Protein & Peptide Delivery Systems MCQs With Answer

Introduction: Protein and peptide therapeutics are increasingly important in modern pharmacotherapy due to their high potency and specificity. However, their delivery presents unique challenges including enzymatic degradation, poor membrane permeability, short systemic half-life, immunogenicity, and stability issues during formulation and storage. This quiz set focuses on core concepts, formulation strategies, and advanced delivery platforms used to overcome these obstacles—such as PEGylation, liposomes, polymeric nanoparticles, microspheres, hydrogels, mucosal delivery, and controlled-release implants. Designed for M.Pharm students preparing for MIP 103T, these MCQs emphasize mechanistic understanding, formulation choices, and practical considerations in development and clinical translation of protein and peptide delivery systems.

Q1. Which of the following is the primary reason proteins and peptides show very low oral bioavailability?

• Limited solubility in gastrointestinal fluids
• Extensive enzymatic degradation and poor epithelial permeability in the GI tract
• Rapid renal clearance due to small molecular size
• First-pass hepatic metabolism following lymphatic uptake

Correct Answer: Extensive enzymatic degradation and poor epithelial permeability in the GI tract

Q2. PEGylation of therapeutic peptides is commonly used to:

• Increase enzymatic degradation to shorten half-life
• Enhance receptor affinity through conformational change
• Increase hydrodynamic size to reduce renal clearance and mask immunogenic epitopes
• Promote cellular uptake by increasing lipophilicity

Correct Answer: Increase hydrodynamic size to reduce renal clearance and mask immunogenic epitopes

Q3. Which delivery system is most appropriate for achieving sustained release of a peptide over weeks to months from a single subcutaneous injection?

• Lyophilized peptide powder for reconstitution
• Biodegradable polymeric microspheres (e.g., PLGA microspheres)
• Immediate-release aqueous solution
• Non-biodegradable metal implant

Correct Answer: Biodegradable polymeric microspheres (e.g., PLGA microspheres)

Q4. A major stability concern for protein therapeutics during manufacturing and storage is:

• Spontaneous glycosylation under ambient conditions
• Protein aggregation and denaturation leading to loss of activity and increased immunogenicity
• Excessive covalent crosslinking with excipient salts
• Transformation into a crystalline form that is inactive

Correct Answer: Protein aggregation and denaturation leading to loss of activity and increased immunogenicity

Q5. Which excipient is commonly used as a stabilizer to protect proteins from aggregation during freeze-drying?

• Sodium lauryl sulfate
• Sucrose or trehalose as lyoprotectants
• Glycine at high ionic strength
• Ethyl alcohol

Correct Answer: Sucrose or trehalose as lyoprotectants

Q6. For pulmonary delivery of therapeutic peptides, which characteristic of the formulation particles is most critical for deep lung deposition?

• Average particle density above 5 g/cm³
• Mass median aerodynamic diameter (MMAD) in the range 1–5 µm
• Particle zeta potential of +50 mV
• Hydrophobicity sufficient to resist mucociliary clearance

Correct Answer: Mass median aerodynamic diameter (MMAD) in the range 1–5 µm

Q7. Which mechanism best describes how lipid nanoparticles (LNPs) improve mRNA and peptide delivery into cells?

• LNPs chemically modify nucleic acids to become membrane permeable
• LNPs facilitate endocytosis and promote endosomal escape of cargo into the cytosol
• LNPs form covalent bonds with cell-surface receptors to transport cargo
• LNPs degrade extracellular enzymes to prevent cargo breakdown

Correct Answer: LNPs facilitate endocytosis and promote endosomal escape of cargo into the cytosol

Q8. Which strategy can reduce proteolytic degradation of peptides in the gastrointestinal tract for oral delivery?

• Co-administration with enteric-coated capsules containing protease inhibitors and permeation enhancers
• Administering the peptide as an aqueous solution with sugar
• Using highly acidic formulation to inactivate proteases in the stomach
• Increasing formulation osmolarity to draw fluid away from the epithelium

Correct Answer: Co-administration with enteric-coated capsules containing protease inhibitors and permeation enhancers

Q9. Which property of PLGA polymers primarily controls the release rate of encapsulated protein from microspheres?

• Polymer color and crystallinity
• Lactic/glycolic acid ratio and polymer molecular weight affecting degradation rate
• Presence of residual solvents only
• Surface charge of the polymer particles

Correct Answer: Lactic/glycolic acid ratio and polymer molecular weight affecting degradation rate

Q10. Which delivery route offers rapid systemic absorption with lower proteolytic exposure compared to oral administration and is often used for peptides like insulin?

