Pholcodine stimulates a dramatic increase of IgE in IgE-sensitized individuals. A pilot study

Pholcodine and allergy to neuromuscular blocking agents: where are we and how did we get here?

Despite the purported link between pholcodine and neuromuscular blocking agent allergy, screening for prior pholcodine use offers no practical benefit to patients, and anaesthetists should continue to use a neuromuscular blocking agent where this is clinically indicated.

Neuromuscular blocking agent re-exposure in a retrospective cohort with neuromuscular blocking agent-associated anaphylaxis

BACKGROUND

Neuromuscular blocking agents (NMBAs) are one of the most common causes of perioperative anaphylaxis. Although skin test positivity may help identify reactive NMBAs, it is unclear whether skin test negativity can guarantee the safety of systemically administered NMBAs.

OBJECTIVE

This study aimed to evaluate the real-world safety of alternative NMBAs screened using skin tests in patients with suspected NMBA-induced anaphylaxis.

METHODS

A retrospective cohort of suspected NMBA-induced anaphylaxis were recruited among patients at Seoul National University Hospital from June 2009 to May 2021, and their characteristics and outcomes were assessed.

RESULTS

A total of 47 cases (0.017%) of suspected anaphylaxis occurred in 282,707 patients who received NMBAs. Cardiovascular manifestations were observed in 95.7%, whereas cutaneous findings were observed in 59.6%. Whereas 83% had a history of undergoing general anesthesia, 17% had no history of NMBA use. In skin tests, the overall positivity to any NMBA was 94.6% (81.1% to culprit NMBAs) and the cross-reactivity was 75.7%, which is related to the chemical structural similarity among NMBAs; the cross-reactivity and chemical structure similarity of rocuronium were 85.3% and 0.814, respectively, with vecuronium; this is in contrast to 50% and 0.015 with cisatracurium and 12.5% and 0.208 with succinylcholine. There were 15 patients who underwent subsequent surgery with a skin test-negative NMBA; whereas 80.0% (12/15) safely completed surgery, 20.0% (3/15) experienced hypotension.

CONCLUSION

Similarities in chemical structure may contribute to the cross-reactivity of NMBAs in skin tests. Despite the high negative predictability of skin tests for suspected NMBA-induced anaphylaxis, the potential risk of recurrent anaphylaxis has not been eliminated.

Pholcodine, perioperative anaphylaxis, and the European Medicines Agency: finally the decision to remove pholcodine from the market in the European Union

Two recent case-control studies, both published in the British Journal of Anaesthesia, have shown that intake of pholcodine-containing cough medicines during the year preceding general anaesthesia significantly increased the risk of anaphylaxis caused by neuromuscular blocking agents. Both a French multicentre study and a single-centre study from Western Australia offer strong support to the pholcodine hypothesis for IgE-sensitisation to neuromuscular blocking agents. The European Medicines Agency, criticised for not taking preventive action at its first assessment of pholcodine in 2011, finally recommended a stop to sales of all pholcodine-containing medicines throughout the EU on December 1, 2022. Time will tell whether this reduces the incidence of perioperative anaphylaxis in the EU, as in Scandinavia.

Allergenic and Mas-Related G Protein-Coupled Receptor X2-Activating Properties of Drugs: Resolving the Two

Since the seminal description implicating occupation of the Mas-related G protein-coupled receptor X2 (MRGPRX2) in mast cell (MC) degranulation by drugs, many investigations have been undertaken into this potential new endotype of immediate drug hypersensitivity reaction. However, current evidence for this mechanism predominantly comes from (mutant) animal models or in vitro studies, and irrefutable clinical evidence in humans is still missing. Moreover, translation of these preclinical findings into clinical relevance in humans is difficult and should be critically interpreted. Starting from our clinical priorities and experience with flow-assisted functional analyses of basophils and cultured human MCs, the objectives of this rostrum are to identify some of these difficulties, emphasize the obstacles that might hamper translation from preclinical observations into the clinics, and highlight differences between IgE- and MRPGRX2-mediated reactions. Inevitably, as with any subject still beset by many questions, alternative interpretations, hypotheses, or explanations expressed here may not find universal acceptance. Nevertheless, we believe that for the time being, many questions remain unanswered. Finally, a theoretical mechanistic algorithm is proposed that might advance discrimination between MC degranulation from MRGPRX2 activation and cross-linking of membrane-bound drug-reactive IgE antibodies.

Effect of Meperidine on Equine Blood Histamine, Tryptase, and Immunoglobulin-E Concentrations

Objectives: To evaluate changes in immunological parameters following subcutaneous (SC) and intramuscular (IM) administration of meperidine in horses through quantitative analysis of plasma tryptase, histamine, and IgE levels.

Methods: Six adult horses were enrolled in a prospective randomized crossover design. Horses were administered one treatment per day, with a seven day washout period: (a) meperidine 1 mg/kg IM, saline 6 mL SC; (b) saline 6 mL IM, meperidine 1 mg/kg SC; (c) saline 6 mL SC, saline 6 mL IM. Blood samples were obtained for plasmatic histamine (baseline, 5, 10, 15, 30, and 60 min) via LC-MS/MS and plasmatic tryptase (baseline, 15, 30, 60, 120, and 240 min) quantification with enzyme-linked immunoabsorbent assays. Serum immunoglobulin E (IgE) concentrations prior to any meperidine treatment and 7–14 days following the first meperidine treatment were evaluated with enzyme-linked immunoabsorbent assays. Histamine and tryptase concentrations were evaluated with a mixed-effect analysis of variance. The levels of IgE at baseline (before the administration of the first dose of meperidine) were compared with the IgE values at 60 min following the second meperidine administration with the Paired t test. Biopsies of localized injection site reactions from subcutaneous meperidine administration were collected from two horses.

Results: No statistically significant elevations from baseline in histamine (p = 0.595), tryptase (p = 0.836), or IgE (p = 0.844) were found in any of the horses in this study. There were no differences between treatment groups. Administration of SC meperidine caused a localized vasculitis and thrombosis with regional edema and hemorrhage.

