Pack size and paracetamol overdose: 16 years later

A retrospective analysis of therapeutic drug exposures in New Zealand National Poisons Centre data 2018-2020

OBJECTIVE

The New Zealand National Poisons Centre advises the general public and health professionals on management of exposures to various substances. The epidemiology of medicine exposures was used to characterise inappropriate use of medicines across age groups.

METHODS

Data from contacts in 2018-2020 were analysed: patient demographics (age, gender), number of therapeutic substances, and advice given. The most frequent individual therapeutic substance exposures across age groups and the reasons for these occurring were determined.

RESULTS

A total of 76% of children's (aged 0-12 or unknown child) exposures were exploratory in nature, involving a variety of medicines. Youth (aged 13-19) had frequently engaged in intentional self-poisoning (61% of their exposures), and most commonly by exposure to paracetamol, antidepressants, and quetiapine. Adults (aged 20-64) and older adults (aged 65 and over) were frequently affected by therapeutic errors (50% and 86% of their exposures, respectively). Adults were most frequently exposed to paracetamol, codeine, tramadol, antidepressants, and hypnotics, while older adults were exposed to paracetamol and various cardiac medications.

CONCLUSIONS

Types of inappropriate medicine exposures vary in different age groups.

IMPLICATIONS FOR PUBLIC HEALTH

Poisons centre data add to pharmacovigilance monitoring of potential harm from medicines and inform medication safety policies and interventions.

Paracetamol (acetaminophen): A familiar drug with an unexplained mechanism of action

Paracetamol (acetaminophen) is undoubtedly one of the most widely used drugs worldwide. As an over-the-counter medication, paracetamol is the standard and first-line treatment for fever and acute pain and is believed to remain so for many years to come. Despite being in clinical use for over a century, the precise mechanism of action of this familiar drug remains a mystery. The oldest and most prevailing theory on the mechanism of analgesic and antipyretic actions of paracetamol relates to the inhibition of CNS cyclooxygenase (COX) enzyme activities, with conflicting views on the COX isoenzyme/variant targeted by paracetamol and on the nature of the molecular interactions with these enzymes. Paracetamol has been proposed to selectively inhibit COX-2 by working as a reducing agent, despite the fact that in vitro screens demonstrate low potency on the inhibition of COX-1 and COX-2. In vivo data from COX-1 transgenic mice suggest that paracetamol works through inhibition of a COX-1 variant enzyme to mediate its analgesic and particularly thermoregulatory actions (antipyresis and hypothermia). A separate line of research provides evidence on potentiation of the descending inhibitory serotonergic pathway to mediate the analgesic action of paracetamol, but with no evidence of binding to serotonergic molecules. AM404 as a metabolite for paracetamol has been proposed to activate the endocannabinoid and the transient receptor potential vanilloid-1 (TRPV1) systems. The current review gives an update and in some cases challenges the different theories on the pharmacology of paracetamol and raises questions on some of the inadequately explored actions of paracetamol. List of Abbreviations: AM404, N-(4-hydroxyphenyl)-arachidonamide; CB1R, Cannabinoid receptor-1; Cmax, Maximum concentration; CNS, Central nervous system; COX, Cyclooxygenase; CSF, Cerebrospinal fluid; ED50, 50% of maximal effective dose; FAAH, Fatty acid amidohydrolase; IC50, 50% of the maximal inhibitor concentration; LPS, Lipopolysaccharide; NSAIDs, Non-steroidal anti-inflammatory drugs; PGE2, Prostaglandin E2; TRPV1, Transient receptor potential vanilloid-1.

Restriction of non-opioid analgesics sold over-the-counter in Denmark: A national study of impact on poisonings

OBJECTIVE

Self-poisoning with non-opioid analgesics presents a growing challenge to health care providers. We aimed to assess the impact of an 18-year age restriction of OTC sales and a pack size restriction of non-opioid analgesics sold OTC in pharmacies on hospital-treated poisonings and poisoning severity measured using biomarkers.

