FPGEE Pharmaceutics 3 — Questions and Answers
Question 1: Which property of a drug substance is MOST critical for absorption via passive transcellular diffusion across biological membranes?
- High molecular weight
- Lipophilicity (Correct answer)
- Ionization at physiological pH
- High aqueous solubility only
Correct answer: Lipophilicity
Lipophilicity allows drugs to partition into and diffuse across the lipid bilayer via passive transcellular diffusion.
Question 2: According to USP, a 'dilute solution' for oral use contains what maximum concentration of alcohol?
- 5%
- 10% (Correct answer)
- 15%
- 20%
Correct answer: 10%
USP defines dilute oral solutions as containing not more than 10% alcohol to limit systemic alcohol exposure.
Question 3: Which type of flow behavior is exhibited by a material whose viscosity decreases under shear stress and does not recover immediately when shear is removed?
- Pseudoplastic
- Thixotropic (Correct answer)
- Dilatant
- Plastic (Bingham)
Correct answer: Thixotropic
Thixotropic materials show time-dependent shear thinning; viscosity decreases under shear and recovers slowly after shear removal, forming a hysteresis loop.
Question 4: A suppository base that melts at body temperature and is water-soluble is BEST described as:
- Cocoa butter
- Polyethylene glycol (PEG) (Correct answer)
- Hydrogenated vegetable oil
- Witepsol
Correct answer: Polyethylene glycol (PEG)
PEG suppository bases are water-soluble and dissolve in rectal fluids rather than melting, making them suitable for drugs incompatible with fatty bases.
Question 5: In lyophilization (freeze-drying), primary drying removes water by:
- Evaporation at elevated temperature
- Sublimation of ice under reduced pressure (Correct answer)
- Dissolution in organic solvents
- Adsorption onto excipients
Correct answer: Sublimation of ice under reduced pressure
Primary drying in lyophilization removes frozen water by sublimation under vacuum, bypassing the liquid phase.
Question 6: Which parameter is used to quantify the drug content uniformity of solid dosage forms according to USP?
- Loss on drying
- Relative standard deviation (RSD) (Correct answer)
- Disintegration time
- Angle of repose
Correct answer: Relative standard deviation (RSD)
USP content uniformity testing uses the Acceptance Value (AV) based on the mean and RSD of individual unit drug content.
Question 7: Hydrophilic-lipophilic balance (HLB) values between 8 and 18 are MOST suitable for:
- W/O emulsifiers
- O/W emulsifiers (Correct answer)
- Solubilizing agents
- Wetting agents
Correct answer: O/W emulsifiers
HLB values of 8–18 indicate predominantly hydrophilic surfactants, which are effective stabilizers for oil-in-water emulsions.
FPGEE Pharmaceutics 3
Which property of a drug substance is MOST critical for absorption via passive transcellular diffusion across biological membranes?