Controlled Release Oral Systems MCQs With Answer

Controlled Release Oral Systems MCQs With Answer

Introduction: This quiz collection focuses on controlled release oral systems, a core topic in M.Pharm Novel Drug Delivery Systems. It covers key principles, polymer selection, device architectures (matrix, reservoir, osmotic), drug release kinetics, and advanced multiparticulate approaches. Questions emphasize mechanisms such as diffusion, erosion, osmotic pumping and ion exchange, and include formulation variables, manufacturing techniques, evaluation methods, and regulatory considerations. Designed for M.Pharm students, the set reinforces conceptual understanding and problem-solving skills needed for designing and assessing sustained and controlled oral dosage forms, linking theory to practical aspects like in vitro testing, IVIVC and stability challenges.

Q1. Which mechanism primarily governs drug release from a hydrophilic matrix tablet composed mainly of HPMC?

• Polymer dissolution without swelling
• Diffusion through a non-swollen rigid network
• Swelling followed by diffusion through a hydrated gel layer
• Immediate erosion of the core

Correct Answer: Swelling followed by diffusion through a hydrated gel layer

Q2. Which of the following systems is best described as providing near zero-order release governed by osmotic pressure?

• Hydrophilic matrix tablet
• Coated reservoir tablet with enteric polymer
• Elementary osmotic pump (EOP) or OROS
• Ion-exchange resin capsule

Correct Answer: Elementary osmotic pump (EOP) or OROS

Q3. In the Korsmeyer–Peppas model, a release exponent (n) of 0.45 for a cylindrical matrix indicates which mechanism?

• Purely zero-order release
• Fickian diffusion-controlled release
• Case II transport (relaxation-controlled)
• Super case II transport

Correct Answer: Fickian diffusion-controlled release

Q4. Which polymer is commonly used as a water-insoluble rate-controlling coating for reservoir systems?

• Hydroxypropyl methylcellulose (HPMC)
• Ethylcellulose
• Polyethylene glycol
• Sodium carboxymethylcellulose

Correct Answer: Ethylcellulose

Q5. What is the primary disadvantage of reservoir (core-shell) controlled release tablets compared to matrix tablets?

• Higher risk of dose-dumping if the coating is compromised
• Less control over initial burst release
• Inability to use water-insoluble drugs
• Lower manufacturing complexity

Correct Answer: Higher risk of dose-dumping if the coating is compromised

Q6. Which in vitro release profile is characteristic of Higuchi kinetics?

• Drug release proportional to time (t)
• Drug release proportional to square root of time (t^0.5)
• Sigmoidal release with lag time
• Exponential decay profile

Correct Answer: Drug release proportional to square root of time (t^0.5)

Q7. For weakly basic drugs in controlled release oral systems, what is a major formulation challenge related to gastrointestinal pH?

• Increased solubility and premature fast release in the stomach
• Complete insolubility throughout the GI tract
• Excessive mucoadhesion in the colon
• Irreversible binding to enteric coatings

Correct Answer: Increased solubility and premature fast release in the stomach

Q8. Which multiparticulate approach improves dose flexibility and reduces risk of dose-dumping?

• Large single-unit reservoir tablet
• Multiparticulate pellets or beads in capsule or tablet
• Compressed effervescent tablet
• Immediate-release granules in a pouch

Correct Answer: Multiparticulate pellets or beads in capsule or tablet

Q9. Ion-exchange resin based controlled release relies mainly on which driving force for drug release?

• Diffusion through a hydrophobic membrane
• Polyelectrolyte gel erosion
• Exchange of bound drug ion with counter-ions in GI fluid
• Osmotic pumping through a semi-permeable membrane

Correct Answer: Exchange of bound drug ion with counter-ions in GI fluid

Q10. Which test apparatus is most commonly used for dissolution testing of extended-release oral dosage forms?