METHODS

We applied a before and after design using interrupted time series analysis. Data on all poisonings recorded as hospital admissions were obtained during 2002-2015 and biochemical parameters from laboratory databases during 2011-2015, both covering the entire Danish population.

RESULTS

The age restriction was followed by a 17% level reduction in admissions for non-opioid analgesic poisoning among young people age 10-17 years (RR 0.830; 95% CI 0.697-0.988; p < 0.036). After the pack size restriction, an instant level reduction of 18.5% (RR 0.815; 95% CI 0.729-0.912; p < 0.001) was observed for the entire population. A 27% decrease in the number of poisonings with alanine transaminase levels (ALT) ≥ 210 U/L was observed (RR 0.734; 95% CI 0.579-0.931; p = 0.011) followed by 40% decrease in biomarkers indicative of liver failure (RR 0.597; 95% CI 0.421-0.847; p = 0.004). We also observed similar reductions for other poisonings such as psychotropics.

LIMITATIONS

Although declines in poisonings were observed after implementation of means restrictive measures, a causal link cannot be inferred.

CONCLUSION

Age and pack size restriction were assiociated with a reduction in the numbers of poisonings. This was also observed for pharmaceutical poisonings in general, which might suggest a non-specific or spill-over effect.

Presentations Related to Acute Paracetamol Intoxication in an Urban Emergency Department in Switzerland

Aim

To investigate the characteristics of Emergency Department (ED) presentations due to acute paracetamol intoxication.

Methods

Retrospective observational study of patients presenting to the ED of Bern University Hospital between May 1, 2012, and October 31, 2018, due to a paracetamol overdose (defined as intake of >4 g/24 h). Cases were identified using the full-text search of the electronic patient database and were grouped into intentional (suicidal/parasuicidal) and unintentional intoxications (e.g., patient unaware of maximal daily dose).

Results

During the study period, 181 cases were included and 143 (79%) of those were intentional. Compared to the patients in the unintentional group, patients in the intentional group were more often female (85% vs 45%, p < 0.001) and younger (median age 23.0 vs 43.5 years, p < 0.001), more frequently suffered from psychiatric comorbidities (93%, (including 49% with borderline personality disorder) vs 24%, p < 0.001), and paracetamol was more often taken as a single dose (80% vs 13%, p < 0.001). Although the median daily ingested dose was lower in the unintentional than in the intentional group (8.2 g vs 12.9 g, p < 0.001), patients in the unintentional group presented later (29% vs 84% within 24 h of ingestion, p < 0.001), included more cases of acute liver failure (nine (24%) vs six (4%), p < 0.001), and were more often hospitalised (24% vs 52% treated as outpatients, p=0.002). There were no significant differences between the groups regarding drug-induced liver injury (seven cases (5%) in the intentional and one (3%) in the unintentional group) or fatalities (one in each group).

Conclusions

The majority of presentations due to paracetamol poisoning were intentional, most commonly in female patients with borderline personality disorder. Patients with unintentional paracetamol intoxication had worse outcomes with respect to acute liver failure and hospitalisation. Future preventive measures should raise awareness of paracetamol toxicity in the general population and encourage particular attention and frequent follow-ups when prescribing paracetamol for vulnerable groups.

Increased acetaminophen related calls to Finnish PIC better reflect acetaminophen sales than serious poisonings

OBJECTIVE

Acetaminophen (APAP) or paracetamol is a commonly encountered medicine in poisonings. We studied the changes in APAP related calls to the Finnish poison information centre (FPIC), and serious intoxications, involving hepatotoxicity or death in 2001-2014. These data were compared with paracetamol sales in Finland.

METHODS

This is a retrospective analysis of the FPIC database calls, national cause of death registry, registries of liver transplantations and molecular adsorbent recycling system (MARS)-treated patients from Helsinki University Hospital together with the National Institute of Health and Welfare registry of patients hospitalized. Data on APAP sales were obtained from the Finnish Medicines Agency.

