Description
Two-point research log slope; no terminal-phase selection or dosing inference.
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.
Two-point research log slope; no terminal-phase selection or dosing inference.
When to use this tool
Use PK Log Linear Terminal Slope Two Points 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 firstTime, secondTime, firstConcentration, secondConcentration. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read slope, eliminationRate, halfLife. Use the output convention below.
Require secondTime>firstTime and firstConcentration>secondConcentration>0. Return slope=(ln(secondConcentration)-ln(firstConcentration))/(secondTime-firstTime), eliminationRate=-slope, and halfLife=ln(2)/eliminationRate.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| firstTime | First Time | Required. Finite number. |
| secondTime | Second Time | Required. Finite number. |
| firstConcentration | First Concentration | Required. Finite number. |
| secondConcentration | Second Concentration | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| slope | Slope | Required. Finite number. |
| eliminationRate | Elimination Rate | Required. Finite number. |
| halfLife | Half Life | Required. Finite number. |
{
"input": {
"firstTime": 0,
"secondTime": 2,
"firstConcentration": 8,
"secondConcentration": 4
},
"output": {
"slope": -0.3465735902799726,
"eliminationRate": 0.3465735902799726,
"halfLife": 2.0000000000000004
}
}Limitations and assumptions
- Times need one unit and concentrations one matching assay unit. Two decreasing points do not establish a valid terminal phase; no regression, uncertainty, or dosing guidance is provided.
- 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
- Nonclinical Terminal Slope Point Residual
Compare one nonclinical point to a supplied log-linear curve without fitting a terminal phase or recommending doses.
- Nonclinical Concentration Logstep
Compare explicitly supplied nonclinical concentration observations without dosing or extrapolated patient predictions.