• Topical transdermal patches
• Intranasal or pulmonary administration
• Oral disintegrating tablets
• Rectal suppositories

Correct Answer: Intranasal or pulmonary administration

Q11. Which analytical method is most suitable for detecting and quantifying low-level aggregation in monoclonal antibody formulations?

• Ultraviolet-visible spectroscopy at a single wavelength
• Size-exclusion chromatography (SEC) combined with multi-angle light scattering (MALS)
• Thin-layer chromatography on silica gel
• Simple pH titration curves

Correct Answer: Size-exclusion chromatography (SEC) combined with multi-angle light scattering (MALS)

Q12. A depot formulation using non-biodegradable implants for peptide delivery is limited clinically because:

• They rapidly dissolve and cannot provide sustained release
• They require surgical removal after depletion, posing safety and compliance issues
• They completely prevent immune recognition of the peptide
• They enhance first-pass metabolism

Correct Answer: They require surgical removal after depletion, posing safety and compliance issues

Q13. Which modification to a peptide drug is most likely to decrease immunogenicity while retaining activity?

• Random thermal denaturation before administration
• Covalent attachment of polyethylene glycol (PEGylation) to mask epitopes
• Formulating with strong adjuvants to shift immune response
• Administering as large aggregates to reduce epitope exposure

Correct Answer: Covalent attachment of polyethylene glycol (PEGylation) to mask epitopes

Q14. Mucoadhesive polymers in nasal peptide formulations primarily enhance bioavailability by:

• Acting as enzymatic catalysts for peptide activation
• Prolonging residence time at the mucosal surface and facilitating absorption
• Neutralizing nasal pH to preserve peptide charge
• Increasing mucociliary clearance to transport peptide to lymphatics

Correct Answer: Prolonging residence time at the mucosal surface and facilitating absorption

Q15. Which sterilization method is generally least suitable for most protein and peptide formulations due to denaturation risk?

• Filtration through 0.22 µm filters for solutions
• Gamma irradiation at high doses
• Sterile aseptic manufacturing without terminal sterilization
• Sterile filling under validated conditions at low temperature

Correct Answer: Gamma irradiation at high doses

Q16. Cell-penetrating peptides (CPPs) are used in delivery systems primarily to:

• Enhance systemic clearance of cargo molecules
• Facilitate translocation of cargo across cell membranes into the cytoplasm
• Act as protease inhibitors in extracellular fluids
• Promote rapid renal excretion of therapeutic proteins

Correct Answer: Facilitate translocation of cargo across cell membranes into the cytoplasm

Q17. Which factor is most critical when designing liposomal formulations for intravenous delivery of therapeutic peptides?

• Ensuring liposomes are positively charged to maximize complement activation
• Controlling particle size, surface charge, and PEGylation to minimize RES uptake and prolong circulation
• Maximizing free aqueous peptide content outside liposomes
• Using only saturated lipids to make rigid, non-deformable particles

Correct Answer: Controlling particle size, surface charge, and PEGylation to minimize RES uptake and prolong circulation

Q18. Prodrug approaches for peptides aim to improve delivery by:

• Converting peptides into irreversible enzyme inhibitors systemically
• Temporarily masking polar groups to enhance membrane permeability and then regenerating the active peptide in vivo
• Increasing susceptibility to proteases for faster clearance
• Creating permanent covalent modifications that cannot be reversed in the body

Correct Answer: Temporarily masking polar groups to enhance membrane permeability and then regenerating the active peptide in vivo

Q19. Which of the following is a key advantage of hydrogel-based peptide depots for local delivery?

• Immediate burst release without control
• Ability to provide localized, sustained release while maintaining a hydrated environment that preserves protein stability
• They convert peptides into small molecules to enhance diffusion
• They inherently increase systemic immunogenicity

Correct Answer: Ability to provide localized, sustained release while maintaining a hydrated environment that preserves protein stability

Q20. When developing an oral peptide formulation using permeation enhancers, which safety consideration is most important?

• Enhancers should irreversibly open tight junctions to maximize absorption
• Enhancers must be evaluated for reversible effect, mucosal toxicity, and potential to increase systemic absorption of unwanted luminal antigens
• No need to assess local irritation because peptides are benign
• Selecting enhancers that permanently alter epithelial cell DNA to improve uptake

Correct Answer: Enhancers must be evaluated for reversible effect, mucosal toxicity, and potential to increase systemic absorption of unwanted luminal antigens

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