# What is a Dose Response Curve? - Equation & Pharmacology

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• 0:03 What Is the Dose…
• 1:18 Dose Response Curve Phases
• 1:42 Effective Dose vs. Lethal Dose
• 1:56 Potency Vs Efficacy
• 2:52 Lesson Summary

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Lesson Transcript
Instructor: Emily Sheff

Emily has taught in several nursing courses. She holds a masters degree as a FNP and is currently working on a doctorate in nursing education.

A dose response curve is one of the most important concepts in pharmacology and describes the relationship between an effect of a drug and the amount of drug given.

## What Is the Dose Response Curve?

Have you ever considered how your healthcare provider knows how much of a medication to prescribe? Who creates the dosing guidelines and where do they come from?

The concept of the dose response curve is one of the most important parts of pharmacology. A dose response curve refers to the relationship between an effect of a drug and the amount of drug given. Dose response curves are essential to understand the drug's safe and hazardous levels, so that the therapeutic index can be determined and dosing guidelines can be created.

Dose response curves are charted on a simple x-/y-axis, with the drugs dosage typically on the x-axis and the response to the medication typically on the y-axis. Most dose response curves are graphed on a logarithmic scale as opposed to a linear one and often times, the y-axis is represented by percentages, to indicate the percentages of individuals responding to the drug. When evaluating a dose response curve, one of the main characteristics of the curve is that it's a graded relationship. This means that as the amount of drug given is increased so is the response to the drug. This grading of the dose response curve enables your healthcare provider to tailor their prescription to the individual taking the drug.

## Dose Response Curve Phases

There are three phases of a dose response curve. First, the curve is flat as the amount of drug given is not great enough to initiate a response. In the second phase, the curve steadily rises. With each increase in the drug dose, there is also an increased in desired response. Finally, the curve plateaus at the top, indicating that any further increases in drug dose will not increase a drug response.

## Effective Dose vs. Lethal Dose

Two important terms are associated with the dose response curve. The LD50 refers to the lethal dose in 50% of the population taking the drug and the ED50, refers to the effective dose in 50% of the population taking the drug.

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