Here I share with you some media to begin to understand the concept of drug distribution.

First, a video that analyzes the factors that affect drug distribution: protein binding, molecular weight and lipid solubility.

Authors: Nelson Caetano, Dr. Jef Bratberg. University of Rhode Island

A transcript of the explanatory text:

Unbound drug passes freely through blood vessels and is distributed into the rest of the body. Protein bound drug is trapped within the vessel and is therefore unable to reach its intended sight of action.

Small drug molecules can freely diffuse out of the blood vessel while large drug molecules are confined to the plasma. Heparin is a good example of a drug like this.

Lipid solubility of a drug is a major component in determining its distribution, particularly on the brain. The blood brain barrier prevents the crossing of polarized molecules from capillaries to brain neurons.

The slides below are part of a lecture I give about pharmacokinetics. I chose the slides that explain the meaning of the different values of volume of distribution.

A drug that has a volume of distribution near the plasma volume (e.g. 5 liters) is a drug distributed mainly in the intravascular space. A drug with a very high volume of distribution ( hundreds of liters) should guide us to think that is a drug that bind very strongly to a particular tissue.

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