Flurbiprofen (Ansaid) cross-sensitivity in an aspirin-sensitive asthmatic patient

Classification of reactions to nonsteroidal antiinflammatory drugs

Hypersensitivity reactions to NSAIDs may occur in susceptible individuals and vary in symptom (skin, respiratory tract, and solid organs), severity (from mild skin or respiratory reactions to severe generalized) and timing (from acute to delayed). The current classification of NSAID-induced reactions emerged with the understanding of the pathologic mechanism of reactions to NSAIDs which may be either non-allergic (related to cyclooxygenase inhibition) or immunologically mediated. In this chapter we discuss the implications of accurate NSAIDs hypersensitivity classification for proper diagnosis and patient management.

Crossreacting drugs and chemicals

Aspirin and nonsteroidal antiinflammatory drugs (NSAIDs) exert their clinical effect through inhibition of prostaglandin H synthases 1 and 2, also known as cyclooxygenase. This shared effect of COX-inhibition is also the mechanism for shared adverse effects. Much of our understanding of cross-reacting drugs and chemicals with aspirin comes from studying asthmatics with aspirin-exacerbated respiratory disease (AERD). Aspirin exacerbated respiratory disease is characterized by recalcitrant sinusitis/polyposis, asthma and precipitation of asthma after ingestion of aspirin and most NSAIDs. Cross-reactions between ASA and NSAIDs occur with first exposure unlike IgE-mediated allergic drug reactions. Cross-reactions between aspirin and other drugs are dependent upon inhibition of the cyclooxygenase-1 isoenzyme. Desensitization to aspirin will result in cross-desensitization to all NSATDs that inhibit COX-1. Despite reports in the literature, there does not appear to he cross-reactions between food coloring, hydrocortisone succinate and monosodium glutamate in individuals with aspirin exacerbated respiratory disease. The new highly selective cyclooxygenase 2 inhibitors are well tolerated in AERD asthmatics who have not been desensitized to aspirin. Because low-dose ASA exerts a cardioprotective effect by irreversible inhibition of COX-1, AERD patients who are at risk for coronary artery disease should be considered for aspirin desensitization.

The use of analgesics in patients with asthma

Aspirin (acetylsalicylic acid) and other nonsteroidal anti-inflammatory drugs (NSAIDs) cause deterioration in respiratory function in approximately 10% of adults with asthma and a smaller proportion of children with asthma. We propose evidence-based guidelines for the safe use of NSAIDs in individuals with asthma following systematic review of data from the last 10 years relevant to the use of these drugs in such patients. We would currently recommend that patients with asthma who are known to be intolerant of NSAIDs or who exhibit any of the high risk clinical features for intolerance to these drugs (severe asthma, nasal polyps or chronic rhinosinusitis) should use NSAIDs only under close medical supervision. In those with high risk features formal aspirin provocation testing would be recommended prior to the therapeutic use of NSAIDs. Those individuals with asthma who regularly use NSAIDs can continue to do so but should be warned that intolerance to NSAIDs can develop late in life. Lack of relevant experimental evidence precludes the production of evidence-based guidelines for the group of patients with asthma who do not exhibit high risk clinical features and who have never before used NSAIDs. We would currently recommend that this group be treated as potentially intolerant to NSAIDs and use of these drugs can only be recommended under medical supervision but note that further studies and clinical experience could be expected to relax this restriction for many patients. Recent data have suggested that frequent use of paracetamol (acetaminophen) may contribute to a deterioration of respiratory function in asthma. A small proportion of patients with asthma who are NSAID-intolerant experience short-lived deterioration in respiratory function with the use of high doses of paracetamol but this is uncommon and has not been implicated in life-threatening reactions. Routine warnings about paracetamol use in asthma are, therefore, not warranted. Medical personnel, however, should be aware of the potential for worsening of symptoms in some individuals with asthma using paracetamol and institute formal investigation or withdrawal of the drug if they suspect such a reaction.

Potential renal, haematological and allergic adverse effects associated with nonsteroidal anti-inflammatory drugs

The major benefits of the perioperative administration of nonsteroidal anti-inflammatory drugs (NSAIDs) are related to the ability of these agents to provide analgesia without cardiovascular or respiratory depression. However, there are several possible adverse effects of NSAIDs. All NSAIDs reduce the synthesis of prostaglandins by the kidneys, but their administration in the perioperative period appears to have little potential for renal toxicity when adequate hydration is maintained and renal function is not dependent on renal prostaglandins. However, NSAIDs may cause impairment of renal function in patients with conditions such as hypovolaemia, congestive cardiac failure, or hepatic cirrhosis, since renal function in these patients may be dependent on the vascular effects of prostaglandins. Platelet aggregation is inhibited by the administration of NSAIDs, and most studies of their haematological effects report that NSAIDs are associated with an increase in bleeding times. In patients with normal haemostatic function before NSAID administration, almost all indices of coagulation remain within the normal range after NSAID treatment. Most studies of perioperative blood loss have reported no significant difference between the effects of NSAIDs and placebo in this regard. The incidence of major allergic reactions in the general population appears to be small with NSAIDs. Overall, NSAIDs appear to be safe and well tolerated drugs with a valuable role to play in the treatment of postoperative pain.