The accuracy of the diagnosis of suspected paracetamol (acetaminophen) hypersensitivity: results of a single-blinded trial

An Unusual IgE-Mediated Hypersensitivity: Two Case Reports of Paracetamol Allergy

Paracetamol is one of the most commonly used analgesic and antipyretic agents worldwide, attributed in part to its excellent safety profile when administered at recommended doses. Paracetamol allergy is not common, and the majority of the reactions are related to the pharmacological action of cyclooxygenase 1 inhibition. Selective and Immunoglobulin E (IgE)-mediated hypersensitivity reactions are rare. In this article, the authors report two cases of paracetamol allergy in which the mechanism of IgE-mediated hypersensitivity was demonstrated by positive skin tests and basophil activation tests. We highlight the relevance of identifying the mechanism underlying the reaction since patients with IgE-mediated paracetamol allergies will be able to tolerate non-steroidal anti-inflammatory drugs.

Behind the scene: Paracetamol hypersensitivity in children

BACKGROUND

Paracetamol, a non-steroidal anti-inflammatory drug, is commonly being used for fever and pain relief worldwide. The aim of this study was to evaluate children with a suspected history of paracetamol hypersensitivity.

METHODS

Sixty patients who were referred to our clinic in between January 2015 and December 2018 with a suspected history of paracetamol hypersensitivity were included. Reactions were classified according to the European Network for Drug Allergy (ENDA)/Global Allergy and Asthma European Network classification and European Academy of Allergy and Clinical Immunology (EAACI)/ENDA Position Paper. Diagnoses were confirmed by skin tests and oral challenge tests (OCTs). In those with verified paracetamol hypersensitivity, an OCT with a strong COX-1 inhibitor was performed to classify the type of the reaction to refer as either selective or cross-intolerance hypersensitivity. A subsequent OCT with a selective COX-2 inhibitor was performed in those cross-intolerant patients to find out a safe alternative drug.

RESULTS

Sixty OCTs with paracetamol were performed to patients with a median age of 8.5 years, and hypersensitivity to paracetamol was verified in 8 patients. Four children were classified as selective responders, and 3 were classified as cross-intolerant after OCT with a COX-1 inhibitor. Overall, skin test positivity for paracetamol was detected in only one patient, in whom OCT with paracetamol was negative. In all 3 cross-intolerant patients, a safe alternative non-steroidal anti-inflammatory drug was identified after an OCT with a selective COX-2 inhibitor.

CONCLUSION

OCT stands as the gold-standard procedure in verifying the diagnosis of patients with paracetamol-induced drug hypersensitivity, as well as, in defining the type of reactions and finding out safe alternative drugs.

Stevens-Johnson syndrome in a patient with rheumatoid arthritis during long-term etanercept therapy

BACKGROUND

Etanercept and other anti-TNF-alpha agents have been indicated as a therapeutic option in severe drug reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis. Etanercept has been shown to quickly reduce the detachment of the epidermis and shorten healing time. Cases of etanercept-induced severe adverse drug reactions were also described.

MAIN OBSERVATIONS

A 27-year-old woman with a 4-year history of etanercept and sulfasalazine treatment for rheumatoid arthritis was admitted with Stevens-Johnson syndrome. The patient received one dose of an OTC drug containing acetaminophen, phenylephrine and pheniramine two days prior to developing fist mucocutaneous symptoms. The most probable causative agent was paracetamol. Throughout the successful routine therapy of Stevens-Johnson syndrome etanercept therapy was continued. Sulfosalazin administration was stopped and administered again after recovery with no recurrence of the skin and mucosal symptoms.

CONCLUSIONS

This case indicates that there is no justification for discontinuation of long-term anti-TNF-alpha treatment in patients who develop Stevens- Johnson syndrome / toxic epidermal necrolysis.

