Description
Supplied same-effect reference fractions without inferring synergy thresholds or treatment.
A pharmacodynamic model relates an exposure or occupancy measure to a response under explicitly supplied parameters. Baseline, maximum increment, half-maximal concentration, effect direction, and observation windows have distinct meanings. Evaluating one model term does not fit the curve or establish its clinical validity.
Supplied same-effect reference fractions without inferring synergy thresholds or treatment.
When to use this tool
Use PD Loewe Supplied Isobole Term when you need this particular response-model term, scale conversion, panel duration, or support calculation.
How to use the tool and how it works
- Enter firstAmount, secondAmount, firstReference, secondReference. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read firstFraction, secondFraction, combinationIndex. Use the output convention below.
For nonnegative firstAmount and secondAmount and positive firstReference and secondReference return their amount/reference fractions and combinationIndex as the sum.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| firstAmount | First Amount | Required. Finite number; minimum 0. |
| secondAmount | Second Amount | Required. Finite number; minimum 0. |
| firstReference | Positive first-agent reference amount at the intended common effect. | Required. Finite number; strictly above 0. |
| secondReference | Positive second-agent reference amount at the same effect basis. | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| firstFraction | First Fraction | Required. Finite number. |
| secondFraction | Second Fraction | Required. Finite number. |
| combinationIndex | Combination Index | Required. Finite number. |
{
"input": {
"firstAmount": 2,
"secondAmount": 3,
"firstReference": 4,
"secondReference": 6
},
"output": {
"firstFraction": 0.5,
"secondFraction": 0.5,
"combinationIndex": 1
}
}Limitations and assumptions
- Each reference must represent a comparable effect-level amount in the same unit as its numerator. The tool does not fit isoboles, establish dose equivalence, test uncertainty, or select a combination therapy.
- 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 fitted and validated response model when a supplied local term is insufficient. Check exposure units, response direction, baseline, model assumptions, and observation support before comparing effects.
References
Similar or alternative tools
- PD Assay Ceiling Gap
Compare supplied assay effects to an explicit ceiling, preserving unknown bounds.
- PD Baseline Normalized Effect Fraction
Normalize a supplied response between baseline and maximum, retaining values outside the reference interval.