The molecule has a bicyclic aromatic skeleton, specifically an isoquinoline framework (a pyridine ring fused to a benzene ring, with the pyridine nitrogen not adjacent to the fusion junctions).

For clarity, the atoms are numbered as follows: starting from the pyridine nitrogen as N1, then C2-C3 (fusion junction)-C4-C5-C6-C7-C8 (fusion junction)-C9-C10, returning to N1.

Substitution pattern on this ring system:
- C2 carries a hydroxyl group.
- C7 also carries a hydroxyl group.
- C10 is directly bonded to the nitrogen of a piperidine ring (a fully saturated six-membered heterocycle containing one nitrogen). On the carbon opposite the nitrogen in this piperidine, there is a dimethylamino group (-N(CH3)2).