- CB-03-01 is clascoterone, a topical androgen receptor antagonist.
- Approved as Winlevi (1% acne cream, FDA 2020, EMA 2022).
- Not approved as Breezula, the hair-loss formulation still in development.
- Because an approved form exists, it is not a research-chemical category product, and we do not sell it.
- Research use only framing applies to the unapproved compounds we do supply.
The compound that crossed the line
Clascoterone is the rare topical antiandrogen that completed the entire regulatory journey, at least for one indication. Its mechanism will look familiar from the other compounds on this site: it binds the androgen receptor in skin and blocks DHT signalling locally, while being metabolised quickly enough in circulation that systemic effects are minimal. That is the same design brief as RU-58841, executed forty years later, with modern trial infrastructure, and it is the only one of the group to hold a marketing authorisation.
Winlevi: the approved side
The FDA approved clascoterone 1% cream as Winlevi in August 2020 for acne, with the EMA following in 2022. Two large Phase 3 programmes supported the approval, and the product has real-world safety data accumulating since launch. This is what an approved topical antiandrogen looks like, and it is the reference point every other compound in this space is measured against.
Breezula: the unapproved side
For hair loss, clascoterone is formulated at higher concentration under the brand name Breezula. Its Phase 2 results in androgenetic alopecia have been published and are genuinely interesting: statistically significant hair count improvements versus placebo, with the expected local tolerability profile. But Breezula holds no approval anywhere, and no launch date is confirmed. Same molecule, two very different regulatory statuses, which is exactly why the acne and hair-loss claims about it must be kept separate.
Why we do not sell it
Our catalogue rule is simple and it is the same one from the RU-58841 legality page: we supply unlicensed research compounds with no marketing authorisation anywhere in the world. Clascoterone has one. Selling unlicensed preparations of an approved molecule is a different legal category, and it is not one we operate in. If you are researching topical antiandrogens, the honest comparison is between the approved molecule you cannot buy as a research product (clascoterone) and the unapproved ones you can (RU-58841, pyrilutamide), with the regulatory difference being the point, not a detail.
The evidence table, honestly
| Clascoterone (CB-03-01) | Pyrilutamide (KX-826) | RU-58841 | |
|---|---|---|---|
| Approval status | Approved for acne (Winlevi); hair-loss form unapproved | No marketing authorisation anywhere | No marketing authorisation anywhere |
| Human trial data | Two Phase 3 acne programmes; published Phase 2 hair-loss data | China Phase 3 (company-reported topline) | None completed |
| Research-category status | Not research-category (approved molecule) | Research compound | Research compound |
| Sold by Norwood Labs | No, by policy | Yes | Yes |
Related reading
For the unapproved side of the comparison, see What Is RU58841? and RU-58841 vs Pyrilutamide.
Nothing we sell is a licensed medicine, and no treatment or medical claims are made. All products are research compounds sold strictly for laboratory use.