5PSQ-014 Impact of histamine-2 antagonist shortage on the incidence of hypersensitivity reactions to paclitaxel – towards crisis management and a premedication reconsideration in France (PACLIREACT Study)

Background and ImportanceAt the beginning of October 2019, an international shortage of ranitidine forced us to adjust paclitaxel-based chemotherapy premedication regimens. After several modifications, we implemented an anti-allergic premedication protocol based on Dexchlorpheniramine as histamine-1 antagonist (H1A), Methylprednisolone as corticosteroid (Double dose at first injection) and withdrawal of histamine-2 antagonists (H2A).Aim and ObjectivesThis study aimed to determine the efficacy of this modified regimen and assess the hypersensitivity reactions (HSRs) associated with it.Material and MethodsWe conducted a single-centre observational retrospective study of paclitaxel administrations (n=831 patients). All incidents characterised as drug allergies in the prescribing software were exhaustively recorded over a two-year period from January 2019 to December 2020 (before and after ranitidine shortage, including the period with oral Famotidine as a transitional alternative). To model the risk of allergy at each injection according to the type of injection and possible confounding factors, a mixed logistic regression model was implemented to account for repeated administration per patient.ResultsAmong the 7146 paclitaxel administrations, there were a total of 27 HSRs occurring in 24 patients, among whom three patients had two consecutive events. No protective effect was observed for H2A premedication regimens, neither when comparing the two types of H2A (famotidine or ranitidine) separately (p = 0.94) nor when comparing injections with H2A premedication versus injections without H2A (OR: 1.12, 95% CI, 0.36-3.50, p = 0.84). However, the risk of HSRs was significantly lower for paclitaxel injections with corticosteroids than for those without corticosteroids (OR: 0.08, 95% CI: 0.008-0.78, p = 0.03). In addition, the risk of HSR was significantly higher for the first, second, or third paclitaxel injections than for the subsequent injections (OR: 10.1, 95% CI: 3.23-31.4, p < 0.001).Conclusion and RelevanceWe did not find evidence of an increased risk of HSR due to the absence of H2A in the premedication protocols of Paclitaxel. Our findings support the choice of a premedication protocol without H2A, despite what is historically stated in Paclitaxel monographs.References and/or AcknowledgementsConflict of InterestNo conflict of interest