Therapeutic Index Calculator
Calculate therapeutic index (TI), safety margin, and certain safety factor for drug evaluation.
Safety Parameters
TD50 (mg/kg)
LD50 (mg/kg)
Therapeutic Index Formula
TI = TD50 / ED50 or LD50 / ED50
Higher TI = Wider safety margin
Therapeutic Index
10.00
Very wide safety margin
Safety Parameters
TD50 (Toxic)500 mg/kg
LD50 (Lethal)1000 mg/kg
ED50 (Effective)50 mg/kg
Log TI1.00
TI Interpretation Guide
TI > 10Very wide margin
TI 5-10Wide margin
TI 2-5Moderate margin
TI < 2Narrow margin
Clinical Implications
- - Narrow TI drugs require careful dosing
- - Therapeutic drug monitoring recommended for TI less than 2
- - Consider drug interactions that may alter TI
- - Patient factors (age, weight, organ function) affect safety margin
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
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Formula Source: Standard Mathematical References
by Various
🔄Last reviewed: May 2026
✓Formula checks are based on standard references and internal QA review.