Therapeutic Index Calculator

Analyze dose separation with flexible scientific inputs today. View ratios, margins, and response curves clearly. Make safer comparisons using practical metrics and exportable reports.

Calculator Inputs

This page uses a stacked layout, while the input grid shifts to three, two, or one column based on screen width.

Formula Used

1. Therapeutic Index
TI = Toxic midpoint dose / Effective midpoint dose
TI = TD50 / ED50 or LD50 / ED50
2. Protective Index
Protective Index = Low toxicity threshold / Near-maximal effective dose
Protective Index = TD1 / ED99 or LD1 / ED99
3. Standard Safety Margin
Safety Margin (%) = ((Low toxicity threshold − ED99) / ED99) × 100
4. Therapeutic Window Width
Therapeutic Window = Minimum Toxic Dose − Minimum Effective Dose
5. Window Ratio
Window Ratio = Minimum Toxic Dose / Minimum Effective Dose

These formulas simplify population response data into screening metrics. Real safety evaluation also depends on variability, route, exposure duration, kinetics, and endpoint selection.

How to Use This Calculator

  1. Enter the compound name and preferred dose unit.
  2. Provide ED50 and at least one toxicity midpoint, TD50 or LD50.
  3. Select the toxicity basis manually or keep auto mode.
  4. Add ED99 and TD1 or LD1 for protective index and safety margin.
  5. Optionally enter minimum effective and toxic thresholds for a therapeutic window estimate.
  6. Adjust Hill slopes and graph maximum dose if needed.
  7. Submit the form to see results above the calculator.
  8. Use the CSV or PDF buttons to export the result summary.

Example Data Table

Compound ED50 TD50 ED99 TD1 Min Effective Min Toxic TI
Compound A 8 mg/kg 64 mg/kg 14 mg/kg 21 mg/kg 5 mg/kg 18 mg/kg 8.00
Compound B 4 mg/kg 12 mg/kg 7 mg/kg 9 mg/kg 3 mg/kg 8 mg/kg 3.00
Compound C 10 µM 220 µM 18 µM 30 µM 7 µM 28 µM 22.00

FAQs

1. What does therapeutic index measure?

It compares a toxic or lethal midpoint dose with an effective midpoint dose. A larger value suggests wider separation between benefit and harm in a simplified population model.

2. Why can this calculator use TD50 or LD50?

Some studies report toxicity endpoints, while others report lethality endpoints. This tool supports both so you can match the available dataset and maintain a consistent comparison basis.

3. Is a higher therapeutic index always safer?

Not always. A high index can still hide important risks from variable absorption, metabolism, vulnerable populations, chronic exposure, or different adverse endpoints.

4. What is the protective index?

Protective index compares a low-incidence toxicity point, such as TD1 or LD1, with a near-maximal effective point, such as ED99. It often gives a stricter safety view.

5. What does the safety margin percentage show?

It shows how far the low-toxicity threshold sits above ED99, expressed as a percentage. Positive values imply extra room beyond near-maximal effect.

6. Why include a dose response graph?

The graph helps visualize how effective and toxic responses move across dose levels. It makes overlap and separation easier to understand than a single ratio alone.

7. Can I use this for clinical dosing decisions?

No. This calculator is for educational, screening, and comparative analysis. Clinical decisions require validated studies, patient context, monitoring, and professional oversight.

8. Which inputs are required for a basic calculation?

You need ED50 and at least one toxicity midpoint, either TD50 or LD50. The other fields are optional but improve interpretation and chart detail.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.