Substituted ammonium ions as allergenic determinants in drug allergy

Adverse reactions to neuromuscular blocking agents

Neuromuscular blocking agents (NMBAs) play a predominant role in the incidence of severe adverse reactions occurring during anesthesia. Most hypersensitivity reactions are of immunologic origin (IgE-mediated) or are related to direct stimulation of histamine release. The incidence of IgE-mediated hypersensitivity or anaphylaxis is estimated between 1 in 10,000 and 1 in 20,000 anesthesias, and NMBAs represent the most frequently involved substances, with a range of 50% to 70%. Any suspected anaphylactic reaction must be extensively investigated using combined perioperative and postoperative testing. Because of the frequent cross-reactivity observed with muscle relaxants, every available NMBA should be tested. This should help provide documented advice for future administration of anesthesia. There is no demonstrated evidence for systematic preoperative screening in the general population at this time. Other well-known adverse effects have been described, such as the succinylcholine-triggered cytotoxic effects on muscle cells, but these are responsible for characteristic clinical symptoms, which are usually easy to distinguish from anaphylactic reactions

Allergic reactions occurring during anaesthesia: diagnostic approach

Anaphylactic and anaphylactoid reactions to anaesthetic and associated agents used during the perioperative period have been increasingly reported during the last 3 decades. The frequency of life-threatening hypersensitivity reactions occurring during anaesthesia has been estimated to vary between 1/1.000 and 1/25.0000 procedures, with muscle relaxants being involved in almost three quarters of the cases. The mortality from these reactions is in the range of 3-6%. Nowadays, natural rubber latex also accounts for a significant number of perioperative anaphylaxis, particularly in children. Clinical manifestations do not allow to differentiate between IgE-mediated anaphylaxis and anaphylactoid reactions resulting from non-specific mediator release. Successful management of these patients requires multidisciplinary approach and includes prompt recognition and stabilisation of the acute event by the attending anaesthetist, determination of the responsible agent(s) with avoidance of subsequent administration of incriminated compound(s). The latter is based upon correct identification of the responsible drug and potentially cross-reactive compounds by the allergist and requires a detailed review of the anaesthetic report as well as appropriate in vitro and in vivo allergy tests. At present, the overall performance of skin tests makes them the "gold standard" for diagnosis of muscle relaxant-induced perioperative hypersensitivity reactions. In addition, given their good negative predictive value, skin tests have been proven to be a useful tool to tailor the appropriate therapeutic alternative. For other compounds diagnosis is more difficult but newer techniques such as analysis of in vitro activated basophils can be helpful.

Anaphylaxis during the perioperative period

Anesthesiologists use a myriad of drugs during the provision of an anesthetic. Many of these drugs have side effects that are dose related, and some lead to severe immune-mediated adverse reactions. Anaphylaxis is the most severe immune-mediated reaction; it generally occurs on reexposure to a specific antigen and requires the release of proinflammatory mediators. Anaphylactoid reactions occur through a direct non-immunoglobulin E-mediated release of mediators from mast cells or from complement activation. Muscle relaxants and latex account for most cases of anaphylaxis during the perioperative period. Symptoms may include all organ systems and present with bronchospasm and cardiovascular collapse in the most severe cases. Management of anaphylaxis includes discontinuation of the presumptive drug (or latex) and anesthetic, aggressive pulmonary and cardiovascular support, and epinephrine. Although a serum tryptase confirms the diagnosis of an anaphylactic reaction, the offending drug can be identified by skin-prick, intradermal testing, or serologic testing. Prevention of recurrences is critical to avoid mortality and morbidity.

Screening for mast cell tryptase and serum IgE antibodies in 18 patients with anaphylactic shock during general anaesthesia

BACKGROUND

In the perioperative setting multiple agents can cause anaphylaxis. Often the reactions are dramatic, and due to their lifethreatening potential it is crucial that the responsible agent is identified in order to avoid future adverse reactions. The aim of the present study was to measure the concentration of serum mast cell tryptase (MCT), to investigate the prevalence of serum IgE antibodies against ammonium groups, choline, morphine, suxamethonium, thiopentone and latex and to perform skin prick tests (SPTs) in 18 patients experiencing an anaphylactic reaction during induction of general anaesthesia.

