Approaches to extend GI transit time MCQs With Answer

Approaches to extend GI transit time MCQs With Answer

For many drugs, especially those with a narrow absorption window in the stomach or upper small intestine, extending gastric residence time significantly improves therapeutic outcomes. Gastroretentive drug delivery systems (GRDDS) use multiple design strategies—floating, mucoadhesive, high-density, swelling/expandable, superporous hydrogels, raft-forming, shape-modified, and magnetically retained systems—to resist gastric emptying and optimize exposure. This MCQ set is crafted for M. Pharm (MPH 102T) students to deepen conceptual understanding and application-focused reasoning. Questions span mechanisms, polymer selection, formulation parameters, physiological factors, in vitro/in vivo evaluation, and clinical considerations, helping you connect theory to practice in designing robust, safe, and efficacious gastroretentive formulations.

Q1. What is the primary objective of gastroretentive drug delivery systems (GRDDS)?

• To delay intestinal transit for colonic targeting
• To prolong gastric residence time to enhance local action and/or upper GI absorption
• To protect acid-labile drugs by bypassing the stomach
• To increase hepatic first-pass metabolism

Correct Answer: To prolong gastric residence time to enhance local action and/or upper GI absorption

Q2. Which of the following is NOT an approach used to extend gastric residence time?

• Floating (low-density) systems
• Mucoadhesive (bioadhesive) systems
• High-density (sinking) systems
• Enteric coating to delay release in the stomach

Correct Answer: Enteric coating to delay release in the stomach

Q3. For floating dosage forms, which physical property is critical to ensure buoyancy in gastric contents?

• Apparent density lower than gastric fluid (approximately < 1.0 g/cm³)
• High tensile strength (> 100 MPa)
• Electrical conductivity
• High vapor pressure

Correct Answer: Apparent density lower than gastric fluid (approximately < 1.0 g/cm³)

Q4. Effervescent floating systems typically rely on which combination of excipients to generate in situ gas?

• Sodium bicarbonate with citric or tartaric acid
• Lactose with microcrystalline cellulose
• Magnesium stearate with talc
• Sodium chloride with starch

Correct Answer: Sodium bicarbonate with citric or tartaric acid

Q5. Non-effervescent floating systems such as hydrodynamically balanced systems primarily use which excipient type to maintain low density?

• High-viscosity hydrophilic polymers like HPMC
• Enteric polymers like Eudragit S100
• Cross-linked PVP as disintegrant
• Inorganic salts like sodium chloride

Correct Answer: High-viscosity hydrophilic polymers like HPMC

Q6. High-density gastroretentive systems are designed to sink and resist peristaltic propulsion. A commonly cited target density for this approach is:

• > 1.1 g/cm³
• > 1.5 g/cm³
• > 2.5 g/cm³
• > 3.5 g/cm³

Correct Answer: > 2.5 g/cm³

Q7. Expandable/unfoldable gastroretentive systems rely on increased size to prevent pyloric passage. Which expanded dimension is generally associated with improved gastric retention?

• ≥ 5 mm
• ≥ 9 mm
• ≥ 13 mm
• ≥ 30 mm

Correct Answer: ≥ 13 mm

Q8. Which polymer is particularly effective for mucoadhesion in the acidic gastric environment due to its cationic nature?

• Chitosan
• Cellulose acetate phthalate
• Polyvinyl alcohol (PVA)
• Polyethylene glycol (PEG 400)

Correct Answer: Chitosan

Q9. Which physiological condition most favors prolonged gastric residence of GRDDS?

• Fasted state during phase III of the migrating motor complex
• Fed state with a high-fat, high-calorie meal
• Co-administration with prokinetic agents
• Supine posture immediately post-dose

Correct Answer: Fed state with a high-fat, high-calorie meal

Q10. Co-administration of which type of medication is most likely to decrease the effectiveness of gastroretentive systems by accelerating gastric emptying?

• Proton pump inhibitors
• Prokinetic agents (e.g., metoclopramide)
• Antacids
• Anticholinergic agents

Correct Answer: Prokinetic agents (e.g., metoclopramide)

Q11. Which in vivo technique is most commonly used to track gastric residence of dosage forms in humans?

• Gamma scintigraphy using a radiolabeled dosage form
• HPLC assay of saliva
• DSC thermal profiling
• Polarized light microscopy

Correct Answer: Gamma scintigraphy using a radiolabeled dosage form

Q12. Raft-forming gastroretentive systems are primarily utilized for:

• Enhancing colonic targeting
• Management of gastroesophageal reflux disease (GERD)
• Bypassing first-pass metabolism
• Protection of peptide drugs from enzymatic degradation in the intestine

Correct Answer: Management of gastroesophageal reflux disease (GERD)

Q13. Which statement best describes superporous hydrogels used for gastric retention?

• They swell slowly over 8–12 hours to form a dense plug
• They swell rapidly within minutes due to capillary action and can be mechanically reinforced
• They depend on magnetic fields for retention
• They are primarily composed of enteric polymers

Correct Answer: They swell rapidly within minutes due to capillary action and can be mechanically reinforced

Q14. A key limitation of magnetically retained gastroretentive systems is:

• Inability to incorporate drugs
• Requirement of patient-controlled external magnetic field positioning/alignment
• Incompatibility with any polymeric excipient
• Exclusive suitability only for injectable dosage forms

Correct Answer: Requirement of patient-controlled external magnetic field positioning/alignment

Q15. Which category of drugs is most suitable for delivery via gastroretentive systems?

• Drugs with colonic bacterial activation
• Drugs with narrow absorption window in the stomach/upper small intestine
• Drugs unstable in acidic pH
• Highly lipophilic drugs with extensive lymphatic uptake

Correct Answer: Drugs with narrow absorption window in the stomach/upper small intestine

Q16. Hollow microspheres (microballoons) used as floating systems exhibit prolonged gastric residence primarily because they:

• Have high compressive strength
• Possess a hollow core that reduces average density
• Are coated with enteric polymers
• Contain magnetic nanoparticles

Correct Answer: Possess a hollow core that reduces average density

Q17. Which formulation strategy can help maintain buoyancy by further lowering the density of a floating matrix?

• Incorporation of low-density oils or lipids
• Addition of heavy metal oxides
• Use of highly water-insoluble binders only
• Complete removal of gas-generating agents

Correct Answer: Incorporation of low-density oils or lipids

Q18. Which method is most appropriate for quantifying the mucoadhesive strength of a gastroretentive formulation in vitro?

• Rotating basket dissolution test
• Texture analyzer-based detachment force measurement using gastric mucosa
• Polarimetry
• Infrared spectroscopy

Correct Answer: Texture analyzer-based detachment force measurement using gastric mucosa

Q19. In hypochlorhydric or achlorhydric conditions, effervescent floating tablets may fail to float. Which formulation adjustment best overcomes this?

• Reduce polymer viscosity
• Incorporate an internal acidifier (e.g., citric acid) to ensure CO₂ generation
• Replace sodium bicarbonate with sodium chloride
• Increase tablet hardness only

Correct Answer: Incorporate an internal acidifier (e.g., citric acid) to ensure CO₂ generation

Q20. Which excipients are commonly used to increase density in high-density gastroretentive systems?

• Calcium carbonate and talc
• Barium sulfate and iron powder
• Lactose and sucrose
• Magnesium stearate and stearic acid

Correct Answer: Barium sulfate and iron powder

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