Core7: Dose-effect relationships at population level

📊 High-yield / 要点：Population dose-response focuses on how many subjects respond, not how strongly one subject responds. Key parameter: ED50 = dose effective in 50% of the population.

Core idea / 基本概念

• Dose = amount of drug administered.
• Individuals do not respond identically → individual sensitivity.
• Sensitivity in a population can be shown by a distribution curve, often a Gaussian/normal distribution.

Dose-response types / 用量反応の種類

Type	Meaning	Example
Graded / parametric	Effect gradually increases with dose in one subject	Blood pressure decreases more as dose increases
Quantal / binary	Response is yes/no in each subject	Headache gone; BP reduced by ≥20 mmHg

Quantal dose-response / 量的用量反応

• At population level, we usually examine binary response.
• Y-axis = percentage/number of subjects responding positively.
• Cumulative curve includes subjects who already responded at lower doses.
• Area under the Gaussian curve = 100% of tested subjects.

ED50 / 有効量50

• ED50 = dose at which 50% of the population responds positively.
• ED50 is the midpoint of the population sensitivity distribution.
• ED50 is not always the therapeutic dose:
  • For all-or-none outcomes, one patient either responds or does not.
  • Clinically, ED90 / ED95 / ED99 may be more logical depending on safety.
• Dose choice depends strongly on side-effect risk and available strengths.

Remember / 覚え方

• Graded = “how much effect in one subject?”
• Quantal = “how many subjects respond?”
• ED50 = “50% responder dose,” not automatically the best clinical dose.