Background　Guiding principles in the use of antihistamines for patients with long QT syndrome have not been fully discussed, although there are some case reports showing longer QT interval after administration of antihistamines.
Methods　We exhaustively investigated non-clinical electropharmacological profiles of antihistamines according to the ICH-S7B guideline using the drug interview form and research papers, and assessed their risk of QT interval prolongation.
Results　Both in vitro I_Kr assay and in vivo QT assay have been carried out in 13 out of 27 antihistamines, and most of the drugs are second-generation antihistamine. The remaining 14 antihistamines, including most of the first-generation drugs, do not have enough in vivo or in vitro data for accurately assessing the risk of drug-induced QT interval prolongation.
Conclusions　About half of antihistamines have electropharmacological data, which can be utilized for risk assessment of drug-induced QT interval prolongation. Electropharmacological profiles of the first-generation antihistamines should be checked for safety use for patients with long QT syndrome.