of cannabinoid treatments in the crossover studies. There are multiple sources of bias in the analyzed studies; 2 elements have prevented conclusive results. One element was polypragmazia, a major role being played by the use of psychotropic drugs other than cannabinoids, in an effort to reduce agitation and aggressive behavior. The second one was the large number of concomitant symptoms, for example, pain (commonly causing anxiety and agitation).

CONCLUSIONS

No clear conclusion can be drawn on the effectiveness of psychoactive cannabinoids in the treatment of psychiatric manifestations, in particular agitation and aggression, in AD. In the future, large randomized controlled trial with adequate designs, without crossover and for longer duration, adapted to cannabinoid pharmacokinetics, is required to establish the real efficacy and safety of these drugs in aggressive and/or agitated patients with AD.

Efficacy of Photobiomodulation Therapy for Orthodontic Pain Control Following the Placement of Elastomeric Separators: A Randomized Clinical Trial

Introduction: Controlling pain in orthodontic patients has gained special attention. This study assessed the efficacy of photobiomodulation therapy (PBMT) for pain control following the placement of elastomeric separators. Methods: This split-mouth single-blind randomized clinical trial evaluated 30 orthodontic patients who required posterior elastomeric separators. The two maxillary quadrants were randomized into the laser and control groups. In the laser quadrant, an 808 nm diode laser (400 mW, 15.60 J/cm² , 11 seconds, continuous-wave, contact mode) was irradiated to the cervical third of the maxillary first molar roots 24 hours prior to the placement of separators. The control quadrant received placebo radiation by a light-curing unit. The patients received the second laser cycle right before the placement of separators 24 hours later. The level of self-perceived pain was recorded at 0, 2, 6, 24, and 72 hours and 5 days after the intervention in the laser and control quadrants using a visual analog scale (VAS). Data were analyzed using the analysis of variance (ANOVA) and paired-samples t test. Results: The trend of change in the pain score was similar in both groups. The pain score was significantly lower in the laser group than the control group at all-time points (P <0.05) except at time 0. The pain score increased in the first 6 hours and reached its maximum level in 24 hours in both groups. Conclusion: PBMT by an 808 nm diode laser can effectively decrease pain following the placement of elastomeric separators.

N-acetylcysteine dose-dependently improves the analgesic effect of acetaminophen on the rat hot plate test

BACKGROUND

Acetaminophen (APAP) induced hepatotoxicity is a clinically important problem. Up to now, interventive therapy with n-acetylcysteine (NAC) has been considered as a gold-standard treatment for APAP overdose. However, no study has focused on the efficacy of these drugs' concurrent administration on probable enhancing therapeutic outcomes. Thus, this study was aimed to investigate the analgesic effect of co-administration of NAC and acetaminophen in male rats. The NAC-APAP drug formulation may demonstrate the stranger antinociceptive effect.

METHODS

Forty-eight male Sprague-Dawley rats (12-14 weeks) randomly divided into six equal groups; control, APAP (received 300 mg/kg APAP), NAC (received 600 mg/kg NAC) and APAP+ NAC groups that received simultaneously 300 mg/kg APAP with 200-600 mg/kg NAC (AN200, AN400, AN600). All administrations were done orally for once. The antinociceptive effect was recorded by measurement of latency period on a hot plate in 30, 60, and 90 min after administrations.

RESULTS

The results showed that NAC's concurrent administration with APAP, dose-dependently increased APAP analgesic effects (p< 0.0001). Moreover, NAC treatment exhibited an antinociceptive effect in 60 and 90 min, per se. The treatments had no adverse effect on liver enzymes and oxidative stress.

CONCLUSION

Co-administration of NAC with APAP can improve the antinociceptive effect of APAP. It is suggested that this compound can enhance analgesic effects of APAP and eventually lead to a reduction in acetaminophen dose. Further studies are needed to evaluate the molecular mechanism of this hyper analgesic effect.

Prevalence of use of permitted pharmacological substances for recovery among athletes

Objectives: Food supplements and medicines which are not on the list of prohibited substances of the World Anti-Doping Agency are included in the group of permitted pharmacological agents for athlete’s recovery.

The aim of this study was to describe qualitatively and quantitatively food supplements (FS) and over-the-counter drugs use among athletes in the last six month.

Methods: This was a cross sectional study. Data on food supplements and the over-the-counter drugs, usage were collected during 2018 by self-administered, anonymous questionnaire.

Results: A total of 112 athletes completed the survey. A total of 51.8% (n = 58) athletes reported the use of food supplements. The use of medical supplements was reported by 50.0% (n = 56) of athletes, 26.8% (n = 30) reported using ergogenic supplements, 1.8% (n = 2) using of sports food and 4.5% (n = 5) using other supplements. The use of over-the-counter drugs was reported by 35.7% (n = 40) of athletes. The over-the-counter analgesic drugs were used by 95% (n = 38) of over-the-counter drug users. Concomitant administration two or more over-the-counter drugs was reported by 40% (n = 16) athletes. Doctors and coaches had no advisory role in the use of food supplements or over-the-counter drugs.

