This set of Drug Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Applications of a Prodrug”.
1. Which of the following will be a pharmaceutical application of prodrugs?
a) Enhancement of bioavailability
b) Reduction of toxicity
c) Improvement of odour
d) Site-specific drug delivery
Explanation: Pharmaceutical applications are those where the undesirable properties and the physicochemical problems associated with drug formulations can be solved. These are, for example, improving taste, odour, change of physical form, reduction in GI irritation, reduction of pain on injection.
2. Which of the following will be the pharmacokinetic application of prodrugs?
a) Improvement of taste
b) Improvement of odour
c) Site-specific drug delivery
d) Reduction in GI irritation
Explanation: Pharmaceutical applications are those where the undesirable properties and the physicochemical problems can be solved. These are, for example, improving taste, odour, change of physical form, reduction in GI irritation, reduction of pain on injection. Pharmacokinetic applications are such as enhancement of bioavailability, prevention of presystemic metabolism, prolongation of the duration of action, reduction of toxicity, etc.
3. How improvement of a drug in case of taste is done?
a) Injecting the drug so no taste related problems
b) Reducing the drug solubility in the saliva
c) Lower affinity for the taste receptors and making the drug sweet
d) Reducing drug solubility in saliva and lower affinity for taste receptors
Explanation: Reason for poor patient compliance particularly for children is very important. For children, bitterness, acidity, causticity, and even the color matters a lot. Two approaches for changing or decreasing bad taste are, reducing drug solubility in saliva and lower affinity of the drug for taste receptors, thus patients cannot taste the drug.
4. A liquid with high vapour pressure has a strong odour.
Explanation: The odour of a drug compound depends upon its vapor pressure and boiling point. A compound with high vapour pressure means it can easily mix with the air surrounding it and give a strong odour. High pressure always has a low boiling point.
5. Which one of the following will be an example of changing the physical form of the drug to get a prodrug?
a) Ethyl mercaptan to 1,3-Diesters
b) Trichloroethanol to p-Acetamidobenzene ester
c) Ethyl mercaptan to phthalate esters
d) Chloramphenicol to palmitate ester
Explanation: Ethyl mercaptan to 1,3-Diesters involves the formation of symmetrical molecules having the tendency to form crystals. Trichloroethanol to p-Acetamidobenzene ester is not the correct form, here Trichloroethanol should be converted to p-Acetamidobenzoic acid ester. Ethyl mercaptan to phthalate esters is done for the improvement of odour and chloramphenicol to palmitate ester is done for the improvement of odour.
6. No drug cause damage to the gastric mucosa.
Explanation: Drugs can cause irritation and damage to the gastric mucosa, it can increase stimulation of acid secretion or cause damage to the mucosal layer. NSAIDs cause serious harm to our mucosal layer. They are one of the main causing agents of ulcer.
8. Which of the following reduces the pain of injection?
a) If the drug precipitates
b) If the drug penetrates to the surrounding areas
c) If the solution is strongly acidic
d) More water-soluble drug
Explanation: Drug precipitation, penetration to surrounding cells, strongly acidic, basic or alcohol makes it more painful after injection. Thus prodrugs are made to more water soluble. Making it more polar helps it to diffuse easily to the plasma.
9. Which one of these is the best way to preserve drugs for intravenous use?
d) In solution form
Explanation: Lyophilisation or freeze drying is the easiest and important step for intravenous drugs. Here the product is first frozen and then dried to become powdered form. In this step with the free water, even the bound water is also removed. Thus decreasing the probability of contamination.
10. Why carbenicillin cannot be given orally?
a) Tastes bad
b) Bad odour
c) Degraded by saliva
d) Hydrolysed easily
Explanation: Carbenicillin, broad-spectrum penicillin, gets hydrolyzed very easily. Thus if given orally it will be a reaction with acid in the stomach. Thus these are made into ester prodrugs which are stable at gastric pH and above 7.
11. Why lipophilic drugs are absorbed easily?
a) Less hydrolysed
b) Favours passive diffusion
c) Dissolution rate high
d) Can easily merge with the cell membrane
Explanation: Lipophilic drugs has high membrane-water partition coefficient thus it favours passive diffusion. These are more lipophilic, better absorbed and rapidly hydrolysed to the parent drug in blood.
12. Which of the following is not a disadvantage of site-specific drug delivery?
a) May lead to toxic effects on other non-target tissues
b) May get diluted
c) Less distribution time
d) No penetrable to the target tissue
Explanation: Less distribution time is a advantage for the drug. The disadvantages are may lead to toxic effects to other non-target tissues, may get diluted due to distribution and smaller fraction reach the target tissue, May not be able to penetrate the target tissue, higher distribution time.
13. Which of the following will not be a limitation for prodrug design?
a) Formation of toxic product
b) An inert carrier can be cleaved off forming toxic product
c) Product cleaving off before reaching the target site
d) The cleaving of the carrier is also site-specific
Explanation: The limitation of the prodrug designing is the formation of unexpected metabolite, the inert carrier can be cleaved off forming a toxic molecule, and prodrug might consume vital nutrients. If the carrier cleavage is site specific it is an advantage.
Explanation: Trichloroethanol is in liquid form, converting them to tablets creates a problem with the concentration and has the problem of high dosing. Thus these liquid drugs are converted into their solid prodrugs by the formation of symmetrical molecules which has a higher tendency to crystallize e.g. esters of ethyl mercaptan and Trichloroethanol.
15. How to prevent hepatic first-pass metabolism for corticosteroids?
a) Providing intravenously
b) Providing orally
c) Form esters and ether products
d) By enhancing lipophilicity
Explanation: Providing orally will have to pass through the hepatic 1st pass. Forming ethers and esters can prevent extensive first-pass hepatic metabolism. Propanol has the high hepatic first pass, it is pro-drug hemisuccinate is resistant to esterases of the liver.
Sanfoundry Global Education & Learning Series – Drug and Pharmaceutical Biotechnology.
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