Conclusion: No evidence of anaphylactoid or anaphylactic type reactions occurred following IM or SC meperidine administration.

A Well-Trained Team During Anaphylactic Shock After Rocuronium in a Patient With Aortic Stenosis: A Case Report

A 66-year-old patient with aortic stenosis was scheduled for an aortic valve replacement and coronary artery bypass surgery. Anesthesia was induced by intravenous injection of midazolam, fentanyl, and propofol. After administration of rocuronium, he developed anaphylactic shock, which was diagnosed by clinical signs, vital parameters, and unresponsiveness to the usual vasopressors. After 30 min of cardiopulmonary resuscitation, the patient survived without any neurological deficits. This case is a reminder that early recognition and treatment of intraoperative hypersensitivity reactions are imperative. Anesthetists should also receive simulation training to achieve an adequate experience in a safe environment. With a well-trained team, it is possible to save the life of patients with aortic stenosis.

Rocuronium anaphylaxis in a 7-year-old boy during the induction of anesthesia

We report a case of rocuronium-induced anaphylaxis in a previously healthy 7-year-old boy. The first presenting sign of anaphylaxis was bronchospasm, appearing 11 min after he received intravenous doses of rocuronium (1 mg/kg) (Eslax^®, MSD Co. Ltd., Tokyo, Japan), propofol (2 mg/kg), and cefazolin sodium (25 mg/kg). After the administration of adrenalin and ephedrine hydrochloride, bronchospasm resolved, and the vital signs became stable. Percutaneous pinning of his left humeral supracondylar fracture was performed without problems. The next day, he was successfully liberated from the ventilator support and discharged on the fifth hospital day. On the 76th postoperative day, we performed intradermal tests of rocuronium, propofol, and cefazolin. It showed that diluted rocuronium alone induced 14 mm of flare and 8 mm of wheal within 5 min, both of which disappeared within 15 min after the intradermal injection. The reaction was too quick to mention the possible contribution of rocuronium-specific IgE. His rapid reaction at the rocuronium skin test and anaphylactic reaction upon the first exposure to this drug may highlight the association of rocuronium anaphylaxis with IgE independent mast cell stimulation through mas-related G-protein coupled receptor X2 (MRGPRX2 receptor).

Neuromuscular blocking agents induced anaphylaxis: Results and trends of a French pharmacovigilance survey from 2000 to 2012

BACKGROUND

Perioperative anaphylaxis mainly involves neuromuscular blocking agents (NMBAs) with an IgE-mediated mechanism. In France, this life-threatening condition is reported by anesthetists and allergologists, and two safety alerts concerning suxamethonium were raised in 2011 and 2012. This led to start a national survey over the 2000-2012 period which objectives were to provide a descriptive analysis, to estimate incidence rates, and to analyze the trends over this period.

METHODS

The French pharmacovigilance database was retrospectively queried for all the available NMBAs. Anaphylaxis cases with elevated tryptase and positive skin tests were qualified as "confirmed cases." Subgroup analysis compared atracurium and cisatracurium vs suxamethonium and rocuronium.

RESULTS

A total of 680 confirmed cases and 944 nonconfirmed cases were identified. Suxamethonium was the most implied NMBA (64%). Incidence rates (according to sales data) of suxamethonium and rocuronium were, respectively, 10- and 13-folds higher than those of the others NMBAs, regardless the confirmed/nonconfirmed status. Cisatracurium incidence rates remained stable over the period, while suxamethonium and atracurium increased and rocuronium first decreased but re-increased after 2006. Male patients were more frequent in the subgroup "atracurium-cisatracurium" (P = .019), whereas obesity and emergency setting were more frequent in the subgroup "rocuronium-suxamethonium." Shared characteristics were the poorly documented previous exposure to NMBA(s) and an insufficient adherence of patients to perform skin tests, showing the need to improve this procedure.

CONCLUSION

Suxamethonium and rocuronium are markedly more involved in perioperative anaphylaxis than the other available NMBAs. Patients should be more informed about their perioperative anaphylaxis and its consequences.

In Vitro Diagnosis of Immediate Drug Hypersensitivity Anno 2017: Potentials and Limitations

Background

For most physicians, quantification of drug-specific immunoglobulin E (drug-sIgE) antibodies constitutes the primary in vitro measure to document immediate drug hypersensitivity reactions (IDHR). Unfortunately, this is often insufficient to correctly identify patients with IgE-mediated IDHR and impossible for non-IgE-mediated IDHR that result from alternative routes of basophil and mast cell activation. In these difficult cases, diagnosis might benefit from cellular tests such as basophil activation tests (BAT).

Aim

The aim was to review the potential and limitations of quantification of sIgE and BAT in diagnosing IDHR. The utility of quantification of serum tryptase is discussed.

Methods

A literature search was conducted using the key words allergy, basophil activation, CD63, CD203c, diagnosis, drugs, hypersensitivity, flow cytometry, specific IgE antibodies; this was complemented by the authors’ own experience.

Results

The drugs that have been most studied with both techniques are β-lactam antibiotics and curarizing neuromuscular blocking agents (NMBA). For sIgE morphine, data are available on the value of this test as a biomarker for sensitization to substituted ammonium structures that constitute the major epitope of NMBA, especially rocuronium and suxamethonium. For the BAT, there are also data on non-steroidal anti-inflammatory drugs (NSAIDs) and iodinated radiocontrast media. For β-lactam antibiotics, sensitivity and specificity of sIgE varies between 0 and 85% and 52 and 100%, respectively. For NMBA, sensitivity and specificity varies between 38.5 and 92% and 85.7 and 100%, respectively. Specific IgE to morphine should not be used in isolation to diagnose IDHR to NMBA nor opiates. For the BAT, sensitivity generally varies between 50 and 60%, whereas specificity attains 80%, except for quinolones and NSAIDs.

Conclusions

Although drug-sIgE assays and BAT can provide useful information in the diagnosis of IDHR, their predictive value is not absolute. Large-scale collaborative studies are mandatory to harmonize and optimize test protocols and to establish drug-specific decision thresholds.

