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.
As of the printing of Anabolics 2000 I reported no preparation that was being made in a dosage over 5mg, but just two years later we now have several preparations carrying l0mg, and one weighing in with an incredible 25mg per tablet. That equates to 5 normal Dianabol tablets worth of steroid, which I think is clearly indicative of a new trend in steroid manufacturing. Understanding that the steroid market in many parts of the world really caters to athletes, many producers have seemingly been rushing to release newer and more shockingly high dosed products. Not only Dianabol, but also versions of Testosterone cypionate, Testosterone propionate, nandrolone decanoate, nandrolone laurate, stanozolol, boldenone undecylenate and oxandrolone have been released in the past two years carrying higher dosages than ever before seen commercially. With the extremely lucrative market for steroids at this time there is little doubt that this trend will continue.
Fed up with muscleheads, Ziegler parted ways with York in 1967. But Dianabol continued to haunt him. Ziegler suffered from heart disease, a condition he partially ascribed to his experimentation with steroids. By the time of his 1983 death from heart failure, Ziegler came out against his invention. "It is bad enough to have to deal with drug addicts, but now healthy athletes are putting themselves in the same category," he wrote in the introduction to Bob Goldman's history of drugs and sports, Death in the Locker Room . "It's a disgrace. Who plays sports for fun anymore?"