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.
Anabolic steroid implants are allowed for veterinary use. But if someone diverts this for use in humans, it will be deemed as a distribution of a Schedule III drug leading to prosecution. The law on trenbolone differs in other countries. For instance, in Canada it is a Schedule IV drug. In Canada, all anabolic steroids are classified as Schedule IV drugs. In the UK, anabolic steroids are classified as Class C substances. Their possession can lead to a 2 year jail term, while their production and supply can lead to a 14 year jail term. But many countries do not have strict laws. In some places, you can even buy it over the counter.