[Study of cross reactivity between proton pump inhibitors]

Although rare, anaphylactic reactions induced by PPIs have been reported. The presence of cross-reactivity between different members of the group is not clear. We analyzed all cases of allergic skin reactions to PPIs notified in regional pharmacovigilance center of Sfax during a 12 years period and assessed the possibility of cross-reactions between different molecules of this class. An enquiry of pharmacovigilance was conducted for each case according to the French imputation method. We called then, all patients who developed an allergic reaction to a PPI with a plausible or credible imputation. A patch test to all the molecules was carried out to study the possibility of cross-reactivity between PPIs. Thirty-seven patients have developed skin disease, with a total of 1 172 cutaneous adverse effects (3%) notified in our regional pharmacovigilance center. The skin disease most frequently observed was maculopapular rash (19 cases or 51%), followed by urticaria in 9 cases (24%). The omeprazole was the most implicated in the genesis of these adverse events (in 31 cases: 83.78%). Lansoprazole was administered to 5 patients having allergy to omeprazole with good tolerance. Patch tests were realized for6 patients having allergy to omeprazole. They were positive with omeprazole at 72 h in all cases and negative with lansoprazole in 5 cases. In one third of cases, lansoprazole was a good alternative at patients developing allergy to omeprazole, esomeprazole or pantoprazole. In one case we have contraindicated all PPIs. In the other cases we have preconized surveillance for the use of lansoprazole.