The Formula

Two bottles can both say "RU-58841 5%" and be completely different products. The molecule is the easy part. What it is dissolved in decides whether it reaches the follicle, whether it stays where you put it, and whether your hair looks like you slept in a chip pan.

The carrier is the product

A topical has one job before it has any other: get through the outer layer of skin and into the follicle, then stay there. That is a solvent problem, and it is where the difference between two bottles of "the same" thing actually lives.

• Too little solvent power and the compound never fully dissolves. It crashes back out — sometimes visibly, sometimes not — and you are painting a suspension onto your head.
• Too much of the wrong solvent and you strip and irritate the scalp. That flaking and itching people blame on the active is almost always the vehicle.
• The wrong balance and it sits on the hair instead of the skin. That is the greasy look — and it also means it is not where the receptors are.

The percentage on the label tells you almost nothing on its own. 5% dissolved badly is worse than 5% dissolved well, and both say "5%".

Our carrier is our own

We are not going to publish the exact ratios. In this business that is the one thing genuinely worth keeping.

What we will tell you is what it is built to do: dissolve the compound completely and keep it dissolved, carry it into the skin rather than leave it sitting on the hair, and dry down without a residue. We formulate it, we blend it in the EU, and we do it in small batches.

What we work with, and what each one is for

Most of these are not competing products — they act at different points in the same problem. The blockers are the exception: they are alternatives to each other, and you run one of them, not two.

RU-58841 — the blocker

A nonsteroidal androgen receptor antagonist. CAS 154992-24-2. It came out of Roussel-Uclaf in the late 1980s, designed from the start to be applied to skin — to act where it lands rather than accumulate through the body. It does not lower your DHT; it occupies the receptor so DHT cannot deliver its message. It was never carried through to approval, and why development stopped is not publicly documented in any form we would defend. We are not going to invent a reason for you. RU-58841 5%

Pyrilutamide — the other blocker

A newer nonsteroidal androgen receptor antagonist, same target, different molecule. It exists because a receptor antagonist that stays local is a genuinely good idea and RU-58841 is not the only way to build one. For people who do not tolerate RU. Pyrilutamide 0.5%

CB-03-01 — the documented one

Clascoterone. The same receptor again, reached by a different kind of molecule: RU-58841 and pyrilutamide were designed from scratch to sit in it, while this one is a steroid that already resembles the hormone — and once it has done its work, your own skin takes it apart into cortexolone, something your body already makes. It is the only one of the three taken through Phase 3 trials in the US and Europe, and we are not going to overstate what that buys you: those trials were run by the company developing the licensed version, on their formulation and not on ours, and no approved hair-loss version of it is on sale anywhere yet. It is also where the argument at the top of this page stops being abstract. Clascoterone stops dissolving in plain ethanol at around 2%, which is why a 5% bottle carried in nothing but alcohol is a suspension with a number on it. Whichever of the three you pick — one blocker at a time, never two. CB-03-01 2.5/5%

Minoxidil — the push

A potassium channel opener. It extends the growth phase and it does nothing whatsoever to the hormone, the enzyme or the receptor. It is the accelerator, not the brake. It works — it has decades of trials behind it — but a man running minoxidil alone is growing hair into a headwind, which is why it so often plateaus. It pairs with a blocker. It does not replace one. Minoxidil

GHK-Cu — the ground

A copper peptide. It is not a blocker and it does not act on DHT. It works on the condition of the scalp itself — the ground the follicle is standing in. If your scalp is irritated, inflamed or flaking, that is worth fixing on its own merits. It will not hold a receding hairline by itself, and we will not pretend it will. GHK-Cu spray

Ketoconazole — the wash

An antifungal shampoo, 1%, two or three times a week. It is not a blocker and it does not grow hair. It handles flaking, itch and the low-grade irritation that sits underneath a lot of shedding — the same ground GHK-Cu works on, approached from the other side. It is also the thinnest evidence base of anything we sell: a handful of small studies, and no placebo-controlled trial that would settle it. Scalp housekeeping, and that is all we will claim for it. Ketoconazole shampoo

The growth serum — the support

Scalp conditioning, alongside the rest. Same honest limit as above: support is support. It is a leg, not the table. Hair growth serum

Age is part of the specification

These compounds degrade. Time, heat and daylight are what degrade them. A bottle that has been sitting in a warehouse — or crossing an ocean in a container in July — is not the same product as one blended recently, whatever the label says.

So every bottle we send carries its batch number, its blend date and its expiry, printed on the bottle itself. You should always be able to answer "how old is this?" without emailing anyone. With most sellers in this category, you cannot.

Tested before it ships

Every batch is tested by an independent laboratory before it goes out. Not by us — by a lab with no reason to flatter us. If a batch is not what the label says, it does not ship.

We do not put a printout in every parcel, because most people throw it away. But the result exists for every batch we have ever sold. Ask us about yours and we will tell you what came back.

What this is not

Several of these are research compounds. They are not approved medicines, they have no approved human indication, and for most of them the large human trials that would settle the question were never run. Clascoterone is the exception, and only halfway: the trials exist, but they were another company's, on another company's formulation, and there is still no approved hair-loss version of it anywhere. We sell them for laboratory research, we tell you what is in them, and we do not tell you what they will do to your hair — because nobody honestly can.

RU-58841 5% · The full range · Ask us something specific