alpha 2-Adrenoceptor antagonistic benzoquinolizines

摘要

The invention concerns benzoquinolizines of formula <IMAGE> (I) and their pharmaceutically acceptable acid addition salts. In the formula R1 and R2 which may be the same or different each represent hydrogen, lower alkyl, lower alkoxy or halogen, R3represents methyl or ethyl, A represents a direct bond between the S and N atoms or a lower alkylene group having 1 to 3 carbon atoms in the chain between the S and N atoms, R4 and R5 each independently represent hydrogen, lower alkyl, aryl or aryl(lower)alkyl or together with the nitrogen atom to which they are attached represent a five or six membered heterocyclic ring. The compounds possess alpha 2-adrenoceptor antagonistic activity and can be incorporated into pharmaceutical compositions.