Mechanism · 7 min read
How clascoterone works on hair follicles
It is a local lock on the androgen receptor — not a systemic 5-alpha-reductase inhibitor, not minoxidil.
The DHT problem
In androgenetic alopecia, genetically sensitive follicles miniaturise under androgen signalling. DHT is the high-affinity ligand. Over successive cycles the follicle produces thinner, shorter hairs until the cosmetic density collapses at the temples and vertex.
Receptor block, not enzyme block
Finasteride and dutasteride inhibit 5-alpha-reductase, the enzyme that converts testosterone to DHT. Serum and tissue DHT fall. That is effective and well studied. It is also systemic by design.
Clascoterone is an androgen-receptor antagonist. It occupies the receptor in skin so DHT and testosterone have nowhere to dock. Company and review literature describe minimal systemic absorption when used topically, with rapid hydrolysis to cortexolone, a physiological metabolite.
That is why trial communications lean so hard on “no meaningful hormone-related side effects.” The claim to watch in the full peer-reviewed package is not just hair count — it is the pharmacokinetic and endocrine tables.
What happens after it hits skin
Applied as a solution, the molecule is intended to stay in the pilosebaceous unit. Skin esterases clip it to cortexolone. That local metabolism is part of the safety story: less parent drug circulating, less endocrine noise.
Phase 2 dose-ranging (historical Cassiopea data) tested 2.5%, 5%, and 7.5% once or twice daily. Twice-daily 5% moved forward into Phase 3 as the practical efficacy/tolerability pick. Absolute Phase 2 hair-count gains were on the order of roughly +10 to +14 hairs/cm² versus vehicle depending on arm — useful context when headlines later shouted 539%.
Where it might sit in a stack
Mechanisms that do not collide are how hair protocols get built:
- Minoxidil — growth-phase / vascular / potassium-channel biology
- Finasteride or dutasteride — less DHT made
- Clascoterone — less DHT signalling at the receptor
- Ketoconazole shampoo — adjunct anti-androgen / anti-inflammatory scalp care
Nobody has a large published combination trial of clascoterone plus finasteride plus minoxidil yet. Do not assume “all three is automatically better.” Do assume that if Breezula launches, clinicians will trial it as add-on in men who refuse orals, and as a partner to minoxidil in men who already tolerate a 5-ARI.
Read the head-to-heads: vs finasteride and vs minoxidil.