It is well known that Clenbuterol use results in rapid down-regulation of beta 2 receptors. This is due to the powerful stimulatory effect of the drug. It is therefore pointless to use clen for long periods without a break. Some believe that a two day on, two day off dosing schedule will allow adequate potential for receptor up-regulation. However, I doubt this to be the case due to the relatively long half life of clen, resulting in continued stimulation even throughout the ‘off’ days. A much better regime would be a two week on, two week off cycle. Maximum plasma levels are reached around 2-3 hours after oral administration, and terminal half life at 34 hours (Zimmer, 1976).
As for individual use of a personal nature, outside therapeutic treatment, this is where we will find the vast majority of anabolic steroids. It is here we will also find the biggest problems, not in terms of ill-effects of a physical or mental nature but of those surrounding legality. In places like the . anabolic steroids are controlled substances, and here we will find the strictest of laws. This has created a new class of criminal; most commonly an adult man with a family who is simply living an every day life like everyone else. These are issues that need to be discussed and you will find very few are willing to touch them unlike .
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.