The pharmacokinetics of testosterone cypionate via depot intramuscular injection , including its elimination half-life and duration of action , are said to be extremely comparable to and hence essentially the same as those of testosterone enanthate .   As such, testosterone cypionate and testosterone enanthate are considered to be "functionally interchangeable" as medications.  For reference, testosterone enanthate has an elimination half-life of days and a mean residence time of days and requires frequent administration of approximately once per week.  Large fluctuations in testosterone levels result with it, with levels initially being elevated and supraphysiological.  The pharmacokinetics of testosterone cypionate have been studied and reported. 
Because the ultimate goal of a steroid cycle is to increase strength and muscle size, the associated spike in estrogen which accompanies steroids such as Testosterone is considered undesirable. In order to disassociate the two effects, two classes of drug are used. Medications such as Nolvadex or Clomid target the estrogen receptors. They make it more difficult for the estrogen to exert it’s influence within the body thus allowing the testosterone to act more freely. The second class is aromatase inhibitors such as Femara. They target the aromatase enzyme itself in order to prevent the production of estrogen in the first place. Sometimes, it’s not always clear which option you should go with or even what the differences are between the two. Lets clear that up a little.
Drug abuse is intentional non-therapeutic use of a drug, even once, for its rewarding psychological and physiological effects. Abuse and misuse of testosterone are seen in male and female adults and adolescents. Testosterone, often in combination with other anabolic androgenic steroids (AAS), and not obtained by prescription through a pharmacy, may be abused by athletes and bodybuilders. There have been reports of misuse by men taking higher doses of legally obtained testosterone than prescribed and continuing testosterone despite adverse events or against medical advice.