Introduction to SR and CR formulations MCQs With Answer

Introduction to SR and CR formulations MCQs With Answer

Sustained-release (SR) and controlled-release (CR) systems are cornerstone strategies in modern Drug Delivery Systems, designed to improve therapy by modulating release rate, enhancing adherence, and minimizing adverse effects. This quiz targets key principles M. Pharm students must master: selection of drug candidates, kinetic models, mechanisms (diffusion, erosion, osmotic), formulation design (matrix vs reservoir), polymers, in vitro testing, IVIVC, and clinical/pharmacokinetic implications. The questions are concept-driven yet practice-oriented, reinforcing critical distinctions such as SR vs CR, zero-order targeting, multiparticulate benefits, and food/alcohol effects. Use these MCQs to test understanding, bridge theory with formulation decisions, and prepare for advanced coursework and research in MPH 102T.

Q1. Which statement best differentiates sustained-release (SR) from controlled-release (CR) oral formulations?

• SR prolongs drug release; CR provides rate-controlled release targeting near-constant plasma levels
• SR ensures zero-order release; CR causes burst release
• SR is synonymous with delayed-release; CR is immediate-release
• SR necessarily has a lag time; CR cannot include lag time

Correct Answer: SR prolongs drug release; CR provides rate-controlled release targeting near-constant plasma levels

Q2. For an oral SR/CR product, which drug half-life is generally most suitable?

• Less than 1 hour
• 2–8 hours
• 12–24 hours
• More than 48 hours

Correct Answer: 2–8 hours

Q3. Which release kinetics are most desirable for an ideal CR system aiming at constant plasma concentration?

• Zero-order
• First-order
• Higuchi square-root model
• Hixson–Crowell cube-root model

Correct Answer: Zero-order

Q4. A key disadvantage of a reservoir-type CR system compared to a matrix system is:

• Greater susceptibility to dose dumping if the coating fails
• Inability to achieve zero-order release
• Incompatibility with hydrophobic drugs
• Requirement for ion-exchange polymers

Correct Answer: Greater susceptibility to dose dumping if the coating fails

Q5. The Higuchi model primarily describes:

• Diffusion-controlled release proportional to the square root of time from a matrix
• Membrane-controlled zero-order release from a reservoir
• Dissolution-controlled release from non-porous tablets
• Osmotically driven release independent of agitation

Correct Answer: Diffusion-controlled release proportional to the square root of time from a matrix

Q6. In the Korsmeyer–Peppas model for a cylindrical hydrophilic matrix, an exponent n ≈ 0.45 indicates:

• Fickian diffusion
• Anomalous (non-Fickian) transport
• Case II transport (zero-order relaxation/erosion)
• Super Case II transport

Correct Answer: Fickian diffusion

Q7. Which excipient is commonly used as an insoluble, permeable film former to control release in reservoir systems?

• Ethylcellulose
• Polyethylene glycol 400
• Lactose monohydrate
• Mannitol

Correct Answer: Ethylcellulose

Q8. Which statement is true for an elementary osmotic pump (EOP) tablet?

• Release rate is largely independent of GI pH and motility within the design range
• Release rate is governed mainly by drug solubility in the membrane
• Alcohol co-ingestion always increases release rate
• It requires a disintegrant for function

Correct Answer: Release rate is largely independent of GI pH and motility within the design range

Q9. Drug release from ion-exchange resinates in SR liquids primarily depends on:

• Concentration of counter-ions in gastrointestinal fluid
• Tablet hardness
• Presence of a surfactant in coating solution
• Ambient humidity during storage only

Correct Answer: Concentration of counter-ions in gastrointestinal fluid

Q10. Which USP dissolution apparatus is especially suitable for evaluating bead-coated multiparticulate SR capsules across changing media?

• Apparatus 1 (Basket)
• Apparatus 2 (Paddle)
• Apparatus 3 (Reciprocating cylinder)
• Apparatus 7 (Reciprocating holder)

Correct Answer: Apparatus 3 (Reciprocating cylinder)

Q11. Which level of IVIVC offers a point-to-point relationship between in vitro dissolution and in vivo input rate?

• Level A
• Level B
• Level C
• Multiple Level C

Correct Answer: Level A

Q12. Rapid, unintended release of drug from some CR matrices when co-ingested with ethanol is termed:

• Flip-flop kinetics
• Auto-induction
• Alcohol-induced dose dumping
• First-pass saturation

Correct Answer: Alcohol-induced dose dumping

Q13. A strong rationale for selecting a gastroretentive SR system is a drug that:

• Is primarily absorbed in the upper small intestine
• Has extensive colonic absorption
• Is unstable in gastric fluid
• Has an elimination half-life of 30 hours

Correct Answer: Is primarily absorbed in the upper small intestine

Q14. Which BCS class is generally most suitable for predictable, robust extended-release oral formulations?

• Class I (High solubility, high permeability)
• Class II (Low solubility, high permeability)
• Class III (High solubility, low permeability)
• Class IV (Low solubility, low permeability)

Correct Answer: Class I (High solubility, high permeability)

Q15. In oral SR formulations exhibiting flip-flop kinetics, which statement is correct?

• The terminal half-life reflects absorption rate rather than elimination
• Cmax is unchanged compared to immediate-release
• Volume of distribution increases significantly
• Renal clearance is the rate-limiting step

Correct Answer: The terminal half-life reflects absorption rate rather than elimination

Q16. Compared with monolithic tablets, multiparticulate SR systems (e.g., pellets, beads) generally offer:

• Reduced risk of dose dumping and more uniform GI distribution
• Higher susceptibility to food effects
• Greater local irritation at a single GI site
• Inability to tailor release profiles

Correct Answer: Reduced risk of dose dumping and more uniform GI distribution

Q17. In a reservoir-coated pellet system, increasing the coating thickness primarily:

• Decreases the drug release rate
• Increases porosity and accelerates release
• Eliminates the need for a plasticizer
• Prevents dose dumping caused by alcohol

Correct Answer: Decreases the drug release rate

Q18. In hydrophilic matrix tablets using HPMC, increasing the polymer’s viscosity grade typically:

• Slows drug release by forming a stronger gel layer
• Accelerates release by enhancing erosion
• Has no effect on release kinetics
• Eliminates the need for a filler

Correct Answer: Slows drug release by forming a stronger gel layer

Q19. Which biodegradable polymer is most widely used for parenteral depot CR systems such as microspheres?

• Poly(lactide-co-glycolide) (PLGA)
• Polyvinylpyrrolidone (PVP)
• Polyvinyl chloride (PVC)
• Polydimethylsiloxane (PDMS)

Correct Answer: Poly(lactide-co-glycolide) (PLGA)

Q20. In drug-in-adhesive transdermal CR systems, the primary rate-limiting barrier for systemic delivery is the:

• Stratum corneum
• Adipose tissue
• Dermal microvasculature
• Hair follicles

Correct Answer: Stratum corneum

Download