METHODS

Serum samples from 18 patients with an anaphylactic reaction during general anaesthesia were analyzed for MCT and specific IgE against ammonium groups, choline, morphine, suxamethonium, thiopentone and latex. Skin prick tests were performed in 11 out of 18 patients.

RESULTS

Ten patients had elevated MCT levels and specific IgE against ammonium ion, morphine and (with the exception of patient nos 3, 9 and 10) suxamethonium. Seven of these patients had positive SPTs to suxamethonium. One of the patients tested positive to latex in addition to suxamethonium. Two patients showed elevated MCT, while specific IgE against the drugs tested was not detected. Three patients tested positive to ammonium ion, morphine and suxamethonium, but negative to MCT. Three patients tested negative to both MCT and specific IgE.

CONCLUSIONS

Fifteen out of 18 sera tested positive for MCT and/or specific IgE against neuromuscular blocking drugs (NMBDs). Ten of the 18 patients experienced an IgE-mediated anaphylactic reaction to NMBDs during anaesthesia, verified by detection of specific IgE and elevated levels of MCT.

[Anaphylaxis after rocuronium: advantage of blood tests for early diagnosis]

A 56-year-old patient was scheduled for coronary artery bypass surgery, because of a severe coronary artery disease. Soon after induction of anaesthesia, he rapidly developed a cardiovascular collapse with bronchospasm and rash. Specific immunoglobulin E and tryptase measurements supported the diagnosis of grade III anaphylactic shock due to rocuronium bromide. A few days later, a general anaesthesia was administered without muscle relaxant and was uneventful.

Anaphylaxis during anaesthesia. Results of a two-year survey in France

Between January 1, 1997 and December 31, 1998, 467 patients were referred to one of the allergo-anaesthesia centres of the French GERAP (Groupe d'Etudes des Réactions Anaphylactoïdes Peranesthésiques) network and were diagnosed as having anaphylaxis during anaesthesia. Diagnosis was established on the basis of clinical history, skin tests and/or a specific IgE assay. The most frequent cause of anaphylaxis was a neuromuscular blocking agent (69.2%). Latex was less frequently incriminated (12.1%) than in previous reports. A significant difference was observed between the incidence of anaphylactic reactions observed with each neuromuscular blocking agent and the number of patients who received each drug during anaesthesia in France throughout the study period (P<0.0001). Succinylcholine and rocuronium were most frequently incriminated. Clinical reactions to neuromuscular blocking drugs were more severe than to latex. The diagnostic value of specific IgE assays was confirmed. These results are consistent with changes in the epidemiology of anaphylaxis related to anaesthesia and are an incentive for the further development of allergo-anaesthesia clinical networks.

Rocuronium: high risk for anaphylaxis?

Patients suspected of anaphylaxis during anaesthesia have been referred to the senior author's clinic since 1974 for investigation. Since release of rocuronium on to the worldwide market, concern has been expressed about its propensity to cause anaphylaxis. We identified 24 patients who met clinical and laboratory (intradermal, mast cell tryptase and morphine radioimmunoassay) criteria for anaphylaxis to rocuronium. The incidence of rocuronium allergy in New South Wales, Australia has risen in parallel with sales, while there has been an associated fall in reactions to other neuromuscular blocking drugs. Data from intradermal testing suggested that rocuronium is intermediate in its propensity to cause allergy in known relaxant reactors compared with low-risk agents (e.g. pancuronium, vecuronium) and higher-risk agents (e.g. alcuronium, succinylcholine).

