Drug Biotechnology Questions & Answers for Exams on “Non Linearity of Drugs”.
1. Any changes in fraction bioavailable, elimination half-life indicates nonlinearity of that particular drug.
a) True
b) False
Answer: a
Clarification: Some of the pharmacokinetic factors such as fraction bioavailable, elimination half-life or total systemic clearance at different doses of drug normally remains constant. If any changes occur in these constants, this indicates nonlinearity.
2. Which of the following creates nonlinearity in drug distribution and not in drug absorption?
a) When absorption is solubility or dissolution rate-limited
b) When absorption involves carrier-mediated transport systems
c) When a presystemic gut wall or hepatic metabolism attains saturation
d) Saturation of binding sites on plasma proteins
Answer: d
Clarification: Nonlinearity in drug absorption can arise from 3 important sources these are when absorption is solubility or dissolution rate-limited, when absorption involves carrier-mediated transport systems and when presystemic gut wall or hepatic metabolism attains saturation. Nonlinearity in drug distribution occurs when saturation of binding sites on plasma proteins or saturation of tissue binding sites.
3. Which one of these are correct Michaelis-Menten equation?
a) –dC/dt = Vmax C/Km+C
b) dC/dt = Vmax C/Km+C
c) –dC/dt = Vmax C/Km
d) –dC/dt = Km+C/Vmax C
Answer: a
Clarification: The kinetics of capacity-limited or saturation process is described by Michaelis-Menten equation, the equation is –dC/dt = Vmax C/Km+C, where –dC/dt = rate of decline of drug concentration with time, Vmax is the theoretical maximum rate of the process and Km is Michaelis constant.
4. Which equation plot is being shown in the picture?
a) Michaelis-Menten plot
b) One compartment characteristics graph
c) Two compartment characteristics graph
d) Two compartment administered extravascularly characteristics plot
Answer: a
Clarification: The plot is of Michaelis-Menten equation –dC/dt = Vmax C/Km+C, Initially the rate increases linearly with concentration thus showing first order kinetics. It becomes mixed order at higher concentration and then reaches maximum Vmax. Beyond this, it proceeds at a constant rate.
5. In the given picture, which kinetic order the graph is following at the marked place?
a) 1st order kinetics
b) 2nd order kinetics
c) Mixed order kinetics
d) 1st order at higher doses
Answer: a
Clarification: The plot is of Michaelis-Menten equation –dC/dt = Vmax C/Km+C, Initially the rate increases linearly with concentration thus showing first order kinetics. At lower doses, it follows 1st order kinetics. It becomes mixed order at higher concentration and then reaches maximum Vmax. Beyond this, it proceeds at a constant rate thus following zero order kinetics.
6. In the given picture, which kinetic order the graph is following at the marked place?
a) 1st order kinetics
b) 2nd order kinetics
c) Mixed order kinetics
d) 1st order at higher doses
Answer: c
Clarification: The plot is of Michaelis-Menten equation –dC/dt = Vmax C/Km+C, Initially the rate increases linearly with concentration thus showing first order kinetics. It becomes mixed order at intermediate doses and then reaches maximum Vmax. Beyond this, it proceeds at a constant rate.
7. In the given picture, which kinetic order the graph is following at the marked place?
a) 1st order kinetics
b) 2nd order kinetics
c) Mixed order kinetics
d) Zero-order rate
Answer: d
Clarification: The plot is of Michaelis-Menten equation –dC/dt = Vmax C/Km+C, Initially the rate increases linearly with concentration thus showing first order kinetics. At lower doses, it follows 1st order kinetics. It becomes mixed order at intermediate doses and then reaches maximum Vmax. Beyond this, it proceeds at a constant rate thus following zero order kinetics.
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