Paracetamol induced Steven-Johnson syndrome: A rare case report

In the contemporary era, use of drugs is the dominant paradigm of health care. The most quotidian drug used for fever and pain is paracetamol. Although adverse reactions to paracetamol in India are rare, at times they can cause life-threatening situations. Stevens-Johnson syndrome (SJS) is one such potentially lethal adverse drug reaction. The most reported cases of analgesic-induced SJS were due to oxicams or propionic acid derivatives. There are very few detailed reports of SJS due to the use of paracetamol. We report a case of SJS, which occurred due to the use of paracetamol. The clinical features of this condition and multidisciplinary management of the patient are described in brief.

Report of an adverse incident in a randomized clinical trial

This is a case report of a child who experienced a possible adverse reaction to paracetamol, in a randomized clinical trial comparing paracetamol with ibuprofen for control of orthodontic pain. Through this case report we highlight the importance of formulating a protocol for management of adverse events when designing a randomized clinical trial.

Anaphylaxis to Paracetamol in a Twelve-Year-Old Girl

Paracetamol (acetaminophen) is widely used and considered safe, since adverse reactions to this drug in therapeutic doses are rare, especially in children.^1,2 Only a few cases worldwide of anaphylaxis to paracetamol in children have previously been described.^2-11 Anaphylaxis is defined as a life-threatening reaction resulting from mast cell derived mediator release.¹² This report illustrates a case of anaphylaxis to oral paracetamol confirmed by an oral provocation test and an increase in serum tryptase level.

Rapid onset of Stevens-Johnson syndrome and toxic epidermal necrolysis after ingestion of acetaminophen

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare, but life-threatening, severe cutaneous adverse reactions most frequently caused by exposure to drugs. Several reports have associated the use of acetaminophen with the risk of SJS or TEN. A typical interval from the beginning of drug therapy to the onset of an adverse reaction is 1-3 weeks. A 43-year-old woman and a 60-year-old man developed skin lesions within 3 days after administration of acetaminophen for a 3-day period. Rapid identification of the symptoms of SJS and TEN caused by ingestion of acetaminophen enabled prompt withdrawal of the culprit drug. After administration of intravenous immunoglobulin G, both patients recovered fully and were discharged. These two cases of rapidly developed SJS/TEN after ingestion of acetaminophen highlight the possibility that these complications can develop within only a few days following ingestion of over-the-counter medications such as acetaminophen.

Optimising the management of fever and pain in children

Fever and pain in children, especially associated with infections, such as otitis media, are very common. In paediatric populations, ibuprofen and paracetamol (acetaminophen) are both commonly used over-the-counter medicines for the management of fever or mild-to-moderate pain associated with sore throat, otitis media, toothache, earache and headache. Widespread use of ibuprofen and paracetamol has shown that they are both effective and generally well tolerated in the reduction in paediatric fever and pain. However, ibuprofen has the advantage of less frequent dosing (every 6-8 h vs. every 4 h for paracetamol) and its longer duration of action makes it a suitable alternative to paracetamol. In comparative trials, ibuprofen has been shown to be at least as effective as paracetamol as an analgesic and more effective as an antipyretic. The safety profile of ibuprofen is comparable to that of paracetamol if both drugs are used appropriately with the correct dosing regimens. However, in the overdose situation, the toxicity of paracetamol is not only reached much earlier, but is also more severe and more difficult to manage as compared with an overdose of ibuprofen. There is clearly a need for advanced studies to investigate the safety of these medications in paediatric populations of different ages and especially during prolonged use. Finally, the recently reported association between frequency and severity of asthma and paracetamol use needs urgent additional investigations.

Severe drug-induced anaphylaxis: analysis of 333 cases recorded by the Allergy Vigilance Network from 2002 to 2010

BACKGROUND

A few series of well-documented cases of severe drug-induced anaphylaxis (SDA) are available.

METHODS

Cases collected by the Allergy Vigilance Network from 2002 to 2010 were analyzed for clinical signs, causative drugs, and efficacy of a stepwise approach to diagnosis, using skin tests, laboratory tests, and oral challenges.

