Equation 17.2.1 Hepatic Clearance according to the Well Stirred Model
Equation 17.2.2 Hepatic Clearance according to the Parallel Tube Model
Parameter | Example Value | Range of Values | Comment |
F*Dose | 100 mg | 100 mg ± | Linear system in this example |
Absorption Rate Constant | 1.5 hr^{-1} | 0.1 - 10.0 hr^{-1} | |
Volume of Distribution V |
20 L | 7 - 200+ L | |
Excretion Rate Constant ke |
0.05 hr^{-1} | 0 - 5+ hr^{-1} | Non hepatic excretion/elimination |
Unbound Intrinsic Clearance CL_{int, ub} |
10 L/hr | 0 - 1500+ L/hr | Shargel and Yu, 3rd, 1993 |
Hepatic Blood Flow Q_{H} |
80 L/hr | 60-120 L/hr | 70 Kg adult, Shargel and Yu, 3rd, 1993 |
Fraction unbound, in blood fu, b |
0.5 | 0 - 1 |
Equations used in this simple pharmacokinetic model.
Equation 17.2.3 Elimination Rate Constant as a function of CL_{H}, V and ke
Equation 17.2.4 Concencentration versus Time after a single Oral Dose
Equation 17.2.5 Extraction Ratio calculated from CL_{H} and Q_{H}
Explore flow limited drug behavior by setting CL_{int} somewhat larger (> 200 L/hr) than the hepatic blood flow rate. Change Q_{H}, fu and CL_{int} to see which parameters have the greatest influence of half-life and AUC. Capacity limited drug behavior can be explored by setting CL_{int} to a lower value (< 40 L/hr). Explore the effect of V on drug half-life.
Explore the equation by changing the parameter(s). Add additional lines with different parameter values using the Add Line button.