Drug a acts on a receptor that’s only expressed in the brain. drug b is a blood pressure-lowering compound that cannot cross the blood-brain barrier. is it more likely that drug a causes a pharmacodynamic interaction on the action of drug b, or drug b to have a pharmacodynamic interaction on drug a? explain your thinking.

Explanation:

drug A is probably an antidepressant or antipsychotic drug. drug B lowers blood pressure.

Both are serious conditions, therefore, a doctor would recommend taking drug A first, drug b would interfere drug A's efficiency. dr. would recommend taking drug B at least 4 hrs. after drug A, so both drugs are effective for it's intended cause...

I hope this makes sense, it's more about which condition is more serious that you would need to treat first..