RESULTS

Between 2001 and 2014, the number of calls/year related to human APAP exposures to the FPIC increased from 227 to 1058. No change in the age distribution of enquiries was seen. Most calls involved minors: 58% (range 52-64%) for children under 6 years old, and 9% (range 6-14%) for children of 6-15 years. In Finland, APAP related fatalities have gradually increased from an average of 7/year (range 4-10) in 2000-2005 to an average of 11/year (range 6-17) in 2010-2013, whereas the number of liver transplantations remained low, average 0.6/year (range 0-2). For patients in need of MARS-treatment, a slight decrease was seen. Total APAP sales increased from 5.6 (47% prescription, 53% OTC) to 29.7 (81% prescription, 19% OTC). DDD/1000 inhabitants/day from 2001 to 2014 is recorded. Best linear relationship (R² = 0.97; p < .001) was observed between total FPIC calls and total sales of APAP in 2001-2014. Fatalities show a weaker relationship with sales (R² = 0.317; p = .045).

CONCLUSIONS

During the study period, we see an increase in FPIC exposure calls accompanied by an increase in APAP sales. Changes in the chosen indicators for serious poisonings show only a weak association. Despite an evident trend between sales and fatalities, the correlation with fatality remains weak due to the small number of fatalities.

Oral paracetamol (acetaminophen) for cancer pain

BACKGROUND

Pain is a common symptom with cancer, and 30% to 50% of all people with cancer will experience moderate to severe pain that can have a major negative impact on their quality of life. Non-opioid drugs are commonly used to treat mild to moderate cancer pain, and are recommended for this purpose in the WHO cancer pain treatment ladder, either alone or in combination with opioids.A previous Cochrane review that examined the evidence for nonsteroidal anti-inflammatory drugs (NSAIDs) or paracetamol, alone or combined with opioids, for cancer pain was withdrawn in 2015 because it was out of date; the date of the last search was 2005. This review, and another on NSAIDs, updates the evidence.

OBJECTIVES

To assess the efficacy of oral paracetamol (acetaminophen) for cancer pain in adults and children, and the adverse events reported during its use in clinical trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase from inception to March 2017, together with reference lists of retrieved papers and reviews, and two online study registries.

SELECTION CRITERIA

We included randomised, double-blind, studies of five days' duration or longer, comparing paracetamol alone with placebo, or paracetamol in combination with an opioid compared with the same dose of the opioid alone, for cancer pain of any intensity. Single-blind and open studies were also eligible for inclusion. The minimum study size was 25 participants per treatment arm at the initial randomisation.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality and potential bias. We did not carry out any pooled analyses. We assessed the quality of the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

Three studies in adults satisfied the inclusion criteria, lasting up to one week; 122 participants were randomised initially, and 95 completed treatment. We found no studies in children. One study was parallel-group, and two had a cross-over design. All used paracetamol as an add-on to established treatment with strong opioids (median daily morphine equivalent doses of 60 mg, 70 mg, and 225 mg, with some participants taking several hundred mg of oral morphine equivalents daily). Other non-paracetamol medication included non-steroidal anti-inflammatory drugs (NSAIDs), tricyclic antidepressants, or neuroleptics. All studies were at high risk of bias for incomplete outcome data and small size; none was unequivocally at low risk of bias.None of the studies reported any of our primary outcomes: participants with pain reduction of at least 50%, and at least 30%, from baseline; participants with pain no worse than mild at the end of the treatment period; participants with Patient Global Impression of Change (PGIC) of much improved or very much improved (or equivalent wording). What pain reports there were indicated no difference between paracetamol and placebo when added to another treatment. There was no convincing evidence of paracetamol being different from placebo with regards to quality of life, use of rescue medication, or participant satisfaction or preference. Measures of harm (serious adverse events, other adverse events, and withdrawal due to lack of efficacy) were inconsistently reported and provided no clear evidence of difference.Our GRADE assessment of evidence quality was very low for all outcomes, because studies were at high risk of bias from several sources.

AUTHORS' CONCLUSIONS

There is no high-quality evidence to support or refute the use of paracetamol alone or in combination with opioids for the first two steps of the three-step WHO cancer pain ladder. It is not clear whether any additional analgesic benefit of paracetamol could be detected in the available studies, in view of the doses of opioids used.

