QuestionSBA
QuestionChoice
This is incorrect. In zero-order reactions, the half-life can vary. In fact, the half-life will get longer as the concentration of the drug increases.
10007534
d
The half life is always constant
QuestionChoice
This is incorrect. Phenytoin works by pseudo-zero order reactions. This means that at high concentrations the elimination process is saturated, and processing appears similar to zero-order reactions in which the rate of the reaction is independent of the drug concentration. However, at lower concentrations, the process is not saturated and the reaction appears like first-order reactions. Here, the rate of the reaction is proportional to the concentration of the reactant.
10007532
b
Phenytoin works by zero order reactions
QuestionChoice
This is the correct answer. Zero-order reactions have a rate of elimination that is independent of the drug concentration.
10007531
a
The rate of degradation is independent of the plasma concentration
QuestionChoice
This is incorrect. Zero-order reactions are rare. The most common order of elimination is first-order reactions, whereby the half-life is constant, and the rate of elimination increases with plasma concentration.
10007535
e
It is the most common order of elimination
QuestionChoice
This answer is incorrect. The rate of degradation does not rely on the concentration of the reactant in zero-order reactions.
10007533
c
The rate of degradation is dependent on the concentration of reactant
Concept
Chapter
2693
4609
Zero order kinetics
Topic
166
General pharmacological concepts
14053
A 75-year-old female attends the emergency department after accidentally taking too much of her regular medication. She is keen to know for how long the medication will remain in her bloodstream.

Which of the following statements is correct about zero order kinetics?
a