In BioShock all versions of this tonic can be equipped together for an increased effect.
In Worlds of Hurt, Medical Expert 2 can be bought at the Gatherer's Garden in the central hub for 50 ADAM.
Medical Expert is also a Tonic available to the player in BioShock 2, but it has a very different effect. Instead of making First Aid Kits more effective, it increases the carry capacity by one. When carrying 6 First Aid kits, the player can choose to swap this tonic for another without dumping the extra First Aid kit. The same goes for EVE Expert, which affects EVE Hypos and their capacity.