Increased availability of paracetamol in Sweden and incidence of paracetamol poisoning: using laboratory data to increase validity of a population-based registry study

PURPOSE

To estimate the incidence trend and outcome of paracetamol poisoning, in relation to increased availability of paracetamol from non-pharmacy outlets in 2009.

METHOD

Patients' serum paracetamol results over 14 years (2000-2013) from 20 (out of 21) regions in Sweden were linked to national registers of hospital care, cause of death, and prescriptions. Paracetamol poisonings were defined by serum paracetamol levels, hospital diagnoses, or cause of death. The change in incidence of poisonings following increased availability of paracetamol was analysed by using segmental regression of time series.

RESULTS

Of the 12 068 paracetamol poisonings, 85% were classified as intentional self-harm. Following increased availability from non-pharmacy outlets, there was a 40.5% increase in the incidence of paracetamol poisoning, from 11.5/100 000 in 2009 to 16.2/100 000 in 2013. Regression analyses indicated a change in the trend (p < 0.0001) but not an immediate jump in the incidence (p = 0.5991) following the increased availability. Adjusting for trends in hospital episodes for self-harm, suicides, and the sales volume of paracetamol did not influence the result. All-cause mortality at 30 days (3.2%) did not change over time.

CONCLUSIONS

The incidence of paracetamol poisoning in Sweden has increased since 2009, contrasting the decreased incidence in the period of 2007-2009. The change in trend was temporally associated with the introduction of availability of paracetamol from non-pharmacy outlets but did not appear to be related to sales volume of paracetamol or general trends in self-harm or suicides. © 2017 Commonwealth of Australia. Pharmacoepidemiology and Drug Safety © 2017 John Wiley & Sons, Ltd.

Paracetamol (acetaminophen) with or without codeine or dihydrocodeine for neuropathic pain in adults

BACKGROUND

Paracetamol, either alone or in combination with codeine or dihydrocodeine, is commonly used to treat chronic neuropathic pain. This review sought evidence for efficacy and harm from randomised double-blind studies.

OBJECTIVES

To assess the analgesic efficacy and adverse events of paracetamol with or without codeine or dihydrocodeine for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase from inception to July 2016, together with reference lists of retrieved papers and reviews, and two online study registries.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks' duration or longer, comparing paracetamol, alone or in combination with codeine or dihydrocodeine, with placebo or another active treatment in chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality and potential bias. We did not carry out any pooled analyses. We assessed the quality of the evidence using GRADE.

MAIN RESULTS

No study satisfied the inclusion criteria. Effects of interventions were not assessed as there were no included studies. We have only very low quality evidence and have no reliable indication of the likely effect.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or refute the suggestion that paracetamol alone, or in combination with codeine or dihydrocodeine, works in any neuropathic pain condition.

Recent Advances in Means Safety as a Suicide Prevention Strategy

Despite advances in theory and the development and implementation of evidence-based treatments, the United States suicide rate has been rising continuously for over a decade. Although this does not indicate that traditional treatment approaches should be abandoned, it does highlight the need to supplement such approaches with alternatives. One seemingly highly valuable option is means safety, defined as the reduced access to and/or increased safe storage of potentially lethal methods for suicide. This paper provides a review of the current literature on the prevalence of six methods for suicide and preventative efforts aimed to reduce suicide rates. The majority of means safety interventions seem promising given that these methods are common and highly lethal. However, cultural and practical barriers will need to be taken into consideration when implementing these plans. Overall, means safety efforts and preventative measures seem to be promising ways to reduce the national suicide rate if implemented.

The 100 most influential publications in paracetamol poisoning treatment: a bibliometric analysis of human studies

BACKGROUND

Analysis of the most influential publications within paracetamol poisoning treatment can be helpful in recognizing main and novel treatment issues within the field of toxicology. The current study was performed to recognize and describe the most highly cited articles related to paracetamol poisoning treatment.

