LD50 is defined as which of the following?

LD50 is defined as which of the following?

• A. The dose that produces lethality in 25% of subjects.
• B. The dose that causes death in all tested subjects.
• C. The dose required to produce lethality in 50% of the subjects.
• D. The amount of drug that would kill 0% of the population.

Answer: (C)

LD50 is the dose that would kill 50% of the subjects under defined conditions. This comes from dose–response studies used to gauge acute toxicity and compare how potent different substances are. It’s a practical benchmark because it summarizes the likelihood of death at a given dose, allowing comparison across compounds, species, and routes of exposure. It’s not a fixed value for all situations, since it depends on factors like species, age, health, route of administration, and experimental conditions. It’s not the dose that kills everyone, nor the dose that kills only 25%, nor a dose that kills none.

LD50 is the dose that would kill 50% of the subjects under defined conditions. This comes from dose–response studies used to gauge acute toxicity and compare how potent different substances are. It’s a practical benchmark because it summarizes the likelihood of death at a given dose, allowing comparison across compounds, species, and routes of exposure. It’s not a fixed value for all situations, since it depends on factors like species, age, health, route of administration, and experimental conditions. It’s not the dose that kills everyone, nor the dose that kills only 25%, nor a dose that kills none.