Sensitization to omeprazole in the occupational setting

Summary Background Omeprazole is a proton pump inhibitor for the treatment of gastric acid-related disorders. In recent years, reports of dermatitis upon exposure to omeprazole during manufacture have been noted. Objective To present diagnostic findings in workers who reported suspected hypersensitivity reactions resulting from occupational exposure to omeprazole. Methods Ninety-six workers exposed to omeprazole during the manufacturing process underwent investigation by the AstraZeneca Occupational Health Centre (Sodertalje, Sweden) for suspected allergy. All subjects underwent a lymphocyte transformation test (LTT) and a skin test within 6 months of the clinical reaction. Predictive tests on guinea-pigs were conducted to establish omeprazole's sensitizing potential. Results Thirty-one subjects with clinical symptoms had a positive LTT result. Twenty-eight subjects had positive patch test results; of these, 23 also had a positive LTT result (sensitivity of the LTT: 82%). Fifty-six subjects had negative patch test results; 46 of these had a negative LTT result (specificity: 82%). All subjects who underwent prick testing (n = 18) had negative results. Delayed contact hypersensitivity was observed in 18 of 20 test animals. Conclusions These findings confirm the risk of sensitization to omeprazole from occupational exposure. They are of importance for the development of new formulations of omeprazole, or its enantiomers, in light of the potential for inducing skin allergy.