METHODS

The 100 most highly cited articles in paracetamol poisoning treatment were identified from the Scopus database in November 2015. All eligible articles were read for basic information, including total number of citations, average citations per year, authors' names, journal name, impact factors, document types and countries of authors of publications.

RESULTS

The median number of citations was 75 (interquartile range 56-137). These publications were published between 1974 and 2013. The average number of years since publication was 17.6 years, and 45 of the publications were from the 2000s. A significant, modest positive correlation was found between years since publication and the number of citations among the top 100 cited articles (r = 0.316; p = 0.001). A total of 55 journals published these 100 most cited articles. Nine documents were published in Clinical Toxicology, whereas eight documents were published in Annals of Emergency Medicine. Citations per year since publication for the top 100 most-cited articles ranged from 1.5 to 42.6 and had a mean of 8.5 citations per year and a median of 5.9 with an interquartile range of 3.75-10.35. In relation to the origin of the research publications, they were from 8 countries. The USA had the largest number of articles, 47, followed by the UK and Australia with 38 and nine articles respectively.

CONCLUSIONS

This study is the first bibliometric assessment of the top 100 cited articles in toxicology literature. Interest in paracetamol poisoning as a serious clinical problem continues to grow. Research published in high-impact journals and from high income countries is most likely to be cited in published paracetamol research.

Paracetamol (acetaminophen) for acute treatment of episodic tension-type headache in adults

BACKGROUND

Tension-type headache (TTH) affects about 1 person in 5 worldwide. It is divided into infrequent episodic TTH (fewer than one headache per month), frequent episodic TTH (two to 14 headaches per month), and chronic TTH (15 headache days a month or more). Paracetamol (acetaminophen) is one of a number of analgesics suggested for acute treatment of headaches in frequent episodic TTH.

OBJECTIVES

To assess the efficacy and safety of paracetamol for the acute treatment of frequent episodic TTH in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (CRSO), MEDLINE, EMBASE, and the Oxford Pain Relief Database to October 2015, and also reference lists of relevant published studies and reviews. We sought unpublished studies by asking personal contacts and searching online clinical trial registers and manufacturers' websites.

SELECTION CRITERIA

We included randomised, double-blind, placebo-controlled studies (parallel-group or cross-over) using oral paracetamol for symptomatic relief of an acute episode of TTH. Studies had to be prospective, with participants aged 18 years or over, and include at least 10 participants per treatment arm.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion and extracted data. We used the numbers of participants achieving each outcome to calculate the risk ratio (RR) and number needed to treat for one additional beneficial outcome (NNT) or one additional harmful outcome (NNH) for oral paracetamol compared to placebo or an active intervention for a range of outcomes, predominantly those recommended by the International Headache Society (IHS).We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created 'Summary of findings' tables.

MAIN RESULTS

We included 23 studies, all of which enrolled adults with frequent episodic TTH. Twelve studies used the IHS diagnostic criteria or similar, six used the older classification of the Ad Hoc Committee, and five did not describe specific diagnostic criteria but generally excluded participants with migraines. Participants had moderate or severe pain at the start of treatment. While 8079 people with TTH participated in these studies, the numbers available for any analysis were lower than this because outcomes were inconsistently reported and because many participants received active comparators.None of the included studies were at low risk of bias across all domains considered, although for most studies and domains this was likely to be due to inadequate reporting rather than poor methods. We judged five studies to be at high risk of bias for incomplete outcome reporting, and seven due to small size.For the IHS preferred outcome of being pain free at two hours the NNT for paracetamol 1000 mg compared with placebo was 22 (95% confidence interval (CI) 15 to 40) in eight studies (5890 participants; high quality evidence), with no significant difference from placebo at one hour. The NNT was 10 (7.9 to 14) for pain-free or mild pain at two hours in five studies (5238 participants; high quality evidence). The use of rescue medication was lower with paracetamol 1000 mg than with placebo, with an NNTp to prevent an event of 7.8 (6.0 to 11) in six studies (1856 participants; moderate quality evidence). On limited data, the efficacy of paracetamol 500 mg to 650 mg was not superior to placebo, and paracetamol 1000 mg was not different from either ketoprofen 25 mg or ibuprofen 400 mg (low quality evidence).Adverse events were not different between paracetamol 1000 mg and placebo (RR 1.1 (0.94 to 1.3); 5605 participants; 11 studies; high quality evidence). Studies reported no serious adverse events.The quality of the evidence using GRADE comparing paracetamol 1000 mg with placebo was moderate to high. Where evidence was downgraded it was because a minority of studies reported the outcome. For comparisons of paracetamol 500 mg to 650 mg with placebo, and of paracetamol 1000 mg with active comparators, we downgraded the evidence to low quality or very low quality because of the small number of studies and events.