Reclassifying Anaphylaxis to Neuromuscular Blocking Agents Based on the Presumed Patho-Mechanism: IgE-Mediated, Pharmacological Adverse Reaction or "Innate Hypersensitivity"?

Approximately 60% of perioperative anaphylactic reactions are thought to be immunoglobulin IgE mediated, whereas 40% are thought to be non-IgE mediated hypersensitivity reactions (both considered non-dose-related type B adverse drug reactions). In both cases, symptoms are elicited by mast cell degranulation. Also, pharmacological reactions to drugs (type A, dose-related) may sometimes mimic symptoms triggered by mast cell degranulation. In case of hypotension, bronchospasm, or urticarial rash due to mast cell degranulation, identification of the responsible mechanism is complicated. However, determination of the type of the underlying adverse drug reaction is of paramount interest for the decision of whether the culprit drug may be re-administered. Neuromuscular blocking agents (NMBA) are among the most frequent cause of perioperative anaphylaxis. Recently, it has been shown that NMBA may activate mast cells independently from IgE antibodies via the human Mas-related G-protein-coupled receptor member X2 (MRGPRX2). In light of this new insight into the patho-mechanism of pseudo-allergic adverse drug reactions, in which as drug-receptor interaction results in anaphylaxis like symptoms, we critically reviewed the literature on NMBA-induced perioperative anaphylaxis. We challenge the dogma that NMBA mainly cause IgE-mediated anaphylaxis via an IgE-mediated mechanism, which is based on studies that consider positive skin test to be specific for IgE-mediated hypersensitivity. Finally, we discuss the question whether MRGPRX2 mediated pseudo-allergic reactions should be re-classified as type A adverse reactions.

Six years without pholcodine; Norwegians are significantly less IgE-sensitized and clinically more tolerant to neuromuscular blocking agents

BACKGROUND

As a strong inducer of IgE antibodies to substituted ammonium ion epitopes (QAI), pholcodine (PHO) is a postulated cause of allergic anaphylaxis to neuromuscular blocking agents (NMBAs). Three years after withdrawal of PHO in Norway, a significant reduction in IgE sensitization and anaphylaxis reporting was seen.

OBJECTIVE

Six-year follow-up study on the effects of PHO withdrawal on IgE sensitization and anaphylaxis reporting.

METHODS

From 650 acute consecutive reports (2005-2013) to the Norwegian Network for Anaphylaxis under Anaesthesia (NARA), total number of reports on suspected anaphylactic reactions, number of reactions where NMBAs were administered, number of reactions where serum IgE antibodies (≥0.35 kU_A /l) to suxamethonium (SUX) and PHO were present at time of reaction and anaphylaxis severity grades were retrieved. In addition, NMBA sales and prevalence of IgE sensitization to PHO and SUX among 'allergics' were monitored.

RESULTS

From baseline period P0 (PHO on the market) through the first (P1) and second (P2), three-year periods after withdrawal, significant falls in total reports (P < 0.001) and reports with IgE antibodies to PHO (P = 0.008) and SUX (P = 0.001) at time of reaction were found. Total NMBA sales in P2 were 83% of P0, and SUX and rocuronium (ROC) together made up 86% of sales throughout the study. Five NMBA-related anaphylactic deaths occurred during P0 and P1 and, however, none during P2. Prevalence of IgE sensitization to SUX in 'allergics' fell to 0% at 4 and 5 years after withdrawal.

CONCLUSIONS

Six years after PHO withdrawal, the Norwegian population has become significantly less IgE-sensitized and clinically more tolerant to NMBAs.

Atypical presentation to rocuronium allergy in a 19-year-old female patient

The danger of anaphylaxis, a rare but life threatening complication of general anesthesia (GA) can be summarized in two: 1. General Anesthesia masks the typical early signs of allergy which can be seen in an awake patient. 2. Anaphylaxis during GA manifests mostly as circulatory/ventilatory failures which can be interpreted as adverse effects of anesthetics or surgery and this can lead to critical delay of effective therapy. A 19-year-old female admitted for posterior spinal fusion and instrumentation (the 5th surgery in patient's life) desaturated seconds after intubation. Cardiopulmonary resuscitation (CPR) was started and the absence of cutaneous signs along with a loud holosystolic murmur were questioned. The patient was promptly resuscitated and allergy to rocuronium was confirmed by intradermal tests 6weeks later. Factors influencing decision making and potential etiology of the newly heard holosystolic murmur during anaphylaxis are discussed.

Quantification of specific IgE antibodies in immediate drug hypersensitivity: More shortcomings than potentials?

BACKGROUND

For many physicians, quantification of serum drug-specific IgE (sIgE) antibodies constitutes the first measure in the diagnostic approach of immediate drug hypersensitivity reactions (IDHR).

AIM

To review the accuracy and limitations of the main drug-sIgE tests, especially those that are commercially available.

METHODS

A literature search was conducted, using the key-words allergy, diagnosis, drugs, hypersensitivity, specific IgE antibodies; this was complemented by the authors' own experience.

RESULTS

The drugs that have mostly been studied appeared to be β-lactam antibiotics, neuromuscular blocking agents (NMBA) and morphine, the latter as a biomarker for sensitisation to substituted ammonium structures that constitute the major epitope of NMBA. For β-lactams sensitivity and specificity varied between 0-85% and 52-100%, respectively. For NMBA, sensitivity and specificity varied between 38.5-92% and 92-100%, respectively. With respect to sIgE to morphine it appears this drug to be a sensitive biomarker for sensitisation to rocuronium and suxamethonium but not for atracurium. However, sIgE morphine should not be applied in isolation to diagnose IDHR to NMBA nor opiates.

CONCLUSIONS

Although drug-sIgE assay can provide valuable information they should not be performed in isolation to establish correct diagnosis, as their predictive value is not per se absolute. Larger comprehensive studies are urgently required to determine the accuracy of drug-sIgE assays.

Perioperative anaphylaxis: what should be known?

