This set of Drug Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “One & Two Compartment Open Model”.

1. What does the word “open” mean in the one compartment open model?

a) The drug easily enters

b) The drug readily mixes with the blood

c) Unidirectional input and output

d) Easy absorption

View Answer

Explanation: The term open indicates that the input and the output are unidirectional and the drug can be eliminated from the body. One compartment open model does not assume that drug concentration in plasma is equal to that in other body tissue.

2. How much time does an intravenously administered drug take to complete a complete circulation?

a) 5-8 min

b) 7-10 min

c) 1-3 min

d) 1 min

View Answer

Explanation: When any drug is administered intravenously, it takes 1-3min for a complete circulation of the whole body. Thus the rate of absorption is not taken into account when any drug is administered intravenously.

3. In the equation log C = log Co – KEt/2.303, what does Co stand for _______

a) Plasma drug concentration after 60 min of i.v. injection

b) Plasma drug concentration after 15 min of i.v. injection

c) Plasma drug concentration after 30 min of i.v. injection

d) Plasma drug concentration immediately after i.v. injection

View Answer

Explanation: In the equation log C = log Co – KEt/2.303, C is the drug concentration in plasma, Co is the plasma drug concentration immediately after i.v. injection, KE is the overall elimination rate constant, t is time.

4. What is meant by elimination half-life?

a) Time take for half of the amount of drug to get completely eliminated from only the organs

b) Time take for half of the amount of drug to get completely eliminated from only blood

c) Time take for half of the amount of drug to get completely eliminated from only plasma

d) Time take for half of the amount of drug to get completely eliminated from the body as well as plasma

View Answer

Explanation: Also known as the biological half-life. It is defined as the time taken for half amount of drug in the body and plasma concentration to decline by one-half of its initial value. It is expressed in hours or minutes. T-half = 0.693/KE.

5. What is the equation to find out the apparent volume of distribution?

a) Amount of drug in the body/plasma drug concentration

b) Plasma drug concentration/amount of drug in the body

c) 1 / plasma drug concentration

d) 1 / Amount of drug in the body

View Answer

Explanation: The apparent volume of distribution Vd is given by Amount of drug in the body (X) / plasma drug concentration (C). Vd is expressed in liters.

6. The i.v. bolus dosage is 500mg and the plasma drug concentration is 0.8 mg/ml. What should be the volume of distribution?

a) 625 mg/ml

b) 625 l

c) 625 ml

d) 0.0016 mg/ml

View Answer

Explanation: The apparent volume of distribution Vd is given by Amount of drug in the body (X) / plasma drug concentration (C). Vd is expressed in liters or milliliters. Thus 500/0.8=625.

7. To have a plasma distribution value of 900 ml and plasma drug concentration to be 1.2 mg/ml what should be the amount of drug that should be given to the patient?

a) 1080 ml

b) 1080 g

c) 1080 mg

d) 1g/ml

View Answer

Explanation: The apparent volume of distribution Vd is given by Amount of drug in the body (X) / plasma drug concentration (C). Vd is expressed in liters or ml. to find out the amount of drug, the equation is the apparent volume of distribution (Vd)*plasma drug concentration (C).

8. What is the equation to find out hepatic clearance?

a) Plasma drug concentration/rate of elimination by the kidney

b) Rate of elimination by kidney/plasma drug concentration

c) 1 / rate of elimination by the kidney

d) 1 / plasma drug concentration

View Answer

Explanation: The hepatic clearance is given by the equation Rate of elimination by kidney/plasma drug concentration. The renal clearance is given by the equation Rate of elimination by liver/ plasma drug concentration.

9. At which of the four marked points of the plasma drug concentration versus time graph, absorption rate = elimination rate?

a) a

b) b

c) c

d) d

View Answer

Explanation: At Cmax, where the plasma concentration rate is at the maximum that is absorption rate is at the maximum at that point for that short interval of time the elimination rate is equal to the absorption rate.

10. Which organs comprise the central compartment in a two compartment model?

a) Muscles

b) Skin

c) Adipose

d) Liver

View Answer

Explanation: The central compartment or the compartment 1 in a two compartment model comprises of the blood and the highly perfused tissues like liver, lungs, and kidneys, etc. which equilibrate blood rapidly. These compartments will have the elimination from them.

11. Which organ comprises the peripheral compartment in a two compartment model?

a) Liver

b) Lungs

c) Kidneys

d) Muscles

View Answer

Explanation: The peripheral compartment or compartment 2 in a two compartment model comprises of poorly perfused and slowly equilibrating tissues such as muscles, skin, adipose tissue, etc. These are considered as a hybrid of several functional physiologic units.

12. Which of the following is not a category of 2 compartment model?

a) Two compartment model with elimination from the central compartment

b) Two compartment model with elimination from the peripheral compartment

c) Two compartment model with elimination from only plasma and blood

d) Two compartment model with elimination from both the compartments

View Answer

Explanation: Depending upon the compartment from which the drug is eliminated, the two compartment model can be categorized into 3 types, these are, two compartment model with elimination from the central compartment, peripheral compartment, and both the compartments.

13. In the given picture, the marking “a” represents the drug concentration of which compartment?

a) The central compartment in a two compartment model

b) A peripheral compartment in a two compartment model

c) The central compartment in a one compartment model

d) Drug concentration of the plasma

View Answer

Explanation: In the graph, the marked curve is showing the drug concentration of the central compartment. Initially, the drug concentration of the central compartment in a two compartment model declines rapidly because of the rapid distribution of the drug from the central compartment to the peripheral compartment. This phase is known as the distributive phase.

14. In the given picture, the marking “b” represents the drug concentration of which compartment?

a) The central compartment in a two compartment model

b) The peripheral compartment in a two compartment model

c) The central compartment in a one compartment model

d) Drug concentration of the plasma

View Answer

Explanation: In the graph, the marked curve is showing the drug concentration of the peripheral compartment of a two compartment model. The drug concentration in the peripheral compartment first increases and reaches the maximum. Then due to loss of drug starts due to elimination. This is the post distributive or elimination phase.

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