Testosterone enanthate ( USAN , BAN ) (brand names Delatestryl , Testostroval , Testro LA , Andro LA , Durathate , Everone , Testrin , Andropository ), or testosterone heptanoate , is an androgen and anabolic steroid and a testosterone ester .    Along with testosterone cypionate and testosterone propionate , it is one of the most widely used testosterone esters.  Testosterone enanthate was first introduced in 1952.  Administered via intramuscular injection , it is the most widely used form of testosterone in androgen replacement therapy . 
Androgens are responsible for the growth spurt of adolescence and for the eventual termination of linear growth which is brought about by the fusion of the epiphyseal growth centers. In children, exogenous androgens accelerate linear growth rates, but may cause a disproportionate advancement in bone maturation. Use over long periods may result in fusion of the epiphyseal growth centers and termination of growth process. Androgens have been reported to stimulate the production of red blood cells by enhancing the production of erythropoietic stimulating factor.
The number of pellets to be implanted depends upon the minimal daily requirements of testosterone propionate determined by a gradual reduction of the amount administered parenterally. The usual dosage is as follows: implant two 75mg pellets for each 25mg testosterone propionate required weekly. Thus when a patient requires injections of 75mg per week, it is usually necessary to implant 450mg (6 pellets). With injections of 50mg per week, implantation of 300mg (4 pellets) may suffice for approximately three months. With lower requirements by injection, correspondingly lower amounts may be implanted. It has been found that approximately one-third of the material is absorbed in the first month, one-fourth in the second month and one-sixth in the third month. Adequate effect of the pellets ordinarily continues for three to four months, sometimes as long as six months.