Azaprocin is a drug which is an opioid analgesic with approximately ten times the potency of morphine, and a fast onset and short duration of action.

[1][2][3] It was discovered in 1963, but has never been marketed.

The derivative substituted on the phenyl ring with a p-nitro group is more potent than the parent compound, around 25× the potency of morphine.

[4] The ring-opened 2,6-dimethylpiperazine analogues are also active,[5] and a large family of opioid analgesic compounds derived from this parent structure have been developed over the last 40 years.

[6][7][8][9][10][11][12][13][14][15] One analogue, AP-237, has been used in China to treat the pain caused by cancer.