Description
Calculate a first-order remaining fraction from supplied rate and elapsed time.
Pharmacokinetic records distinguish concentration, amount, elapsed time, dilution basis and assay quantification status. Multiplying concentration by compatible volume gives an amount, while a first-order decay factor assumes a supplied constant rate. These local terms and labels do not estimate a person's drug exposure or establish a dose, therapeutic threshold or safe medication decision.
Calculate a first-order remaining fraction from supplied rate and elapsed time.
When to use this tool
Use PK Terminal Decay Factor when you already have ratePerHour, elapsedHours and need to calculate a first-order remaining fraction from supplied rate and elapsed time.
How to use the tool and how it works
- Enter ratePerHour, elapsedHours. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read remainingFraction. Use the output convention below.
Require ratePerHour>=0 and elapsedHours>=0; return exp(-rate*time).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| ratePerHour | Supplied nonnegative constant first-order rate in 1/h, not a dose or measured patient parameter. | Required. Finite number; minimum 0. |
| elapsedHours | Elapsed Hours | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| remainingFraction | Remaining Fraction | Required. Finite number. |
{
"input": {
"ratePerHour": 0.5,
"elapsedHours": 2
},
"output": {
"remainingFraction": 0.36787944117144233
}
}Limitations and assumptions
- Assumes a constant nonnegative first-order rate; does not estimate elimination, dosing, patient exposure or suitable medication use. Extreme decay can underflow to zero.
- 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. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use verified assay data and an appropriate complete pharmacokinetic model for exposure analysis. Keep dilution, concentration/amount units, sampling time and quantification conventions attached to the observations; a scalar decay or limit comparison does not estimate a regimen.
References
Similar or alternative tools
- PK Collected Volume Recovery Term
Calculate an amount from supplied concentration and collected volume.
- PK Concentration Dilution Adjustment
Apply an explicit dilution multiplier to a reported concentration.