(2) A substance is a controlled drug if the substance (the drug analogue) is, in relation to a controlled drug listed in subsection (1) (or a
stereoisomer, a structural isomer (with the same constituent groups) or an alkaloid of such a controlled drug):
(a) a stereoisomer; or
(b) a structural isomer having the same constituent groups; or
(c) an alkaloid; or
(d) a structural modification obtained by the addition of one or more of the following groups:
(i) alkoxy, cyclic diether, acyl, acyloxy, mono‑amino or dialkylamino groups with up to 6 carbon atoms in any alkyl
residue;
(ii) alkyl, alkenyl or alkynyl groups with up to 6 carbon atoms in the group, where the group is attached to oxygen
(for example, an ester or an ether group), nitrogen, sulphur or carbon;
(iii) halogen, hydroxy, nitro or amino groups; or
(e) a structural modification obtained in one or more of the following ways:
(i) by the replacement of up to 2 carbocyclic or heterocyclic ring structures with different carbocyclic or
heterocyclic ring structures;
(ii) by the addition of hydrogen atoms to one or more unsaturated bonds;
(iii) by the replacement of one or more of the groups specified in paragraph (d) with another such group or groups;
(iv) by the conversion of a carboxyl or an ester group into an amide group; or
(f) otherwise a homologue, analogue, chemical derivative or substance substantially similar in chemical structure;
however obtained, except where the drug analogue is separately listed in subsection (1).