Floating drug delivery systems and their mechanisms MCQs With Answer introduce B. Pharm students to buoyant formulations designed for prolonged gastric retention and targeted upper GI release. This concise, informative overview covers key concepts: hydrodynamically balanced systems, effervescent and non-effervescent approaches, low-density polymers, swellable matrices, microballoons, raft-forming systems, float lag time, in vitro buoyancy testing, and factors affecting gastric residence (motility, fed/fasted state, formulation density). Understanding these mechanisms improves control of drug release, bioavailability, and site-specific therapy. These MCQs emphasize formulation principles, evaluation techniques, and clinical implications to deepen your conceptual and practical knowledge. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary goal of a floating drug delivery system (FDDS)?
- To reduce drug solubility in gastric fluid
- To localize drug delivery in the colon
- To prolong gastric residence time and sustain drug release
- To increase drug metabolism in the liver
Correct Answer: To prolong gastric residence time and sustain drug release
Q2. Which characteristic is most essential for a formulation to float in gastric fluid?
- High molecular weight drug
- Apparent density lower than gastric fluid
- Rapid disintegration time
- Enteric coating
Correct Answer: Apparent density lower than gastric fluid
Q3. Which polymer is commonly used in hydrodynamically balanced systems (HBS)?
- Hydroxypropyl methylcellulose (HPMC)
- Ethyl cellulose
- Polyvinylpyrrolidone (PVP)
- Polyacrylic acid
Correct Answer: Hydroxypropyl methylcellulose (HPMC)
Q4. An effervescent floating system typically generates buoyancy by producing which gas?
- Oxygen
- Carbon dioxide
- Nitrogen
- Hydrogen
Correct Answer: Carbon dioxide
Q5. Which pair of ingredients is commonly used in effervescent FDDS to produce CO2?
- Sodium alginate and ethyl cellulose
- Sodium bicarbonate and citric acid (or tartaric acid)
- Gelatin and glycerin
- Calcium carbonate and HPMC
Correct Answer: Sodium bicarbonate and citric acid (or tartaric acid)
Q6. Non-effervescent floating systems rely primarily on which mechanism?
- Gas generation by reaction in stomach
- Swelling of hydrophilic polymers to form a low-density gel matrix
- Rapid disintegration into micro-particles
- Enzymatic degradation
Correct Answer: Swelling of hydrophilic polymers to form a low-density gel matrix
Q7. Which formulation is an example of a non-effervescent FDDS?
- Hydrodynamically balanced tablet (HBS)
- Gas-generating effervescent granule
- Raft-forming antacid requiring CO2
- Floating microspheres with internal gas core
Correct Answer: Hydrodynamically balanced tablet (HBS)
Q8. Floating microspheres (microballoons) gain buoyancy primarily due to:
- Entrapped air or low-density hollow core
- Use of high-density fillers
- Immediate erosion in gastric fluid
- Coating with enteric polymers
Correct Answer: Entrapped air or low-density hollow core
Q9. Which parameter describes the time taken for a dosage form to emerge on the surface of the dissolution medium?
- Floating duration
- Float lag time
- Disintegration time
- Residence index
Correct Answer: Float lag time
Q10. Which test is commonly used to evaluate in vitro buoyancy of a floating dosage form?
- USP disintegration test only
- Buoyancy test measuring floating lag time and duration in simulated gastric fluid
- Friability test only
- Viscosity measurement of the medium
Correct Answer: Buoyancy test measuring floating lag time and duration in simulated gastric fluid
Q11. Raft-forming systems are primarily used for which therapeutic application?
- Colonic delivery of macromolecules
- Treatment of gastroesophageal reflux disease (GERD) and reflux prevention
- Enhancing hepatic first-pass metabolism
- Delivering peptides via buccal route
Correct Answer: Treatment of gastroesophageal reflux disease (GERD) and reflux prevention
Q12. Which property of a drug makes it most suitable for FDDS?
- Absorption window in the upper GI tract
- Extensive colonic absorption
- Short biological half-life less than 5 minutes
- High instability in acidic pH
Correct Answer: Absorption window in the upper GI tract
Q13. Which physiological factor can decrease gastric retention of floating systems?
- Fed state with high-calorie meal
- Low gastric motility (gastroparesis)
- High-frequency migrating motor complex (fasted state MMC phase III)
- Prolonged gastric emptying time
Correct Answer: High-frequency migrating motor complex (fasted state MMC phase III)
Q14. The ideal apparent density of a floating dosage form to ensure buoyancy in gastric fluid (~1.004 g/cm3) should be:
- Greater than 1.2 g/cm3
- Approximately 2.0 g/cm3
- Less than gastric fluid density, typically <1.0 g/cm3
- Equal to 1.5 g/cm3
Correct Answer: Less than gastric fluid density, typically <1.0 g/cm3
Q15. Which polymer combination can enhance mucoadhesion and buoyancy when used in FDDS?
