; and (B) in the absence of guidance with respect to a substance or group of substances as described in paragraph (A), use equivalencies for the following structural classes of substances as if they were included on the Drug Equivalency Tables: Drug Class Marihuana Equivalency of 1 gm of subject substance Synthetic Opioids 1 gm = 10 kg Synthetic Cannabinoids 1 gm = 167 gm Synthetic Cathinones 1 gm = 380 gm Tryptamine 1 gm = 80 gm Phenethylamines 1 gm = 2.5 kg Piperazines 1 gm = 2 kg Benzofurans 1 gm = 500 gm Arylcyclohexylamines (PCP-like substances) 1 gm = 1 kg Methylphenidate analogs 1 gm = 100 gm Benzodiazepines 1 unit (as defined in Note (F) to the Drug Quantity Table in 2D1.1) = 0.0625 gm In the case of a substance for which paragraphs (A) and (B) above are not applicable, the court shall determine an equivalency or ratio by considering the following factors, to the extent practicable: . 10. Rules of construction Nothing in this Act, or the amendments made by this Act, may be construed to limit— (1) the prosecution of offenses involving controlled substance analogues under the Controlled Substances Act ( 21 U.S.C. 801 et seq.); or (2) the authority of the Attorney General to temporarily or permanently schedule, reschedule, or decontrol controlled substances under provisions of section 201 of the Controlled Substances Act ( 21 U.S.C. 811 ) that are in effect on the day before the date of enactment of this Act.