RESULTS

Three hundred and thirty-three cases concerned 300 adults (90.1%) and 33 children (9.9%): 206 females (61.9%) and 127 males (38.1%). Mean age was 42.7 ± 18 years. Anaphylactic shock (76.6%), severe systemic reactions (10.5%), acute laryngeal edema (9%), severe bronchospasm (2.1%), and six fatal cases (1.8%) were recorded. There were 270 cases (81.1%) of ambulatory anaphylaxis. Sixty-three cases (18.9%) occurred during anesthesia. Hospitalization was required in 94.8% of cases. 23.7% of patients were admitted to an intensive care unit. Epinephrine was used in 57.9% of cases. Eighty-four drugs were incriminated: antibiotics (49.6%), muscle relaxants, latex and anesthetics (15%), nonsteroidal anti-inflammatory drugs (10.2%), acetaminophen (3.9%), iodinated or magnetic resonance imaging contrast media (4.2%), immunotherapy and vaccines (3.9%), and other drugs (13%). Among antibiotics, amoxicillin (97 cases), other penicillins (four cases), cephalosporins (41 cases), quinolones (15 cases), and pristinamycin (seven cases) were the most common. The diagnosis of drug hypersensitivity was obtained by skin tests in 72.9%, laboratory tests only in 2.4% of cases, and oral challenges (OCs) only in 3.9% of cases.

CONCLUSIONS

Three hundred and thirty-three case reports provided data on drugs involved in severe anaphylaxis. The efficacy of skin tests and poor use of laboratory tests are underlined. Further progress may depend on OCs.

[Allergic and non-allergic hypersensitivity to non-opioid analgesics, antipyretics and nonsteroidal anti-inflammatory drugs in children: epidemiology, clinical aspects, pathophysiology, diagnosis and prevention]

Non-opioid analgesics, antipyretics and nonsteroidal anti-inflammatory drugs are widely used, but suspected allergic reactions to these drugs are rare, especially in children. Most frequent reactions are cutaneous (urticaria, angioedema) and respiratory (rhinitis, asthma). Other reactions (anaphylaxis, potentially harmful toxidermias) are rare. In a few patients, reactions may result from a specific (allergic) hypersensitivity, with positive responses in prick and intradermal tests (anaphylaxis, immediate urticaria and/or angioedema) and in intradermal and patch tests (non-immediate reactions). However, most reactions result from a non-specific (non-allergic) hypersensitivity (intolerance), with a frequent cross-reactivity between the various families of analgesics, antipyretics and nonsteroidal anti-inflammatory drugs, including paracetamol. Based on a convincing clinical history and/or positive responses in challenge tests, intolerance to non-opioid analgesics, antipyretics and nonsteroidal anti-inflammatory drugs has been diagnosed in 13 to 50% of the patients with allergic-like reactions to these drugs. Risk factors are a personal atopy and age. Prevention is based on administration of other (families of) analgesics, antipyretics and nonsteroidal anti-inflammatory drugs in patients with allergic hypersensitivity to these drugs. In patients with non-allergic hypersensitivity, prevention is based on administration of drugs with a low cyclo-oxygenase-1 inhibitory activity (if tolerated). Desensitization is efficient in patients with respiratory reactions, but does not work in patients with mucocutaneous reactions and anaphylaxis.

Paracetamol in therapeutic dosages and acute liver injury: causality assessment in a prospective case series

Background

Acute liver injury (ALI) induced by paracetamol overdose is a well known cause of emergency hospital admission and death. However, there is debate regarding the risk of ALI after therapeutic dosages of the drug.

The aim is to describe the characteristics of patients admitted to hospital with jaundice who had previous exposure to therapeutic doses of paracetamol. An assessment of the causality role of paracetamol was performed in each case.

Methods

Based on the evaluation of prospectively gathered cases of ALI with detailed clinical information, thirty-two cases of ALI in non-alcoholic patients exposed to therapeutic doses of paracetamol were identified. Two authors assessed all drug exposures by using the CIOMS/RUCAM scale. Each case was classified into one of five categories based on the causality score for paracetamol.

Results

In four cases the role of paracetamol was judged to be unrelated, in two unlikely, and these were excluded from evaluation. In seven of the remaining 26 cases, the RUCAM score associated with paracetamol was higher than that associated with other concomitant medications. The estimated incidence of ALI related to the use of paracetamol in therapeutic dosages was 0.4 per million inhabitants older than 15 years of age and per year (99%CI, 0.2-0.8) and of 10 per million paracetamol users-year (95% CI 4.3-19.4).

