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Created March 8, 2019, last updated over 1 year ago.
Collection: 95, Score: 2341, Trend score: 0, Read count: 3055, Articles count: 16, Created: 2019-03-08 23:34:17 UTC. Updated: 2023-02-28 22:37:01 UTC.Notes
Pholcodine is an opioid anti-tussive (ie. cough suppressant). It is a common component of over-the-counter cough medications. However it has a special significance to anesthesiologists in relation to anaphylaxis risk, particularly related to neuromuscular agents.
Florvaag et al's 2009 review covers this issue very comprehensively. Earlier 2006 research from Florvaag et al attempting to explain some of the regional variability in anaphylaxis rates showed that exposure to pholcodine causes an 60-105 times increase in IgE levels!
Countries where pholcodine use is common (eg Norway) seem to have experienced higher levels of anaphylaxis to neuromuscular blocking agents than countries where it is not common (eg Sweden). In fact, in Norway rocuronium anaphylaxis was such a problem that its use was restricted to modified rapid sequence inductions. A pholcodine containing cough syrup has been withdrawn from the market in Norway because of this (and levels of sensitisation seem to be dropping although it is still too early to draw conclusions). It will be interesting to see if there are other compounds that have a similar effect on IgE sensitisation and whether other countries will consider withdrawing pholcodine products.
In addition to the two articles from Florvaag that specifically look at Pholcodine and it's effects, there is also an interesting review looking at recent insights into anaphylaxis in the anaesthetic setting from Dewachter and team.
Also interesting is Lee et al.'s 2016 case report describing two patients with pholcodine anaphylaxis who then when tested also showed NMBD sensitivity.
Helen Crilly & Michael Rose's 2014 review in Australian Prescriber Anaphylaxis and anaesthesia – can treating a cough kill? is another great summary of the issue.
Daniel Jolley
As of February 28th 2023, pholcodine has FINALLY been banned in Australia by the Therapeutic Goods Administration (TGA).
Press release here: TGA - Pholcodine
It's very sad that it took 14 years after Florvaag & Johansson's landmark 2009 paper describing the connection between pholcodine and NMBD anaphylaxis, for this problem to be addressed.
How many patients were exposed to avoidable harm?
Collected Articles
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Anaphylactic reactions to neuromuscular blocking agents during general anesthesia constitute a major cause of concern and a great source of debate among anesthesiologists. The authors' recent investigations, taking the striking differences of incidence between Norway and Sweden as the point of departure, have provided valuable insights into the pathogenetic mechanisms and the highly uneven geographical distribution of these rare, but dramatic and notoriously unpredictable, events. ⋯ This new knowledge led to the withdrawal of the drug from the Norwegian market and to the examination of the role of pholcodine-containing drugs in other countries. The present article is a brief summary of the research behind this development.
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Comparative Study
Pholcodine stimulates a dramatic increase of IgE in IgE-sensitized individuals. A pilot study.
A previous study showed a relation between pholcodine (PHO) consumption, prevalence of IgE-sensitization to PHO, morphine (MOR) and suxamethonium (SUX) and anaphylaxis to neuromuscular blocking agents (NMBA). The purpose of this pilot study was to explore the effect on IgE production, in IgE-sensitized and nonsensitized individuals, of exposure to cough syrup and environmental chemicals containing PHO, MOR and SUX related allergenic structures. ⋯ It seems as cough syrups containing PHO have a most remarkable IgE boostering effect in persons IgE-sensitized to PHO, MOR and SUX related allergens. Household chemicals containing such allergenic epitopes seem capable of some, minor, stimulation.
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Pholcodine consumption greatly increases the risk of NMBD anaphylaxis (OR 14.0).
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Multicenter Study
National pholcodine consumption and prevalence of IgE-sensitization: a multicentre study.
The aim of this study was to test, on a multinational level, the pholcodine (PHO) hypothesis, i.e. that the consumption of PHO-containing cough mixtures could cause higher prevalence of IgE antibodies to PHO, morphine (MOR) and suxamethonium (SUX). As a consequence the risk of anaphylaxis to neuromuscular blocking agents (NMBA) will be increased. ⋯ This international prevalence study lends additional support to the PHO hypothesis and, consequently, that continued use of drugs containing this substance should be seriously questioned. The results also indicate that other, yet unknown, substances may lead to IgE-sensitization towards NMBAs.
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Randomized Controlled Trial
Pholcodine exposure raises serum IgE in patients with previous anaphylaxis to neuromuscular blocking agents.
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. ⋯ 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.
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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. ⋯ 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.
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World Allergy Organ J · Jul 2012
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. ⋯ 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.
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Asia Pacific allergy · Apr 2014
Pholcodine consumption and immunoglobulin E-sensitization in atopics from Australia, Korea, and Japan.
High pholcodine consumption in Australia is associated with higher prevalence of IgE antibodies to suxamethonium and probably a higher risk of anaphylaxis to NMBDs.
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Hairdressers demonstrate increased IgE sensitisation to neuromuscular blocking drugs due to occupational exposure to quaternary ammonium ion compounds.
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Neuromuscular blocking agents (NMBAs) remain the leading cause of perioperative anaphylaxis in Australia. Standard evaluation comprises history, skin tests, and in vitro specific immunoglobulin E tests. Drug provocation tests to suspected NMBA culprits are associated with a significant risk. Basophil activation testing (BAT) is a potentially useful in vitro test that is not commercially available in Australia or as part of standard evaluation. ⋯ BAT may be a useful supplement to the standard evaluation in diagnosing NMBA anaphylaxis in patients with suggestive histories, but no sensitisation on skin tests. Ongoing study of this specific group of patients is required to clarify its utility in clinical practice.
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Anaesth Intensive Care · Nov 2012
Case ReportsFailure to investigate anaesthetic anaphylaxis resulting in a preventable second anaphylactic reaction.
We present a case of anaphylaxis to suxamethonium and/or vecuronium in a patient who had previously suffered an anaphylactic reaction, presumably to rocuronium. The patient had not been referred for formal allergy testing after the first anaphylactic reaction. Subsequent formal allergy testing revealed sensitivities to suxamethonium, rocuronium and vecuronium. ⋯ It is recommended that all patients with suspected perioperative anaphylaxis are referred for testing. This is the responsibility of the anaesthetist. Particular caution should be used with suspected neuromuscular blocking drug allergy as cross-reactivity is common and not predictable by drug structure.
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Br J Clin Pharmacol · Jul 2014
ReviewExploring 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. ⋯ 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.
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