That certainly is curious. The bottle only holds 100 units, so he might put in a larger amount of saline so he can disperse it over a larger area but it does not multiply it to 400 units. You are only getting 100 units
I know that Botox bottles are single use only, and my physician does follow that. But I have a question. He opens a 100 unit vial for me and uses the whole thing (I have my forehead, glabella, periorbital and perioral areas as well as some of my platysmal bands treated): but when he mixes it with saline, he tells me that he gets 400 units out of that one bottle of 100 units. Am I getting 100 or 400 (!!) units of Botox when he treats me with one bottle? I don't understand. Thank you.