Boldenone is an anabolic steroid which is administered as boldenone undecylenate and is approved by the United States FDA for use in horses not intended for human consumption. (12) Following intramuscular injection, the parent drug is hydrolysed to 17 beta -boldenone. 17 alpha -boldenone is reported to be one of the main urinary metabolites of 17 beta -boldenone.