Conclusions

Our results indicate that paracetamol in therapeutic dosages may be considered in the causality assessment in non-alcoholic patients with liver injury, even if the estimated incidence of ALI related to paracetamol appears to be low.

Systematic review and meta-analysis of the clinical safety and tolerability of ibuprofen compared with paracetamol in paediatric pain and fever

OBJECTIVE

The main aim of this review was to compare the tolerability and safety between ibuprofen and paracetamol when used as anti-pyretic and analgesic agents in children up to 18 years of age.

METHODS

MEDLINE (1950 to November 2008), EMBASE (1980 to November 2008), The Cochrane Library (2007, Issue 3), ACP Journal Club (1991 to November 2007) and Pascal (1987 to November 2007) were searched for randomised controlled trails (RCTs) (comparing ibuprofen and/or paracetamol with placebo), controlled observational studies and large case series comprised more than 1000 participants.

MAIN OUTCOME MEASURES

Adverse events (AEs) requiring discontinuation of medication; systemic reactions related to ibuprofen or paracetamol; serious AEs that are fatal, life-threatening or require hospitalisation; and serious AEs not requiring hospitalisation.

RESULTS

A total of 24 RCTs examined either ibuprofen and/or paracetamol versus placebo for AE data. Twelve other studies meeting our criteria were also included for AE data. Meta-analysis of systemic reactions demonstrated that tolerability and safety of ibuprofen was similar to placebo, as was paracetamol: ibuprofen versus placebo relative risk (RR) 1.39 (95% CI: 0.92, 2.10); paracetamol versus placebo RR 1.57 (95% CI 0.74, 3.33). A total of 2937 systemic AEs occurred in 21,305 patients taking ibuprofen compared with 1,466 systemic AEs in 11,164 patients taking paracetamol: RR 1.03 (95% CI 0.98, 1.10). There was no significant difference between the two groups. Narrative analysis of AE data identified conflicting evidence regarding hepatic injury with paracetamol and group A streptococcal infections with ibuprofen or paracetamol treatment.

CONCLUSIONS

Ibuprofen, paracetamol and placebo have similar tolerability and safety profiles in terms of gastrointestinal symptoms, asthma and renal adverse effects. While the study data investigated here may not reflect over-the-counter use, these results are still relevant in the context of any safety concerns relating to general ibuprofen or paracetamol treatment in children.

Negative predictive value of drug skin tests in investigating cutaneous adverse drug reactions

BACKGROUND

Drug skin tests are useful in aetiological analyses of cutaneous adverse drug reactions to determine if the drug can be rechallenged, or to avoid a cross-reaction with a substitute drug.

OBJECTIVES

To evaluate the negative predictive value of drug skin tests.

METHODS

We retrospectively analysed the files of patients referred for drug reactions. We have enrolled those having strictly determined drug reactions with clinical features, delayed onset after drug intake, drug causality assessment, and negative drug skin tests followed by drug administration. Oral provocation tests or substitution tests with a drug of the same class as that suspected of causing the drug reactions were performed.

RESULTS

From 1957 files analysed, 200 patients were included. After 403 patch tests, 403 prick tests and 304 intradermal tests, which were all negative, 260 oral provocation tests and 143 substitution tests were done; 307 different drugs were rechallenged. There were 42 positive drug re-administrations in 27 oral provocation tests and 15 substitution tests. The negative predictive value of our drug skin tests was 89.6%. The negative predictive value for beta-lactams was 87% for oral provocation tests and 96% for substitution tests, and for corticosteroids it was 100% and 74%, respectively.

CONCLUSIONS

Negative drug skin tests do not eliminate the responsibility of a drug in drug reactions, and must be followed by drug re-administration under hospital surveillance.

Drug allergy claims in children: from self-reporting to confirmed diagnosis

BACKGROUND

Poorly documented self-reported drug allergy (DAll) is a frequent problem in daily clinical practice and has a considerable impact on prescription choices. The diagnostic work-up of drug hypersensitivity (DHs) allows a better classification of the reactions and provides patients with more reliable information and recommendations for future treatments.

