Advanced Pharmacokinetic Converter
Choose one mode. Enter the matching inputs. Leave unrelated fields blank.
Example Data Table
| Use case | Inputs | Formula | Example result |
|---|---|---|---|
| Absolute bioavailability | AUC oral 46 mg·h/L, AUC IV 28 mg·h/L, oral dose 250 mg, IV dose 100 mg | F = (AUC oral × Dose IV) ÷ (AUC IV × Dose oral) | 65.71% |
| IV clearance | Dose IV 100 mg, AUC IV 28 mg·h/L | CL = Dose ÷ AUC | 3.571 L/h |
| Half-life method | Vd 42 L, half-life 6.2 h | CL = 0.693 × Vd ÷ t1/2 | 4.695 L/h |
| Steady state infusion | R0 40 mg/h, Css 2.5 mg/L | CL = R0 ÷ Css | 16 L/h |
Formula Used
Absolute bioavailability: F = (AUCtest × DoseIV) ÷ (AUCIV × Dosetest). Multiply by 100 for percent.
IV clearance: CL = DoseIV ÷ AUCIV. Dose is converted to mg. AUC is converted to mg·h/L.
Apparent clearance: CL/F = Dosetest ÷ AUCtest. This is used for oral or extravascular routes.
Rate constant method: CL = ke × Vd. The calculator converts ke to 1/h and Vd to liters.
Half-life method: CL = 0.693 × Vd ÷ t1/2. Half-life is converted to hours.
Renal clearance: CLr = Ae ÷ AUC. Ae means unchanged amount excreted in urine.
Hepatic well-stirred model: CLh = Qh × fu × Clint ÷ (Qh + fu × Clint).
Infusion at steady state: CL = R0 ÷ Css. R0 is infusion rate. Css is steady state concentration.
How to Use This Calculator
- Select the calculation mode that matches your available pharmacokinetic data.
- Enter dose, AUC, volume, half-life, or flow values as needed.
- Choose the correct unit beside each entered value.
- Add body weight if you need mL/min/kg output or use L/kg volume.
- Press the calculate button to show results below the header.
- Review the formula, notes, and converted result units.
- Download a CSV file for spreadsheets or a PDF file for reports.
Pharmacokinetic Meaning
Clearance and bioavailability are core pharmacokinetic ideas. They show how a drug moves through the body. Clearance estimates the virtual plasma volume cleared of drug per time. Bioavailability estimates the fraction of a dose that reaches systemic circulation.
These measures guide comparison between routes. They also help learners understand exposure. A high AUC means greater exposure. A low clearance may mean slower removal. A low bioavailability may mean poor absorption or strong first pass loss. These patterns need context before any decision.
Why A Better Equation Helps
A simple equation can be misleading when units differ. Dose may be entered in micrograms, milligrams, or grams. AUC may use hours or minutes. Concentration may use ng/mL or mg/L. This calculator converts units before using equations. That reduces common mistakes.
The best equation depends on available data. For an intravenous dose, absolute clearance is dose divided by AUC. For an oral dose, the value is apparent clearance, because bioavailability is unknown. For route comparison, absolute bioavailability uses dose normalized AUC values. This is stronger than comparing raw AUC alone.
Clearance Inputs
Clearance can be estimated in several ways. The dose and AUC method is common after intravenous dosing. The elimination rate method uses CL = ke × Vd. The half life method uses CL = 0.693 × Vd ÷ t1/2. Renal clearance uses unchanged amount excreted divided by AUC. Infusion clearance uses infusion rate divided by steady state concentration.
Each method answers a slightly different question. Renal clearance measures kidney removal of unchanged drug. Hepatic clearance estimates liver removal from blood flow, free fraction, and intrinsic clearance. Infusion clearance assumes steady state has been reached. The selected mode should match the study design.
Bioavailability Inputs
Absolute bioavailability compares an extravascular route with an intravenous route. The equation is F = (AUC oral × Dose IV) ÷ (AUC IV × Dose oral). The result can be shown as a fraction or percent. Dose normalization is important because the two doses may not match.
Bioavailability can vary by formulation. Food, solubility, metabolism, and transporters may change absorption. First pass metabolism can lower systemic entry. This calculator does not judge safety or efficacy. It only organizes the numerical relationship.
Interpreting Results
The calculator returns clearance in L/h and mL/min. When body weight is entered, it also gives mL/min/kg. Bioavailability is shown as percent and fraction. Export files can support notes, audits, or classroom records.
Use results carefully. Units must describe the same analyte and matrix. AUC values should come from comparable sampling windows. Interpolation, extrapolation, and assay limits can affect the answer. Clinical dosing should always be checked by a qualified professional.
Practical Workflow
Start by choosing the calculation mode. Enter only the fields needed for that mode. Select units carefully. Add body weight when normalized clearance is useful. Press calculate, then review the formula and warning notes. Use the CSV file for spreadsheets. Use the PDF file for a compact report.
This tool is useful for study, teaching, and documentation. It makes assumptions visible. It also keeps the formulas beside the result. That makes review easier and reduces hidden conversion errors.
Common Quality Checks
Check the dose route before comparing values. Confirm that AUC is not dose normalized already. Make sure time units match the study report. Review whether bioavailability should be written as fraction or percent. Small unit errors can create large pharmacokinetic differences. Document key assumptions before final reporting.
FAQs
1. What does clearance mean?
Clearance is the virtual volume of plasma or blood cleared of drug per unit time. It is commonly shown as L/h or mL/min.
2. What does bioavailability mean?
Bioavailability is the fraction of an administered dose that reaches systemic circulation. It is often shown as a percentage.
3. Why is IV data used for absolute bioavailability?
IV dosing is treated as fully available to systemic circulation. That makes it the reference route for calculating absolute bioavailability.
4. What is CL/F?
CL/F is apparent clearance after an extravascular dose. It combines true clearance and bioavailability because F is not separately known.
5. Can I compare different doses?
Yes. The absolute bioavailability equation normalizes by dose. This allows comparison when IV and oral doses are not the same.
6. Which AUC should I enter?
Use the AUC reported for the same analyte, matrix, and sampling window. Total AUC is often preferred when available.
7. Does the calculator handle unit conversion?
Yes. It converts dose, AUC, time, volume, flow, infusion rate, and concentration units before calculating results.
8. What is renal clearance?
Renal clearance estimates kidney removal of unchanged drug. It uses the unchanged urinary amount divided by plasma AUC.
9. What is hepatic extraction ratio?
It is hepatic clearance divided by hepatic blood flow. It helps classify low, intermediate, or high extraction behavior.
10. When should I use the infusion mode?
Use infusion mode when a constant infusion rate and steady state concentration are available. Steady state is required.
11. Why enter body weight?
Body weight allows normalized clearance in mL/min/kg. It is also required when volume is entered as L/kg.
12. Can results guide patient dosing?
No. This page is for learning and documentation. Clinical dosing should be reviewed by qualified healthcare professionals.
13. Why can bioavailability exceed 100%?
It may happen from assay variation, study design issues, nonlinearity, or mismatched AUC windows. Review the source data carefully.
14. What can I download?
You can download the calculated result as a CSV file for spreadsheets or a PDF file for compact reporting.