Time-Varying Covariates

Population simulation with covariates that change over time (e.g., renal function).

Model

Creatinine clearance (CrCL) affecting drug clearance:

CL(t) = CL_pop × (CrCL(t)/100)^0.5 × exp(η_CL)

Use Cases

• Critically ill patients (changing renal function)
• Chronic therapy (disease progression)
• Drug interactions (enzyme induction over time)