• USP Apparatus 1 (basket) or Apparatus 2 (paddle) with extended sampling times
• USP Apparatus 3 (reciprocating cylinder) exclusively
• Franz diffusion cell
• USP Apparatus 6 (cylinder) only

Correct Answer: USP Apparatus 1 (basket) or Apparatus 2 (paddle) with extended sampling times

Q11. In developing a controlled release formulation, an in vitro–in vivo correlation (IVIVC) Level A indicates what relationship?

• A single-point correlation at peak plasma concentration only
• A direct point-to-point relationship between in vitro dissolution and in vivo input rate
• No correlation exists between in vitro and in vivo data
• Only rank-order correlation of release rates

Correct Answer: A direct point-to-point relationship between in vitro dissolution and in vivo input rate

Q12. Which excipient function is critical in floating gastroretentive dosage forms?

• Providing immediate solubility in gastric fluid
• Reducing tablet density to maintain buoyancy
• Increasing gastric enzymatic degradation
• Enhancing coating brittleness

Correct Answer: Reducing tablet density to maintain buoyancy

Q13. Which manufacturing technique is commonly used to produce uniform spherical pellets for controlled release by extrusion and spheronization?

• Spray drying
• Extrusion–spheronization
• Direct compression only
• Hot-melt extrusion without spheronization

Correct Answer: Extrusion–spheronization

Q14. Which statement about pH-sensitive enteric polymers in controlled release coatings is correct?

• They dissolve at low pH in the stomach to release drug rapidly
• They remain intact in the stomach and dissolve at higher intestinal pH
• They are used to increase swelling in gastric fluids
• They always provide constant zero-order release throughout the GI tract

Correct Answer: They remain intact in the stomach and dissolve at higher intestinal pH

Q15. What is the primary role of plasticizers in polymeric coatings for controlled release tablets?

• To increase the drug loading in the core
• To reduce tensile strength of the coating
• To improve film flexibility and reduce brittleness
• To accelerate drug diffusion by creating pores

Correct Answer: To improve film flexibility and reduce brittleness

Q16. A pulsatile oral delivery system is most appropriate for which clinical scenario?

• Continuous basal hormone replacement where steady plasma levels are required
• Diseases with circadian rhythms where a delayed timed release is beneficial
• Immediate pain relief requiring rapid onset
• Formulations needing complete gastric retention for a week

Correct Answer: Diseases with circadian rhythms where a delayed timed release is beneficial

Q17. Which factor does NOT significantly influence drug release from a matrix tablet?

• Drug solubility in gastrointestinal fluids
• Matrix polymer swelling and viscosity
• Surface area to volume ratio of the dosage form
• Ambient atmospheric humidity at manufacturing only without storage relevance

Correct Answer: Ambient atmospheric humidity at manufacturing only without storage relevance

Q18. Burst release from controlled release formulations is often reduced by which formulation strategy?

• Increasing drug particle size and embedding drug within polymer matrix
• Using highly soluble salts of the drug
• Coating with a fast-dissolving polymer
• Eliminating polymeric excipients

Correct Answer: Increasing drug particle size and embedding drug within polymer matrix

Q19. Which regulatory guideline is most relevant when seeking biowaiver or establishing IVIVC for extended-release oral products?

• ICH Q1A(R2) on stability testing
• ICH M9 on Biopharmaceutics Classification System-based biowaivers and FDA guidance on IVIVC
• ICH Q3A on impurities
• Guidance only on parenteral products

Correct Answer: ICH M9 on Biopharmaceutics Classification System-based biowaivers and FDA guidance on IVIVC

Q20. Which analytical approach is commonly used to distinguish between diffusion-controlled and erosion-controlled release mechanisms experimentally?

• Measuring color changes of the polymer
• Evaluating release kinetics using models like Higuchi and Korsmeyer–Peppas and monitoring polymer mass loss
• Only measuring initial burst release at 5 minutes
• Assessing tablet hardness without dissolution testing

Correct Answer: Evaluating release kinetics using models like Higuchi and Korsmeyer–Peppas and monitoring polymer mass loss

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