Testosterone can be administered parenterally , but it has more irregular prolonged absorption time and greater activity in muscle in enanthate , undecanoate , or cypionate ester form. These derivatives are hydrolyzed to release free testosterone at the site of injection; absorption rate (and thus injection schedule) varies among different esters, but medical injections are normally done anywhere between semi-weekly to once every 12 weeks. A more frequent schedule may be desirable in order to maintain a more constant level of hormone in the system.  Injectable steroids are typically administered into the muscle, not into the vein, to avoid sudden changes in the amount of the drug in the bloodstream. In addition, because estered testosterone is dissolved in oil, intravenous injection has the potential to cause a dangerous embolism (clot) in the bloodstream.
According to the US Food and Drug Administration , "Piracetam is not a vitamin, mineral, amino acid, herb or other botanical, or dietary substance for use by man to supplement the diet by increasing the total dietary intake. Further, piracetam is not a concentrate, metabolite, constituent, extract or combination of any such dietary ingredient. [...] Accordingly, these products are drugs, under section 201(g)(1)(C) of the Act, 21 . § 321(g)(1)(C), because they are not foods and they are intended to affect the structure or any function of the body. Moreover, these products are new drugs as defined by section 201(p) of the Act, 21 . § 321(p), because they are not generally recognized as safe and effective for use under the conditions prescribed, recommended, or suggested in their labeling." 
Even if he’s not on steroids now he most definitely has been at one point in his life before. As a doctor who has dedicated his life to bodybuilding and the science behind it, being a trainer to a lot of celebrities who take steroids without any doubt, plus the impressive (naturally very! unlikely to reach) stats that he has, I can’t believe that he never even tried any kind of body-enhancing drugs. Even if you do steroids for only 1 or 2 years in your life the impact will always be visible and your results much better than those of someone who always stayed natural, even if it’s 30 years after the last time you did it. I think the likeliness of him having done steroids at least once is %.