1. What is Therapeutic Index?

The Therapeutic Index (TI) is a quantitative measurement of the relative safety of a drug. It compares the dose that produces a toxic effect to the dose needed to produce the desired therapeutic response.

2. How Does the Calculator Work?

The calculator uses the Therapeutic Index formula:

Where:

• \( LD_{50} \) — Lethal dose for 50% of the population (mg/kg)
• \( ED_{50} \) — Effective dose for 50% of the population (mg/kg)

Explanation: A higher therapeutic index indicates a wider margin of safety between the effective dose and the toxic dose.

3. Importance of Therapeutic Index

Details: The therapeutic index is a crucial parameter in pharmacology that helps determine the safety profile of pharmaceutical compounds and guides dosing recommendations.

4. Using the Calculator

Tips: Enter LD50 and ED50 values in mg/kg. Both values must be valid (greater than 0).

5. Frequently Asked Questions (FAQ)

Q1: What is considered a good therapeutic index?
A: Generally, a higher TI is better. Drugs with TI > 10 are considered relatively safe, while those with TI < 3 require careful monitoring.

Q2: How is LD50 determined?
A: LD50 is typically determined through animal studies where increasing doses of a substance are administered to determine the dose lethal to 50% of the test population.

Q3: What are the limitations of therapeutic index?
A: TI doesn't account for individual variations, allergic reactions, or idiosyncratic responses. It's also based on animal data which may not perfectly translate to humans.

Q4: Are there drugs with very low therapeutic index?
A: Yes, drugs like digoxin, warfarin, and lithium have narrow therapeutic indices and require careful monitoring and dose adjustment.

Q5: What's the difference between therapeutic index and therapeutic window?
A: Therapeutic index is a ratio, while therapeutic window refers to the range of doses between the minimum effective concentration and the minimum toxic concentration.