If you have two sets of data (placebo and drug) then you may want to use a t-test or an equivalent t-test in non-parametric form.
You can then test if there is a statistically significant difference between the means of the distributions and use that to help you come to a conclusion based on evidence.
If you need to look at individual cases then another test would be worth considering.
What exactly are you trying to figure out specifically? (In other words, what is the specific nature of your question and inquiry? What do you hope to answer in full?)