True about zero order kinetics ?
**Core Concept**
Zero order kinetics refers to a type of pharmacokinetic process where the rate of drug elimination is constant and does not depend on the drug's plasma concentration. This is in contrast to **first-order kinetics**, where the rate of elimination is directly proportional to the drug's concentration. Zero order kinetics can occur with certain drugs at high doses.
**Why the Correct Answer is Right**
In zero order kinetics, the rate of drug elimination is constant, meaning that a constant amount of drug is eliminated per unit time, regardless of the drug's concentration. This can lead to a prolonged **half-life** as the concentration of the drug decreases, since the same amount of drug is being eliminated over a longer period.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because zero order kinetics is not dependent on the dose in the way that **first-order kinetics** is.
**Option B:** Incorrect because it is first order kinetics where the rate of elimination is proportional to the concentration.
**Option C:** Incorrect as zero order kinetics involves a constant rate of elimination.
**Option D:** Incorrect as the relationship between concentration and elimination rate is not directly proportional.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that zero order kinetics can lead to **toxicity** more easily than first-order kinetics, since small increases in dose can lead to large increases in plasma concentration.
**Correct Answer:** D. Constant rate of elimination regardless of plasma concentration.