Perioperative anaphylaxis is a unique condition as a result of the additive cardiovascular effects of anesthetics on the cardiovascular disturbances of anaphylaxis. It occurs mainly in adulthood, primarily follows anesthetic induction, and for the most part, is an IgE-mediated pathomechanism. Neuromuscular blocking agents (NMBAs) and antibiotics are the main culprit drugs, while latex is now infrequently involved. The Ring and Messmer scale is a useful tool for demonstrating the clinical severity of perioperative immediate hypersensitivity and guiding its management. Grades III and IV are life-threatening and are referred to as anaphylaxis. Three different clinical patterns of grade III may be observed, where cardiovascular collapse is the cardinal sign. Grade IV presents as cardiac arrest. The initial diagnosis is presumptive, whereas the etiological assessment is linked to the clinical presentation, tryptase levels, and skin test results. Since anaphylaxis presents with significant hypovolemia and vasoplegia, aggressive fluid therapy and epinephrine are the cornerstones of management. Whenever possible, anesthetic discontinuation is also recommended. Scientific evidence in favor of preemptive therapeutic strategies to prevent anaphylaxis in the operative setting is lacking.

Exploring the link between pholcodine exposure and neuromuscular blocking agent anaphylaxis

Neuromuscular blocking agents (NMBAs) are the most commonly implicated drugs in IgE-mediated anaphylaxis during anaesthesia that can lead to perioperative morbidity and mortality. The rate of NMBA anaphylaxis shows marked geographical variation in patients who have had no known prior exposure to NMBAs, suggesting that there may be external or environmental factors that contribute to the underlying aetiology and pathophysiology of reactions. Substituted ammonium ions are shared among NMBAs and are therefore thought to be the main allergenic determinant of this class of drugs. Substituted ammonium ions are found in a wide variety of chemical structures, including prescription medications, over-the-counter medications and common household chemicals, such as the quaternary ammonium disinfectants. Epidemiological studies have shown parallels in the consumption of pholcodine, a nonprescription antitussive drug which contains a tertiary ammonium ion, and the incidence of NMBA anaphylaxis. This link has prompted the withdrawal of pholcodine in some countries, with an ensuing fall in the observed rate of NMBA anaphylaxis. While such observations are compelling in their suggestion of a relationship between pholcodine exposure and NMBA hypersensitivity, important questions remain regarding the mechanisms by which pholcodine is able to sensitize against NMBAs and whether there are other, as yet unidentified, agents that can elicit similar hypersensitivity reactions. This review aims to explore the evidence linking pholcodine exposure to NMBA hypersensitivity and discuss the implications for our understanding of the pathophysiology of these reactions.

Pholcodine consumption and immunoglobulin E-sensitization in atopics from Australia, Korea, and Japan

Background

Accumulating data indicates that pholcodine (PHO)-consuming countries have higher sero-prevalences of immunoglobulin E (IgE)-antibodies to PHO and suxamethonium (SUX) and increased frequencies of IgE-mediated anaphylaxis to neuromuscular blocking agents (NMBAs) than nonconsuming. Withdrawing PHO-containing cough syrups resulted in a significant decrease of cases with anaphylaxis in Scandinavia. Nevertheless, the European Medicines Agency in 2011 advised to continue the unrestricted use throughout the European Union.

Objective

To extend studies on PHO consumption and prevalence of IgE-sensitization to morphine (MOR), PHO, and SUX to countries representing high (Australia), and low (Korea and Japan), consumers, respectively.

Methods

IgE-antibodies to SUX, MOR, and PHO in atopic subjects were determined by immunoassay and compared with official figures for PHO consumption and reported anaphylaxis to NMBA.

Results

The prevalences of IgE-antibodies to PHO, MOR, and SUX were 10%, 8.6%, and 4.3%, respectively, in Australia. The corresponding figures for Japan were 0.8%, 0.8%, and 1.5%, and for Korea 1.0% to PHO and 0.5% to MOR and SUX. Of the SUX-positive sera, 100% were positive to PHO or MOR in Australia and 0% in Japan and Korea.

Conclusion

The study supports previous findings; exposure to PHO may induce IgE-antibodies to the substituted ammonium ion epitope of NMBAs, thus increasing risk of NMBA-induced anaphylaxis considerably. However, other, still unknown factors occasionally might induce IgE-antibodies to SUX.

Utility of opium seed extract tests in preventing hypersensitivity reactions during surgery

BACKGROUND

Anaphylaxis during anaesthesia is fatal in 3-9% of patients and analgesics, including opioids, and is the second most common medicament-related cause, although the prevalence is underestimated. We recently found that patients may generate IgE antibodies to opium seeds.

OBJECTIVES

To determine the diagnostic accuracy of specific antibodies to morphine, codeine, rocuronium and oil body and aqueous fractions of Papaver somniferum seeds in the diagnosis and prevention of allergy to opioids.

METHODS

Patients with hypersensitivity reactions during surgery, and severe clinical allergy (pollen, tobacco), and illicit heroin users were selected. The sensitivity, specificity and predictive values of in vivo and in vitro diagnostic techniques including oil body and aqueous fractions of P. somniferum seeds were measured.

RESULTS

We studied 203 patients, with mean age 35.1±17.1 and 200 healthy controls. Patients sensitised to heroin or with hypersensitivity reactions during surgery responded to P. somniferum seed tests. Of patients not known to be sensitised to opioids, the highest positivity was in patients sensitised to tobacco (p<0.001). Opium seed skin tests and IgE, especially the oil body fraction, were more sensitive (64.2%) and specific (98.4%) than morphine, codeine and rocuronium tests for opioid sensitivity. Pollen allergy was not a risk factor for sensitisation to morphine.

CONCLUSIONS

Sensitivity to opioids and intraoperative anaphylaxis can be diagnosed by routine tests. IgE and skin tests for the oil body fraction of P. somniferum had the highest sensitivity for sensitisation to opioids.

IgE-mediated allergy to pholcodine and cross-reactivity to neuromuscular blocking agents: Lessons from flow cytometry

BACKGROUND

Immunoglubulin E antibody-mediated allergic reactions to opioids are rare and difficult to document correctly.

