Pharmacy Drug Delivery Systems 5 — Questions and Answers
Question 1: Which nasal drug delivery feature allows direct drug transport to the brain, bypassing the blood-brain barrier?
- Mucociliary clearance
- Nose-to-brain pathway via olfactory neurons (Correct answer)
- Hepatic first-pass metabolism
- Pulmonary absorption
Correct answer: Nose-to-brain pathway via olfactory neurons
The olfactory and trigeminal nerve pathways in the nasal cavity allow direct drug transport to the CNS, bypassing the BBB.
Question 2: A matrix tablet formulated with HPMC releases drug by:
- Osmotic pumping
- Erosion and diffusion through a gel layer (Correct answer)
- pH-triggered membrane rupture
- Enzymatic degradation
Correct answer: Erosion and diffusion through a gel layer
HPMC hydrates to form a viscous gel on contact with water; drug releases by diffusing through this gel and by gel erosion.
Question 3: For a drug to be suitable for pulmonary delivery to the deep lung, the aerodynamic particle size should be:
- 10–100 µm
- 1–5 µm (Correct answer)
- >100 µm
- 0.01–0.1 µm
Correct answer: 1–5 µm
Particles of 1–5 µm MMAD deposit in the alveolar region; larger particles impact in the upper airways and smaller ones are exhaled.
Question 4: Which statement about microemulsions is TRUE?
- They are thermodynamically unstable systems
- They are optically opaque formulations
- They are thermodynamically stable, clear systems with droplet size 10–100 nm (Correct answer)
- They require high-energy homogenization to form
Correct answer: They are thermodynamically stable, clear systems with droplet size 10–100 nm
Microemulsions form spontaneously and are thermodynamically stable, with very small (10–100 nm) isotropic droplets that appear clear.
Question 5: An implantable drug delivery device made of ethylene-vinyl acetate (EVA) releases drug by:
- Polymer degradation
- Diffusion through the non-degradable polymer matrix (Correct answer)
- Osmosis
- Enzymatic cleavage
Correct answer: Diffusion through the non-degradable polymer matrix
EVA is a non-biodegradable polymer; drug molecules diffuse through the polymer matrix down the concentration gradient.
Question 6: The concept of 'stealth liposomes' refers to liposomes coated with PEG to:
- Increase drug loading efficiency
- Target liver macrophages specifically
- Prolong circulation time by avoiding phagocytic uptake (Correct answer)
- Increase drug release rate
Correct answer: Prolong circulation time by avoiding phagocytic uptake
PEG coating prevents opsonization and recognition by the reticuloendothelial system, significantly extending liposome circulation half-life.
Question 7: Which dissolution test apparatus is MOST appropriate for evaluating drug release from a transdermal patch?
- USP Apparatus 1 (basket)
- USP Apparatus 2 (paddle)
- USP Apparatus 5 (paddle over disk) or 6 (cylinder) (Correct answer)
- USP Apparatus 4 (flow-through cell)
Correct answer: USP Apparatus 5 (paddle over disk) or 6 (cylinder)
USP Apparatus 5 (paddle over disk) and Apparatus 6 (rotating cylinder) are specifically designed for transdermal patch dissolution testing.
Pharmacy Drug Delivery Systems 5
Which nasal drug delivery feature allows direct drug transport to the brain, bypassing the blood-brain barrier?