Page 143 - Interactive Theoritical Notes of Bioharmaceutics and pharamcokinetics.docx compressed

PharmD clinical pharmacy program Level 3, Semester 2 Biopharmaceutics & Pharmacokinetics (PT608(

 Fat As a Reservoir: Many lipid-soluble drugs are stored by physical solution in the

neutral fat.

 In obese persons, the fat content of the body may be as high as 50%, and even in
lean individuals it constitutes 10% of body weight;

 Hence fat may serve as a reservoir for lipid-soluble drugs.
• Drugs with a high lipid/water partition coefficient are very fat soluble and

tend to accumulate in lipid or adipose (fat) tissue.

• In this case, the lipid-soluble drug partitions from the aqueous environment of

the plasma into the fat.

• This process is reversible,

• but the extraction of drug out of the tissue is so slow that the drug may remain

for days or even longer in adipose tissues, long after the drug is depleted from

the blood.

• Because the adipose tissue is poorly perfused with blood, drug accumulation

is slow.

• However, once the drug is concentrated in fat tissue, drug removal from fat

may also be slow.

• For example, the chlorinated hydrocarbon DDT

(dichlorodiphenyltrichloroethane) is highly lipid soluble and remains in fat

tissue for years.

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