TABLE 1

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, k_in, k_out	1, 2–8
B: time delay	Time delay between expected plasma peak concentration and peak of response	k_out, K, K_a	1–6
C: onset of action	Concave or convex rise of response (onset of action); overshoot during onset	k_out, K, K_a, number of transit compartments, k_tol	1–7
D: peak shift	Peak shift or not; a shift suggests a nonlinear stimulation/inhibition of action	S_max/I_max, 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	S_max/I_max, 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	k_out, K, K_a, k_tol	1–3, 5–8