Injectable steroids are injected into muscle tissue, not into the veins. They are slowly released from the muscles into the rest of the body, and may be detectable for months after last use. Injectable steroids can be oil-based or water-based. Injectable anabolic steroids which are oil-based have longer half-life than water-based steroids. Both steroid types have much longer half-lives than oral anabolic steroids. And this is proving to be a drawback for injectables as they have high probability of being detected in drug screening since their clearance times tend to be longer than orals. Athletes resolve this problem by using injectable testosterone early in the cycle then switch to orals when approaching the end of the cycle and drug testing is imminent.
Drugs can be added and removed from this list by WADA annually, although not all of the banned substances are explicitly named. Caroline Hatton, PhD , a sports anti-doping science consultant, told in a Mar. 12, 2010 email that "A key concept in prohibited lists is that they avoid being finite. Instead of listing all banned drugs one by one, they list entire drug classes and name drugs merely as examples. This is to keep users who took designer drugs from claiming that they didn't break the rules because the drugs they took weren't listed."