It is commonly found as a contaminant in samples of drugs containing fentanyl, which may include samples represented by the supplier as heroin or other opioids.

[4] It is not psychoactive and is present only as a result of improper chemical purification.

4-ANPP is useful in the synthesis of pharmaceuticals, primarily fentanyl and related analogs.

Paul Janssen (founder of Janssen Pharmaceutica) first synthesized fentanyl in 1960 using a similar method, with Benzylfentanyl as an intermediate.

[5] The following synthesis, developed by an individual under the pseudonym of Siegfried, involves the reductive amination of N-phenethyl-4-piperidinone (NPP) with aniline to make to 4-ANPP.