Acetaminophen Modulates the Expression of Steroidogenesis-Associated Genes and Estradiol Levels in Human Placental JEG-3 Cells

Acetaminophen is the only medication recommended for pain and fever management during pregnancy. However, studies have reported an association between in utero acetaminophen and neurocognitive disorders later in life. Additionally, acetaminophen has been shown to have endocrine disrupting properties altering hormones critical for normal fetal development. As the placenta is an endocrine organ that produces hormones for fetal development, any attempts to elucidate the mechanism underlying in utero acetaminophen and birth outcomes must also focus on the placenta. The present study set out to examine the effect of acetaminophen on mRNA expression, protein expression, and hormone synthesis in placental JEG-3 cells. The analysis focused on genes involved in steroidogenesis and acetaminophen metabolism as well those with known roles as nuclear receptors and transporters. The results highlight that at high concentrations, acetaminophen reduced the gene expression of aromatase (CYP19A1) and type 1 3β-hydroxysteroid dehydrogenase (HSD3B1), and increased the expression of 17β-hydroxysteroid dehydrogenase (HSD17B1). Additionally, acetaminophen at high concentrations also reduced the protein expression of aromatase (CYP19A1). These effects were accompanied by a significant dose-dependent decrease in estradiol secretion. Estradiol plays an important role in the development of reproductive organs and the brain of the developing fetus. This study highlights the potential for acetaminophen to interfere with hormone regulation during pregnancy and underscores the need for additional studies aimed at understanding the endocrine disruption activity of acetaminophen during fetal development.

Paracetamol - An old drug with new mechanisms of action

Paracetamol (acetaminophen) is the most commonly used over-the-counter (OTC) drug in the world. Despite its popularity and use for many years, the safety of its application and its mechanism of action are still unclear. Currently, it is believed that paracetamol is a multidirectional drug and at least several metabolic pathways are involved in its analgesic and antipyretic action. The mechanism of paracetamol action consists in inhibition of cyclooxygenases (COX-1, COX-2, and COX-3) and involvement in the endocannabinoid system and serotonergic pathways. Additionally, paracetamol influences transient receptor potential (TRP) channels and voltage-gated Kv7 potassium channels and inhibits T-type Cav3.2 calcium channels. It also exerts an impact on L-arginine in the nitric oxide (NO) synthesis pathway. However, not all of these effects have been clearly confirmed. Therefore, the aim of our paper was to summarize the current state of knowledge of the mechanism of paracetamol action with special attention to its safety concerns.

Randomised controlled trial of paracetamol or ibuprofen, as required for fever and pain in the first year of life, for prevention of asthma at age 6 years: paracetamol or ibuprofen in the primary prevention of asthma in Tamariki (PIPPA Tamariki) protocol

INTRODUCTION

Asthma is one of the most common diseases in the world and is a global public health burden. There is an urgent need for research that leads to evidenced-based primary prevention strategies to reduce the prevalence of asthma. One novel risk factor that might have a role in the pathogenesis of asthma is the use of paracetamol in early life. This trial aims to determine if paracetamol, compared with ibuprofen use, as required for fever and pain in the first year of life, increases the risk of asthma at age 6 years.

METHODS AND ANALYSIS

The Paracetamol and Ibuprofen in Primary Prevention of Asthma in Tamariki trial is a multicentre, open-label, two-arm parallel randomised controlled trial. 3922 infants born at ≥32 weeks' gestation will be randomly allocated to receive only paracetamol or only ibuprofen for treatment of fever and pain, if required in the first year of life. The primary outcome is asthma at 6 years of age, defined as the presence of wheeze in the preceding 12 months. Secondary outcomes include hospital admissions for bronchiolitis, wheeze or asthma in the first year of life, and within the first 6 years of life; wheeze at 3 years of age; eczema within the first year and at 3 and 6 years of age; atopy at 3 and 6 years of age.

ETHICS AND DISSEMINATION

The trial has been approved by the Northern A Health and Disability Ethics Committee of New Zealand (17/NTA/233). Dissemination plans include publication in international peer-reviewed journals, and presentation at national and international scientific meetings, assimilation into national and international guidelines, and presentation of findings to lay audiences through established media links.

TRIAL REGISTRATION NUMBER

ACTRN12618000303246; Pre-results.

