This group comprises preparations used in the treatment of epilepsy and related conditions (e.g. seizures).
Combined preparations are classified at separate 5th levels using the corresponding 50-series.
The group is subdivided according to chemical structure.

Barbiturates used mainly as hypnotics/sedatives are classified in N05C - Hypnotics and sedatives.
Phenobarbital, which is used both as an antiepileptic and as a sedative, is classified in this group.
Combinations with phenytoin are classified in N03AB.