RU-58841 (also known as PSK-3841 or HMR-3841) is a nonsteroidal antiandrogen (NSAA) which was previously investigated for use as a topical treatment for acne, androgenetic alopecia, and hirsutism. The compound is similar in structure to RU-58642 but contains a different side-chain. These compounds are similar in chemical structure to nilutamide, which is related to flutamide, bicalutamide, and enzalutamide. RU-58841 can be synthesized either by building the hydantoin moiety or by aryl coupling to 5,5-dimethylhydantoin.
RU-58841 is the drug for the treatment of hair loss dwindled, perhaps due more to commercial potential and chemical stability reasons than efficacy as the later studies of RU-58841 have focused on different chemical forms of the drug and combining it with various nanoparticles to enhance delivery.