Page 163 - Interactive Theoritical Notes of Bioharmaceutics and pharamcokinetics.docx compressed

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

Elimination

Elimination is the irreversible loss of drug from the site of measurement (blood,

serum, plasma) Elimination of drugs occurs by one or both of metabolism and

excretion.

Excretion: Excretion is defined as the irreversible loss of a drug in a chemically

unchanged or unaltered fo

Routes of elimination

The two principal organs responsible for drug elimination are the kidney and the liver.

The kidney is the primary site for removal of a drug in a chemically unaltered or

unchanged form (i.e. excretion) as well as for metabolites.

The liver is the primary organ where drug metabolism occurs.

The lungs, occasionally, may be an important route of elimination for substances of

high vapor pressure (i.e. gaseous anesthetics, alcohol, etc.).

Some compounds are also excreted via:
▪ Bile,
▪ Sweat,
▪ Saliva,

▪ Exhaled air, or
▪ Milk.
• Some orally administered drugs are not easily absorbed from the GIT and as a result

are significantly excreted in the feces.

Excretion can also occur through the bile (if enterohepatic cycling does not occur) and

certain drugs are removed through the lungs in the expired breath.

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