This set of Tough Drug Biotechnology Questions and Answers focuses on “Drugs Absorption – Factors Affecting Rate of Drug Dissolution”.
1. Absorption of drugs can be categorized into 2 classes, physicochemical properties of drugs and Dosage form of the drug, on the basis of drug dissolution.
a) True
b) False
View Answer
Explanation: Factors that are of in vivo importance, those which can affect the drug dissolution and absorption into the cell membrane can be divided into 2 classes. One is the physicochemical properties of the drug and the dosage form factors.
2. Which option will be the best example of the physicochemical properties of drugs?
a) Solubility, particle size, polymorphism, salt form, pseudopolymorphism, complexation, wettability, pH, Pressure of disintegration
b) Pressure of disintegration, polymorphism, salt form, pseudopolymorphism, complexation, wettability, pH
c) Solubility, particle size, polymorphism, salt form
d) Solubility, particle size, polymorphism, salt form, pseudopolymorphism, complexation, wettability
View Answer
Explanation: The various Physicochemical properties of the drug that affect drug dissolution and its rate are Solubility, particle size, polymorphism, salt form, pseudopolymorphism, complexation, wettability, etc. Dosage form factors include formulation factors and excipients in the formulation.
3. For oral formulation, what should be the minimum aqueous solubility to avoid bioavailability problems?
a) 0.9%
b) 1%
c) 2%
d) 0.11%
View Answer
Explanation: Experiments have shown that a drug should have a minimum aqueous solubility of 1% to avoid bioavailability problems. Lesser than that it becomes a very serious issue for the drug to dissolve and give the proper effect.
4. The total solid surface area of any particle is known as ___________
a) Absolute surface area
b) Effective surface area
c) Total surface area
d) Surface area
View Answer
Explanation: Particle size and surface area of a solid drug are inversely related to each other. Absolute surface area is the total area of the solid surface of any particle and an effective surface area is the area of the solid surface exposed to the dissolution medium. Smaller the drug particle greater the surface area.
5. Particle size and surface area of a drug are directly related to each other.
a) True
b) False
View Answer
Explanation: Particle size and surface area of a solid drug are inversely related to each other. Smaller the drug particle greater the surface area. Larger the area is higher the dissolution rate.
6. Absolute surface area is proportional to the dissolution rate of a drug.
a) True
b) False
View Answer
Explanation: Absolute surface area is not proportional to the Dissolution rate. Effective surface area is proportional to the dissolution rate. Absolute surface area is the total area of the solid surface of any particle and an effective surface area is the area of the solid surface exposed to the dissolution medium. Effective surface area is the area of the solid surface exposed to the dissolution medium.
7. In the case of hydrophobic drugs, micronization results in a decrease in effective surface area and thus fall is dissolution rate. Which of the below sentences cannot be a reason for the given statement?
a) The hydrophobic surface of the drugs adsorbs onto their surface which inhibits their wettability
b) The particles reaggregate to form larger particles due to their high surface free energy
c) Extreme reduction in the particle size imparts surface charges that may prevent wetting
d) Extreme reduction in the size brings the hydrophobic amino acids to the surface
View Answer
Explanation: In the case of hydrophobic drugs, micronization results in a decrease in effective surface area and thus fall is dissolution rate. Three reasons are, Hydrophobic surface of the drugs adsorbs onto their surface which inhibits their wettability, the particles reaggregate to form larger particles due to their high surface free energy, extreme reduction in the particle size impart surface charges that may prevent wetting.
8. How the absolute surface area of hydrophobic drugs can be converted to their effective surface area?
a) Use of surfactant
b) Use of Hydrophobic diluents
c) Use of surfactant and hydrophilic diluents
d) No need of doing micronization
View Answer
Explanation: Use of surfactant as a wetting agent decreases the interfacial tension and displaces the adsorbed air with the solvent and using hydrophilic diluents coat the surface and render them hydrophilic.
9. Which one of these is not an example of hydrophilic diluents?
a) PVC
b) Dextrose
c) PVP
d) PEG
View Answer
Explanation: PVC is polyvinyl chloride not used as a drug formulation. Hydrophilic diluents such as PEG < PVP, dextrose coat the surface of a hydrophobic molecule to give hydrophilic surface.
10. The solvate can exist in different crystalline forms called as _________
a) Solvates
b) Pseudopolymorphs
c) Pseudopolymorphism
d) Hydrate
View Answer
Explanation: Stoichiometric type of adducts of the solid where the solvent molecules are incorporated into the crystal lattice of any solid are known as solvates. The solvates that can exist in different crystalline forms are known as pseudopolymorphs. The phenomenon is known as pseudopolymorphism.
11. Which form of a drug has greater solubility?
a) Anhydrous
b) Hydrate
c) Crystallised
d) Monohydrate
View Answer
Explanation: Anhydrous form of a drug has a greater aqueous solubility than the hydrates. This is because the hydrates are already in interaction with the water and therefore have less energy for crystal breakup.
12. Which one will be the easiest approach to enhance the solubility and dissolution of any drug?
a) Micronize the drug
b) Convert drug into their anhydrous form
c) Convert drug into their hydrous form
d) Convert drug into their salt form
View Answer
Explanation: Most drugs are weak acids or weak base3s. Thus, one of the easiest approaches to enhance the solubility and dissolution of any drug is to convert them into their salt forms.
13. What is pH?
a) –ve log of H+ concentration
b) +ve log of H+ concentration
c) Log of H+ concentration
d) H+ concentration
View Answer
Explanation: pH is a scale used to measure how much acidic or basic a solution is. PH is logarithmic and negative of the 10-base logarithm of the molar concentration of the hydrogen ions present.
14. Which one of these is not an advantage of buffered aspirin tablets?
a) Enhanced bioavailability
b) Reduced gastric irritation
c) Increased stability
d) Increased ulcerogenic tendency
View Answer
Explanation: Including enhanced bioavailability, buffered aspirin tablets have more two advantages that are, reduction of the gastric irritation and ulcerogenic tendency of the drug. And second is the stability is increased by in-situ salt formation.
15. Larger the size of the counterion, greater the solubility.
a) True
b) False
View Answer
Explanation: The size of the counterion influences the solubility of the salt forms. Smaller the size of the counterion greater the solubility of the salt. If the counter ion has a larger size or poor ionic strength, the solubility decreases to a large extent.
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