Testosterone cypionate is a synthetic derivative of testosterone in the form of an oil-soluble 17 (beta)-cyclopentylpropionate ester. Its benefit compared to other testosterone derivatives is the slow rate of release after injection and longer half-life. The characteristics of testosterone cypionate and testosterone enanthate are very similar, therefore both of them tend to be interchangeable. It was developed by the company Pharmacia and Upjohn and FDA approved on July 25, 1979.