Coaches fall under the AFL anti doping code.
Coaches do indeed fall under the AFL anti-doping code (section 3), but this sub-section is relevant;
3.2 Any Player, Club, Officer, Official or other Person to whom this Code applies who commits an Anti Doping Rule Violation or otherwise breaches the provisions of this Code is liable to the sanctions provided by the Code
particularly in relation to section 11 'ANTI DOPING RULE VIOLATIONS' (the 'prohibition' section);
11.2 Use or Attempted Use by a Player of a Prohibited Substance or a Prohibited Method
11.6 Possession of Prohibited Substances or Prohibited Methods
11.8 Administration or Attempted administration to any Player In-Competition of any
Prohibited Method or Prohibited Substance, or administration or Attempted
administration to any Player Out-of-Competition of any Prohibited Method or any
Prohibited Substance that is prohibited Out-of-Competition
You will note that the code differentiates between 'use' (by a player) and 'possession/administration' (by all
those covered by the code).
AFL/ASADA/WADA regulations regarding coaches/support personnel relate to the possession/administration of substances banned for athletes/players, not the personal use of those substances by the coaches/support personnel.
http://www.aflcommunityclub.com.au/fileadmin/user_upload/Play_AFL/AFLAnti-DopingCode2010ASADA.pdf