Drug Synergy Calculator

Calculate Combination Index (CI) to determine synergistic, additive, or antagonistic effects in drug combinations using the Chou-Talalay method.

Drug A Parameters

Drug B Parameters

What is Drug Synergy Calculator?

This tool calculates the Combination Index (CI) to quantify drug interactions in combination therapy. Based on the Chou-Talalay method, it determines whether drug combinations show synergistic (CI < 1), additive (CI = 1), or antagonistic (CI > 1) effects.

How to Use This Calculator

Quick guide to get results:

  1. Enter drug combination dose-response data
  2. Input IC50 values for each drug (if known)
  3. View CI values and synergy interpretation
  4. CI < 1 = Synergy, CI = 1 = Additive, CI > 1 = Antagonism

When to Use

This tool is useful when you need to:

  • Evaluate drug combination efficacy
  • Optimize combination therapy dosing
  • Screen for synergistic drug pairs
  • Reduce drug toxicity through synergistic combinations

Example Input

Sample dose-response data:

Dose A, Dose B, Effect (%)
1.0, 0, 25
0, 0.5, 20
1.0, 0.5, 50

Format: dose A, dose B, effect percentage

Example Output

Expected output format:

Dose A, Dose B, Effect, CI, Interpretation
1.00, 0.50, 50.0%, 0.646, Synergism
4.00, 1.00, 92.0%, 0.167, Strong Synergism

CI < 1 indicates a synergistic interaction (Cisplatin + Paclitaxel, IC50 3.2 / 1.5 μM).

FAQ

Q: What is the Chou-Talalay method?
A: A widely accepted mathematical model for quantifying drug synergy based on the median-effect principle.

Q: What CI value indicates synergy?
A: CI < 1 indicates synergy, CI = 1 is additive, CI > 1 is antagonism.