Testosterone undecanoate is an esterified form of testosterone which is attached to a long fatty acid chain. The lack of a methylated site on the carbon 17 eliminates the adverse effects on the liver found in other testosterone analogs.[5] It is currently getting further developed to be an alternative to testosterone enanthate or testosterone cypionate by Paddock labs, and this new injectable has an FDA status of tentative approval. The original approval by the FDA of a product from testosterone undecanoate was done in 1953.