ボツリヌストキシンの1単位は、他社の1単位ではない

Quotes for botulinum toxin are written in units, and units look like a currency. They are not. A unit is a measure of that manufacturer’s own potency assay, and it is defined against that manufacturer’s own product. Twenty units of one brand and twenty units of another are two different quantities of two different things.

What the molecule does

Botulinum toxin type A blocks the release of acetylcholine at the junction between nerve and muscle, by cleaving a protein called SNAP-25 that the release depends on. The muscle is not paralysed in the sense of being damaged; it stops receiving the instruction to contract. Nerve terminals re-sprout over the following months, which is why the effect is temporary and why no honest page states a duration as a fixed number.

That mechanism is the same across the type A products used in Korea. What differs is the protein complex around the molecule, the manufacturing process, and the assay each maker uses to define a unit.

Why the unit does not travel

Each manufacturer establishes potency with its own reference standard. There is no regulator-issued conversion factor between brands, and clinical dose ranges published for one product are not transferable to another. A clinic that quotes only a unit count has told you a number whose meaning depends entirely on a brand it has not yet named.

This is the practical consequence: a cheaper price per unit is not a cheaper treatment until you know which product the unit belongs to. Comparing two quotes without both brand names is comparing nothing.

What to ask instead

Ask which product, then ask how many units of that product, then ask which muscles. The third question matters more than patients expect: the same total dose distributed differently produces a different face, and the distribution is where the operator’s judgement actually sits.