Medical research 
Is going on mainly to understand effect of drugs on diseases rather than finding out new drug for every thing. So basically we learn with time optimization of drugs.
So it is not important to know what drug to be used for disease but important is how much to be used disease-wise.
Drugs do not change much. It is our knowledge that keep improving.
There is no simple solution which fits all .
I find it extremely difficult to prescribe medicines before examining the patient.
Like lasix is a beautiful drug, and its usage keeps changing with disease and stage of disease...