Anaphylaxis to omeprazole.
BACKGROUND
Omeprazole is a non-competitive inhibitor of the parietal cell enzyme H+-K--adenosine triphosphatase. To date, two cases of angioedema and urticaria and two cases of anaphylaxis from omeprazole have been published.


OBJECTIVE
To report a new patient with omeprazole-induced anaphylaxis demonstrated by skin tests and increased serum tryptase levels.


RESULTS
Elevated serum tryptase levels (5.1 U/L) were detected 6 hours after the onset of the anaphylaxis. Skin intradermal tests were positive with omeprazole i.v. (4 mg/mL), omeprazole capsules diluted in saline serum (20 mg/ mL), and lansoprazole (30 mg/mL). Serum specific IgE anti-omeprazole was negative.


CONCLUSIONS
According to the elevated serum tryptase levels and the positive skin test results, anaphylaxis was due to use of omeprazole. We think the adverse reaction to omeprazole was induced by an IgE-mediated hypersensitivity mechanism to omeprazole itself and not to a metabolite. We have also demonstrated crossreactivity, at least by skin tests, between omeprazole and lansoprazole.
Galindo
P A
PA
Allergy Section, Hospital Complex, Ciudad Real, Spain.
Borja
J
J
Feo
F
F
Gómez
E
E
García
R
R
Cabrera
M
M
Martínez
C
C
D000328:Adult; D000707:Anaphylaxis / Q000139:chemically induced*; D053818:Chymases; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D018836:Inflammation Mediators / Q000097:blood; D007428:Intradermal Tests; D008297:Male; D009853:Omeprazole / Q000009:adverse effects*; D011863:Radioimmunoassay; D012697:Serine Endopeptidases / Q000097:blood; D053802:Tryptases