Both the alien biogel and adapted biogel have a 50% chance to randomly apply 1 of the following 10 effects for 30 seconds. Multiple effects can be applied at once through repeated consumption, however, the same effect cannot be applied twice at once.
Adapted biogel can only be obtained from Elliott, by asking him to convert any alien biogel currently in inventory. This option is available from the first encounter with him onward, including after completing This Galaxy Ain't Big Enough... Because of this, and because one of the random items Sally can provide (when asked if she's found anything on the ship) is alien biogel, the potential supply of adapted biogel is effectively unlimited.
This item can heal 1.667 times more hit points than a Stimpak, but has a 25% chance of applying a negative effect to the user.