Master of Pharmacy: Pharmaceutical Technology and Drug Delivery Systems Flashcards
7 cards from real MPharm Master of Pharmacy practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
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Which transdermal drug delivery parameter measures the maximum rate of drug flux across a unit area of skin?
Answer: Steady-state flux (Jss)
Steady-state flux (Jss) is the maximum rate of drug permeation per unit area of skin under a constant concentration gradient, determined by Fick's first law of diffusion.
In spray drying of pharmaceutical powders, what is the primary variable that controls final particle size?
Answer: Atomization pressure or nozzle tip speed
Atomization conditions (pressure for two-fluid nozzles or rotational speed for rotary atomizers) determine initial droplet size, which directly controls the final dry particle size.
Which release profile is described as 'zero-order' drug release?
Answer: Release rate is constant and independent of drug concentration
Zero-order release means a constant amount of drug is released per unit time regardless of remaining drug concentration, which is ideal for maintaining steady plasma levels.
What is the purpose of the 'pore former' component added to ethylcellulose membrane coatings on pellets?
Answer: To dissolve and create micropores that control drug permeation
Water-soluble pore formers (e.g., HPMC, PVP) dissolve upon contact with aqueous media, creating channels in the otherwise impermeable ethylcellulose membrane through which drug can diffuse.
In the preparation of microspheres by solvent evaporation, which method is used when the drug is dissolved in the polymer solution?
Answer: Single emulsion (O/W) solvent evaporation
For hydrophobic drugs soluble in an organic solvent, the drug-polymer solution is emulsified in an aqueous continuous phase (O/W), and solvent is evaporated to harden the polymer microspheres.
Which lyophilization (freeze-drying) stage involves removal of bound or unfrozen water under reduced pressure and elevated temperature?
Answer: Secondary drying (desorption)
Secondary drying removes residual bound water (unfrozen water molecules attached to the dried product) by raising shelf temperature above 0°C under vacuum, reducing moisture content to 0.5–3%.
What is the critical micelle concentration (CMC) in the context of surfactant-based drug formulations?
Answer: The minimum concentration above which surfactant molecules form aggregated micellar structures
Above the CMC, additional surfactant molecules self-assemble into micelles rather than remaining as monomers; drugs can be solubilized within micelle cores above this concentration.