Protein and peptide delivery barriers MCQs With Answer

Protein and peptide delivery barriers MCQs With Answer is designed to help M. Pharm students master critical concepts in Drug Delivery Systems (MPH 102T). Proteins and peptides face unique challenges: enzymatic degradation, poor epithelial permeability, rapid renal clearance, immunogenicity, and stability issues during formulation and storage. These MCQs explore biological barriers across oral, nasal, pulmonary, parenteral, and brain delivery routes; physicochemical determinants like size, charge, and hydrophobicity; and enabling strategies—PEGylation, Fc-fusion, permeation enhancers, protease inhibitors, mucoadhesion, nanoparticles, and depot systems. By engaging with clinically relevant examples (e.g., SNAC, PLGA microspheres, FcRn-mediated recycling), students can connect mechanistic understanding with formulation choices and regulatory considerations, strengthening problem-solving skills for translational peptide/protein therapeutics.

Q1. The primary reason for the very low oral bioavailability of most protein and peptide drugs is:

• Extensive enzymatic degradation and very limited epithelial permeability
• Rapid gastric emptying alone
• High P-glycoprotein efflux susceptibility
• High hepatic first-pass metabolism

Correct Answer: Extensive enzymatic degradation and very limited epithelial permeability

Q2. Which set best represents the sequential enzymatic barriers to oral peptide delivery along the GI tract?

• Pepsin in the stomach; trypsin, chymotrypsin, and elastase in the intestine; brush-border peptidases
• Amylase in the stomach; lipase in the intestine; CYP3A4 in enterocytes
• Pepsin in the colon; trypsin in the stomach; urease in the duodenum
• Lactase in the stomach; catalase in the colon; carboxylesterase in the ileum

Correct Answer: Pepsin in the stomach; trypsin, chymotrypsin, and elastase in the intestine; brush-border peptidases

Q3. Which modification primarily prolongs systemic half-life of protein therapeutics by increasing hydrodynamic size and reducing renal filtration?

• PEGylation
• Enteric coating
• Co-administration of a permeation enhancer
• Cyclodextrin inclusion complexation

Correct Answer: PEGylation

Q4. The small-intestinal paracellular pathway effectively allows passage of molecules of approximately which maximum size?

• Small hydrophilic molecules roughly below 200–500 Da
• Peptides up to 5 kDa
• Proteins up to 70 kDa
• Any size if a permeation enhancer is present

Correct Answer: Small hydrophilic molecules roughly below 200–500 Da

Q5. Which statement about nasal delivery of peptides is most accurate?

• Mucociliary clearance limits residence time to about 15–20 minutes
• Large dose volumes (>500 μL per nostril) are well tolerated
• The nasal cavity lacks peptidases, so degradation is negligible
• Nasal delivery consistently achieves 100% bioavailability for peptides

Correct Answer: Mucociliary clearance limits residence time to about 15–20 minutes

Q6. In pulmonary delivery, particles within which size range are most susceptible to phagocytosis by alveolar macrophages, reducing bioavailability?

• < 100 nm
• Approximately 1–3 μm
• 10–20 μm
• Dissolved molecules are equivalently phagocytosed

Correct Answer: Approximately 1–3 μm

Q7. For subcutaneous administration, proteins above which approximate molecular size preferentially enter the lymphatics rather than directly entering blood capillaries?

• > 16–20 kDa
• > 1 kDa
• > 100 kDa
• > 500 Da

Correct Answer: > 16–20 kDa

Q8. Which strategy most directly exploits neonatal Fc receptor (FcRn) recycling to extend in vivo half-life?

