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Ru53.0
RU58841 Research
Mostly mechanism / observationalLimited safety
5 peer-reviewed studies
What the evidence says
Mostly mechanism / observational
Most RU58841 studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from mixed-quality studies published 1994–1998.
Based on 5 studies
Confidence
Low
By outcome
Safety profile
Mostly mechanism / observational5 studies
Hair regrowth (preclinical, unproven for RU58841 in humans)
Antiandrogens, hydroxyflutamide, bicalutamide (casodex), cyproterone acetate, and RU58841 ... can promote the interaction between AR and its coactivator, ARA70 ... these antiandrogens and related compounds significantly enhance the AR transcriptional activity by cotransfection of AR and ARA70 ... in DU145 cells.
Miyamoto H, Yeh S, Wilding G, Chang C. · Proceedings of the National Academy of Sciences of the USA (1998)
In-vitro pharmacology showing RU58841, like other antiandrogens, can act as a partial androgen-receptor AGONIST in the presence of the coactivator ARA70 in human prostate DU145 cells — its receptor effect is context-dependent, not a clean block
Important honesty check on the 'pure antagonist' framing: in some cellular contexts RU58841 enhanced rather than suppressed AR transcriptional activity
Underscores that RU58841's receptor behaviour, and therefore its net effect in human tissue, is not fully predictable — relevant to the uncharacterised systemic/endocrine risk
RU58841, on topical application, revealed a potent increase in density, thickening, and length of hair in the macaque model of androgenetic alopecia, whereas no systemic effects were detected ... RU58841 may have potent antagonism to the wt AR and could be considered as a topically applied active anti-androgen for the treatment of androgen-dependent skin disorders.
Pan HJ, Wilding G, Uno H, Inui S, Goldsmith L, Messing E, Chang C. · Endocrine (1998)
The classic preclinical anti-alopecia study: topical RU58841 in the stumptail-macaque model of androgenetic alopecia increased hair density, thickness and length, with NO detected systemic effects — the headline result behind its grey-market reputation, but in macaques, not humans
In-vitro, RU58841 competitively suppressed DHT activation of wild-type androgen receptor in human prostate PC3 cells, with potency comparable to hydroxyflutamide — characterising the AR-antagonist mechanism in cells
Establishes local hair regrowth and AR blockade in an animal/in-vitro model only; it is NOT evidence of human efficacy or safety (animal + in-vitro)
The values for the linear hair growth rates (LHGR) were significantly (P < 0.04) higher in the RU58841-treated group. Recycling and increased LHGR indicate a positive action for RU58841 on human hair growth from balding samples grafted on to testosterone-conditioned nude mice, and encourage a clinical trial to evaluate its potential in the treatment of androgen-dependent alopecia.
De Brouwer B, Tételin C, Leroy T, Bonfils A, Van Neste D. · British Journal of Dermatology (1997)
The closest thing to human data: human balding-scalp grafts from men were maintained on testosterone-conditioned nude mice and treated topically with 1% RU58841 in ethanol vs ethanol control for 6 months — human follicles, but grown ex-vivo on mice
RU58841-treated grafts showed significantly higher linear hair-growth rates and more follicles initiating a second hair cycle (8/29 active follicles recycled vs 2/28 in controls)
An ex-vivo human-tissue model; it supports plausibility but is NOT a controlled trial in living humans and does not establish safety (animal / ex-vivo human-graft)
4Animal1994
It displays high affinity for the hamster prostate and flank organ (F.O.) androgen receptors ... when topically applied, it exerts a potent dose-dependent regression of F.O. area at a dose as low as 1 microgram/animal while being devoid of antiandrogenic activity on deep accessory sex organs ... RU 58841 might [be] useful for the topical treatment of androgen-dependent skin disorders such as acne, androgenetic alopecia and hirsutism.
Battmann T, Bonfils A, Branche C, Humbert J, Goubet F, Teutsch G, Philibert D. · Journal of Steroid Biochemistry and Molecular Biology (1994)
The originating characterisation: RU58841 binds androgen receptors with high affinity and, topically, produces potent dose-dependent local anti-androgen effects (hamster flank-organ regression) at microgram doses
Crucially, it was devoid of anti-androgen activity on deep accessory sex organs and had no effect on testosterone at those doses — the basis of its 'local action without systemic effects' design rationale
Frames the intended indications (acne, androgenetic alopecia, hirsutism) and the local-vs-systemic selectivity that made it attractive — all in a rodent model
The pharmacological profile of RU 58841 which displays a potent local antiandrogenic activity without systemic effects can be related to its very low propensity to form the N-desalkyl metabolite [RU 56279].
Cousty-Berlin D, Bergaud B, Bruyant MC, Battmann T, Branche C, Philibert D. · Journal of Steroid Biochemistry and Molecular Biology (1994)
Rat pharmacokinetics: RU58841 is cleared relatively rapidly (elimination half-life ~1 h) and forms only ~1% of the systemically active N-desalkyl metabolite RU56279 — the mechanistic explanation for its local-without-systemic profile
Links low systemic anti-androgen activity to the low metabolite formation, supporting the topical design rationale in rodents
Provides the only preclinical pharmacokinetic picture; human pharmacokinetics and chronic systemic absorption through the scalp remain uncharacterised