Drug Delivery Systems Flashcards

Which nasal drug delivery feature allows direct drug transport to the brain, bypassing the blood-brain barrier?

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.

A matrix tablet formulated with HPMC releases drug by:

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.

For a drug to be suitable for pulmonary delivery to the deep lung, the aerodynamic particle size should be:

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.

Which statement about microemulsions is TRUE?

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.

An implantable drug delivery device made of ethylene-vinyl acetate (EVA) releases drug by:

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.

The concept of 'stealth liposomes' refers to liposomes coated with PEG to:

Answer: Prolong circulation time by avoiding phagocytic uptake

PEG coating prevents opsonization and recognition by the reticuloendothelial system, significantly extending liposome circulation half-life.

Which dissolution test apparatus is MOST appropriate for evaluating drug release from a transdermal patch?

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.