The ganglion-blocking activity of aminobicyclo[2,2,1]heptanes (congeners of mecamylamine) and bicyclo[3,2,1]azaoctanes (bridged congeners of pempidine).

The structural requirements for strong ganglion-blocking activity and long duration of action amongst some lower homologues of mecamylamine, together with the discovery of similar activities amongst isomers with enlarged ring structures, are described. In both series of compounds it was found that the successive introduction of C-methyl groups surrounding the nitrogen atom resulted in a progressive increase in ganglion-blocking activity and duration of action.