Effect of Switching the Histamine-1 Receptor Antagonist Clemastine to Cetirizine in Paclitaxel Premedication Regimens: The H1-Switch Study

PURPOSEPremedication, including a histamine-1 receptor (H1) antagonist, is recommended to all patients treated with paclitaxel chemotherapy to reduce the incidence of hypersensitivity reactions (HSRs). However, the scientific basis for this premedication is not robust, which provides opportunities for optimization. Substitution of intravenously administered first-generation H1 antagonist for orally administered second-generation H1 antagonist could reduce side effects, and improve efficiency and sustainability. This study investigates the efficacy and safety of substituting intravenous clemastine for oral cetirizine as prophylaxis for paclitaxel-induced HSRs.METHODSThis single-center, prospective, noninferiority study compares a historic cohort receiving a premedication regimen with intravenous clemastine to a prospective cohort receiving oral cetirizine. Primary end point of the study is HSR grade >= 3. The difference in incidence was calculated together with the 90% CI. We determined that the two-sided 90% CI of HSR grade >= 3 incidence in the oral cetirizine cohort should not be more than 4% higher (ie, the noninferiority margin) compared with the intravenous clemastine cohort.RESULTSTwo hundred and twelve patients were included in the oral cetirizine cohort (June 2022 and May 2023) and 183 in the intravenous clemastine cohort. HSR grade >= 3 incidence was 1.6% (n = 3) in the intravenous clemastine cohort and 0.5% (n = 1) in the oral cetirizine cohort, resulting in a difference of -1.2% (90% CI, -3.4 to 1.1).CONCLUSIONPremedication containing oral cetirizine is as safe as premedication containing intravenous clemastine in preventing paclitaxel-induced HSR grade >= 3. These findings could contribute to optimization of care for patients and improve efficiency and sustainability. Oral cetirizine is a nonsedative, easy, and effective alternative for IV antihistamines before paclitaxel.