Postoperative Pain Management in Pediatric Spinal Fusion Surgery for Idiopathic Scoliosis

This article reviews and summarizes current evidence and knowledge gaps regarding postoperative analgesia after pediatric posterior spine fusion for adolescent idiopathic scoliosis, a common procedure that results in severe acute postoperative pain. Inadequate analgesia may delay recovery, cause patient dissatisfaction, and increase chronic pain risk. Despite significant adverse effects, opioids are the analgesic mainstay after scoliosis surgery. However, growing emphasis on opioid minimization and enhanced recovery has increased adoption of multimodal analgesia (MMA) regimens. While opioid adverse effects remain a concern, MMA protocols must also consider risks and benefits of adjunct medications. We discuss use of opioids via different administration routes and elaborate on the effect of MMA components on opioid/pain and recovery outcomes including upcoming regional analgesia. We also discuss risk for prolonged opioid use after surgery and chronic post-surgical pain risk in this population. Evidence supports use of neuraxial opioids at safe doses, low-dose ketorolac, and methadone for postoperative analgesia. There may be a role for low-dose ketamine in those who are opioid-tolerant or have chronic pain, but the evidence for preoperative gabapentinoids and intravenous lidocaine is currently insufficient. There is a need for further studies to evaluate pediatric-specific optimal MMA dosing regimens after scoliosis surgery. Questions remain regarding how best to prevent acute opioid tolerance, opioid-induced hyperalgesia, and chronic postsurgical pain. We anticipate that this timely update will enable clinicians to develop efficient pain regimens and provide impetus for future research to optimize recovery outcomes after spine fusion.

Effect of paracetamol treatment on maternal care and reproductive outcomes in female rat offspring

Paracetamol (PAR) is one of the most commonly used drugs by pregnant women because it is considered safe for the mother and fetus. However, PAR is transferred into breast milk and crosses the blood-placental barrier, being present in the progeny during important stages of development. Intrauterine exposure to PAR may decrease the anogenital distance and follicle reserve in female rodent offspring. Therefore, the aim of the present study was to evaluate whether maternal PAR treatment altered the reproductive behaviour of dams and the sexual development of female rat offspring. Pregnant Wistar rats were gavaged daily with 350mg kg-1 day-1 PAR or water during gestation (from Gestation Day (GD) 6 until delivery) or during gestation and lactation (from GD6 until weaning). Maternal PAR treatment had maternal effects (increased grooming behaviour), and resulted in impaired sexual behaviour, decreased follicle reserve and increased plasma oestradiol concentrations in female offspring.

Analgesic Effect of Acetaminophen: A Review of Known and Novel Mechanisms of Action

Acetaminophen is one of the most commonly used analgesic agents for treating acute and chronic pain. However, its metabolism is complex, and its analgesic mechanisms have not been completely understood. Previously, it was believed that acetaminophen induces analgesia by inhibiting cyclooxygenase enzymes; however, it has been considered recently that the main analgesic mechanism of acetaminophen is its metabolization to N-acylphenolamine (AM404), which then acts on the transient receptor potential vanilloid 1 (TRPV1) and cannabinoid 1 receptors in the brain. We also recently revealed that the acetaminophen metabolite AM404 directly induces analgesia via TRPV1 receptors on terminals of C-fibers in the spinal dorsal horn. It is known that, similar to the brain, the spinal dorsal horn is critical to pain pathways and modulates nociceptive transmission. Therefore, acetaminophen induces analgesia by acting not only on the brain but also the spinal cord. In addition, acetaminophen is not considered to possess any anti-inflammatory activity because of its weak inhibition of cyclooxygenase (COX). However, we also revealed that AM404 induces analgesia via TRPV1 receptors on the spinal dorsal horn in an inflammatory pain rat model, and these analgesic effects were stronger in the model than in naïve rats. The purpose of this review was to summarize the previous and new issues related to the analgesic mechanisms of acetaminophen. We believe that it will allow clinicians to consider new pain management techniques involving acetaminophen.

Evaluation of the dentate gyrus in adult mice exposed to acetaminophen (paracetamol) on postnatal day 10

Acetaminophen (AAP; or paracetamol) is a widely used nonprescription drug with antipyretic and analgesic properties. Alarmingly, there is an increasing body of evidence showing that developmental exposure to AAP is associated with adverse behavioural outcomes later in life. We have previously shown that relevant doses of AAP in 10-day-old mice affected memory, learning and locomotor activity in the adult animals. Interestingly, the neurons of the dentate gyrus (DG) have a relatively late time of origin as they are generated during the first two weeks of postnatal life in rodents. Since the generation of these cells, which are important for memory processing, coincides with our AAP exposure, we aim to investigate if the cytoarchitecture of the DG is affected by postnatal day 10 AAP treatment. In addition, we investigate if markers for differentiation and migration in the hippocampus were affected by the same treatment. We did not observe any visual effects in adult DG cytoarchitecture, nor any changes of markers for differentiation/migration in the hippocampus in 24 hr after exposure. Even though a large effect size was estimated on adult DG thickness following AAP exposure, the estimated 95% CIs around the differences of the means reveal no significant effect. Hence, larger sample sizes are warranted to clarify if neonatal AAP exposure affects adult DG thickness in mice.