OBJECTIVE

Assessment of the basophil activation test in the diagnosis of IgE-mediated allergy to the antitussive pholcodine and associated sensitizations to neuromuscular blocking agents (NMBA).

METHODS

Three patients with a suspected IgE-mediated allergy to pholcodine were investigated using skin tests, quantification of specific IgE, and flow cytometric activation of basophils.

RESULTS AND CONCLUSION

Flow cytometric activation of basophils, with simultaneous analysis of CD63 appearance and median histamine content per cell, is the only technique capable to correctly document pholcodine allergy. The negative predictive value of basophil activation tests might help to elucidate on the controversial putative cross-reactivity between pholcodine and NMBA.

Clinical value of morphine, pholcodine and poppy seed IgE assays in drug-abusers and allergic people

BACKGROUND

The diagnosis of anaphylactic reactions due to opiates during anaesthesia can be difficult, since in most cases various drugs may have been administered. Detection of specific IgE to poppy seed might be a marker for sensitisation to opiates in allergic people and heroin-abusers. This study assessed the clinical value of morphine, pholcodine and poppy seed skin-prick and IgE determination in people suffering hypersensitivity reactions during anaesthesia or analgesia and drug-abusers with allergic symptoms.

METHODS

We selected heroin abusers and patients who suffered severe reactions during anaesthesia and analgesia from a database of 23,873 patients. The diagnostic yield (sensitivity, specificity and predictive value) of prick and IgE tests in determining opiate allergy was analysed.

RESULTS

Overall, 149 patients and 200 controls, mean age 32.9 ± 14.7 years, were included. All patients with positive prick to opiates showed positive prick and IgE to poppy seeds, but not to morphine or pholcodine IgE. Among drug-abusers, 13/42 patients (31%) presented opium hypersensitivity confirmed by challenge tests. Among non-drug abusers, sensitisation to opiates was higher in people allergic to tobacco (25%), P<.001. Prick tests and IgE against poppy seed had a good sensitivity (95.6% and 82.6%, respectively) and specificity (98.5% and 100%, respectively) in the diagnosis of opiate allergy.

CONCLUSIONS

Opiates may be significant allergens. Drug-abusers and people sensitised to tobacco are at risk. Both the prick and specific IgE tests efficiently detected sensitisation to opiates. The highest levels were related to more-severe clinical profiles.

The Pholcodine Case. Cough Medicines, IgE-Sensitization, and Anaphylaxis: A Devious Connection

: The Scandinavian data on pholcodine (PHO) strongly indicates that there is a biological chain from PHO exposure through IgE-sensitization to IgE-mediated anaphylaxis to neuromuscular blocking agents (NMBA). PHO is probably one of the strongest inducer of an IgE antibody response known. Of individuals taking PHO in cough medicines, over-the-counter accessibility to large populations, as many as 20 to 25% may become IgE sensitized. Once sensitized, PHO re-exposure will booster IgE antibody levels and IgE by around 100-fold. PHO is monovalent for 2 non-cross-reacting epitopes the quaternary ammonium ion (QAI), the main allergenic epitope of NMBA, and a non-QAI epitope. Thus, PHO most unlikely would initiate an allergic inflammatory response. Consequently, IgE sensitization is not revealed by obvious clinical signs, neither through tests based on IgE-sensitized effector cells. Therefore, it will escape detection if not assayed serologically. However, when subjected to general anesthesia, and thus the IgE-sensitized individual is administered a bivalent NMBA intravenously, the unrecognized presence of serum IgE antibodies to QAI may increase the risk of anaphylaxis 200- to 300-fold. Severe damages to patient's health can result, and mortality rates of 3 to 10% are reported. The Scandinavian experience indicates that the chain of events can efficiently be avoided by stopping PHO exposure: Within 1 year, the prevalence of IgE sensitization to PHO and QAI decreases significantly, and after 2 to 3 years, the numbers of reported anaphylactic reactions decreases equally so.

Restricting cough and cold medicines in children

AIMS

Based on concerns about safety and efficacy, international authorities have either advised against the use of cough and cold medication or considering such action. We aimed to systematically review the evidence for the effectiveness and safety of cough and cold medicines in children.

METHODS

We conducted a systematic review to identify studies relating to the use of products to treat symptoms of the common cold, influenza or allergic rhinitis, and relating to poisoning or toxicity from unintentional ingestion or overdose in children (<12 years). Medline, Embase and the Cochrane database were searched. No meta-analysis was undertaken because of the paucity of evidence, multiple medicines available, and the need to consider both effectiveness and safety.

RESULTS

Seventy two relevant studies or clinical reports were identified. There was little support for the effectiveness of these medicines for acute cough or the common cold in children. However, the majority of these medicines do not appear to be highly toxic in children and are not a major cause of severe effects following unintentional poisoning. The common use of these agents does not appear to be responsible for increased deaths in young children. Many cases of toxicity from cough and cold medications in young children are a result of therapeutic error. Particular medications, including diphenhydramine and codeine, appear to be associated with a high frequency of severe adverse effects and toxicity.

CONCLUSION

Restriction of cough and cold medicines in children is supported by currently available evidence.

Omalizumab decreases IgE production in patients with allergic (IgE-mediated) asthma; PKPD analysis of a biomarker, total IgE

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Omalizumab is a humanized anti-IgE monoclonal antibody that binds and captures circulating IgE, preventing interaction with receptors on mast cells and basophils, thereby interrupting the allergic cascade. It has a well-characterized efficacy and safety profile in patients with asthma. While omalizumab is known to reduce serum free IgE concentrations, effects on total IgE and IgE production are less well characterized.

WHAT THIS STUDY ADDS

(i) Confirmation of prior hypotheses that IgE production can decrease with time when patients are given anti-IgE therapy; (ii) guidance on a biomarker, total IgE, which can be used to ascertain whether individual patients experience a change in their IgE production; and (iii) a way to assess whether patients' IgE production has been sufficiently down-regulated such that they may consider stopping anti-IgE therapy.

