When it comes down to it, those who study the hardest for the longest tend to be the better players, no matter what drugs anyone is or isnt using. So just chill out, do what your most comfortable doing ( drugwise) and leave drugtesting to the physical sports, where drugs have actually been proven to make a difference.
I have found that I play best stone cold sober, so if I play that way in a tournament, does that give me an unfair advantage? of course not. So if my opponent plays best on a combination of idebenone and oxiracetam, he is just playing in his comfort zone, where he has found, or thinks he has found, he plays best. not an unfair advantage over me. Just learn about yourself and do what fits.
nobody needs any drugs to play chess or any other game. just hard work and honesty.