Distribution

Definition

Distribution is the process by which a drug is dispersed throughout the body’s fluids and tissues following administration. It determines the extent and rate at which active drug reaches its site of action.

5 Must Know Facts For Your Next Test

1. Distribution depends on factors like blood flow, tissue permeability, and binding to plasma proteins.
2. The volume of distribution (Vd) is a theoretical value that describes how extensively a drug disperses into body tissues compared to the plasma.
3. Highly lipophilic drugs tend to distribute widely in adipose tissue.
4. Drugs bound to plasma proteins are usually inactive until they are released into free form.
5. Certain barriers, such as the blood-brain barrier, can limit distribution to specific organs.

Review Questions

• What factors influence the distribution of a drug within the body?
• How does plasma protein binding affect drug activity?
• Why is the volume of distribution an important parameter in pharmacokinetics?

Related terms

Absorption:

The process by which a drug enters the bloodstream from its site of administration.

Metabolism:

The chemical alteration of a drug by the body, primarily occurring in the liver.

Excretion:

The removal of drugs and their metabolites from the body, mainly through urine or feces.