The character does know drugs well (wouldn't this be more drug knowledge than chemistry?) and interacts with at least two ~trusted chemists regularly. He'd also

The character does know drugs well (wouldn't this be more drug knowledge than chemistry?) and interacts with at least two ~trusted chemists regularly. He'd also have many available people to ask for help, including a medical doctor who is definitely in on the plan. If I had to guess, it probably just worked out better in terms of story and visuals the way it was done. (going from memory, take with salt): the scene with him vomiting up the poison was a nice quirky/mystereous start to the reveal, and having to rush him to medical assistance both added suspense and gave a reason that Mike could be wounded (to add realism) and be treated by the doctor (to not lose the character).