(20) Tetrahydrocannabinols. Synthetic tetrahydrocannabinols not derived from the cannabis plant that are equivalents of the substances contained in the plant, or in the resinous extractives of cannabis, sp. and/or synthetic substances, derivatives, and their isomers with similar chemical structure and pharmacological activity such as the following:
delta 1 cis or trans tetrahydrocannabinol, and their optical isomers
delta 6 cis or trans tetrahydrocannabinol, and their optical isomers
delta 3, 4 cis or trans tetrahydrocannabinol, and its optical isomers (since nomenclature of these substances is not internationally standardized, compounds of these structures, regardless of numerical designation of atomic positions covered). Any Federal Food and Drug Administration approved product containing tetrahydrocannabinol shall not be considered a synthetic tetrahydrocannabinol.