Median Effective Dose

TL;DR

• A single-number summary of a substance’s potency: the dose at which 50% of subjects achieve the target effect.
• Commonly used to compare drugs and to help set dosing ranges.
• Does not capture individual variability or all safety considerations.

Definition

The median effective dose, also known as the ED50, is a measure of the potency of a drug or other chemical substance. It is defined as the dose that produces a specified effect in 50% of the population.

Explanation

The median effective dose indicates how much of a substance is required for half of a studied population to exhibit a predefined response. It is commonly used in pharmacology and toxicology to assess potential hazards and to determine safe and effective dosing ranges. The ED50 provides a basis for comparing the potency of different drugs: substances with the same ED50 are considered equally effective at producing the specified effect, while differences in ED50 suggest differences in required dose for effect. Individual response can vary, so the ED50 is one part of dosing assessment and is typically determined under controlled laboratory conditions.

Examples

Pain treatment (opioids)

Painkillers, such as opioids, are commonly used to relieve moderate to severe pain. The median effective dose of an opioid painkiller, such as morphine, is the dose that provides pain relief in 50% of patients. This dose can vary widely depending on the individual, their pain severity, and other factors.

Cancer treatment (chemotherapy)

Chemotherapy drugs are used to kill cancer cells, but they can also have toxic effects on healthy cells. The median effective dose of a chemotherapy drug is the dose that effectively kills cancer cells in 50% of patients, while minimizing the toxic effects on healthy cells. This dose must be carefully determined and monitored by a healthcare provider to ensure the best possible outcome for the patient.

Use cases

• Assessing the potency of drugs and chemicals in pharmacology and toxicology.
• Comparing different drugs’ required doses for a specified effect.
• Informing the determination of safe and effective dosing ranges.

Notes or pitfalls

• The median effective dose is only one factor in determining a drug’s overall safety and effectiveness.
• Individual differences, potential side effects, and drug interactions must also be considered.
• The ED50 is determined in controlled laboratory experiments and may not always reflect real-world situations.

Related terms

• ED50 (alternative name)
• Potency
• Pharmacology
• Toxicology
• Opioid
• Morphine
• Chemotherapy