What Is Pyrilutamide (KX-826)? A Research Overview

The only topical antiandrogen in this niche with human clinical trial data. Here is what Kintor's KX-826 actually is, what the trials showed on both continents, and what nobody can honestly promise yet.

What pyrilutamide actually is

Pyrilutamide, research code KX-826, is a small-molecule androgen receptor (AR) antagonist developed by Kintor Pharmaceutical (Suzhou, China) specifically as a topical treatment for androgenetic alopecia and acne. Unlike RU-58841, a 1980s molecule that outlived its corporate owners, pyrilutamide is a modern, purpose-built drug candidate that has actually been through the clinical machinery: designed for topical delivery, potent receptor binding, and fast systemic clearance so the antiandrogen effect stays at the scalp.

Kintor also runs a sibling programme, GT20029, a topical AR degrader (PROTAC) that removes the receptor rather than blocking it. That distinction matters mostly as context: KX-826 is the conventional antagonist of the two.

How it works

The mechanism is the same androgen-receptor blockade described in our RU-58841 overview: dihydrotestosterone (DHT) drives follicle miniaturisation by binding the AR in susceptible follicles, and an antagonist that occupies the receptor without activating it interrupts the signal locally. Pyrilutamide's distinguishing feature is potency: reported AR binding around IC50 ≈ 0.28 nM, which is why working concentrations are a tenth of RU-58841's (0.5% vs 5%).

The clinical record, both halves of it

China Phase 3: the positive result

In March 2026 Kintor reported that KX-826 met its primary endpoint in a 666-patient, 24-week, randomised, vehicle-controlled Phase 3 in Chinese men with androgenetic alopecia: about +15.3 hairs/cm² from baseline at the 1.0% twice-daily dose, roughly +10.65 hairs/cm² over placebo (p<0.0001), with no drug-related serious adverse events reported. For a niche whose favourite compound (RU-58841) has zero completed trials, this is the single strongest piece of human evidence that exists.

US Phase 2: the miss

The other half is less quotable and more important than most vendor pages admit: Kintor's US Phase 2 in AGA missed statistical significance on its primary endpoint in 2023. Different population, different dosing arms, and a shorter programme. But a miss is a miss. Combined with the fact that the Phase 3 numbers are company-reported top-line data from a China-only trial, the honest scientific position is: a genuinely promising molecule whose efficacy is indicated, not established.

"When is it coming out?"

Not on any confirmed date. There is no approved pyrilutamide product anywhere in the world. If approval comes, it will come first in China through Kintor's own programme. Every "release date" floating around forums is extrapolation. In the meantime the compound exists only as a research chemical, which is the capacity in which we supply it, with no treatment claims attached.

Tolerability and what users report

Pyrilutamide's community reputation is the mirror image of RU-58841's: gentler, less scalp irritation at its much lower working concentration, very few systemic-feeling reports, and a recurring theme of results plateauing for some users around the six-month mark. The trial record supports the tolerability half (no drug-related SAEs across the reported programmes); the plateau half is pure anecdote. Neither replaces long-term controlled safety data, which does not yet exist.

Quality: the same trap as RU

Pyrilutamide is harder to source as a raw material than RU-58841 and more expensive per gram, which raises the incentive to underdose it. The defence is identical: batch-specific, publicly verifiable analysis of the finished solution. Our pyrilutamide powder (batch 10237) was independently assayed before formulation, the weigh-in corrected by its purity, and the finished 0.5% solution (batch 41276) is with the lab now. It ships only once its own Certificate of Analysis is published on the lab results page.

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The honest caveats

Pyrilutamide is not a licensed medicine. Its positive trial data is company-reported and China-only; its US Phase 2 missed. Norwood Labs supplies it strictly for laboratory research use and makes no medical claims. For the full comparison against the other compound in this niche, read RU-58841 vs Pyrilutamide.

Frequently asked

What were the pyrilutamide Phase 3 results?

Kintor reported that KX-826 met its primary endpoint in a 666-patient, 24-week, vehicle-controlled Phase 3 trial in China: roughly +15.3 hairs/cm2 from baseline at the 1.0% twice-daily dose, about +10.65 hairs/cm2 over placebo (p<0.0001), with no drug-related serious adverse events. It is company-reported top-line data from a China-only trial, a real result that still deserves caution.

Did pyrilutamide fail its US trial?

Kintor's US Phase 2 in androgenetic alopecia missed statistical significance on its primary endpoint in 2023. That miss, alongside the positive China Phase 3, is exactly why the honest summary is 'promising but unsettled' rather than 'proven'.

When will pyrilutamide be released as an approved drug?

There is no approved pyrilutamide product anywhere. Any regulatory approval would come first in China via Kintor, and no confirmed approval or launch date exists. Treat any specific 'release date' you read as speculation.

What is pyrilutamide's half-life?

No reliable published human pharmacokinetic numbers exist in the public domain. KX-826 was designed as a topical with rapid systemic clearance (the point is high local receptor occupancy with minimal systemic exposure), but a precise human half-life figure would be invented if we quoted one.

Is pyrilutamide stronger than RU-58841?

Per molecule, yes. Its androgen receptor binding is very potent (IC50 reported around 0.28 nM), which is why it is used at 0.5% against RU-58841's 5%. Whether that translates to better results on a scalp is unresolved: there has never been a head-to-head study.

Can I buy pyrilutamide in the UK?

Norwood Labs supplies pyrilutamide (KX-826) 0.5% topical solution strictly as a reference material for laboratory research use. It is not a licensed medicine and we make no treatment claims. Our batch 41276 is with the lab now; it ships only once its Certificate of Analysis is published.