Androgen Receptor Blockers
The Hair Loss Pipeline, Ranked

Overview

The lock, not the key

Pattern hair loss is an androgen problem. Testosterone is converted into the more potent dihydrotestosterone (DHT), and in genetically sensitive scalps DHT gradually shrinks the follicle until it stops making visible hair.

Finasteride and dutasteride block the enzyme that makes DHT, 5-alpha-reductase. They work, but they only address the amount of DHT. They do nothing to the part of the cell DHT actually talks to: the androgen receptor (AR). If DHT is the key, the AR is the lock. A wave of new drugs has decided to go after the lock instead.

The leaderboard

The ranking

Ranked by clinical maturity first, then by the quality and independence of the data, then by practical factors like route of administration.

Ranks 1–2

The frontrunners

Pyrilutamide (KX-826) is the most clinically advanced AR drug built for hair. It is a topical AR antagonist applied twice daily. In a US Phase 2 of 123 men, the 0.5% twice-daily arm increased hair count by about 10 hairs/cm² over baseline at 24 weeks (P = .0088).^[3] A 666-patient China Phase 3 then reached its primary endpoint, and Kintor has guided to a China filing in 2026 with a possible launch in 2027.^[3] The honest caveat: its separation over placebo has been inconsistent. An earlier China Phase 3 beat placebo at every visit but not significantly. Most advanced, with an asterisk.

Clascoterone (Breezula) is the most de-risked, and a very close second. The same molecule is already FDA-approved as Winlevi for acne, so its safety and manufacturing are established.^[4] Its Phase 2b showed a clean dose response, with the top arm beating placebo by roughly 14 hairs/cm² at 12 months and no systemic hormonal effects. Western Phase 3 (SCALP-1 and SCALP-2) reported six-month topline in December 2025, but no filing on hair endpoints yet. The cleanest dataset and the clearest US path.

Ranks 3–5

The degraders

GT20029 is the most scientifically interesting drug on the board, described as the first topical PROTAC. Instead of blocking the receptor, it tags it for destruction. Its China Phase 2 met the primary endpoint, and the effect held with twice-weekly dosing, a real adherence edge over daily drugs.^[1]

AH-001 is the second PROTAC degrader in the clinic, and it was AI-designed. Its US Phase 1 finished in 2025 with no drug-related side effects and almost no drug reaching the bloodstream, exactly the profile you want from a topical.^[5]

MI-131 is a third degrader, and a non-PROTAC one. Dosing began in early 2026.^[7] Novel and worth watching, but there is almost no public human data yet.

Ranks 6–8

The RNA silencers

OLX104C is a small interfering RNA that silences the AR gene so the receptor is never made. Its Phase 1 is complete.^[6] The catch is the route: it is injected into the scalp, not applied topically, which is a hard sell for a lifelong condition.

CosmeRNA is also an AR-silencing RNA, and the only product on this list you can actually buy, sold in Europe since 2023. But it is sold as a cosmetic, not an approved drug, and the published effect is modest, about +7.7 hairs/cm² over 24 weeks.^[2] It has also drawn skepticism in online hair-loss communities, where a number of users report little or no benefit. Those are anecdotal reports, not controlled data, but combined with the thin published evidence they are reason to keep expectations measured.

ADA-308 is a topical AR antagonist repurposed from prostate-cancer chemistry. It is still preclinical, with no human hair data, which is why it ranks last.^[8]

Available now

The ones you can already get, off-label

Three older AR blockers can be prescribed today, off-label, almost always for women. They are oral, feminizing in men, and none is approved for hair loss. This is a clinician-guided decision.

History

The graveyard

RU58841 is the famous one: a topical antiandrogen that reached Phase 2 around 2003 and was then dropped. Its reputation as being as effective as finasteride is widespread online, and community lore holds that it grew hair well but was abandoned over safety concerns, sometimes described as heart and lung effects. The honest picture is murkier: the trial results were never published, and the official reason for abandonment was never disclosed, with corporate restructuring the best-supported explanation. Treat both the efficacy and the safety stories as unverified.^[11] Fluridil (Eucapil) survives only as a small European cosmetic. Cyoctol and inocoterone died in development for weak efficacy or poor skin penetration. Penetration and local safety, it turns out, are the recurring reasons topical antiandrogens fail.

The honest read

Limitations