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Pyrilutamide
KX-826 / 'Pyri' — Kintor Pharmaceuticals' topical AR antagonist for AGA; Phase 3 in China missed primary endpoint (2023-2024). Sister compound to topilutamide / fluridil.
Aliases (3)
Overview
What is Pyrilutamide?
Pyrilutamide (KX-826) is Kintor Pharmaceuticals' topical AR antagonist developed for androgenetic alopecia. It is structurally distinct from but mechanistically related to topilutamide (fluridil / Eucapil) and RU58841 — all members of the topical-AR-antagonist class designed for local DHT/AR blockade at scalp follicles with reduced systemic anti-androgen activity. Pyrilutamide entered Phase 3 in China for AGA; the program reported a disappointing primary-endpoint readout in 2023-2024, with the trial failing to meet its prespecified primary efficacy endpoint despite some positive secondary trends. Not FDA-approved in the US; sold domestically as a research chemical (RUO). Hair-loss community shorthand: 'Pyri'.
Key Benefits
Topical-only AR antagonist for AGA users seeking to avoid systemic 5α-reductase inhibitor side effects. Designed for low systemic exposure. Continues to be used in the bodybuilding / PED community for AAS-cycle scalp protection despite the Phase 3 efficacy miss.
Mechanism of Action
Non-steroidal topical AR antagonist; competitively binds DHT/testosterone at scalp dermal-papilla AR to halt AGA miniaturization. Designed for local activity with rapid systemic deactivation. The 2023-2024 Kintor Phase 3 miss in China is the most salient public fact: the trial's effect size was insufficient to meet the prespecified primary endpoint, though community use and AAS-cycle adjunct application continue. For the same indication, the sister compound topilutamide (fluridil / Eucapil) has a published 3-month RCT (Sovak 2002) and ~20+ years of Czech/Slovak commercial pharmacovigilance — arguably the better-supported topical AR antagonist option.
Quality Indicators
Reputable RUO vendor with COA
Verify HPLC purity ≥98% on a recent batch COA; pyrilutamide has more counterfeiting risk than topilutamide because of community demand built up during Phase 3 hype 2020-2023.
Vendor with no Phase 3 awareness in marketing
Vendors still marketing pyrilutamide as 'breakthrough Phase 3 candidate' without acknowledging the 2023-2024 primary endpoint miss are red-flag for staleness or hype-cycle misrepresentation.
Missing or counterfeit COA
Pyrilutamide's pre-Phase-3 hype built a market that has continued post-failure; verify provenance carefully.
What to Expect
- Week 1Tolerability and dose-response.
- Week 2-4Early effect window.
- Week 4-8Peak benefit assessment.
- Week 8+Cycle decision point.
How was your experience with this compound?
Anonymous · one vote per session · results below at 5+ votes.
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