Introduction to Nonlinear Pharmacokinetics

Introduction to Nonlinear Pharmacokinetics explains dose-dependent absorption, metabolism, and elimination processes in drug kinetics.

Introduction to Nonlinear Pharmacokinetics

• Pharmacokinetics (PK) studies how drugs are absorbed, distributed, metabolized, and eliminated.
• Typically, drug concentration follows linear PK, where drug levels are proportional to the administered dose.
• However, in some cases, drug kinetics deviate from this pattern, leading to nonlinear pharmacokinetics (also called dose-dependent or saturation kinetics).

Definition of Nonlinear Pharmacokinetics

• Nonlinear pharmacokinetics occurs when drug dose changes do not result in proportional changes in drug concentration.
• This often arises due to the saturation of physiological processes involved in metabolism, distribution, or excretion.

Characteristics of Nonlinear Pharmacokinetics

• Drug elimination does not follow first-order kinetics.
• Plasma drug concentration increases disproportionately with dose.
• Pharmacokinetic parameters (e.g., clearance, half-life) change with dose.
• Often linked to enzyme saturation, active transport, or plasma protein binding saturation.

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