Comparison of effects of high and low dose paracetamol treatment and toxicity on brain and liver in rats

OBJECTIVE

Paracetamol is thought that it acts by inhibiting the central cyclooxygenase (COX) enzyme; its mechanism of action is still not fully explained. Although its most important side effect is hepatoxicity, it is thought to cause toxicity on the brain in recent years. The present study aims to investigate the treatment and toxic effects of low and high doses of paracetamol on the liver and brain.

METHODS

Wistar-albino rats were used in this study. At doses of 20-500 mg/kg, paracetamol was administered intraperitoneally once a day for one and three days. The brain and liver were used for immunohistochemical evaluation using COX-3, prostaglandin E₂ (PGE₂) and caspase 3 antibodies and for total antioxidant (TAS), total oxidant (TOS) and oxidative stress index (OSI) measurements. Results were evaluated using the Kruskal Wallis test (SPSS ver.24).

RESULTS

The liver COX-3 levels were significantly lower in both groups with higher doses (p<0.05). In the brain, there was no statistically significant difference in COX-3 levels between the groups. There was no statistically significant difference in PGE₂ levels in the liver and brain between the groups (p>0.05). The caspase 3 level in the liver was statistically significantly higher in the low dose group compared to the other groups (p<0.05). In both liver and brain, OSI values were significantly higher in the 3-day high-dose group compared to others (p<0.05). There was no statistically significant difference between the groups in ALT and AST values (p>0.05).

CONCLUSION

The results of our study show that paracetamol inhibits the COX-3 enzyme in the liver but has no effect in the brain, and COX-3 does not have an effect on PGE₂. Paracetamol causes apoptosis in the liver only in low doses; higher doses may cause toxicity by increasing oxidative stress, especially in the brain.

Bioavailability of the Common Cold Medicines in Jellies for Oral Administration

Jellies for oral administration have been suggested as alternative dosage forms to conventional tablets for improved palatability and compliances for pediatric and geriatric patients. To evaluate the effect of jelly formulation on the bioavailability of cold medicines, two types of jellies were prepared for a fixed-dose combination of acetaminophen (AAP), chlorpheniramine maleate (CPM), dextromethorphan hydrobromide (DMH), and dl-methylephedrine hydrochloride (MEH). Jelly-S and Jelly-H were fabricated using carrageenan and locust bean gum in the absence and presence of xanthan gum, respectively. In vitro dissolution and in vivo absorption of the four drugs in the jellies were compared with other conventional formulations, a syrup and two types of immediate-release (IR) tablets with different hardness, Tablet-S (15 kPa) and Tablet-H (20 kPa). All the formulations exhibited more than 80% dissolution rate within 2 h even though the syrup, Jelly-S, and Tablet-S showed higher 30-min dissolution compared to Jelly-H and Tablet-H. The dissolution rates from the jellies decreased with increasing pH, which resulted in the slowest dissolution in pH 6.8 compared to the syrup and IR tablets. When administered orally to beagle dogs, all five formulations were determined not to be bioequivalent. However, Jelly-S and Jelly-H showed 0.82-1.05 of the geometric mean ratios (GMRs) of AUC_0-t for all four drugs compared to the syrup suggesting comparable absorption. In two IR tablets, GMRs of AUC_0-t were in a range of 0.55-0.95 indicating a tendency of lower absorption than the syrup and jellies. In conclusion, jelly can be a patient-centered formulation with comparable bioavailability to syrup.

Spectroscopic evaluation of Zn (II) complexes with drug analogues: Interactions with BSA and the pH effect on the drug-Zn (II) system

Using UV-Vis, FT-IR, fluorescence spectroscopy and protein-ligand docking, the interactions between the zinc complexes with drug analogues and bovine serum albumin were investigated. In addition, considering the ubiquitous presence of zinc ions in the human system, we studied the interactions between this ion with hymecromone, dihydropyridine analogue, and acetamide, as well as the pH influence on these systems. The complexes were synthesized by interaction between the ligands and the Zn (II) ion in a 2:1 M ratio. Elemental analysis, FT-IR, and UV-Vis spectroscopy studies investigated the structure of the synthesized complexes. Fluorescence spectroscopy, UV-Vis, molecular docking and molecular dynamics were used to study the interactions of the Zn complexes with the BSA. The drug-Zn (II) system's pH effect was investigated using UV-Vis spectroscopy. After the complexation with the zinc, the drug molecules exhibited higher apparent binding affinity to BSA. BSA's fluorescence efficiency by the drug analogues was enhanced. In addition, molecular modelling was used to classify the residue of amino acids in the BSA playing key roles in this binding interaction. An increase in pH appears to contribute to alkaline hydrolysis of the Zn (II) molecules.