- Carbopol with HPMC
- Sucrose with lactose
- Stearic acid with magnesium stearate
- Polyethylene glycol with talc
Correct Answer: Carbopol with HPMC
Q16. Which advantage is specific to FDDS for drugs with narrow absorption windows?
- Reduced dissolution rate
- Increased systemic metabolism
- Improved bioavailability by prolonged exposure in absorption window
- Faster renal elimination
Correct Answer: Improved bioavailability by prolonged exposure in absorption window
Q17. Which technique is commonly used to prepare hollow microspheres for floating systems?
- Spray drying to form porous microspheres
- Solvent evaporation/ diffusion to form hollow microballoons
- Direct compression without excipients
- Hot-melt extrusion only
Correct Answer: Solvent evaporation/ diffusion to form hollow microballoons
Q18. Which factor does NOT significantly affect the floatation behavior of FDDS?
- Tablet size and shape
- Ambient humidity during storage
- Formulation density
- Viscosity of gel layer formed
Correct Answer: Ambient humidity during storage
Q19. Floating dosage forms intended for once-daily dosing should primarily control which parameter?
- Immediate burst release within 15 minutes
- Zero-order or sustained release over ~24 hours
- Complete release in the mouth
- Rapid enzymatic degradation
Correct Answer: Zero-order or sustained release over ~24 hours
Q20. Which in vivo method is commonly used to evaluate gastric residence time of FDDS in humans?
- Gamma scintigraphy with radiolabeled dosage form
- Surface pH meter in the stomach
- Urine colorimetry
- Skin patch monitoring
Correct Answer: Gamma scintigraphy with radiolabeled dosage form
Q21. Which statement about hydrodynamically balanced systems (HBS) is true?
- HBS rely on gas generation to float
- HBS are made of rapidly dissolving excipients only
- HBS combine drug with gel-forming polymers to maintain buoyancy without gas
- HBS are specifically enteric-coated to release in the intestine
Correct Answer: HBS combine drug with gel-forming polymers to maintain buoyancy without gas
Q22. Floatation of a dosage form in vivo can be compromised by which patient-related factor?
- Taking the formulation with a high-calorie meal
- Abnormal gastric motility disorders like gastroparesis
- Co-administration of antacids
- Positioning upright after dosing
Correct Answer: Abnormal gastric motility disorders like gastroparesis
Q23. Which release mechanism is commonly observed from swellable FDDS matrices?
- Osmotic pump-controlled zero-order only
- Fickian diffusion and swelling-controlled (anomalous) release
- Complete enzymatic cleavage dependent release
- Immediate-release by erosion within 5 minutes
Correct Answer: Fickian diffusion and swelling-controlled (anomalous) release
Q24. Which evaluation parameter assesses how long a floating system remains buoyant in vitro?
- Floating duration (total floating time)
- Mechanical strength
- Drug assay by HPLC only
- Bulk density measurement only
Correct Answer: Floating duration (total floating time)
Q25. To design an FDDS for a weakly basic drug that degrades in the intestine, which approach is preferred?
- Non-floatable immediate-release tablet
- Floating sustained-release formulation to retain drug in stomach
- Enteric-coated pellet to bypass stomach
- Rectal suppository
Correct Answer: Floating sustained-release formulation to retain drug in stomach
Q26. Which excipient is used to create porosity and reduce density in FDDS microspheres?
- Polyethylene glycol (PEG) as a plasticizer
- Porogen like ammonium bicarbonate or PVP (removed during processing)
- Talc for lubrication
- Lactose as a high-density filler
Correct Answer: Porogen like ammonium bicarbonate or PVP (removed during processing)
Q27. Which limitation is commonly associated with floating drug delivery systems?
- Inability to sustain drug release
- Dependence on gastric conditions and variable residence time
- Excessive systemic toxicity due to immediate release
- Complete avoidance of first-pass metabolism
Correct Answer: Dependence on gastric conditions and variable residence time
Q28. In formulation development, reducing float lag time can be achieved by:
- Increasing tablet density
- Optimizing gas-generating agent concentration and rapid wetting
- Removing all hydrophilic polymers
- Coating with an impermeable shell that prevents wetting
Correct Answer: Optimizing gas-generating agent concentration and rapid wetting
Q29. Which mathematical model is often applied to analyze release kinetics from swelling-controlled FDDS?
- Higuchi, Korsmeyer-Peppas and zero/first-order models
- Michaelis-Menten enzyme kinetics only
- Arrhenius thermal degradation model
- Log-normal distribution of particle size only
Correct Answer: Higuchi, Korsmeyer-Peppas and zero/first-order models
Q30. Which strategy can combine mucoadhesion and buoyancy for enhanced gastric retention?
- Using only hydrophobic fillers like talc
- Formulating a low-density matrix with mucoadhesive polymers (e.g., HPMC + Carbopol)
- Applying an enteric coat to the floating tablet
- Designing capsules that rapidly disintegrate in the esophagus
Correct Answer: Formulating a low-density matrix with mucoadhesive polymers (e.g., HPMC + Carbopol)
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