Oddworld: Stranger's Wrath HD

Missable!
Inside the Wolvark barracks, you will come to a room with toilet stalls and Wolvarks inside them. Facing the stalls, look to the left and you will see a tower of green boxes. Head to the other side of the boxes, destroy the ammo crates blocking your way and climb to the top. Head inside the air vent and keep walking until you get to the other side. At the vent’s exit you will see boxes of the ‘medicine’ and the trophy will pop.

See the spoiler below for a video walkthrough. Be warned, this video may contain spoilers. Credit to kamijordan.