Which kinetic order is defined by a constant amount of drug being removed per unit of time?

Which kinetic order is defined by a constant amount of drug being removed per unit of time?

• A. First-order kinetics
• B. Zero-order kinetics
• C. Second-order kinetics
• D. Third-order kinetics

Answer: (B)

Think about how the body handles drug removal in terms of its dependence on how much drug is present. In zero-order kinetics, the body eliminates a fixed amount of drug per unit time, regardless of the current concentration. That means if you start with more drug, you still remove the same steady chunk each hour until the concentration gets low enough that the process can no longer stay saturated and the pattern may shift toward first-order behavior. This contrasts with first-order kinetics, where the elimination rate depends on how much drug is present—the amount removed per unit time decreases as concentration falls, and the half-life remains constant. The other orders imply rates that depend on concentration in more complex ways (like squared or cubed), which isn’t how elimination usually operates under normal circumstances. So, a constant amount removed per unit time points to zero-order kinetics.

Think about how the body handles drug removal in terms of its dependence on how much drug is present. In zero-order kinetics, the body eliminates a fixed amount of drug per unit time, regardless of the current concentration. That means if you start with more drug, you still remove the same steady chunk each hour until the concentration gets low enough that the process can no longer stay saturated and the pattern may shift toward first-order behavior. This contrasts with first-order kinetics, where the elimination rate depends on how much drug is present—the amount removed per unit time decreases as concentration falls, and the half-life remains constant. The other orders imply rates that depend on concentration in more complex ways (like squared or cubed), which isn’t how elimination usually operates under normal circumstances. So, a constant amount removed per unit time points to zero-order kinetics.