KAPS Drug Formulation and Development 2 — Questions and Answers
Question 1: Which excipient class is primarily used to prevent crystal growth in amorphous solid dispersions?
- Polymeric stabilizers like HPMC or PVP (Correct answer)
- Lubricants like magnesium stearate
- Disintegrants like croscarmellose sodium
- Surfactants like sodium lauryl sulfate
Correct answer: Polymeric stabilizers like HPMC or PVP
Polymeric stabilizers such as HPMC and PVP inhibit recrystallization of amorphous drug by increasing viscosity and forming intermolecular interactions.
Question 2: A hot-melt extrusion process is BEST suited for drugs with which property?
- High melting point above 250°C
- Thermal stability at processing temperatures (Correct answer)
- Poor aqueous solubility only with high melting point
- Hygroscopicity that prevents granule flow
Correct answer: Thermal stability at processing temperatures
Hot-melt extrusion requires the drug to be thermally stable at the elevated processing temperatures typically ranging from 80–200°C.
Question 3: In a spray-dried dispersion, which parameter most directly controls particle size distribution?
- Inlet air temperature
- Feed concentration
- Atomization pressure or nozzle design (Correct answer)
- Outlet air humidity
Correct answer: Atomization pressure or nozzle design
Atomization pressure and nozzle design determine droplet size, which directly dictates the final spray-dried particle size distribution.
Question 4: Which dissolution model describes drug release from a matrix tablet where release rate decreases over time proportionally to the square root of time?
- Zero-order model
- First-order model
- Higuchi model (Correct answer)
- Korsmeyer-Peppas model
Correct answer: Higuchi model
The Higuchi model (Q = A√Dt) describes diffusion-controlled release from a homogeneous matrix, where cumulative release is proportional to √t.
Question 5: The 'BCS classification' system categorizes drugs based on which two properties?
- Solubility and permeability (Correct answer)
- Stability and bioavailability
- Particle size and dissolution rate
- LogP and molecular weight
Correct answer: Solubility and permeability
The Biopharmaceutics Classification System (BCS) classifies drugs into four classes based on aqueous solubility and intestinal permeability.
Question 6: Which approach is used to improve the dissolution rate of a poorly water-soluble drug by reducing its particle size to the nanometer range?
- Lyophilization
- Granulation
- Nanosuspension technology (Correct answer)
- Microencapsulation
Correct answer: Nanosuspension technology
Nanosuspension technology reduces drug particle size to 100–1000 nm, dramatically increasing surface area and dissolution rate per the Noyes-Whitney equation.
Question 7: A formulator wants to delay drug release until the tablet reaches the small intestine. Which coating polymer is MOST appropriate?
- Ethylcellulose
- HPMC (hydroxypropyl methylcellulose)
- Eudragit L100 (methacrylic acid copolymer) (Correct answer)
- Polyvinyl alcohol
Correct answer: Eudragit L100 (methacrylic acid copolymer)
Eudragit L100 dissolves above pH 6.0, making it an enteric polymer that protects the drug in the acidic stomach and releases it in the small intestine.
KAPS Drug Formulation and Development 2
Which excipient class is primarily used to prevent crystal growth in amorphous solid dispersions?