Which statement about TD50 is true?

Which statement about TD50 is true?

• A. It is the dose that produces a specified toxic effect in 50% of the population
• B. It is the dose that produces a therapeutic effect in 50% of the population
• C. It measures the dose to avoid toxicity in 50%
• D. It measures the maximum tolerated dose

Answer: (A)

TD50 is the dose that produces a defined toxic effect in 50% of the population. This metric comes from the toxicity side of the dose–response curve and is used to gauge how potent a drug’s adverse effects are. It’s distinct from the therapeutic ED50, which is the dose giving the desired effect in 50% of people, and from LD50, which is the lethal dose for 50%. The maximum tolerated dose is a different concept, referring to the highest dose that can be given without unacceptable adverse effects, not the 50% toxic-dose point. The idea of a “specified toxic effect” means you pick a particular adverse outcome to define the end point for the TD50 calculation, which is why this option is the correct description.

TD50 is the dose that produces a defined toxic effect in 50% of the population. This metric comes from the toxicity side of the dose–response curve and is used to gauge how potent a drug’s adverse effects are. It’s distinct from the therapeutic ED50, which is the dose giving the desired effect in 50% of people, and from LD50, which is the lethal dose for 50%. The maximum tolerated dose is a different concept, referring to the highest dose that can be given without unacceptable adverse effects, not the 50% toxic-dose point. The idea of a “specified toxic effect” means you pick a particular adverse outcome to define the end point for the TD50 calculation, which is why this option is the correct description.