Drug Biotechnology Questions and Answers – Factors Affecting Protein Drug Binding

This set of Drug Biotechnology written test Questions & Answers focuses on “Factors Affecting Protein Drug Binding”.

1. Which one of the following factors related to protein-drug binding is not related to drugs?
a) Physicochemical characteristics of a drug
b) The concentration of the drug in the body
c) The affinity of the drug for binding
d) Number of binding sites on the binding agent
View Answer

Answer: d
Explanation: There are many factors affecting protein-drug binding. The factors related to the drug, are physicochemical characteristics of a drug, concentration of the drug in the body, affinity of the drug for binding. A number of binding sites on the binding agent are related to the protein and other binding components.

2. Which one of the following factor related to protein-drug binding is not related to drug interactions with the binding site?
a) Competition between the drug and the binding site
b) Competition between drugs and normal body constituents
c) Allosteric changes in a protein molecule
d) Inter subject variation
View Answer

Answer: d
Explanation: Competition between the drug and the binding site, competition between drugs and normal body constituents, allosteric changes in protein molecule these factors are related to drug interactions. Inter subject variation is a patient-related factor.

3. Which of the following factors for protein drug binding is a drug interaction factor?
a) Competition between drugs for the binding site
b) Age
c) Physicochemical characteristics of a drug
d) Physicochemical characteristics of the protein or binding agent
View Answer

Answer: a
Explanation: Physicochemical interaction is not a drug interaction factor. Competition between the drug and the binding site and competition between drug and other normal body constituents, allosteric changes in protein molecule all these factors are related to drug interaction with the protein. Age is a patient-related factor.
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4. Which drugs bind to HSA easily?
a) Cationic drug
b) Anionic drug
c) Lipophilic drug
d) Neutral drug
View Answer

Answer: b
Explanation: Anionic or acidic drugs bind to HSA easily, for example, penicillin and sulphonamides. Cationic or basic drugs bind easily to alpha 1 acid glycoprotein, for example, imipramine and alprenolol. Neutral and unionized drugs bind to lipoproteins. Lipophilic drugs localize more into adipose tissue.

5. Which drugs easily bind to adipose tissue?
a) Cationic drug
b) Anionic drug
c) Lipophilic drug
d) Neutral drug
View Answer

Answer: c
Explanation: Anionic or acidic drugs bind to HSA easily. Cationic or basic drugs bind easily to alpha 1 acid glycoprotein. Neutral and unionized drugs bind to lipoproteins. Lipophilic drugs localize more into adipose tissue. Since lipophilic drugs are lipid loving they can easily get deposited on the adipose tissue.
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6. Which drug easily bind to AAG?
a) Cationic drug
b) Anionic drug
c) Lipophilic drug
d) Neutral drug
View Answer

Answer: a
Explanation: Anionic or acidic drugs bind to HSA easily. Cationic or basic drugs having negative charge can bind easily to alpha 1 acid glycoprotein, for example, imipramine and alprenolol. Neutral and unionized drugs bind to lipoproteins. Lipophilic drugs localize more into adipose tissue.

7. The extent of drug-protein binding can change with both changes in protein and drug concentration.
a) True
b) False
View Answer

Answer: a
Explanation: The concentration of drug that binds to HSA do not have much influence on HA, since any concentration of drug in less than the concentration of HSA. The therapeutic concentration of lidocaine can saturate AAG with which it binds as the concentration of AAG is much less in comparison to that of HSA in blood.
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8. In the equation X= Vd C, what does X stands for?
a) Amount of drug in the blood
b) Amount of drug in plasma
c) Amount of drug in the tablet
d) Amount of drug in the body
View Answer

Answer: d
Explanation: The relationship between tissue-drug binding and apparent volume of distribution can be established as Vd = amount of drug in the body (X)/ Plasma drug concentration (C).

9. Only unbound or free drug is capable of being eliminated.
a) True
b) False
View Answer

Answer: a
Explanation: Unbound or free drug is capable of being eliminated. Because the drug-protein complex cannot penetrate into the metabolizing organ. The large molecular size of the complex also prevents it from getting filtered through the glomerulus.
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10. Penicillin has short plasma half-life although it can bind to plasma protein rigidly.
a) True
b) False
View Answer

Answer: a
Explanation: Penicillin has a short plasma half-life. Though it can rigidly bind to the plasma still it has short elimination half live. This is because equilibration occurs between the free and the bound protein and the free drug is equally rapidly excreted by active secretion in renal tubules.

11. What kind of graph is shown in the picture?
The graph got by potting r v/s D is direct plot
a) Direct plot
b) Scatchard plot
c) Double reciprocal plot
d) Michele’s menten plot
View Answer

Answer: a
Explanation: The graph which is got by potting r v/s D then we call it a direct plot. When all the binding sites are occupied by the drug, the protein is saturated and plateau is reached. At the plateau r=N.

12. What kind of graph is shown in the picture?
The plot between r/d v/s r is known as Scatchard plot which is a straight line
a) Direct plot
b) Scatchard plot
c) Double reciprocal plot
d) Michele’s menten plot
View Answer

Answer: b
Explanation: The plot between r/d v/s r is known as Scatchard plot. This plot is a straight line. The slope of the line –Ka, Y intercept is NKa and X intercept is N.

13. What kind of graph is shown in the picture?
Double reciprocal plot is Lineweaver Burk plot of 1/r versus 1/D yields straight line
a) Direct plot
b) Scatchard plot
c) Double reciprocal plot
d) Michele’s menten plot
View Answer

Answer: c
Explanation: Double reciprocal plot is also known as Lineweaver Burk plot. This plot of 1/r versus 1/D yields a straight line with slope 1/NKa and Y-intercept 1/N.

14. Displacement interactions are significant in the case of drugs which are more than 95% bound.
a) True
b) False
View Answer

Answer: a
Explanation: A displacement of 1% and 99% bound drug results in doubling of the free drug concentration i.e. a 100% rise. For a drug which is bound to 99% and a displacement of 1% results in only a 10% rise in freed rug concentration which may be insignificant clinically.

15. Which of the following is a correct method to find the fraction of unbound drug in plasma? Given where Cu is the concentration of unbound drug and C is total plasma drug concentration.
a) CuC
b) C / Cu
c) Cu/C
d) 1/C Cu
View Answer

Answer: c
Explanation: The fraction of unbound drug can be calculated with the formula fu = Cu/C, where Cu is the concentration of unbound drug and C is total plasma drug concentration and fu is the unbound drug.

Sanfoundry Global Education & Learning Series – Drug and Pharmaceutical Biotechnology.

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