Clinical doses of available H1 antihistamines are limited mainly by sedative side effects. However, higher doses are often required to obtain optimal therapeutic activity, especially in dermatology. We report the synthesis of three norpiperidine imidazoazepines representative of a new class of selective and nonsedating H1 antihistamines. The compounds were at least as potent as cetirizine and loratadine as measured by H1 receptor binding affinity, by ...