Especially for someone taking what was clearly a complex treatment, perhaps it was assumed that, say, the drug that increases BP was given for some other reason, and then the drug to decrease BP was given specifically to counteract the effect of the first drug.

Of course, it seems that in this case that assumption (if indeed that happened) was tragically wrong, and instead the cocktail was a product of doctors disinterested in communication. But such complex treatments can be intentionally prescribed.