Mechanism · Research Data · Protocols · Compound Information
RU58841 (also referenced in early literature as PSK-3841) is a non-steroidal topical antiandrogen originally developed by Roussel-UCLAF in the early 1990s. It was designed to act locally at the site of application — primarily the scalp — without the systemic hormonal effects associated with oral antiandrogen compounds.
Research interest in RU58841 centres on androgenetic alopecia, where dihydrotestosterone (DHT) sensitivity at the hair follicle is the primary driver of progressive hair miniaturisation. Because RU58841 was designed for topical, localised action, it has been studied as a potential alternative to systemic antiandrogens for this specific research application. This guide is for educational and research purposes only. Not medical advice, and the compound is not approved for human therapeutic use.
The following table summarises the current types of evidence available for RU58841 in scientific literature.
| Evidence Type | Status |
|---|---|
| Human Randomised Controlled Trials (RCTs) | ✗ (No large-scale published human RCTs identified) |
| Ex Vivo / Scalp Graft Studies | ✔ (Human balding scalp grafts studied on immunodeficient mouse models) |
| Animal Studies | ✔ (Stump-tailed macaque model of androgenetic alopecia) |
| In Vitro Studies | ✔ (Androgen receptor binding and prostate cell line research) |
| Regulatory Approval for Human Therapeutic Use | ✗ (Not approved by HPRA, FDA, or EMA — development was discontinued) |
RU58841 is classified as a non-steroidal antiandrogen. Mechanistically, it is studied as a competitive antagonist at the androgen receptor, reducing the receptor's sensitivity to DHT at the point of application. In androgenetic alopecia research, DHT binding to androgen receptors in genetically susceptible hair follicles is understood to drive progressive follicular miniaturisation over successive hair cycles.
Because RU58841 was formulated for topical use, research has focused on whether meaningful androgen receptor blockade can be achieved locally at the scalp without significant systemic absorption — distinguishing it in research discussion from oral antiandrogens, which act systemically and carry a different side-effect profile.
A controlled study transplanted balding human scalp grafts onto testosterone-conditioned nude mice and compared topical RU58841 against an ethanol control. Researchers reported that RU58841-treated grafts showed a higher proportion of follicles re-entering a second hair growth cycle compared to control grafts, along with significantly higher linear hair growth rates in the treated group. The study's authors described this as evidence of a positive action on human hair growth from balding tissue.
In a stump-tailed macaque model of androgenetic alopecia — a species that develops a balding pattern similar to humans — topical RU58841 application was associated with reported increases in hair density, shaft thickness, and length, with no systemic hormonal effects detected in that research model.
Earlier research characterised RU58841 as a candidate topical antiandrogen for a range of androgen-driven skin and follicle conditions, including androgenetic alopecia, acne, and hirsutism, based on its receptor-binding profile and local mechanism of action.
| Study / Model | Reported Effect |
|---|---|
| Human Balding Scalp Grafts (Nude Mouse Model) | Higher proportion of follicles re-entering a second hair cycle and increased linear hair growth rate versus ethanol control. |
| Stump-Tailed Macaque Model | Reported increases in hair density, shaft thickness, and length with topical application; no systemic effects detected in the research model. |
| In Vitro Androgen Receptor Binding | Demonstrated competitive antagonism at the androgen receptor, supporting the proposed local mechanism. |
⚠️ Stack combinations listed for research reference only. Not safety or efficacy guidance.
Because human trial data for RU58841 is limited, the available safety picture comes primarily from animal and ex vivo research:
Development of RU58841 by its originating pharmaceutical sponsor was discontinued, and it has never progressed through full clinical trials or received regulatory approval. Researchers should treat the limited human evidence base as a significant caveat.
Peptide dosing calculator, cycle planner, macro guide and more. No signup required.
Explore Free Tools