AIM

To determine whether excessive IgE production by patients with atopic allergic asthma decreases with omalizumab therapy.

METHODS

Omalizumab, free and total IgE data were obtained from an epidemiological study and six randomized, double-blind, placebo-controlled trials in patients with allergic asthma. The binding between omalizumab and IgE together with the production and elimination of IgE were modelled as previously, except that, in order to explain why total IgE was decreasing over a period of 5 years, the expression of IgE was allowed to change.

RESULTS

The prior constant IgE production model failed to converge on the data once long-term observations were included, whereas models allowing IgE production to decrease fitted. A feedback model indicated that, on average, IgE production decreased by 54% per year. This model was further developed with covariate searches indicating clinically small but statistically significant effects of age, gender, body mass index and race on some parameters. Model predictions were checked internally and externally against 3-5 year data from paediatric and adult atopic asthmatic patients and externally against extensive total IgE data from a long-duration (>1 year) phase 1 study which was not used in the model building.

CONCLUSIONS

A pharmacokinetic-pharmacodynamic model incorporating omalizumab-IgE binding and feedback for control of IgE production indicates that omalizumab reduces production of IgE. This raises the possibility that indefinite treatment may not be required, only for perhaps a few years. After the initial accumulation, total IgE should provide a means to monitor IgE production and guide individual treatment decisions.

The in vitro diagnosis of drug allergy: status and perspectives

Adverse drug reactions (ADR) can result from immune-mediated (drug allergy) and nonimmune-mediated mechanisms. In both types of reaction, conclusive diagnosis and appropriate management remain major problems in daily clinical practice. This review summarizes the potentials and shortcomings of the currently available in vitro tests in the diagnosis of immediate (mostly IgE mediated) and nonimmediate (mostly T-cell mediated) drug allergy, particularly quantification of specific IgE, flow-assisted analysis of in vitro activated lymphocytes and basophils and the enzyme-linked immunosorbent spot.

Allergy to rocuronium: from clinical suspicion to correct diagnosis

BACKGROUND

Allergy to rocuronium can be life-threatening. Correct diagnosis is a prerequisite because of serious consequences of diagnostic error.

OBJECTIVE

To assess skin testing, quantification of specific IgE (sIgE) and flow-assisted activation of basophils [basophil activation test (BAT)] in the diagnosis of rocuronium allergy.

METHODS

This study comprises 104 curarized patients with a history of profound hypotension and severe bronchospasm immediately after induction of anaesthesia. All patients had skin tests, quantification of sIgE and BAT to rocuronium, together with investigations for all relevant compounds administered during anaesthesia that could have evoked the reaction. Diagnosis of rocuronium allergy was considered definite when the patient demonstrated a positive outcome for at least two of the three aforementioned tests.

RESULTS

The positive predictive value for skin testing, BAT and sIgE was 98% (CI 95%: 92-99%), 97% (CI 95%: 88-100%) and 83% (CI 95%: 74-89%), respectively. The negative predictive value for skin testing, BAT and sIgE was 96% (CI 95%: 86-99%), 75% (CI 95%: 67-75%) and 72% (CI 95%: 58-83%), respectively. Cross-reactivity with vecuronium was documented in 69% of the patients.

CONCLUSION

Skin testing merits the status of primary diagnostic investigation to document rocuronium allergy and cannot be substituted by quantification of sIgE or BAT. SIgE can offer a diagnostic advantage in cases where skin tests yield negative results. However, additional tests (e.g. BAT) are of capital importance in patients with negative skin tests and positive sIgE results to help in interpreting the clinical significance of a positive sIgE result. Optimal assessment of cross-reactivity between rocuronium and vecuronium implies both skin testing and BAT.

Drug-specific cyclodextrins with emphasis on sugammadex, the neuromuscular blocker rocuronium and perioperative anaphylaxis: implications for drug allergy

Cyclodextrins, oligosaccharides linked in a circular arrangement around a central cavity, are used extensively in the pharmaceutical industry to improve drug delivery. Their usefulness depends on their capacity to form a drug inclusion, or host-guest, complex within the cavity. In an attempt to improve the delivery of the widely used neuromuscular blocking drug (NMBD) rocuronium, a rocuronium inclusion complex was formed with a chemically modified γ-cyclodextrin. The high binding affinity and specificity of the modified carrier (named sugammadex) for rocuronium (and other aminosteroid NMBDs) led to its use in anaesthesia as an innovative and useful agent for rapid reversal of rocuronium-induced neuromuscular block by sequestering the drug as an inclusion complex. This, in turn, led to the suggestion that sugammadex might be useful to remove the NMBD from the circulation of patients experiencing rocuronium-induced anaphylaxis, a suggestion subsequently supported in case reports where traditional treatment had failed. Successful resuscitations suggested that sugammadex might be a valuable new treatment for such intractable cases but, given the inappropriateness of clinical trials, confirmation or refutation will have to await the slow accumulation of results of individual case reports. Important questions related to antibody accessibility of drug allergenic structures on the rocuronium-sugammadex inclusion complex, and the competition between sugammadex and IgE antibodies (both free and cell bound) for rocuronium, also remain and can be investigated in vitro. The sugammadex findings indicate that the use of carrier molecules such as the cyclodextrins to improve drug delivery will sometimes give rise to changed immunologic and allergenic behaviour of some drugs and this will have to be taken into account in preclinical drug safety assessments of drug-carrier complexes. The possibility of encapsulating and removing other allergenic drugs, e.g., penicillins and cephalosporins, in cases of difficult-to-reverse anaphylaxis to these drugs is discussed.

IgE-sensitization to the cough suppressant pholcodine and the effects of its withdrawal from the Norwegian market

BACKGROUND

IgE-mediated anaphylaxis to neuromuscular blocking agents (NMBA), frequent in Norway, was proposed to be caused by exposure to pholcodine (PHO) carrying the allergenic quarternary ammonium ion epitope. Consequently, the PHO-containing drug was withdrawn from the market in March 2007.

