This group comprises agents which produce general anesthesia, surgical analgesia or neuroleptanalgesia. See also M03A - Peripherally acting muscle relaxants.
Benzodiazepine derivatives are classified in N05BA or N05CD.

Opioid anesthetics in combination with other anesthetics are classified in this group at separate 5th levels using the corresponding 50-series.
Transdermal, nasal and sublingual formulations of fentanyl are classified in N02AB.
Fentanyl in combination with bupivacaine for e.g. postoperative pain is classified in N01AH51 - fentanyl, combinations.