A61K 31/4015

Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having five-membered rings with one nitrogen as the only ring hetero atom, e.g. sulpiride, succinimide, tolmetin, buflomedil having oxo groups directly attached to the heterocyclic ring, e.g. piracetam, ethosuximide