Spiro compounds have at least two molecular rings with only one common atom. The simplest spiro compounds are bicyclic, or have a bicyclic portion as part of the larger ring system, in either case with the two rings connected through the defining single common atom.

What are spiro compound drugs?

A group of compounds consisting in part of two rings sharing one atom (usually a carbon) in common. An anxiolytic agent used for short-term treatment of generalized anxiety and second-line treatment of depression.

What are bicyclo and spiro compounds?

In “bridged bicyclic” molecules, the two bridgeheads are separated by “bridges” containing at least one carbon. In “spiro” fused molecules, the two rings are both joined at the same carbon.