1. Which are the two rate-determining step of drug absorption when given orally?
a) Disintegration and deaggregation
b) Disintegration and Dissolution
c) Dissolution and permeation through the membrane
d) Permeation through the membrane and Disintegration
Explanation: The two critical slower rate-determining processes in the absorption of orally administered drugs are the rate of dissolution and rate of the solute or the drug permeation through the cell membrane or biomembrane
2. The maximum amount of solute dissolved in a given solvent under standard conditions of temperature, pressure, and pH is known as __________
a) Dissolution rate
b) Intrinsic dissolution
c) Rate limiting step
d) Absolute or intrinsic solubility
Explanation: Absolute or intrinsic solubility is defined as the maximum amount of solute dissolved in a given solvent under standard conditions of temperature, pressure, and pH. It is a static property. Dissolution rate is the amount of a solid substance that dissolves into solution under given conditions
3. In the equation, V dC/dt = dm/dt = A(Cs-Cb).√ γ D, what does γ stands for?
a) Mass of the solid dissolved
b) Rate of surface renewal
c) Concentration of solute
d) Concentration of the drug
Explanation: The Danckwert’s model is expressed by the equation, V dC/dt = dm/dt = A (Cs-Cb).√ γ D, where γ is the rate of surface renewal, m is the mass of solid dissolved. Cs concentration of the solute
4.Each face of the crystal has a different interfacial barrier.
a) True
b) False
Explanation: The statement is true. According to the interfacial barrier model, each face of a crystal has a different interfacial barrier. This concept is given by G=Ki (Cs-Cb).
5. 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
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
6. 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
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.
7. For oral formulation, what should be the minimum aqueous solubility to avoid bioavailability problems?
a) 0.9%
b) 1%
c) 2%
d) 0.11%
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.
8. 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
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.
9. Particle size and surface area of a drug are directly related to each other.
a) True
b) False
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.
10. Absolute surface area is proportional to the dissolution rate of a drug.
a) True
b) False
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.