The occurrence and frequency of anaphylactic reactions in the use of infliximab – a prospective study in a large single center

Introduction: Antagonizing Tumor Necrosis Factor Alpha (TNFα) has become an effective strategy in treatment of moderate and severe Crohn's disease (CD) and ulcerative colitis (UC). Infliximab (Remicade, Schering Plough), a recombinant IgG1 monoclonal antibody, was the first TNF-α-antibody approved for the treatment of CD and UC, respectively. Since anaphylactic reactions occur frequently with infliximab, we analyzed prospectively the frequency of these reactions in a normal clinical single center. Methods: Frequency and character of infliximab induced anaphylactic reactions in treatment of severe and refractory CD and UC were analyzed prospectively between February 2007 and February 2008. In all patients, infliximab infusions were performed every 8 weeks after an induction treatment at weeks 0, 2, and 6. 5mg/kg infliximab were infused over 2 hours in 250ml of NaCl solution for injection. No patient was given antihistamines or steroids other than baseline treatment of their UC or CD. In all patients who once experienced allergic reaction, study participation was terminated. Results: A total collective of 177 patients received treatment with a median of 4 (range 1–11) infusions each. Overall 716 infusions were performed containing a median dose of 350mg (range 150–700mg). During 12 months of observation, 33 anaphylactic reactions appeared, resulting in an overall rate of 4.6% based on the number of infusions and of 15.8% based on the number of patients. In median, allergic reaction occurred at the second infusion (range 1–9). They consisted of tachycardia, flush, dyspnea, abdominal spasms and edema. Infusions were stopped immediately at the onset of symptoms. All patients recovered completely within 40 minutes after treatment with antihistamines and prednisolone (150–250mg). One patient was admitted to hospital over night for safety reasons without further complications observed. Seven of 12, who were retreated with infliximab after a pause of more than 5 months, developed allergic reactions. Conclusion: Anaphylactic reactions are the most frequent side effect of infliximab (16%), whereas most reactions are mild to moderate, characterized by flush and edema. Resumption of infliximab therapy after an interval of more than 5 months seems to enhance its allergic potential.