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 (LD50) to the dose that produces a therapeutic effect (ED50). A higher TI indicates a safer drug.

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: The TI represents the margin of safety for a drug. Higher values indicate a wider margin between effective and toxic doses.

3. Importance of Therapeutic Index

Details: Therapeutic Index is crucial in pharmacology for assessing drug safety, determining appropriate dosing regimens, and comparing the safety profiles of different medications.

4. Using the Calculator

Tips: Enter both LD50 and ED50 values in mg/kg. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is considered a good Therapeutic Index?
A: Generally, a TI greater than 10 is considered acceptable, while values above 100 indicate very safe drugs. However, this varies by drug class and intended use.

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 in drug metabolism, drug interactions, or differences in patient populations. 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 warfarin, digoxin, and lithium have narrow therapeutic indices and require careful monitoring during treatment.

Q5: How does Therapeutic Index relate to therapeutic window?
A: Therapeutic Index is a ratio, while therapeutic window describes the range between the minimum effective concentration and the minimum toxic concentration of a drug in the blood.