OBJECTIVE

To assess the prevalence of self-reported adverse drug reactions (ADRs) and DAll in a paediatric population and to investigate children reporting suspected DAll in order to achieve a firm diagnosis.

DESIGN

The first phase was based on a cross-sectional survey assessing the life occurrence of ADRs and self-reported DAll carried out at the outpatient clinic of a paediatric hospital. The second phase was based on the diagnostic work-up in children with parent-reported DAll, including detailed anamnesis and in vitro and in vivo investigations (skin and provocation tests). Participants One thousand four hundred and twenty-six parents responded to the initial survey. Sixty of the 67 patients with reported DAll were evaluated at the allergy clinic.

RESULTS

The prevalences of self-reported ADRs and DAll were 10.2% and 6.0%, respectively. Most of the suspected allergic reactions were non-immediate cutaneous events attributable to beta-lactam antibiotics and occurred in very young children. Thirty-nine of the 60 patients consulting for evaluation had a plausible clinical history and were recommended further investigation. DHs was diagnosed in three children only, based on positive responses in skin (n=1) and oral provocation (n=2) tests.

CONCLUSION

ADRs are frequently reported in children, and many children are classified as having a DAll. After complete evaluation, only a few of these reactions can be attributed to DHs and DAll. Most of the patients (94% in this study) could actually tolerate the initially suspected drug.

Scandinavian Clinical Practice Guidelines on the diagnosis, management and follow-up of anaphylaxis during anaesthesia

The present approach to the diagnosis, management and follow-up of anaphylaxis during anaesthesia varies in the Scandinavian countries. The main purpose of these Scandinavian Clinical Practice Guidelines is to increase the awareness about anaphylaxis during anaesthesia amongst anaesthesiologists. It is hoped that increased focus on the subject will lead to prompt diagnosis, rapid and correct treatment, and standardised management of patients with anaphylactic reactions during anaesthesia across Scandinavia. The recommendations are based on the best available evidence in the literature, which, owing to the rare and unforeseeable nature of anaphylaxis, mainly includes case series and expert opinion (grade of evidence IV and V). These guidelines include an overview of the epidemiology of anaphylactic reactions during anaesthesia. A treatment algorithm is suggested, with emphasis on the incremental titration of adrenaline (epinephrine) and fluid therapy as first-line treatment. Recommendations for primary and secondary follow-up are given, bearing in mind that there are variations in geography and resources in the different countries. A list of National Centres from which anaesthesiologists can seek advice concerning follow-up procedures is provided. In addition, an algorithm is included with advice on how to manage patients with previous suspected anaphylaxis during anaesthesia. Lastly, Appendix 2 provides an overview of the incidence, mechanisms and possibilities for follow-up for some common drug groups.

Hypersensitivity reactions to paracetamol in children: a study of 25 cases

BACKGROUND

Allergic-like reactions to paracetamol (acetaminophen) are rare. Paracetamol allergic and nonallergic hypersensitivity (HS) has been diagnosed in a few patients with skin and/or respiratory symptoms, immediate and accelerated urticaria, and angioedema especially. Most patients with HS to paracetamol were also hypersensitive to anti-inflammatory drugs (i.e. acetylsalicylic acid, ASA), suggesting that their reactions resulted from a nonallergic HS. However, anaphylactic reactions, and potentially harmful toxidermias, such as acute generalized exanthematic pustulosis and toxic epidermal necrolysis, have been related to specific paracetamol allergic HS, with tolerance to anti-inflammatory drugs.

PATIENTS AND METHODS

We report the results of a study performed in 25 children with suspected paracetamol HS. Diagnosis of paracetamol HS was based on a suggestive clinical history and a positive response in an oral challenge (OC) test.

RESULTS

Paracetamol HS was diagnosed in only one child (4%). In this child, a positive response to an OC with ASA diagnosed HS to anti-inflammatory drugs.

CONCLUSIONS

Our results in children agree with those of the literature, showing that paracetamol HS is rare, and is associated with HS to anti-inflammatory drugs in most patients.

