; (2) in subsection (b), by adding at the end the following: (6) Schedule A (A) In general The drug or substance— (i) has— (I) a chemical structure that is substantially similar to the chemical structure of a controlled substance in schedule I, II, III, IV, or V; and (II) an actual or predicted stimulant, depressant, or hallucinogenic effect on the central nervous system that is substantially similar to or greater than the stimulant, depressant, or hallucinogenic effect on the central nervous system of a controlled substance in schedule I, II, III, IV, or V; and (ii) is not— (I) listed or otherwise included in any other schedule in this section or by regulation of the Attorney General; and (II) with respect to a particular person, subject to an exemption that is in effect for investigational use, for that person, under section 505 of the Federal Food, Drug, and Cosmetic Act ( 21 U.S.C. 355 ) to the extent conduct with respect to such substance is pursuant to such exemption. (B) Predicted stimulant, depressant, or hallucinogenic effect For purpose of this paragraph, a predicted stimulant, depressant, or hallucinogenic effect on the central nervous system may be based on— (i) the chemical structure and— (I) the structure activity relationships; or (II) binding receptor assays and other relevant scientific information about the substance; (ii) (I) the current or relative potential for abuse of the substance; and (II) the clandestine importation, manufacture, or distribution, or diversion from legitimate channels, of the substance; or (iii) the capacity of the substance to cause a state of dependence, including physical or psychological dependence that is similar to or greater than that of a controlled substance in schedule I, II, III, IV, or V.