OBJECTIVE

Describe the effects of withdrawal of PHO on IgE, IgE-antibodies and reported frequencies of anaphylaxis to NMBAs.

METHODS

Three hundred sera from supposedly allergic patients sampled yearly through 2006 to 2010 were analysed for IgE antibodies to PHO, suxamethonium (SUX) and morphine (MOR). Furthermore, IgE and preliminary reports from the Norwegian Network for Anaphylaxis under Anaesthesia (NARA) were monitored.

RESULTS

PHO exposure was associated with IgE sensitization to PHO, MOR and SUX. However, after withdrawal, within 1 year, antibody prevalences to PHO and SUX fell significantly from 11.0% to 5.0% and from 3.7% to 0.7%, respectively. At 3 years, SUX had fallen to 0.3%, PHO to 2.7% and MOR to 1.3%. By 2 years, the prevalence of elevated IgE was significantly reduced. After 3 years, the incidence of reported suspected anaesthetic anaphylaxis fell significantly, both the total number, the reactions related to NMBAs and those with IgE antibodies to SUX.

CONCLUSIONS

Withdrawing of PHO lowered significantly within 1-2 years levels of IgE and IgE antibodies to PHO, MOR and SUX, and, within 3 years, the frequency of NMBA suspected anaphylaxis. The results strengthen the PHO hypothesis considerably and equally the need to question the existence of cough depressants containing PHO.

Anesthesia in the patient with multiple drug allergies: are all allergies the same?

PURPOSE OF REVIEW

During the preoperative evaluation, patients frequently indicate 'multiple drug allergies', most of which have not been validated. Potential allergic cross-reactivity between drugs and foods is frequently considered as a risk factor for perioperative hypersensitivity. The aim of this review is to facilitate the recognition of risk factors for perioperative anaphylaxis and help the management of patients with 'multiple drug allergies' during the perioperative period.

RECENT FINDINGS

Neuromuscular blocking agents (NMBAs) and antibiotics are the most common drugs triggering perioperative anaphylaxis. Quaternary ammonium ions have been suggested to be the allergenic determinant of NMBAs. Even though the 'pholcodine hypothesis' has been suggested to explain the occurrence of NMBA-induced allergy, this concept remains unclear. Although many practitioners believe that certain food allergies present an issue with the use of propofol, there is no role to contraindicate propofol in egg-allergic, soy-allergic or peanut-allergic patients. IgE-mediated hypersensitivity has been reported with seafood and iodinated drugs, IgE-mediated hypersensitivity has been reported with seafood and iodinated drugs, but there is no cross-reactivity between them. The allergenic determinants have been characterized for fish, shellfish and povidone iodine and remain unknown for contrast agents.

SUMMARY

There are many false assumptions regarding drug allergies. The main goal of this article is to review the potential cross-reactivity among specific families of drugs and foods in order to facilitate the anesthetic management of patients with 'multiple drug allergies'.

[Anaphylaxis during anaesthesia]

BACKGROUND

Anaphylaxis is a serious life-threatening generalized or systemic hypersensitivity reaction. The aim of this paper is to provide knowledge on how to diagnose, treat and follow up patients with suspected anaphylaxis during general and local anaesthesia.

MATERIAL AND METHODS

The article is based on literature identified through a non-systematic search in PubMed, the Scandinavian Guidelines on anaphylaxis during anaesthesia and on own research.

RESULTS

Anaphylactic symptoms during anaesthesia vary with respect to severity. Manifestations from skin and the cardiovascular and respiratory systems are present simultaneously in approximately 70 % of patients. Early treatment with adrenaline, fluid and extra oxygen may be vital for survival without sequelae. The following patients should be assessed before anaesthesia: those with moderate or serious reactions or with reactions that raise suspicion of allergy which may cause problems in connection with future treatment. Neuromuscular blocking agents are the main cause of IgE-mediated anaphylaxis during anaesthesia in Norway. New research has shown that allergy towards neuromuscular blocking agents can develop after ingestion of cough syrup containing pholcodine (stimulates asymptomatic production of antibodies). These antibodies cause cross-sensibilisation with neuromuscular blocking agents. The cough syrup Tuxi was withdrawn from the Norwegian market during spring 2007.

INTERPRETATION

Allergic reactions during anaesthesia are rare and potentially life-threatening; patients should be followed up and treated in a standardized way.

[Muscle relaxants]

BACKGROUND

Muscle relaxants were introduced into clinical anaesthesia for the first time in 1942. The purpose of this article is to provide an overview of the history of muscle relaxants, their mode of action and their role in current anaesthetic practice.

MATERIAL AND METHOD

The review is based on clinical experience, own research and a non-systematic literature search using PubMed.

RESULTS

A muscle relaxant is either suxamethonium (curacit) or one of many curare compounds. One of the curare drugs was brought to Europe from South America in the 1700 s and the active substance (called d-tubocurarine) was isolated in 1935. This type of drug paralyses striated muscles that are under voluntary control by interfering with the normal signalling system between nerve and muscle. Muscle relaxants provide optimal relaxation of skeletal muscles during surgical procedures, an effect that otherwise may require the use of high doses of anaesthetic drugs. However, muscle relaxants are not anaesthetic drugs, do not affect consciousness and have no pain relieving effect. A muscle relaxant that works optimally in all clinical settings has unfortunately not been developed so far.

INTERPRETATION

Muscle relaxants are generally safe drugs when used appropriately, but especially suxamethonium may have serious side effects. A muscle relaxant is regularly used during induction of anaesthesia, but less during surgery, because modern anaesthetics possess some muscle relaxing effect.

