Anaphylaxis to omeprazole: diagnosis and desensitization protocol.
BACKGROUND
Omeprazole is an inhibitor of the parietal cell enzyme H+/K+ adenosine triphosphatase. Immediate-type hypersensitivity reactions, such as urticaria, angioedema, and hypotension, induced by omeprazole and other proton pump inhibitors are rare.


OBJECTIVE
To confirm the immediate-type mechanism of recurrent anaphylactic reactions to the repeated administration of omeprazole using skin testing and to enable safe administration of the drug after successful oral desensitization.


METHODS
Intradermal skin tests were performed with omeprazole (0.04 and 0.4 mg/mL) prepared from the oral and intravenous commercial preparations and with pantoprazole (0.02 and 0.2 mg/mL) prepared from the oral commercial preparation. Skin tests were repeated after completion of the desensitization. Oral desensitization was applied at a starting dose of 0.001 mg of omeprazole, and a full dose of 16 mg was achieved after 5.6 hours (cumulative dose of 32.6 mg).


RESULTS
Intradermal skin test results were positive to omeprazole and pantoprazole at all tested concentrations. After successful desensitization, omeprazole was administered in the full dose uneventfully. The wheal size of the intradermal skin tests performed after completion of the desensitization was significantly reduced.


CONCLUSIONS
When indicated, this newly designed desensitization protocol may be used in patients with omeprazole-induced anaphylaxis.
Confino-Cohen
Ronit
R
Allergy and Clinical Immunology Unit, Meir General Hospital, Kfar-Saba, Tel-Aviv University Sackler School of Medicine, Tel-Aviv, Israel. ronitco@clalit.org.il
Goldberg
Arnon
A
D000328:Adult; D000707:Anaphylaxis / Q000139:chemically induced / Q000276:immunology / Q000517:prevention & control*; D003888:Desensitization, Immunologic / Q000379:methods*; D004791:Enzyme Inhibitors / Q000009:adverse effects* / Q000276:immunology / Q000627:therapeutic use; D005756:Gastritis / Q000188:drug therapy; D016481:Helicobacter Infections / Q000188:drug therapy; D006801:Humans; D008297:Male; D009853:Omeprazole / Q000009:adverse effects* / Q000276:immunology / Q000627:therapeutic use; D012882:Skin Tests
D004791:Enzyme Inhibitors; D009853:Omeprazole