Persistent anaphylactic reaction after induction with thiopentone and cisatracurium

A 6-year-old boy presented for surgery for phimosis. The anaesthetic technique included intravenous induction with thiopentone and neuromuscular blockade with cisatracurium. Severe persistent bronchospasm and central cyanosis followed the administration of these drugs. A continuous i.v. infusion of epinephrine at 0.2 microg. kg(-1) x min(-1) was necessary to break the severe refractory bronchial hyperresponsiveness. There was no previous exposure to anaesthetic drugs and no definite family history of allergy. Through increased serum eosinophil cationic protein, tryptase and histamine levels and IgE levels specific to cisatracurium, we demonstrated an IgE-mediated anaphylactic reaction to cisatracurium in the child's first exposure to this new neuromuscular blocking agent. Anaphylactic reactions to new anaesthetic drugs may be challenging to recognize and treat during general anaesthesia in children. The pathogenesis, diagnosis and management of life threatening persistent allergic reactions to intravenous anaesthetics are discussed.

Anaphylactic reactions during induction of anaesthesia using rocuronium for muscle relaxation: a report including 3 cases

Anaphylaxis during induction of anaesthesia is a dreaded complication with a mortality rate of 3-6%, most frequently associated with the use of muscle relaxants. Current knowledge on this matter is reviewed in relation to the presentation of 3 cases of anaphylaxis and bronchospasm associated with the use of the recently released nondepolarizing muscle relaxant rocuronium. Bronchospasm may be the sole sign of a serious drug reaction, triggered by precipitation of insoluble thiopental crystals when mixed with a muscle relaxant in the intravenous (iv) line. It is recommended that these drugs are administered via different injection ports. The hypotension requires immediate treatment with oxygen, epinephrine and large amounts of iv fluids. Epinephrine infusion may be needed for hours. It is recommended that serum tryptase is measured approximately 2 h after debut of the serious drug reaction. Allergy testing should be performed for all the drugs the patient was exposed to, 4-8 weeks after the incident, and due to cross-reactivity, including all available muscle relaxants. Doctors are urged to inform their patients, and systematically register adverse drug reactions.

Reaction with, and fine structural recognition of polyamines by human IgE antibodies

Human IgE antibodies from nine allergic subjects were found to react with poly-L-lysine (PLL) and other polyamines. Radioimmunoassay inhibition studies indicated that the two amino groups, but not the carboxyl, in lysine contributed to the antibody binding and 4-aminomethyl-1,8-octanediamine, a compound containing three primary amino groups, was a better inhibitor than compounds containing only two primary amino groups. Ethylamine showed weak but clear inhibition indicating that even a single amino group could bind to the antibody combining site. Substituted ethanolamine and quaternary ammonium compounds were well recognized by some sera but with others, substitution hampered recognition. Inhibition studies with compounds containing an amino and a carboxyl group at different distances revealed that an adjacent carboxyl group interfered with recognition of the amino group by some IgE antibodies. IgE binding to PLL was examined at different pHs and ionic strengths. Binding was greatest at pH 5-6 to 8 and decreased markedly outside this range. Ionic strengths higher than 0.3 M significantly diminished the binding. These results indicated that binding of specific antibody to polyamine was due to electrostatic interactions of positively charged amino groups in the polyamine with the antibody combining site. These results may be relevant to mechanisms underlying recognition of some allergens in some atopic conditions.

Immunoassays in the diagnosis of anaphylaxis to neuromuscular blocking drugs: the value of morphine for the detection of IgE antibodies in allergic subjects

Radioimmunoassays (RIAs) for IgE antibodies to specific neuromuscular blocking drugs (NMBDs) are an important tool in the diagnosis of anaphylaxis during anaesthesia although they are performed in only a few laboratories throughout the world. NMBDs bind to antibodies by their substituted ammonium ions. We measured serum IgE antibodies to morphine and specific NMBDs in 347 patients with suspected anaphylaxis using blood specimens sent for mast cell tryptase assays. Morphine, which has a single substituted ammonium group, avidly binds in vitro to antibodies that react with NMBDs. The morphine RIA proved to be both a more sensitive and efficient test for the detection of IgE antibodies to NMBDs than the specific NMBD RIAs. We have adopted the morphine RIA in our laboratory in preference to the specific RIAs and predict that use of this single assay will become widespread for the in vitro diagnosis of allergic sensitivities to NMBDs.

