FPGEE Pharmaceutics 4 — Questions and Answers
Question 1: Which excipient acts as both a binder and a disintegrant in direct compression tablet formulations?
- Crospovidone
- Microcrystalline cellulose (MCC) (Correct answer)
- Colloidal silicon dioxide
- Stearic acid
Correct answer: Microcrystalline cellulose (MCC)
MCC provides excellent binding under compression and also promotes disintegration via wicking and swelling mechanisms.
Question 2: The Henderson-Hasselbalch equation predicts that a weak acid drug with pKa 4.0 in gastric fluid (pH 1.0) will be predominantly:
- Ionized
- Unionized (Correct answer)
- Zwitterionic
- Complexed
Correct answer: Unionized
When pH is much lower than pKa for a weak acid, the drug exists predominantly in the unionized form, favoring gastric absorption.
Question 3: A transdermal drug delivery system is designed to deliver drug at a constant rate through the skin. This BEST describes which type of system?
- Matrix-controlled system
- Membrane-controlled (reservoir) system (Correct answer)
- Microencapsulated system
- Solid dispersion system
Correct answer: Membrane-controlled (reservoir) system
Reservoir (membrane-controlled) transdermal systems use a rate-controlling membrane to deliver drug at a near-constant (zero-order) rate.
Question 4: Which sterilization method is MOST suitable for heat-labile ophthalmic solutions?
- Autoclaving at 121°C
- Dry heat at 160°C
- Filtration through 0.22 μm membrane (Correct answer)
- Gamma irradiation
Correct answer: Filtration through 0.22 μm membrane
Membrane filtration through a 0.22 μm filter removes microorganisms without exposing heat-labile drugs to high temperatures.
Question 5: Which phenomenon occurs when two incompatible drugs are mixed in solution and form an insoluble complex that precipitates?
- Salting out
- Complex coacervation
- Incompatibility precipitation (Correct answer)
- Flocculation
Correct answer: Incompatibility precipitation
Incompatibility precipitation results from a chemical reaction between two drug components or a drug and excipient, forming an insoluble product.
Question 6: The concept of 'apparent volume of distribution' (Vd) in pharmacokinetics relates to:
- Actual plasma volume
- Hypothetical volume in which the drug would need to be dissolved to achieve observed plasma concentration (Correct answer)
- Total body water only
- Extracellular fluid volume
Correct answer: Hypothetical volume in which the drug would need to be dissolved to achieve observed plasma concentration
Vd is a theoretical volume relating total drug in the body to plasma drug concentration; high Vd indicates extensive tissue distribution.
Question 7: Which particle size reduction technique is MOST appropriate for producing nanosized drug particles (< 500 nm)?
- Hammer milling
- Fluid energy (jet) milling
- High-pressure homogenization (Correct answer)
- Ball milling at low pressure
Correct answer: High-pressure homogenization
High-pressure homogenization can reduce drug particle size to the nanometer range, producing nanosuspensions with improved dissolution.
FPGEE Pharmaceutics 4
Which excipient acts as both a binder and a disintegrant in direct compression tablet formulations?