The Therapeutic Index (TI) is a ratio that compares the toxic dose of a substance to its therapeutic dose. A higher TI indicates a greater margin of safety between the effective dose and the toxic dose. The formula for TI is:
TI = TD50 / ED50
where TD50 is the dose that causes toxicity in 50% of the population, and ED50 is the dose that is effective in 50% of the population.
