Question

Zero-order kinetics is otherwise known as saturation kinetics. It is independent of :

• A. Plasma concentration
• B. Clearance
• C. Volume of distribution
• D. Half life

Answer 1

The Correct Option is A

Zero-order kinetics, also known as saturation kinetics, describes a situation where the rate of a reaction (often a drug's metabolism or elimination) is constant irrespective of the concentration of the reactant. In pharmacokinetics, this means that a constant amount of drug is metabolized per unit time. This contrasts with first-order kinetics, where the rate is proportional to the drug concentration.

In zero-order kinetics, the processes are typically saturated because the enzymes responsible for metabolizing the drug are operating at full capacity. As a result:

• The rate of reaction does not increase with an increase in drug concentration, thus it is independent of plasma concentration.
• The elimination mechanism often becomes a constant rate process, leading to a linear decrease in drug concentration over time.
• Parameters such as clearance, volume of distribution, and half-life may still be relevant but are not the key distinguishing features of zero-order kinetics. These parameters depend on the physiological features of a drug but vary differently for zero-order processes.

Considering the options given, zero-order kinetics is independent of plasma concentration. This is because the metabolic rate has reached its maximum capacity and cannot increase with further increases in drug concentration.