Transmucosal permeability and formulation factors is a vital topic for B. Pharm students focusing on mucosal absorption, drug delivery and bioavailability. This introduction explains how mucosal barriers, epithelial structure, paracellular and transcellular routes, and enzymatic degradation influence permeation. Key formulation factors — pH, drug ionization, molecular size, lipophilicity, partition coefficient, mucoadhesive polymers, permeation enhancers, and delivery systems (gels, patches, nanoparticles) — determine rate and extent of transmucosal uptake. Understanding experimental models (Franz cell, Ussing chamber), evaluation parameters (flux, permeability coefficient, lag time), and safety of enhancers is essential for rational design of transmucosal dosage forms. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which mucosal component primarily acts as the rate-limiting barrier for drug permeation across most mucosa?
- Basement membrane
- Epithelium
- Lamina propria
- Submucosal glands
Correct Answer: Epithelium
Q2. Which route is favored by small, hydrophilic drugs crossing mucosal tissues?
- Transcellular diffusion
- Paracellular diffusion
- Endocytosis
- Bulk flow
Correct Answer: Paracellular diffusion
Q3. Lipophilicity primarily enhances which aspect of transmucosal permeability?
- Paracellular transport
- Transcellular membrane permeation
- Enzymatic stability
- Mucoadhesion
Correct Answer: Transcellular membrane permeation
Q4. According to Fick’s first law, which parameter directly increases steady-state flux across mucosa?
- Decreased concentration gradient
- Increased permeability coefficient
- Increased lag time
- Decreased surface area
Correct Answer: Increased permeability coefficient
Q5. Which formulation strategy can avoid first-pass hepatic metabolism for systemic delivery?
- Conventional oral tablet
- Sublingual film
- Rectal suppository only reaching upper rectum
- Enteric-coated capsule targeting stomach
Correct Answer: Sublingual film
Q6. Which excipient class is commonly used as chemical permeation enhancers for mucosa?
- Plasticizers
- Surfactants
- Diluent fillers
- Antioxidants
Correct Answer: Surfactants
Q7. Which mechanism is NOT a typical action of permeation enhancers?
- Lipid bilayer fluidization
- Tight junction modulation
- Enzyme induction to increase degradation
- Mucus layer disruption
Correct Answer: Enzyme induction to increase degradation
Q8. Mucoadhesive polymers primarily improve transmucosal delivery by:
- Increasing enzymatic degradation
- Prolonging residence time at the absorption site
- Reducing drug solubility
- Denaturing epithelial proteins
Correct Answer: Prolonging residence time at the absorption site
Q9. Which experimental model is most suitable for measuring steady-state permeation and flux across excised mucosal tissue?
- Dissolution apparatus USP II
- Franz diffusion cell
- High-performance liquid chromatography
- Spray-drying chamber
Correct Answer: Franz diffusion cell
Q10. A drug with pKa 4.5 given to buccal mucosa at pH 6.5 will predominantly be in which form, affecting permeability?
- Fully protonated
- Predominantly unionized
- Completely degraded
- Complexed with mucin
Correct Answer: Predominantly unionized
Q11. Which statement best describes the paracellular route?
- Transport through epithelial cells via endocytosis
- Movement between cells through tight junctions
- Passive diffusion through lipid bilayers only
- Active transport via carrier proteins exclusively
Correct Answer: Movement between cells through tight junctions
Q12. Which parameter is determined from the slope of cumulative amount permeated versus time in steady-state permeation experiments?
- Lag time
- Steady-state flux
- Partition coefficient
- Mucoadhesive strength
Correct Answer: Steady-state flux
Q13. Which formulation form is most likely to provide controlled transmucosal release with prolonged contact?
- Immediate-release tablet
- Mucoadhesive patch
- Oral solution
- Injectable bolus
Correct Answer: Mucoadhesive patch
Q14. Cyclodextrins are used in transmucosal formulations mainly to:
- Increase mucociliary clearance
- Form inclusion complexes to enhance solubility
- Cross-link mucin chains to increase viscosity
- Denature epithelial tight junctions
Correct Answer: Form inclusion complexes to enhance solubility
Q15. Enzymatic degradation in mucosa can be reduced by which formulation approach?
