Introduction: Gastroretentive drug delivery systems (GRDDS) enhance sustained drug release by prolonging gastric residence time, improving bioavailability for drugs with a narrow absorption window. GRDDS applications include floating systems, bioadhesive/mucoadhesive systems, expandable and high-density designs that control buoyancy, swelling and adhesion. Key formulation considerations include choice of polymers like HPMC and Carbopol, gas-generating agents (e.g., sodium bicarbonate), tablet size, and in vitro metrics such as floating lag time, total floating duration and swelling index. GRDDS are especially valuable for sustained drug release, targeted gastric action, and dose reduction, but are influenced by gastric motility, fed state and drug stability. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary goal of gastroretentive drug delivery systems (GRDDS) in sustained drug release?
- To increase drug solubility in intestinal fluid
- To prolong gastric residence time and sustain release
- To target colonic bacteria for activation
- To reduce tablet hardness for faster disintegration
Correct Answer: To prolong gastric residence time and sustain release
Q2. Which drug property makes it most suitable for GRDDS formulation?
- Extensive absorption throughout the entire GI tract
- Narrow absorption window in the upper GIT
- Stability only in alkaline pH
- High molecular weight peptides degraded in stomach
Correct Answer: Narrow absorption window in the upper GIT
Q3. Which of the following is a common polymer used to achieve swelling in non-effervescent floating systems?
- Hydroxypropyl methylcellulose (HPMC)
- Sodium chloride
- Poloxamer 188
- Magnesium stearate
Correct Answer: Hydroxypropyl methylcellulose (HPMC)
Q4. Floating lag time in a floating tablet refers to:
- Total time the tablet remains in the stomach
- Time taken for a tablet to begin floating on dissolution medium
- Time required for complete drug release
- Time taken for tablet disintegration
Correct Answer: Time taken for a tablet to begin floating on dissolution medium
Q5. Which mechanism is used in effervescent floating systems to provide buoyancy?
- Gas generation from effervescent reaction (CO2)
- Polymer bioadhesion to mucosa
- Increasing tablet density with metal powders
- Enzymatic gel degradation in stomach
Correct Answer: Gas generation from effervescent reaction (CO2)
Q6. A mucoadhesive GRDDS primarily relies on which interaction with gastric mucosa?
- Hydrophobic partitioning
- Electrostatic and hydrogen bonding between polymer and mucin
- Formation of insoluble complexes
- Enzymatic crosslinking with mucus
Correct Answer: Electrostatic and hydrogen bonding between polymer and mucin
Q7. Which evaluation parameter measures swelling behavior of an expandable GRDDS?
- Floating lag time
- Swelling index
- Particle size distribution
- Friability
Correct Answer: Swelling index
Q8. Which polymer is widely used for mucoadhesive strength due to high carboxylic content?
- Carbopol (carbomer)
- Ethyl cellulose
- Lactose
- Sodium chloride
Correct Answer: Carbopol (carbomer)
Q9. Which in vitro test is most relevant to predict in vivo gastric retention of floating tablets?
- Dissolution in simulated intestinal fluid only
- Floating duration and floating lag time in simulated gastric fluid
- Disintegration in water at 50°C
- Friability in dry conditions
Correct Answer: Floating duration and floating lag time in simulated gastric fluid
Q10. Which of the following drug types is NOT ideal for GRDDS?
- Drug primarily absorbed in stomach or proximal small intestine
- Drug unstable in acidic medium
- Drug with narrow absorption window
- Drug requiring local gastric action
Correct Answer: Drug unstable in acidic medium
Q11. Raft-forming systems are a type of GRDDS used commonly for which application?
- Prolonged systemic delivery of peptides
- Treatment of gastroesophageal reflux disease (GERD)
- Colon-targeted prodrugs
- Pulmonary delivery
Correct Answer: Treatment of gastroesophageal reflux disease (GERD)
Q12. High-density gastroretentive systems rely on which principle?
- Floating on gastric fluid
- Settling in stomach due to density greater than gastric contents
- Rapid disintegration to release drug
- Oscillating buoyancy via gas cycles
Correct Answer: Settling in stomach due to density greater than gastric contents
Q13. Which excipient is commonly used as a gas-generating agent in effervescent floating tablets?
- Sodium bicarbonate
- Microcrystalline cellulose
- Magnesium stearate
- Silicon dioxide
Correct Answer: Sodium bicarbonate
Q14. Which manufacturing method is frequently used to prepare floating tablets by incorporating low-density excipients?
- Direct compression
- Spray drying for nanoparticles
- Freeze-drying of protein formulations
- Sublimation of volatile components only
Correct Answer: Direct compression
Q15. Which factor does NOT significantly affect gastric residence time of GRDDS?