AUTHORS' CONCLUSIONS

Paracetamol 1000 mg provided a small benefit in terms of being pain free at two hours for people with frequent episodic TTH who have an acute headache of moderate or severe intensity.

Changing the Management of Paracetamol Poisoning

PURPOSE

The management of paracetamol poisoning was revolutionized after use of acetylcysteine in the 1970s. The protocol used, 3 weight-related infusions, requires almost 24 hours in hospital. It is associated with adverse events in treated patients, particularly anaphylactoid reactions and vomiting. Present treatment nomograms were based on a small series of untreated patients: only 5 of 22 (23%) and 6 of 25 (24%) between the 100 to 200 mg/L and 200 to 300 mg/L nomogram lines, respectively, developed liver injury (alanine transaminase >1000 IU/L). Many patients treated today are unlikely to be at actual risk for major hepatotoxicity. This article discusses the background to future prospects in this area.

METHODS

The history behind approaches to the use of acetylcysteine is presented briefly. The rationale for, and key findings of, a new 12-hour antidote regimen for paracetamol poisoning are detailed. Newer markers of hepatotoxicity, such as miR-122, HMGB1, and necrosis K18, which predict patients at risk more reliably and earlier than existing tests, are discussed.

FINDINGS

A 2-phase 12-hour acetylcysteine infusion protocol (100 mg/kg over 2 hours: 200 mg/kg over 10 hours) was studied in a formal factorial design against the traditional 3-phase 20.25-hour infusion protocol, with and without pretreatment with ondansetron or placebo. The 12-hour regimen was associated with very significant reductions in anaphylactoid reactions (odds ratio = 0.23; 95% CI, 0.12-0.43; P < 0.0001) and vomiting (odds ratio = 0.37; 95% CI, 0.18-0.79; P = .003) compared with the 20.25-hour infusion protocol. There were few withdrawals from the clinical trial, indicating the feasibility of conducting such studies in Europe.

IMPLICATIONS

Novel proteomic markers are better than existing standard tests (alanine transaminase and international normalized ratio) early in the course of paracetamol poisoning. Together with these new biomarkers of hepatotoxicity, a 12-hour acetylcysteine protocol offers clinicians and patients the possibility for better targeting of therapy, fewer adverse effects, a simpler dosing regimen, and shorter hospital stay.

Current management of acute liver failure

PURPOSE OF REVIEW

Acute liver failure (ALF) is a rare but life-threatening systemic disorder. Survival rates with or without emergency liver transplantation (ELT) are increasing. The benefit of ELT in some cases has been questioned and the potential for survival with medical management alone is changing our approach to the management of this disease.

RECENT FINDINGS

Survival rates for all causes of ALF are increasing because of improvements in the care of the critically ill patient. A multifactorial approach involving support of respiratory, circulatory and renal function together with measures to avoid intracranial hypertension, metabolic disequilibrium and sepsis are required. For those who do not respond to these measures or specific antidotes, the selection methods for those likely to benefit from transplantation remain imperfect and novel methods based on the prediction of hepatic regeneration are required. For patients with ALF secondary to acetaminophen overdose, some experts believe a randomized controlled trial is required to find those most likely to benefit from ELT.

SUMMARY

ALF remains a life-threatening condition with a high mortality rate requiring prompt support of multiorgan failure. Historical listing criteria for ELT are being questioned and improvement in medical management offers the option of continued improvements in transplant-free survival.