Drug Delivery Systems Flashcards

Ophthalmic solutions must be sterile AND typically buffered to a pH of approximately:

Answer: 7.4

Ophthalmic formulations are buffered near physiologic tear pH of 7.4 to minimize irritation and maintain drug stability.

A drug with a narrow therapeutic index is BEST suited for which delivery strategy?

Answer: Extended-release formulation to minimize peak-trough fluctuation

Extended-release systems reduce peak-trough fluctuations, keeping plasma concentrations within the narrow therapeutic window.

The rate-limiting step in drug release from a reservoir-type transdermal system is:

Answer: The rate-controlling membrane

In reservoir systems, the synthetic rate-controlling membrane (not the skin) governs the drug flux into and through the skin.

Cyclodextrins improve drug delivery primarily by:

Answer: Complexing drugs in their hydrophobic cavity to increase solubility

Cyclodextrins form inclusion complexes with hydrophobic drugs in their central cavity, dramatically improving aqueous solubility.

Which of the following is a characteristic of a Class II BCS drug?

Answer: Low solubility, high permeability

BCS Class II drugs are poorly soluble but highly permeable; dissolution rate is the rate-limiting step for absorption.

Pegylation of a nanoparticle drug carrier is done PRIMARILY to:

Answer: Evade opsonization and extend circulation time

PEG coating creates a steric shield that prevents opsonin adsorption, reducing uptake by the mononuclear phagocyte system.

A rectal suppository base melts at body temperature; this type of base is classified as:

Answer: Fatty (oleaginous) base such as cocoa butter

Fatty bases like cocoa butter and Witepsol melt near 37°C (body temperature) to release drug in the rectal cavity.