What literature do physicians use to know the onset times of medications? I have pdrs and nursing drug handbooks and nothing?

PAckage insert. Usually the package insert, which is basically what the pdr is, has the data about the onset and duration and half-life of the medication. You can get a pretty good idea from that about when the medication starts to have an onset of action. This is all data the fda requires the companies to analyze before they approve a drug.