Antihistamine activity, central nervous system and cardiovascular profiles of histamine H₁ antagonists: comparative studies with loratadine, terfenadine and sedating antihistamines in guinea‐pigs

Abstract

The CNS depressant effects of H1 antihistamines are promethazine approximately diphenhydramine >> loratadine = placebo. Of the non-sedating antihistamines, loratadine was devoid of adverse cardiovascular effects whereas terfenadine caused a pronounced disruption of the normal ECG, characterized by a torsades de pointes-like effect.