Overview of in vivo drug response phases, features of data, parameters, and case studies
Phase | Features in Data | Parameter | Case Study |
---|---|---|---|
A: baseline | Stable, variable, oscillating, or drifting (e.g., due to disease) | R0, kin, kout | 1, 2–8 |
B: time delay | Time delay between expected plasma peak concentration and peak of response | kout, K, Ka | 1–6 |
C: onset of action | Concave or convex rise of response (onset of action); overshoot during onset | kout, K, Ka, number of transit compartments, ktol | 1–7 |
D: peak shift | Peak shift or not; a shift suggests a nonlinear stimulation/inhibition of action | Smax/Imax, SD50/ID50, n | 1–6, 8 |
E: response maximum or minimum | May indicate a nonlinear drug action or physiologic limit; the same with an inhibitory drug action | Smax/Imax, SD50/ID50, n, physiologic limit | 1–5, 7, 8 |
F: return to baseline | Different dose routes may reveal absorption rate–limited elimination of drug from biophase; rebound during washout | kout, K, Ka, ktol | 1–3, 5–8 |