Drug hypersensitivity reactions involving skin

Immune reactions to drugs can cause a variety of diseases involving the skin, liver, kidney, lungs, and other organs. Beside immediate, IgE-mediated reactions of varying degrees (urticaria to anaphylactic shock), many drug hypersensitivity reactions appear delayed, namely hours to days after starting drug treatment, showing a variety of clinical manifestations from solely skin involvement to fulminant systemic diseases which may be fatal. Immunohistochemical and functional studies of drug-specific T cells in patients with delayed reactions confirmed a predominant role for T cells in the onset and maintenance of immune-mediated delayed drug hypersensitivity reactions (type IV reactions). In these reactions, drug-specific CD4+ and CD8+ T cells are stimulated by drugs through their T cell receptors (TCR). Drugs can stimulate T cells in two ways: they can act as haptens and bind covalently to larger protein structures (hapten-carrier model), inducing a specific immune response. In addition, they may accidentally bind in a labile, noncovalent way to a particular TCR of the whole TCR repertoire and possibly also major histocompatibility complex (MHC)-molecules - similar to their pharmacologic action. This seems to be sufficient to reactivate certain, probably in vivo preactivated T cells, if an additional interaction of the drug-stimulated TCR with MHC molecules occurs. The mechanism was named pharmacological interaction of a drug with (immune) receptor and thus termed the p-i concept. This new concept may explain the frequent skin symptoms in drug hypersensitivity to oral or parenteral drugs. Furthermore, the various clinical manifestations of T cell-mediated drug hypersensitivity may be explained by distinct T cell functions leading to different clinical phenotypes. These data allowed a subclassification of the delayed hypersensitivity reactions (type IV) into T cell reactions which, by releasing certain cytokines and chemokines, preferentially activate and recruit monocytes (type IVa), eosinophils (type IVb), or neutrophils (type IVd).

Anaphylaxis to Patent Blue V. I. Clinical aspects

BACKGROUND

The dye Patent Blue V (PBV) is increasingly used for staging procedures in operable breast cancer, but is reported to cause adverse reactions. The aim of this study was to present the clinical features and the results of follow-up examinations in patients with such reactions.

METHODS

We studied nine patients with hypersensitivity reactions to PBV between 1999 and 2006 who were identified through the Norwegian network for reporting and investigating allergic reactions during anesthesia.

RESULTS

We observed incidences of 0.5% (7/1418) for all kinds of PBV reactions and 0.4% (5/1418) for anaphylaxis. Typical clinical features included: (i) cardiovascular and/or cutaneous symptoms, (ii) a delay in symptoms, compared to the time of dye injection, (iii) poor response to ephedrine and intravenous fluid, and (iv) need for adrenaline administration, sometimes prolonged, for circulatory stabilization. Cutaneous manifestations were noted in five of the seven patients with anaphylaxis and two additional patients without circulatory instability. During anaphylactic reactions, serum tryptase was increased in six patients and normal in one. Serum tryptase was normal in one patient with skin symptoms only. Skin prick tests to PBV were positive in all eight patients tested, including the two with skin manifestations only.

CONCLUSION

The clinical features and the results of follow-up studies strongly suggest that these reactions are IgE mediated.

Pholcodine exposure raises serum IgE in patients with previous anaphylaxis to neuromuscular blocking agents

BACKGROUND

Neuromuscular blocking agents (NMBAs) can cause anaphylaxis through immunoglobulin E (IgE) antibodies that bind quaternary ammonium ion epitopes. These epitopes are present in numerous common chemicals and drugs, exposure to which, theoretically, could be of importance in the development and maintenance of the IgE sensitization promoting allergic reactions. Pholcodine is one such drug, which in a recent pilot study was shown to induce a remarkable increase in serum IgE levels in two IgE-sensitized individuals. The present study explores the effect of pholcodine exposure on IgE in a population with previously diagnosed IgE-mediated anaphylaxis towards NMBAs.

METHODS

Seventeen patients were randomized to 1 week's exposure with cough syrup containing either pholcodine or guaifenesin. The primary variables serum IgE and IgE antibodies towards pholcodine, morphine and suxamethonium were measured before and 4 and 8 weeks after start of exposure.

RESULTS

Patients exposed to pholcodine had a sharp rise in levels of IgE antibodies towards pholcodine, morphine and suxamethonium, the median proportional increases 4 weeks after exposure reaching 39.0, 38.6 and 93.0 times that of the base levels respectively. Median proportional increase of IgE was 19.0. No changes were observed in the guaifenesin group.

CONCLUSION

Serum levels of IgE antibodies associated with allergy towards NMBAs increase significantly in sensitized patients after exposure to cough syrup containing pholcodine. Availability of pholcodine should be restricted by medical authorities because of the potential risk of future allergic reactions to muscle relaxants.

No consumption of IgE antibody in serum during allergic drug anaphylaxis

BACKGROUND

The general understanding is that a blood sample for analysis of immunoglobulin (Ig) E antibodies to an allergen suspected to cause an anaphylaxis cannot be drawn until several weeks after the reaction. As this is most unpractical, the changes in IgE antibody levels during anaphylaxis were studied to evaluate the possibility of using samples drawn at the time of the reaction.

METHODS

Immunoglobulin E antibodies to suxamethonium were quantitated with ImmunoCAP before, during and after an anaphylactic reaction occurring during anaesthesia using neuromuscular blocking agents.

RESULTS

Serum IgE antibody concentrations against suxamethonium in blood samples collected up to 6 h after the reaction were not different from those in samples drawn before or days and weeks after the anaphylaxis.

CONCLUSIONS

A serum sample intended to trace the drug involved in an IgE-mediated anaphylactic reaction can be drawn in direct relation to the reaction.

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.

Anaphylaxis during anaesthesia: diagnostic approach

Correct management of anaphylaxis during anaesthesia requires a multidisciplinary approach with prompt recognition and treatment of the acute event by the attending anaesthesiologist, and subsequent determination of the responsible agent(s) with strict avoidance of subsequent administration of all incriminated and/or cross-reacting compounds. However, correct identification of the causative compound(s) and safe alternatives is not always straightforward and, too often, not done. This review is not intended to discuss acute management of anaesthesia-related anaphylaxis but summarizes the major causes of anaphylaxis during anaesthesia and the diagnostic approach of this rare but potentially life-threatening complication. Apart from general principles about the diagnostic approach, history taking and importance of tryptase quantification, more specific confirmatory diagnostic procedures are organized on the basis of the major causes of perioperative anaphylactic reactions.