- Fed versus fasted state of the patient
- Particle shape and size of the dosage form
- Ambient room temperature where tablet was stored
- Gastric motility and contractions
Correct Answer: Ambient room temperature where tablet was stored
Q16. Superporous hydrogels are advantageous in GRDDS because they:
- Have very slow water uptake
- Swell rapidly to large size and maintain integrity
- Require high compression force to form matrices
- Are highly permeable to bile salts only
Correct Answer: Swell rapidly to large size and maintain integrity
Q17. Which parameter indicates how long a floating tablet remains buoyant?
- Swelling index
- Total floating time (TFT)
- Gelation pH
- Moisture content
Correct Answer: Total floating time (TFT)
Q18. Which release mechanism is commonly observed in GRDDS matrix tablets containing HPMC?
- Immediate burst release with no diffusion control
- Diffusion and erosion-controlled sustained release
- Only enzymatic cleavage-controlled release
- Osmotic pump without polymer swelling
Correct Answer: Diffusion and erosion-controlled sustained release
Q19. Gamma scintigraphy is used in GRDDS studies to:
- Measure tablet mechanical strength
- Visualize and quantify in vivo gastric residence time
- Determine polymer viscosity
- Assess tablet color stability
Correct Answer: Visualize and quantify in vivo gastric residence time
Q20. Which of the following is a limitation of GRDDS?
- Predictable gastric retention across all patients
- Dependence on gastric physiology leading to variable retention
- Enhanced bioavailability for all drugs
- Universal applicability to large-dose drugs
Correct Answer: Dependence on gastric physiology leading to variable retention
Q21. Non-effervescent floating systems typically achieve buoyancy by:
- Incorporation of gas-generating effervescent salts
- Swelling of hydrocolloid polymers to decrease density
- Adding heavy metal fillers
- Coating with enteric polymers
Correct Answer: Swelling of hydrocolloid polymers to decrease density
Q22. Which in vitro measurement assesses adhesive force of a mucoadhesive formulation?
- Texture analyzer or balance method measuring detachment force
- pH titration
- Mercury intrusion porosimetry
- Thermogravimetric analysis
Correct Answer: Texture analyzer or balance method measuring detachment force
Q23. Which formulation strategy is suitable for delivering a local anti-H. pylori antibiotic in the stomach?
- Colon-targeted coated pellets
- Gastroretentive mucoadhesive or floating systems
- Pulmonary inhalation aerosols
- Transdermal patches
Correct Answer: Gastroretentive mucoadhesive or floating systems
Q24. For GRDDS tablets, increasing HPMC viscosity grade typically results in:
- Faster drug release and shorter floating time
- Slower drug release and longer matrix integrity
- Increased tablet porosity leading to rapid disintegration
- No change in release profile
Correct Answer: Slower drug release and longer matrix integrity
Q25. Which is a common method to evaluate in vitro-in vivo correlation (IVIVC) for GRDDS?
- Comparing in vitro dissolution profiles with in vivo plasma concentration-time profiles
- Only measuring tablet hardness
- Assessing color change in gastric fluid
- Measuring moisture uptake under ambient light
Correct Answer: Comparing in vitro dissolution profiles with in vivo plasma concentration-time profiles
Q26. Which patient factor can reduce effectiveness of a floating GRDDS?
- Fed state slowing gastric emptying
- High gastric pH after a meal
- Increased gastric motility in fasted state
- All of the above
Correct Answer: All of the above
Q27. Which technique creates hollow or low-density units for multiparticulate floating systems?
- Inclusion of gas-generating core or microballoons
- Compression with high-density fillers
- Coating with crystalline sugars only
- Lyophilization followed by sintering
Correct Answer: Inclusion of gas-generating core or microballoons
Q28. Which analytical parameter is critical to control when designing GRDDS for narrow absorption window drugs?
- Particle color
- Release kinetics to maintain therapeutic concentration in proximal GI
- Tablet advertising label font
- Storage box dimensions
Correct Answer: Release kinetics to maintain therapeutic concentration in proximal GI
Q29. Which statement best describes raft-forming GRDDS composition?
- Non-gelling powders that sink immediately
- Viscous gel barrier forms on contact with gastric acid to prevent reflux
- High-density metallic tablets that lodge in pylorus
- Osmotic cores releasing gas for buoyancy
Correct Answer: Viscous gel barrier forms on contact with gastric acid to prevent reflux
Q30. Which optimization strategy can improve gastric retention of a floating tablet in vivo?
- Reducing tablet size below 1 mm to pass pylorus quickly
- Balancing gas generation and polymer swelling to ensure rapid buoyancy and prolonged floatation
- Eliminating polymers to avoid swelling
- Formulating tablets to disintegrate within 5 minutes
Correct Answer: Balancing gas generation and polymer swelling to ensure rapid buoyancy and prolonged floatation
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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