Description
For positive observedAuc and terminalRate and nonnegative lastConcentration return tailArea=lastConcentration/terminalRate, totalArea=observedAuc+tailArea, and extrapolatedFraction=lastConcentration/(terminalRate*observedAuc+lastConcentration).
Pharmacokinetic research describes concentration over time using measurement units and an explicit model. Concentration-time area, its time-weighted moment, inverse-time rate constants, clearance, and volume are related but distinct quantities. A conversion or local model term does not estimate every parameter or validate a complete study.
For positive observedAuc and terminalRate and nonnegative lastConcentration return tailArea=lastConcentration/terminalRate, totalArea=observedAuc+tailArea, and extrapolatedFraction=lastConcentration/(terminalRate*observedAuc+lastConcentration).
When to use this tool
Use PK Noncompartmental Extrapolated Tail Share when you need this concentration-time conversion, sampling check, local integral panel, or explicitly supplied kinetic-model term.
How to use the tool and how it works
- Enter observedAuc, lastConcentration, terminalRate. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read tailArea, totalArea, extrapolatedFraction. Use the output convention below.
For positive observedAuc and terminalRate and nonnegative lastConcentration return tailArea=lastConcentration/terminalRate, totalArea=observedAuc+tailArea, and extrapolatedFraction=lastConcentration/(terminalRate*observedAuc+lastConcentration).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| observedAuc | Observed Auc | Required. Finite number; strictly above 0. |
| lastConcentration | Last Concentration | Required. Finite number; minimum 0. |
| terminalRate | Positive terminal decay constant in inverse AUC-time units. | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| tailArea | Tail Area | Required. Finite number. |
| totalArea | Total Area | Required. Finite number. |
| extrapolatedFraction | Extrapolated Fraction | Required. Finite number. |
{
"input": {
"observedAuc": 40,
"lastConcentration": 2,
"terminalRate": 0.5
},
"output": {
"tailArea": 4,
"totalArea": 44,
"extrapolatedFraction": 0.09090909090909091
}
}Limitations and assumptions
- AUC uses concentration times time and terminalRate uses inverse that time unit. Extrapolation assumes a valid terminal exponential decay; no slope fitting, terminal-window validation, or acceptance cutoff is supplied.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Signed zero is exported as zero.
Alternative or Complementary methods
Use a complete study analysis when a local panel, transformation, or model factor is insufficient. Check sampling times, censoring, assay support, unit conventions, and the validity of the assumed kinetic regime.
References
Similar or alternative tools
- PK Censored Tail Reference Base
Compare already supplied research exposure areas; no tail extrapolation model or dose adjustment is inferred.
- PK AUC One Trapezoid Panel
One linear or logarithmic research AUC panel under an explicit convention.