Picenadol (LY-97435) is a 4-phenylpiperidine derivative that is an opioid analgesic drug developed by Eli Lilly in the 1970s.

[1] Picenadol is an effective analgesic with similar efficacy to pethidine (meperidine).

It has been investigated for some applications such as obstetrics[2] and dentistry,[3] but never commercialised.

It is unusual in that one enantiomer is a pure μ-opioid agonist, while the other is an antagonist.

[5] This means that the racemic mix of the two enantiomers is a mixed agonist-antagonist, with relatively low abuse potential, and little of the κ-opioid activity that tends to cause problems with other opioid mixed agonist-antagonists such as pentazocine.