RU-58841, also known as PSK-3841 or HMR-3841, is a nonsteroidal antiandrogen (NSAA) which was initially developed in the 1980s by Roussel Uclaf, the French pharmaceutical company from which it received its name. It was formerly under investigation by ProStrakan (previously ProSkelia and Strakan) for potential use as a topical treatment for androgen-dependent conditions including acne, pattern hair loss,[1] and excessive hair growth. The compound is similar in structure to the NSAA RU-58642 but contains a different side-chain.