Indolo[2,1-c][1,4]benzodiazepines: a new class of antiallergic agents

A series of 12-(cyclic alkylamino)-6H-indolo[2,1-c][1,4]benzodiazepines were synthesized that possess antihistamine and antiserotonin activities as well as ability to inhibit mediator release. Compound 6a, 12-(4-methyl-1-piperazinyl)-6H-indolo[2,1-c][1,4]benzodiazepine was a more potent inhibitor of serotonin release than disodium cromoglycate (DSCG) and ketotifen and approximately equivalent to oxatomide. In the in vivo tests (PCA and ALA), compound 6a was equivalent or superior to DSCG and oxatomide. These agents have potential for the treatment of a variety of allergic conditions.