Same AUC with different dosing intervals
Equal exposure over the same time window can coexist with different peak and trough concentrations.
Equal exposure over the same time window can coexist with different peak and trough concentrations (FDA. Exposure–Response Relationships: Study Design, Data Analysis, and Regulatory Applications. 2003.).
For an IV bolus one-compartment model with CL = 1 L/h and V = 10 L, compare 12 mg every 12 h with 24 mg every 24 h. Both give steady-state AUC over 24 h of 24 mg·h/L. Using Cmax = (dose/V)/(1 − exp(−CL × interval/V)) and Ctrough = Cmax × exp(−CL × interval/V), the peaks are about 1.72 and 2.64 mg/L, and troughs 0.52 and 0.24 mg/L. Clinical interpretation requires evidence for the exposure measure linked to the endpoint.