• Fc-fusion to an IgG Fc domain
• PEGylation with 20–40 kDa PEG
• N-terminal acetylation
• Simple lipidation with a C16 fatty acid

Correct Answer: Fc-fusion to an IgG Fc domain

Q9. The dominant chemical degradation pathway for asparagine residues in peptides/proteins under physiological conditions is:

• Deamidation to aspartate/isoaspartate
• Disulfide scrambling
• Selective oxidation to sulfoxides
• Complete racemization to D-amino acids

Correct Answer: Deamidation to aspartate/isoaspartate

Q10. Which clinically used excipient functions as an oral absorption enhancer for certain peptides (e.g., semaglutide)?

• Salcaprozate sodium (SNAC)
• Sodium dodecyl sulfate (SDS)
• Benzalkonium chloride
• Cremophor EL

Correct Answer: Salcaprozate sodium (SNAC)

Q11. Mucoadhesive polymers such as chitosan aid peptide delivery primarily by:

• Transiently opening tight junctions and increasing residence time at the mucosa
• Inhibiting hepatic CYP enzymes
• Blocking renal filtration at the glomerulus
• Providing receptor-mediated transcytosis via transferrin

Correct Answer: Transiently opening tight junctions and increasing residence time at the mucosa

Q12. Prodrug targeting of which transporter can enhance intestinal uptake of small peptidomimetics?

• PepT1 (H+-coupled oligopeptide transporter)
• GLUT2
• OATP1B1
• P-glycoprotein (ABCB1)

Correct Answer: PepT1 (H+-coupled oligopeptide transporter)

Q13. Which approach facilitates peptide delivery across the blood–brain barrier via receptor-mediated transcytosis?

• Conjugation to ligands targeting the transferrin receptor
• Enteric coating
• Use of bile salt surfactants
• PEGylation alone without targeting

Correct Answer: Conjugation to ligands targeting the transferrin receptor

Q14. What primarily drives the rapid systemic clearance of small peptides after intravenous administration?

• Glomerular filtration governed by size and charge
• Biliary excretion as intact peptide
• Extensive metabolism by hepatic CYP450 enzymes
• Pulmonary exhalation

Correct Answer: Glomerular filtration governed by size and charge

Q15. In parenteral protein formulations, which excipient class is most commonly used to minimize interfacial adsorption and aggregation?

• Nonionic surfactants (e.g., polysorbate 80, poloxamer 188)
• Sodium chloride
• Colloidal iron oxide
• Talc

Correct Answer: Nonionic surfactants (e.g., polysorbate 80, poloxamer 188)

Q16. Which statement regarding immunogenicity risk for protein therapeutics is most accurate?

• Protein aggregation increases the risk of antidrug antibody formation
• PEGylation invariably increases immunogenicity
• Subcutaneous delivery eliminates immune exposure
• Silicone oil droplets from syringes have no impact on immunogenicity

Correct Answer: Protein aggregation increases the risk of antidrug antibody formation

Q17. For oral delivery via Peyer’s patches, particles in which size range are most efficiently taken up by M cells?

• 50–500 nm
• 5–10 μm
• < 2 nm
• > 100 μm

Correct Answer: 50–500 nm

Q18. Which protease inhibitor has been studied to protect peptides from gastrointestinal proteolysis?

• Aprotinin
• Acetazolamide
• Atorvastatin
• Aspirin

Correct Answer: Aprotinin

Q19. In long-acting peptide formulations using PLGA microspheres (e.g., leuprolide depot), the dominant in vivo release mechanism is:

• Diffusion through the polymer matrix coupled with polymer degradation (erosion)
• Hepatic metabolism of PLGA
• Dissolution of crystalline sugar carriers
• Photolysis of ester bonds by ambient light

Correct Answer: Diffusion through the polymer matrix coupled with polymer degradation (erosion)

Q20. For nanoparticles intended to penetrate mucus and deliver peptides to the epithelium, which surface property best promotes rapid diffusion without adhesion?

• Dense PEGylation to create a neutral, muco-inert hydration layer
• High positive charge and hydrophobic surface
• Large hydrodynamic diameter
• Covalent attachment to mucin fibers

Correct Answer: Dense PEGylation to create a neutral, muco-inert hydration layer

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