Black market vials?

So I see these two vials in the black market, red and blue, for 20k. I've never seen any info about them - What are they for?

They are gender changing potions. They allow you to change the genders of your creatures. Pink allows you to change a male into a female and Blue allows you to change a female to male.

Ah. Cool Do you know if they're one use only or can I use one vial more than once?

you can use them only once.