True about first order kinetics is –
**Core Concept**
First-order kinetics refers to the relationship between the concentration of a drug and its elimination rate. In this context, the elimination rate is directly proportional to the concentration of the drug. This means that as the concentration of the drug decreases, its elimination rate also decreases, resulting in a predictable and linear decline in concentration over time.
**Why the Correct Answer is Right**
The key characteristic of first-order kinetics is that the elimination rate of a drug is directly proportional to its concentration. This is often represented mathematically as: rate of elimination = k × concentration, where k is the elimination rate constant. As the concentration of the drug decreases, the rate of elimination also decreases, resulting in a predictable decline in concentration. This is in contrast to zero-order kinetics, where the elimination rate is constant regardless of the concentration.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the relationship between concentration and elimination rate in first-order kinetics. In first-order kinetics, the elimination rate is directly proportional to the concentration, not independent of it.
**Option B:** This option is incorrect because it suggests that first-order kinetics is only relevant at high concentrations, which is not the case. First-order kinetics applies to all concentrations, not just high ones.
**Option C:** This option is incorrect because it suggests that first-order kinetics is a characteristic of a specific class of drugs, which is not the case. First-order kinetics is a general property of drug elimination that applies to many different types of drugs.
**Clinical Pearl / High-Yield Fact**
A key clinical implication of first-order kinetics is that the half-life of a drug is constant, regardless of the dose. This means that the time it takes for the concentration of a drug to decrease by half is the same at all doses, making it easier to predict and manage drug levels.
**Correct Answer:** C.