I was reading this item on page 150 of Complete Arcane and it does not specify either way. Are these a one time use or a reusable item?
It is reusable.
Generally speaking, unless an item specifies that it is consumed, it isn't. Not to mention this item is a bottle (albeit a magical one), which is by definition a reusable container.
Spoiler alert: most people suggest ripping that page out of your book anyway, because this item is severely broken.