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Binding of drugs to plasma proteins

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  18

2026-09-13

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Binding of drugs to plasma proteins

Many, if not most, drugs bind to proteins in plasma with sufficient affinity to prevent that portion of the drug being biologically active. For example, if a drug is 90% bound to plasma proteins, only 10% can exhibit biological activity. The binding sites for drugs in plasma are predominantly albumin (which preferentially binds acidic drugs), although b-globulin and a1-acid glycoprotein are also significant sites for some drugs (particularly basic ones). The significance of the protein binding of drugs is that the ‘free’ or unbound fraction in plasma may be affected by illness and by the use of other drugs. In disease states (particularly kidney and liver dysfunction), protein binding can be reduced markedly, and often increases the apparent effects of drugs. Since binding sites are saturable, other drugs can compete with the binding and reduce the net binding of the drug. This can cause a net increase in drug action for some drug combinations and may need to be taken into account when interpreting results of an analysis.