Drug Biotechnology Questions and Answers – Drugs Excretion – Different Routes of Excretion

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This set of Drug Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Drugs Excretion – Different Routes of Excretion”.

1. Which one of the following is the principal organ for drug excretion?
a) Lungs
b) Liver
c) Kidneys
d) Sweat glands
View Answer

Answer: c
Explanation: Kidney is the principal organ for drug excretion. Lungs are more helpful in the excretion of volatile compounds. Sweat glands excrete a very minute amount of drugs. Drugs are made to be water soluble to get excreted from the kidneys easily.
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2. Compounds excreted in bile is classified into 3 categories. Which one of the following does not come under the categories?
a) Drugs with bile/plasma concentration ratio approximately 1
b) Drugs with bile/plasma concentration ratio between 10-1000
c) Drugs with bile/plasma concentration ratio of less than 1
d) Drugs with bile/plasma concentration ratio above 1000
View Answer

Answer: d
Explanation: The categories are divided into Group A, Group B, Group C. Group A has drugs with bile/plasma concentration ratio approximately 1 e.g. sodium. Group B has drugs with bile/plasma concentration ratio between 10 -1000 e.g. creatinine. Group C has drugs with bile/plasma concentration ratio less than 1 e.g. sucrose.

3. What is the molecular weight cut off for biliary excretion?
a) Less than 300 Dalton
b) More than 300 Dalton
c) Less than 200 Dalton
d) More than 200 Dalton
View Answer

Answer: b
Explanation: The threshold is 300 Dalton for biliary excretion. The threshold if 300V or greater than 300 Dalton is necessary for the excretion of organic cations and anions respectively. Non-ionic compounds must be highly polar for excretion.

4. What is the equation for biliary clearance?
a) No such equation is there
b) Biliary excretion rate/ plasma drug concentration
c) Plasma drug concentration / biliary excretion rate
d) Plasma drug concentration / Bile flow * biliary drug concentration
View Answer

Answer: b
Explanation: The ability of the liver to excrete drug into the bile is expressed as bile clearance. The equation for bile clearance is biliary excretion rate/ plasma drug concentration. Since biliary excretion can also be written as bile flow * biliary drug concentration. The other equation for bile clearance is bile flow * biliary drug concentration/ plasma drug concentration.

5. For a certain drug, the bile flow rate is 0.7 ml/mm, the biliary drug concentration is 2g/ml and the plasma drug concentration is 0.8g/ml. What will be the bile clearance?
a) 1.50 ml/mm
b) 1.75 ml/mm
c) 2.75 ml/mm
d) 3 ml/mm
View Answer

Answer: b
Explanation: The equation for bile clearance is biliary excretion rate/ plasma drug concentration. Since biliary excretion can also be written as bile flow * biliary drug concentration. The other equation for bile clearance is bile flow * biliary drug concentration/ plasma drug concentration. Thus the answer is 0.7*2*0.8=1.75 ml/mm.
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6. In the following diagram which organ name should be in the place of ‘?’?
drug-biotechnology-questions-answers-different-routes-excretion-q6
a) Small intestine
b) Large intestine
c) Liver
d) Kidney
View Answer

Answer: a
Explanation: Biliary excretion is excreted by the small intestine into our faces. The liver secretes bile and kidney is not at all associated with biliary excretion.

7. Which compounds are excreted through the lungs?
a) Lipophilic
b) Gaseous
c) Liquid and hydrophilic
d) Solid less than 100 Dalton
View Answer

Answer: b
Explanation: Gaseous substances and volatile substances find their excretion way through the lungs into the expired air. These substances easily get absorbed through the tissue of the lungs by simple diffusion. Such as general anesthetics are absorbed through the lungs. Intact gaseous drugs are excreted but not the metabolites.

8. What is the pH of the milk secreted by human mothers?
a) 6.4-7.6
b) 5.4-6.6
c) 7-8
d) 6-7
View Answer

Answer: a
Explanation: The pH of the milk varies 6.4 – 7.6. The mean pH is 7. Unionized and lipid soluble drugs can easily diffuse into the mammary alveolar cells passively.

9. What is the mechanism of drug excretion for skin excretion?
a) Active secretion
b) Glomerular secretion
c) Passive diffusion
d) Passive reabsorption
View Answer

Answer: c
Explanation: Passive excretion of drugs occurs through the skin. In the case of excretion through the skin, drugs follow pH partition hypothesis. Free, unionized, lipophilic drugs can passively be diffused into the sweat.
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10. What is the mechanism of drug excretion for biliary excretion?
a) Active secretion
b) Glomerular secretion
c) Passive diffusion
d) Passive reabsorption
View Answer

Answer: a
Explanation: Hydrophilic, uncharged drugs, metabolites and conjugates get actively secreted out through bile excretion. The metabolic weight must be greater than or equal to 500 Dalton. Glomerular secretion occurs only through the kidneys.

11. Which of the following is not a factor influencing pulmonary excretion?
a) Pulmonary blood flow
b) The solubility of volatile substance
c) Rate of respiration
d) Heart rate
View Answer

Answer: d
Explanation: Heart rate does not directly influence the pulmonary excretion. Though it might be a factor influence is very less. The other three factors are directly related to the lungs and the rate of absorption of the drug from the lungs and out of the lungs back to alveoli.

12. How is renal clearance expressed mathematically?
a) Rate of urinary excretion/plasma drug concentration
b) Plasma drug concentration/rate of urinary excretion
c) 1/ Plasma drug concentration
d) 1/rate of urinary excretion
View Answer

Answer: a
Explanation: Renal clearance is defined as the volume of plasma or blood which is completely cleared of the unchanged drug by the kidney per unit time. It is expressed as an equation that is the Rate of urinary excretion/plasma drug concentration. It is the sum of the rate of glomerular filtration and rate of secretion minus the rate of absorption to the plasma drug concentration.

13. What is the driving force for glomerular filtration?
a) Concentration gradient
b) Hydrostatic pressure of plasma
c) High amount of aqueous pores
d) Hydrostatic pressure of blood flow
View Answer

Answer: d
Explanation: Glomerular filtration is the 1st filtration in the urinary excretion. The driving force for filtration is the hydrostatic pressure of the blood flowing in the capillaries. 1.2 l/min of blood flows through the renal artery. The filtration rate is 120-130 ml/min through the glomeruli.
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14. Which of the following compounds are used as agents to determine Glomerular Filtration Rate?
a) Calcium ion
b) Albumin
c) Creatinine
d) Calcium carbonate
View Answer

Answer: c
Explanation: GFR is determined by agent which is excreted exclusively by glomerular filtration and is neither secreted nor reabsorbed in the tubules. The excretion rate of such compounds is 120-130 ml/min. The compounds used are creatinine, insulin, mannitol, sodium thiosulfate.

15. The rate of urine flow influences the extent of reabsorption.
a) True
b) False
View Answer

Answer: a
Explanation: A higher amount of urine flow leads to less reabsorption. A lower amount of urine flow leads to more reabsorption. Polar drugs whose excretion is independent of urine pH and are not reabsorbed are unaffected by urine flow rate. Those drugs whose reabsorption is pH sensitive is dependent on the flow rate of urine.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn