Key Principles of Pharmacology

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2. Pharmacokinetics

2.4. Excretion

It refers to how the body gets rid of a medicine or its metabolites. There are three main routes of elimination: kidneys (urine), liver, and bowel (bile in faeces). Most medicines are excreted as active, partially active, or inactive metabolites by the kidneys. Infants and elderly have underdeveloped or impaired abilities to metabolise and excrete less of a medicine which usually results in greater sensitivity to medicines.