Immediate-Type Hypersensitivity Cross-Reactions to Proton Pump Inhibitors: A Descriptive Study of Data from the French National Pharmacovigilance Database.

BACKGROUND: Proton pump inhibitors (PPIs) can trigger immediate-type hypersensitivity reactions (HSRs). Three main patterns of cross-reactivity have been identified: reactions to a single PPI, selective cross-reactions, and cross-reactions with all PPIs. Several hypotheses have been advanced, but no consensus has been reached.

OBJECTIVE: We sought to identify immediate-type hypersensitivity cross-reactions to PPIs using real-world data about hypersensitivity testing from French pharmacovigilance cases.

METHODS: Potentially relevant immediate-type HSRs reported from January 1985 to February 2015 were extracted from the French pharmacovigilance database using a standardized MedDRA query (SMQ). Cases describing skin tests or oral provocation tests (OPTs) performed with several PPIs that yielded at least one positive result were included.

RESULTS: The SMQ extracted 2,119 cases, 38 of which were included in our study. Data collected from skin tests and OPTs indicated cross-reactions with all PPIs (n = 1), reactions to a single PPI (n = 14), or selective cross-reactions (n = 23). Esomeprazole, omeprazole, and pantoprazole concerned 78% of all selective cross-reactions. In more than half of the cases (55.3%), only 2 PPIs were tested.

CONCLUSION: To the best of our knowledge, this PPI cross-reactivity study is the largest to date in terms of population size, describing 38 immediate-type HSRs to PPIs explored by skin tests or OPTs. This paucity of data belies the lack of standardized procedures for PPI hypersensitivity testing. It is likely that PPI HSR workups in everyday clinical practice are often incomplete. Further research to gain insight into selective cross-reactions between PPIs is needed. In the meantime, thorough workups should be completed when a PPI is suspected to have triggered an HSR, instead of routine contraindication to all PPIs.