It depends. The pharmacist for my husband's cancer chemotherapy was explaining to us a couple days ago that if you have 100 people with a bacterial infection, they'd probably all be on the same antibiotic but if you have 100 people with even the same cancer, there would be 100 different formulas, each individual would have to be individually assayed. Height, weight, other illnesses, this particular illness, what an individual eats/drinks, how they react "this time", etc. all make a difference.

Unfortunately, I think mental illness pharmacology is very much like chemotherapy in that various meds and combinations have to be tried with that individual to see what will or will not work. "Depression" is not a one-size-fits-all illness. With brain chemistry, they can't really "see"; if you are being treated for something in the blood, they can take your blood and analyze it and see a bit of what may/may not be going on. My husband gets a 40-50 category long blood test before each chemo treatment and the results are then sent to the pharmacist who only then makes up his treatment for this time (he does not get the same thing/amounts each time). That's not possible with brains?