Zero-order elimination kinetics are characterized by which of the following?

Zero-order elimination kinetics are characterized by which of the following?

• A. Constant amount of drug eliminated per unit time.
• B. Constant fraction of drug eliminated per unit time.
• C. Exponential decay of drug concentration.
• D. Dose-dependent half-life.

Answer: (A)

In zero-order elimination, the body's elimination processes are saturated, so the drug is removed at a constant amount per unit time regardless of how much drug remains. This means the rate of elimination does not depend on concentration, and the concentration-versus-time plot is a straight line downward. This contrasts with first-order kinetics, where a constant fraction is eliminated per unit time and the concentration decays exponentially. While a dose-dependent half-life can occur with zero-order kinetics, the hallmark feature is the fixed amount removed per time interval, not the changing half-life.

In zero-order elimination, the body's elimination processes are saturated, so the drug is removed at a constant amount per unit time regardless of how much drug remains. This means the rate of elimination does not depend on concentration, and the concentration-versus-time plot is a straight line downward. This contrasts with first-order kinetics, where a constant fraction is eliminated per unit time and the concentration decays exponentially. While a dose-dependent half-life can occur with zero-order kinetics, the hallmark feature is the fixed amount removed per time interval, not the changing half-life.