Compare prices and buy RU-58841 from 1 research peptide vendor - also called suppliers or sources. Updated daily.
A topical nonsteroidal antiandrogen, not a peptide, first reported by Roussel-Uclaf researchers as a candidate for acne, androgenetic alopecia and hirsutism, and also listed under the codes HMR-3841 and PSK-3841. It binds the androgen receptor, and in the developer's hamster studies it acted on skin with little systemic antiandrogenic activity. It has no FDA approval.
For research purposes only. Not medical advice.
RU-58841 is not a peptide. It is a synthetic small molecule, an N-substituted aryl hydantoin with the formula C17H18F3N3O3, and its systematic name is 4-[3-(4-hydroxybutyl)-4,4-dimethyl-2,5-dioxo-1-imidazolidinyl]-2-(trifluoromethyl)benzonitrile. PeptideScouter catalogues it under Skin & Cosmetic for a commercial reason: research-peptide vendors sell it alongside their peptides. It sits there with the category's other hair-loss compounds, AHK-Cu and PP405.
Its evidence base is preclinical. The published efficacy results come from rodents, monkeys, cultured cells and human scalp grafted onto mice. A Europe PMC search for its four names returns no human efficacy trial, and the only human study it returns, from 2026, measured how much of a scalp application reaches the blood (checked October 22, 2026).
Roussel-Uclaf researchers reported RU-58841 in 1994 as a topically active nonsteroidal antiandrogen with high affinity for androgen receptors in the hamster prostate and flank organ (Battmann et al., Journal of Steroid Biochemistry and Molecular Biology). Applied to hamster skin, it shrank the androgen-dependent flank organ in proportion to the dose, with no antiandrogenic effect on the deep accessory sex organs and no change in testosterone levels at the doses reported.
A companion rat study from the same Roussel-Uclaf research center (Cousty-Berlin et al., 1994) offered an explanation. After intravenous dosing, RU-58841 converted only about 1% into its N-desalkyl metabolite, RU 56279, which is itself antiandrogenic. The authors tied the compound's local action without systemic effects to that low conversion.
A 1998 study tested it in human prostate cancer cells engineered to express the androgen receptor (Pan et al., Endocrine). RU-58841 competitively suppressed activation by dihydrotestosterone with a potency comparable to hydroxyflutamide, and did not activate the receptor itself. From the potency result, the authors wrote, topical application "may induce systemic side effects".
In Syrian hamsters, four weeks of application to one ear reduced the size of its sebaceous glands by up to 60%, left the untreated ear unaffected, and reversed within four weeks of stopping (Matias and Gaillard, Annals of the New York Academy of Sciences, 1995). In male fuzzy rats, a model of androgen-driven sebaceous gland growth, two months of application shrank the glands as much as castration did, without changing serum testosterone or prostate weight (Ye et al., Skin Pharmacology, 1997).
Two studies addressed hair. In stumptailed macaques, a primate model of androgenetic alopecia, the same 1998 Endocrine paper reports that topical application increased hair density, thickness and length on the bald scalp. In balding human scalp grafted onto testosterone-treated nude mice, 8 of 29 active follicles on treated grafts began a second hair cycle against 2 of 28 on vehicle-treated grafts, and linear hair growth was faster (De Brouwer et al., British Journal of Dermatology, 1997).
In 2026 the Center for Preventive Doping Research at the German Sport University Cologne published the first human study of RU-58841's metabolism (Okutan et al., Biomedical Chromatography). Six healthy men each received one scalp application of an RU-58841 hair serum the investigators had bought online. Intact RU-58841 was detected in dried blood spots from all six participants, for up to 168 hours after application, and the authors concluded that topical application "leads to systemic exposure".
The developer's animal work measured systemic antiandrogenic effects and found little. This study measured exposure and reported no clinical endpoints. The urinary steroid profile used in anti-doping testing did not change, a finding the authors call preliminary. The serum's measured RU-58841 content was below its labelled strength.
RU-58841 has no FDA approval. Drugs@FDA returns no application under RU-58841, RU58841 or PSK-3841, and ClinicalTrials.gov holds no record under any of its four names (both checked October 22, 2026). FDA's Global Substance Registration System lists it as UNII 0D8FJQ0ADW, an identifier that confers no approval.
As a small molecule absent from FDA's compounding nomination lists, it sits outside the Category 2 and advisory-committee process that governs many compounded peptides. It appears on neither the 503A nominations list (versions of September 27, 2024 and May 14, 2026) nor the 503B list, on neither the April nor the October 2026 version of FDA's Category 2 page, and in no Pharmacy Compounding Advisory Committee minutes from October and December 2024, its July 2026 agenda or the substance list for its next meeting. FDA's warning-letter search returns no letter naming it (checked October 22, 2026).
No. RU-58841 is a synthetic small molecule, an aryl hydantoin with the formula C17H18F3N3O3, that acts as a nonsteroidal antiandrogen by binding the androgen receptor. PeptideScouter catalogues it under Skin and Cosmetic for a commercial reason: research-peptide vendors sell it next to their peptides, and it sits with the category's other hair-loss compounds.
A Europe PMC literature search returns no published human efficacy trial, and ClinicalTrials.gov holds no record under RU-58841, RU58841, PSK-3841 or HMR-3841 as of October 22, 2026. Its efficacy data come from hamsters, rats, stumptailed macaques, cultured cells and human scalp grafted onto mice. The first human study of its metabolism, published in 2026 by the German Sport University Cologne, gave six healthy men a single scalp application and detected intact RU-58841 in dried blood spots from all six, which the authors read as systemic exposure. The developer's animal studies had found little systemic antiandrogenic activity.
No. Drugs@FDA returns no application under RU-58841, RU58841 or PSK-3841 as of October 22, 2026. It is also absent from FDA's 503A and 503B bulk drug substance nomination lists and from its Category 2 list of substances that may present significant safety risks.
PeptideScouter computes a price per milligram only for vials labelled by mass. As of October 2026, RU-58841 is listed as bulk powder sold by the gram, so it appears in the price table but on no per-milligram ranking.
RU-58841 is sold by 1 research peptide vendor indexed on PeptideScouter, with 1 tracked listing compared per vendor in the table above. Pricing is normalized and refreshed daily.
All 1 indexed research peptide vendor currently have RU-58841 in stock. Stock state is refreshed daily from each vendor's catalog.
Discount codes are issued per vendor rather than per peptide, so any code applies across that vendor's whole catalog. All 1 vendor listing RU-58841 publish a PeptideScouter code, worth 10% off. These listings do not carry a comparable per-milligram price, so code availability is shown without a normalized effective price. Each vendor's code is shown beside its price in the table above.
1 research peptide vendor currently lists RU-58841 on PeptideScouter. We track 1 listing across size and kit variants.
RU-58841's CAS Registry Number is 154992-24-2. It is also sold as PSK-3841, HMR-3841, RU58841.