Cisatracurium and atracurium as antigens

Seventy-five consecutive patients referred to an anaesthetic allergy clinic were intradermally tested with atracurium and cisatracurium. With the exception of one patient the results were identical, suggesting that allergy to either drug is associated with allergy to the stereoisomer. For skin testing for allergy to neuromuscular blocking drugs it is only necessary to use either atracurium or cisatracurium and cisatracurium is the preferred drug.

Anaphylactic/anaphylactoid reactions to anaesthetic and associated agents. Skin prick tests in aetiological diagnosis

Fifty-one patients were referred in one year (1992) for investigation of immediate type anaphylactic/anaphylactoid reactions during anaesthesia. Skin prick tests were made with 23 anaesthetic and associated agents in the concentrations used clinically. Definite or probable causes were identified by immediate type wealing reactions, supported by the clinical history in 36 of the 46 in whom a diagnosis of anaphylaxis was made. These comprised mainly the neuromuscular relaxants, chiefly suxamethonium (18); atracurium (6); gallamine (2); one each alcuronium; pancuronium; vecuronium and tubocurarine, as well as alfentanil (1); Gelofusine (2); cefuroxime (1) and latex (2). The materials for performing the skin prick test are readily available and it can be very helpful in making important aetiological diagnoses.

Adverse effects of depolarising neuromuscular blocking agents. Incidence, prevention and management

Muscle relaxants block neuromuscular transmission, acting at nicotinic acetylcholine receptors of the neuromuscular junction. Suxamethonium (succinylcholine) is a depolarising agent, whereas all other relaxants in clinical use are nondepolarising. The desired neuromuscular block results from the structural similarity of muscle relaxants to acetylcholine, enabling the interaction with receptors at the neuromuscular junction. Adverse effects of suxamethonium are generally related to its agonist mode of action. Autonomic cardiovascular effects may result. Other adverse effects include anaphylactic or anaphylactoid reactions, and histamine release. Various disease states may present specific considerations in the use of muscle relaxants. Although many complications of muscle relaxants (such as prolonged block or resistance) are easily treated, others may require immediate intervention and vigorous therapy. Careful selection of appropriate relaxants for particular patients will usually prevent the occurrence of complications.

Predictive value of in vitro tests for the IgE-dependent and the IgE-independent anaphylactoid reactions to muscle relaxants

Several aspects of in vitro tests for life-threatening anaphylactoid reactions (AR) to neuromuscular blockers (NMB, muscle relaxants) were addressed and highlighted. They include topics which have been under study in our centre in the past few years. Already available tests and newly developed ones were assessed for diagnostic and predictive value, as well as for usefulness in understanding of mechanism(s) of AR. The theoretical and practical aspects of radioallergosorbent tests (RAST) for antibodies to NMB (particularly IgE), their predictive value and their possible use in "screening" with the hope of preventing AR are discussed. Confirmatory tests after AR include plasma or serum histamine/methylhistamine, tryptase and possibly eosinophil cationic protein (ECP), all of which point to activation of mast cells, basophils, eosinophils and possibly other inflammatory cells. Future anesthetics after AR can be guided by measurement of the in vitro release of histamine, leukotrienes and possibly eosinophil cationic protein (ECP) and serum antibodies. Antibody studies (mainly IgE by RAST) are valuable for diagnosis and, together with other tests, can throw light on cross-reaction and further clarify the mechanisms of AR. In RAST (IgE)-negative cases of AR, which may be due to immune or nonimmune mechanisms, mediator release measurements are particularly useful. Lymphocyte stimulation tests may also be useful in such cases. RASTs cannot be advocated for general preoperative screening, as yet. Further development or selection of potentially "susceptible" subpopulations may improve the predictive value of these tests.