- Using enzyme inhibitors in the formulation
- Reducing drug lipophilicity
- Increasing formulation osmolarity only
- Avoiding mucoadhesive polymers
Correct Answer: Using enzyme inhibitors in the formulation
Q16. Which factor does NOT generally increase transmucosal permeability?
- Smaller molecular size
- Higher hydrogen-bonding potential
- Greater lipophilicity (within limits)
- Use of permeation enhancers
Correct Answer: Higher hydrogen-bonding potential
Q17. For nasal delivery, what is a common safety concern with strong permeation enhancers?
- Enhanced mucoadhesion only
- Epithelial irritation and damage
- Improved mucociliary clearance
- Reduced systemic absorption permanently
Correct Answer: Epithelial irritation and damage
Q18. Which property of nanoparticles enhances transmucosal absorption of poorly permeable drugs?
- Large particle size (>10 microns)
- Surface modification for mucoadhesion or mucus penetration
- Neutral density to sink in mucus
- High crystallinity only
Correct Answer: Surface modification for mucoadhesion or mucus penetration
Q19. Which mucosal site typically has the fastest onset for systemic drug absorption?
- Rectal (proximal part with portal drainage)
- Oral (swallowed tablets)
- Sublingual mucosa
- Large intestine mucosa
Correct Answer: Sublingual mucosa
Q20. Which measurement describes the ease with which a drug partitions from vehicle into mucosal tissue?
- Viscosity
- Partition coefficient
- pKa only
- Surface tension
Correct Answer: Partition coefficient
Q21. Tight junction modulators mainly influence which transport route?
- Transcellular lipophilic route
- Paracellular aqueous pathway
- Vesicular endocytosis
- Active carrier-mediated uptake
Correct Answer: Paracellular aqueous pathway
Q22. Which of the following is a commonly used mucoadhesive polymer in buccal formulations?
- Hydroxypropyl methylcellulose (HPMC)
- Sodium lauryl sulfate
- Polyethylene glycol 4000 (as sole adhesive)
- Sucrose
Correct Answer: Hydroxypropyl methylcellulose (HPMC)
Q23. Lag time in a permeation study represents:
- The time to reach steady-state flux across tissue
- Maximum cumulative permeation value only
- Time when drug degrades completely
- Instantaneous permeation onset
Correct Answer: The time to reach steady-state flux across tissue
Q24. Prodrugs are used in transmucosal delivery mainly to:
- Decrease membrane permeation
- Increase enzymatic degradation intentionally
- Improve lipophilicity or stability to enhance absorption
- Make drugs more hygroscopic
Correct Answer: Improve lipophilicity or stability to enhance absorption
Q25. Which physiological factor reduces residence time of formulations on nasal mucosa?
- Mucociliary clearance
- Low enzymatic activity
- High mucoadhesion
- Reduced blood flow
Correct Answer: Mucociliary clearance
Q26. Which analytical parameter assesses drug amount absorbed per unit area per time?
- Permeability coefficient (Papp)
- Steady-state flux (Jss)
- Partition coefficient (Log P)
- Viscosity (η)
Correct Answer: Steady-state flux (Jss)
Q27. What effect does increasing formulation viscosity typically have on transmucosal drug delivery?
- Always decreases permeation by blocking diffusion
- May increase residence time but can slow drug diffusion
- Eliminates need for permeation enhancers
- Automatically increases systemic bioavailability
Correct Answer: May increase residence time but can slow drug diffusion
Q28. Which excipient can chelate calcium and transiently open tight junctions to enhance paracellular transport?
- EDTA
- Glycerin
- Cellulose
- Sucrose
Correct Answer: EDTA
Q29. Which factor is most important when designing a mucoadhesive buccal tablet for peptide drugs?
- Enhancer toxicity only
- Balancing enzyme inhibition, mucoadhesion and permeation enhancement
- Maximizing tablet hardness above all
- Minimizing residence time intentionally
Correct Answer: Balancing enzyme inhibition, mucoadhesion and permeation enhancement
Q30. Which regulatory consideration is critical for using novel permeation enhancers in transmucosal products?
- Only the effect on drug potency matters
- Comprehensive safety and local toxicity evaluation
- Color and flavor acceptability only
- Ignoring systemic exposure assessments
Correct Answer: Comprehensive safety and local toxicity evaluation
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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