Testosterone propionate 100 is a slower releasing anabolic steroid with a short half-life. This characteristic allows the user to run short testosterone propionate cycles of 8-10 weeks as optimal peak blood plasma levels are achieved at 2-4 weeks.
It is a synthetic androstane steroid derivative of testosterone in the form of 17β propionate ester of testosterone.2 Testosterone propionate was developed initially by Watson labs, and FDA approved on February 5, 1974.
Currently, this drug has been discontinued in humans, but the vet application is still available as an OTC.
Testosterone propionate 100 is often used for muscle mass building. The original medical indication is for the treatment of androgen deficiency in male adults either in hypogonadism or andropause. Nowadays testosterone propionate is indicated for its use in heifers in order to stimulate maximal growth.
The effects of testosterone in humans and other vertebrates occur by way of two main mechanisms: by activation of the androgen receptor (directly or as DHT), and by conversion to estradiol and activation of certain estrogen receptors.
Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5alpha-dihydrotestosterone (DHT) by the cytoplasmic enzyme 5alpha-reductase. The areas of binding are called hormone response elements (HREs), and influence transcriptional activity of certain genes, producing the androgen effects.