Mechanisms of activation of human mast cells and basophils by general anesthetic drugs

A study was performed about the effects of increasing concentrations of muscle relaxants (suxamethonium, d-tubocurarine, vecuronium, and atracurium), hypnotics (propofol, ketamine, and thiopental), opioids (morphine, buprenorphine, and fentanyl), and benzodiazepines (diazepam, flunitrazepam, and midazolam) on the release of preformed (histamine and tryptase) and de novo synthesized (prostaglandin D2: PGD2 and peptide-leukotriene C4: LTC4) chemical mediators from human basophils and mast cells isolated from skin (HSMC), lung parenchyma (HLMC) and heart tissue (HHMC). None of the drugs tested induced the release of histamine or LTC4 from basophils of normal donors. Suxamethonium did not induce mediator release from any type of human mast cell tested. Only the highest concentration of d-tubocurarine used caused histamine release from HSMC and HLMC. Atracurium, more than vecuronium, induced concentration-dependent histamine release from HSMC and HLMC. Propofol induced a concentration-dependent histamine release from HLMC, but not from HHMC. Only the highest concentrations of ketamine and thiopental used caused a significant release of histamine from HLMC. The muscle relaxants and hypnotics examined did not induce any de novo synthesis of PGD2 or LTC4 in mast cells. Morphine only induced histamine and tryptase release from HSMC, but not the de novo synthesis of PGD2. In contrast, buprenorphine caused histamine and tryptase release from HLMC, and not from HSMC, whilst it also induced de novo synthesis of PGD2 and LTC4 in HLMC. Fentanyl did not give any histamine and tryptase release from mast cells. Diazepam and flunitrazepam only induced a small release of histamine from mast cells, whereas midazolam caused the release of histamine from HLMC. The biochemical pathways underlying the release of mediators from human mast cells induced by drugs used during general anaesthesia are different from those underlying the immune release of histamine. From the results obtained with the in vitro model described here, it is clear that new drugs promising for the anesthesiologic arena should be tested in vitro before their potential histamine-releasing activity is experienced in vivo.

Mechanisms in IgE-dependent anaphylaxis to anesthetic drugs

The discovery of IgE antibodies to neuromuscular blocking drugs, to thiopentone and narcotics, particularly morphine, reinforced earlier beliefs formed from skin test and other clinical findings that many "anaphylactoid" reactions to drugs were true type 1 immediate hypersensitivity reactions. Immunochemical studies established the fine structural specificities of the drug-reactive IgE antibodies and provided an explanation in molecular terms for a number of observed clinical cross-reactions. Subtleties in interpreting relationships between skin tests and IgE radioimmunoassays are pointed out and mechanisms of drug-induced mediator release, persistence of IgE antibodies and the nature of the sensitizing sources are discussed.

Diagnosis of IgE-dependent anaphylaxis to neuromuscular blocking drugs, thiopentone and opioids

Although allergenic cross-reactivity of neuromuscular blocking drugs (NMBDs) is recognised clinically and has been firmly established at the serological and immunochemical levels, interpretation of in vitro inhibition findings for clinical purposes is not always straightforward. Points to be taken into account when considering serum IgE direct binding and inhibition results and when determining which NMBDs a patient may be sensitive to, include the relationship between in vitro potencies and clinical findings and the nature of the drug solid phase used for testing. It should also be remembered that the stimulating antigenic source for the patients' NMBD-reactive IgE antibodies is almost always unknown. A comparison of skin and IgE radioimmunoassay (RIA) tests for NMBDs in 29 patients is presented and difficulties involved in interpreting the results of both tests are discussed. Methods for increasing the detection of NMBD-reactive IgE antibodies are outlined. In screening sera of patients for IgE antibodies to thiopentone and morphine as well as NMBDs, multiple drug reactivities have been detected in a few subjects. Attention is drawn to defects in the existing thiopentone RIA although it is clear that the test is specific in patients who react to the drug. Addition of the serum tryptase assay to skin tests and IgE RIAs for NMBDs, thiopentone and morphine provides a powerful combination of diagnostic tests for the investigation of anaphylactoid reactions to anaesthetic drugs.

