Skip to main content
. 2022 May 27;42(6):513–524. doi: 10.1007/s40261-022-01156-4

Table 1.

Calculation methods for pharmacokinetic parameters in blood and urine

Parameter Definition Calculation method/equation
Blood
 Cmax Maximum observed blood drug concentration, determined directly from individual concentration-time data Observed value
 Tmax Time to maximum blood concentration, determined directly from individual concentration-time data Occurrence of observed Cmax
 Clast Last quantifiable drug concentration, determined directly from individual concentration-time data Observed value
 Tlast Time of last quantifiable drug concentration, determined directly from individual concentration-time data Occurrence of observed Clast
  AUC0–t Area under the blood concentration-time curves from time 0 to the time of the last quantifiable concentration Linear trapezoidal rule AUC0–t = δt × (C1 + C2)/2
 AUC0–∞ Area under the blood concentration-time curve from time 0 to infinity AUC0–∞ = AUC0–t + Clast/λz
 %AUCext Percentage of area under the curve extrapolated from time t to infinity 100 × (1 − [AUC0–t/AUC0–∞])
 λz Terminal phase elimination rate constant Linear regression of the terminal linear portion of the log concentration versus time curve
 t½ Apparent terminal elimination half-life t½ = ln(2)/λz
 CL/F Apparent systemic clearance following nonintravenous (e.g., oral) administration, where F is the bioavailability CL/F = Dose/AUC0–∞
 Vz/F Apparent volume of distribution following nonintravenous (e.g., oral) administration, where F is the bioavailability Vz/F = Dose/(AUC0–∞ × λz)
Urine
 Ae Amount of drug excreted unchanged into urine per collection interval Ae = urine concentration × volume
 Total Ae Cumulative amount of drug excreted unchanged into urine over the entire collection interval Sum of Ae
 Fe% Percentage of dose excreted in urine per collection interval Fe% = Ae/Dose × 100
 Total Fe% Total percentage of dose excreted in urine over the entire collection interval Fe% = Total Ae/Dose × 100
 CLr Renal clearance CLr = Total Ae/AUC0–∞
 CLnr Nonrenal clearance of drug from blood CLnr = CL/F − CLr
 CLratio Ratio of renal clearance to systemic clearance CLratio = CLr/(CL/F)
 Tmax_Rate Midpoint of the collection interval associated with the maximum observed excretion rate Observed value
 Max_Rate Maximum observed excretion rate, at time Tmax_Rate Observed value