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.