Histamine release assay and radioimmunoassay for the detection of IgE antibodies against neuromuscular blocking drugs

It is well established that muscle-relaxant drugs may be responsible for anaphylactoid reactions during anaesthesia. In the present work we evaluated in 41 patients who had experienced anaphylactoid reactions during general anesthesia, the value of different radioimmunoassays (RIAs) and of an histamine release assay (HRA). The RIA was performed with different solid phases as PAPPC (para amino phenyl phosphoryl choline), morphine, TMA (trimethylamine) and TEA (triethylamine). The results were expressed as the percentage of 125I anti-human IgE adsorbed onto the solid phase. The sensitivity was estimated respectively at 95, 82, 93 and 64%. The results were significantly in accordance with those obtained with QAS-RIA (from Guéant) but a weak correlation was seen with Phadebas Rast succinylcholine (r = 0.85 and 0.53 respectively). The HRA gave with the NMBD incriminated a sensitivity of 88%. The correlation between HRA and IDR for the drug involved was 89% and 43% for the other NMBDs. The PAPPC RIA was apparently the most efficient test to screen sera for the presence of IgE antibodies whatever the NMBDs involved in anaphylaxis. An advantage is that this solid phase is commercially available and therefore this RIA can be used routinely with a high sensitivity, allowing the comparison of the results obtained by different laboratories.

Clinical evaluation of in vitro leukocyte histamine release in allergy to muscle relaxant drugs

We have evaluated the in vitro leukocyte histamine release tests for the diagnosis of allergy to muscle relaxant drugs in 40 patients (Group A) and a control group of 44 subjects with negative leukocyte histamine release (Group B). Non-IgE dependent histamine release, expressed as a percentage of the total blood histamine, was 3.94% +/- 0.49 in Group B. The upper limit of positivity was estimated to be 5% (mean + 2 SD). Leukocyte histamine release tests were positive in 65% of the patients from Group A. The concordance between LHR and QAS-RIA was 64%. The maximal histamine release was observed at dilutions of 10(-2)-10(-4) in 20 of the 26 positive cases. The maximal histamine release was 43.8% +/- 23.3. The spontaneous histamine release was as low as 1.7% +/- 1.1. Cross-reactivity among the 5 different muscle relaxant drugs has been investigated and compared by intradermal testing. The muscle relaxant drugs which gave the lower skin reaction (M2) and the drug responsible for shock (M1) were selected for the study of in vitro leukocyte histamine release. Of 20 M2. All of the 10 cases had negative ID tests with M2. Three of these patients subsequently underwent general anesthesia with the muscle relaxant chosen as harmless (M2) without any clinical reaction.

Drug allergy

Although allergic drug reactions are just one type of adverse reaction to medications, they are clinically very important because of the morbidity and mortality they cause. An ever-expanding pharmacopeia increases the potential for allergic drug reactions. An understanding of the types of allergic drug reactions, their immunopathologic mechanisms, and the most likely medications involved; an approach to determine the drug responsible for the reaction; and ways to prevent future allergic drug reactions are important features in minimizing patient morbidity.

Persistence of allergy to anaesthetic drugs

Intradermal testing and RIA testing for specific IgE antibodies to neuromuscular blocking drugs (NMBDs) were performed in patients referred to an Anaesthetic Allergy Clinic. Six patients were initially investigated four to 29 years after clinical anaphylaxis during anaesthesia and two of these patients and sixteen others were investigated by intradermal testing on two occasions at least four years apart. Seven patients had RIA tests for NMBD-specific IgE antibodies on two occasions at the time of skin testing. In all but two patients the evidence for drug-specific antibodies persisted 4-29 years after the reactions. In one patient all tests became negative and in another the skin test became negative but the positive RIA persisted. Evidence of antibodies to NMBDs persisted in 21 of 22 patients who had had anaphylactic reactions to these drugs during anaesthesia. In the absence of evidence of allergy diminishing with time in the majority of patients it would seem wise to avoid drugs responsible for reactions for the rest of the patient's life.