Pharmacokinetics

Pharmacokinetics (from Ancient Greek pharmakon "drug" and kinetikos "moving, putting in motion"; see chemical kinetics), sometimes abbreviated as PK, is a branch of pharmacology dedicated to determine the fate of substances administered to a living organism. The substances of interest include any chemical xenobiotic such as: pharmaceutical drugs, pesticides, food additives, cosmetics, etc. It attempts to discover the fate of a drug from the moment that it is administered up to the point at which it is completely eliminated from the body. Pharmacokinetics is the study of how an organism affects a drug, whereas pharmacodynamics (PD) is the study of how the drug affects the organism. Both together influence dosing, benefit, and adverse effects.

Principles of pharmacokinetics

Pharmacokinetics is divided into several areas including, but not limited to:

• Absorption - the process of a substance entering the blood circulation.
• Distribution - the dispersion or dissemination of substances throughout the fluids and tissues of the body.
• Metabolism - the recognition by the organism that a foreign substance is present and the irreversible transformation of parent compounds into daughter metabolites.
• Excretion - the removal of the substances from the body. In rare cases, some drugs irreversibly accumulate in body tissue.

The four principles of pharmacokinetics are often graphically depicted by the so-called "ADME scheme". Each principle is described by the rate of the respective process, and these rates are influenced by the physicochemical properties of the drug.

See also

• Bioavailability
• Bioequivalence
• Pharmacogenetics
• Pharmacogenomics
• Pharmacology
• Toxicokinetics

References

Pharmacokinetics Resources
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