Tolerability of Paracetamol

The excellent tolerability of therapeutic doses of paracetamol (acetaminophen) is a major factor in the very wide use of the drug. The major problem in the use of paracetamol is its hepatotoxicity after an overdose. Hepatotoxicity has also been reported after therapeutic doses, but critical analysis indicates that most patients with alleged toxicity from therapeutic doses have taken overdoses. Importantly, prospective studies indicate that therapeutic doses of paracetamol are an unlikely cause of hepatotoxicity in patients who ingest moderate to large amounts of alcohol. Controlled clinical trials have found that paracetamol is very well tolerated by the gastrointestinal tract. While variable results have been found in case control studies, most studies have shown no change or a small increase in the relative risk of perforations, ulcer or bleeding in the upper gastrointestinal tract. However, associations between the use of paracetamol and gastrointestinal toxicity, as well as with chronic renal disease and asthma, are very likely to reflect biases in some case control studies. In particular, such biases may be caused by the perceived high tolerability of paracetamol in these diseases. The consequent use of paracetamol in these diseases states then leads to an apparent association between paracetamol and the disease. Despite metabolism of paracetamol to reactive compounds, hypersensitivity reactions are rare, although urticaria occurs in occasional patients. Paracetamol appears to be well tolerated during pregnancy although prospective studies are required.

Codeine phosphate-induced hypersensitivity syndrome

OBJECTIVE

To report a case of drug-induced hypersensitivity syndrome related to codeine phosphate.

CASE SUMMARY

A 19-year-old Japanese man was prescribed codeine phosphate 10 mg 3 times daily and several other drugs for cold symptoms. About 20 days later, an erythematous, maculopapular rash appeared and progressed to erythroderma; a spiking fever also developed. He had splenomegaly and generalized lymphadenopathy on admission. Laboratory examinations showed atypical lymphocytosis, eosinophilia, and increased liver enzyme values. The platelet count slowly decreased after admission. The increased numbers of megakaryocytes in bone marrow and platelet-associated immunoglobulin (Ig) G antibodies in serum were compatible with a diagnosis of immune thrombocytopenic purpura. A significant increase in IgG antibodies to human herpesvirus 6 (HHV6) and transient viremia were helpful in diagnosing hypersensitivity syndrome. The results of patch tests were positive for codeine phosphate. An objective causality assessment revealed that an adverse drug event was probable.

DISCUSSION

Codeine is an opioid analgesic. Severe adverse cutaneous reactions rarely occur. As of March 3, 2004, our case is, to our knowledge, the first report of hypersensitivity syndrome attributed to codeine phosphate. Drug-induced hypersensitivity syndrome is an acute, potentially life-threatening, idiosyncratic adverse reaction caused mainly by aromatic anticonvulsants. It is characterized by the triad of fever, skin rash, and internal organ involvement. Reactivation of HHV6 is involved in the pathogenesis of this syndrome and may have also caused the immune thrombocytopenic purpura in our patient.

CONCLUSIONS

Codeine phosphate may rarely be associated with hypersensitivity syndrome. Clinicians should be aware that the potentially fatal syndrome can be caused by various drugs.

Aspirin sensitivity and urticaria

The relationship of aspirin sensitivity to urticaria is complex. Aspirin sensitivity can cause acute urticaria in some individuals, aggravate pre-existing chronic urticaria in others or, rarely, act as a cofactor with food or exercise to provoke anaphylaxis. Individuals who react with urticaria appear to come from a different population to those who react with asthma, although there is some overlap. Aspirin-sensitive chronic urticaria patients may also react adversely to some food additives. The pharmacological mechanisms of aspirin-sensitive urticaria are not fully understood but probably involve diversion of arachidonic acid metabolism from prostaglandin to cysteinyl leukotriene formation leading to direct effects on blood vessels and delayed mast cell degranulation with release of histamine. Cross-reactivity amongst all nonsteroidal drugs is common in aspirin-aggravated chronic urticaria but appears not to occur with selective cyclo-oxygenase 2 inhibitors.