"Fentanyl related substance" means any substance not listed in schedule I through V of IC 35-48-2 that is structurally related to fentanyl by one (1) or more of the following modifications:

1. (1) Replacement of the phenyl portion of the phenethyl group by any monocycle, whether or not further substituted in or on the monocycle.
2. (2) Substitution in or on the phenethyl group with alkyl, alkenyl, alkoxyl, hydroxyl, halo, haloalkyl, amino, or nitro groups.
3. (3) Substitution in or on the piperidine ring with alkyl, alkenyl, alkoxyl, ester, ether, hydroxyl, halo, haloalkyl, amino, or nitro groups.
4. (4) Replacement of the aniline ring with any aromatic monocycle whether or not further substituted in or on the aromatic monocycle.
5. (5) Replacement of the N-propionyl group by another acyl group.

As added by P.L.186-2025, SEC.249.