Calculator Inputs
Example Data Table
| Sample Case | Method | Qh (L/h) | fu | Clint (L/h) | Cin (mg/L) | Cout (mg/L) | ER | Hepatic Clearance (L/h) |
|---|---|---|---|---|---|---|---|---|
| Reference compound A | Concentration | 90.0 | 0.12 | 420.0 | 14.0 | 8.2 | 0.4143 | 37.29 |
| Reference compound B | Well-stirred | 85.0 | 0.25 | 180.0 | 10.5 | 6.8 | 0.3462 | 29.43 |
| Reference compound C | Well-stirred | 95.0 | 0.45 | 900.0 | 18.0 | 3.1 | 0.8095 | 76.90 |
Formula Used
1) Concentration Extraction Method
Extraction Ratio: ER = (Cin − Cout) / Cin
Hepatic Clearance: CLh = Qh × ER
2) Well-Stirred Model
Extraction Ratio: ER = (fu × Clint) / (Qh + fu × Clint)
Hepatic Clearance: CLh = Qh × [(fu × Clint) / (Qh + fu × Clint)]
3) Supporting Outputs
Hepatic Availability: Fh = 1 − ER
Plasma Flow: Qp = Qh × (1 − Hematocrit)
Predicted Outlet Concentration: Cout,pred = Cin × (1 − ER)
This page estimates hepatic removal using simplified pharmacokinetic relationships. It is useful for screening, teaching, and internal comparison, not direct clinical dosing decisions.
How to Use This Calculator
- Select the calculation method that matches your available data.
- Enter hepatic blood flow first, since it is required in both methods.
- For the well-stirred method, provide fraction unbound and intrinsic clearance.
- For the concentration method, provide inlet and outlet concentrations.
- Add hematocrit, body weight, dose, and interval for advanced outputs.
- Press the calculate button to show results above the form.
- Review the graph, compare methods, and download CSV or PDF reports.
Frequently Asked Questions
1) What does hepatic clearance represent?
Hepatic clearance estimates how effectively the liver removes a compound from circulating blood over time. Higher values mean faster liver-mediated elimination under the assumptions of the chosen model.
2) When should I use the well-stirred model?
Use it when you know hepatic blood flow, fraction unbound, and intrinsic clearance. It is common in early drug disposition modeling and helps relate binding and enzyme capacity to organ-level clearance.
3) When is the concentration method better?
Choose it when inlet and outlet concentrations are measured experimentally. It directly estimates extraction ratio from observed concentration drop across the liver rather than predicting it from intrinsic parameters.
4) Why does hematocrit matter here?
Hematocrit changes the relationship between blood flow and plasma flow. Including it helps estimate plasma-based clearance, which can be useful when comparing blood and plasma concentration frameworks.
5) What is a high extraction ratio?
An extraction ratio above 0.70 is usually considered high. Such compounds are removed efficiently by the liver and are often more sensitive to changes in hepatic blood flow.
6) Why are two extraction ratios shown sometimes?
If enough inputs are provided, the page calculates the selected method and the alternate method. The comparison gap helps you see how measured concentration loss differs from the mechanistic prediction.
7) Can I use this for clinical treatment decisions?
No. This tool is educational and analytical. Real clinical decisions require validated pharmacokinetic models, patient-specific physiology, disease state assessment, and expert review.
8) What units should I keep consistent?
Use matching time and volume units throughout the calculation. If blood flow is in L/h, intrinsic clearance should also be in L/h, and concentrations should use the same concentration unit.
Interpretation Notes
Low extraction compounds are usually more sensitive to protein binding and intrinsic enzyme activity. High extraction compounds are more dependent on hepatic blood flow.
Compare the primary and alternate extraction ratios when both are available. Large gaps may indicate experimental variability, model mismatch, transporter effects, saturation, or unit inconsistency.