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Clinical data
Drug classOpioid
Legal status
Legal status
CAS Number
Chemical and physical data
Molar mass354.469 g·mol−1
3D model (JSmol)

NFEPP (N-(3-fluoro-1-phenethylpiperidin-4-yl)-N-phenylpropionamide) is an analgesic opioid chemical, similar in structure to fentanyl, designed in 2016 by Spahn et al. from Free University of Berlin[2] to avoid the standard negative side effects of opiates, including opioid overdose, by only targeting inflamed tissue.[3]

Inflamed tissue

Inflamed tissue has a lower pH value (~5–7) than non-inflamed tissue (7.4).[4] Through computer simulation, scientists found a way to make the fentanyl analog only affect inflamed tissue via the addition of fluorine to the chemical structure. In experiment, it was shown that NFEPP produced injury-restricted analgesia in rats with different types of inflammatory pain without exhibiting typical opiate effects, including respiratory depression, sedation, constipation, and chemical seeking behavior.

As a result, NFEPP has the potential to reduce opioid addiction and dependency, as there is no effect on users who are not actually suffering from pain, as the chemical does not interact with non-inflamed brain tissue.


  1. ^ Drug Enforecement Administration, Department of Justice (2018). "Schedules of Controlled Substances:Temporary Placement of Fentanyl-Related Substances in Schedule I. Temporary amendment; temporary scheduling order". Federal Register. 83 (25): 5188–92. PMID 29932611.
  2. ^ Spahn, V.; Del Vecchio, G.; Labuz, D.; Rodriguez-Gaztelumendi, A.; Massaly, N.; Temp, J.; Durmaz, V.; Sabri, P.; Reidelbach, M.; Machelska, H.; Weber, M.; Stein, C. (2017). "A nontoxic pain killer designed by modeling of pathological receptor conformations". Science. 355 (6328): 966–969. doi:10.1126/science.aai8636. PMID 28254944.
  3. ^ "An opioid minus major side effects". Chemical & Engineering News. 95 (10): 8. 2017.
  4. ^ "Early study suggests new opioid is non-addictive, works only where it hurt". Ars Technica. 4 March 2017.