That's a good question. You do have the right to refuse them changing your meds. You also have the right to ask them to go back to the original combination of meds i.e. what you were on before this drastic change. Is it 12 different medications or are you talking about 12 pills as in the actual number of pills you are taking in a day?

You would have to take a very high dose of the blood pressure meds in order for them to kill you, more than what was prescribed. They would make you feel pretty awful if they dropped your pressure, but they likely would not have killed you.