Drug-excipient interactions MCQs With Answer

Drug-Excipient Interactions MCQs With Answer offers a focused, practice-oriented review for M. Pharm students studying Modern Pharmaceutics (MPH 103T). Drug performance in dosage forms depends not only on API properties but also on complex interactions with excipients that can alter stability, bioavailability, manufacturability, and quality. This quiz set explores mechanisms such as Maillard reactions, ionic binding, adsorption, peroxide-induced oxidation, microenvironmental pH effects, and lubricant sensitivity, alongside diagnostic tools like DSC, FTIR, XRPD, and isothermal microcalorimetry. Each question aims to reinforce applied understanding—how to predict, detect, and mitigate incompatibilities through rational excipient selection, preformulation studies, and formulation strategies. Use these MCQs to sharpen clinical–industrial reasoning for high-stakes product development.

Q1. Which combination is most prone to a Maillard-type interaction in solid dosage forms?

• Lactose monohydrate with a primary amine drug
• Mannitol with a primary amine drug
• Dicalcium phosphate dihydrate with a quaternary ammonium drug
• Sucrose with a tertiary amine drug

Correct Answer: Lactose monohydrate with a primary amine drug

Q2. Which analytical technique is most sensitive for early detection of solid-state drug–excipient interactions via heat flow changes at near-ambient conditions?

• Differential scanning calorimetry (DSC)
• Fourier-transform infrared spectroscopy (FTIR)
• Isothermal microcalorimetry (IMC)
• Hot-stage microscopy

Correct Answer: Isothermal microcalorimetry (IMC)

Q3. Which excipient is most likely to catalyze oxidative degradation of susceptible APIs due to trace metal impurities?

• Microcrystalline cellulose
• Talc (magnesium silicate)
• Hypromellose (HPMC)
• Disodium EDTA

Correct Answer: Talc (magnesium silicate)

Q4. For a base-catalyzed hydrolysis–prone API in tablets, which strategy best minimizes degradation linked to excipient microenvironmental pH?

• Replace basic dicalcium phosphate with mannitol
• Add sodium bicarbonate as alkalizer
• Increase magnesium stearate concentration
• Use lactose monohydrate as diluent

Correct Answer: Replace basic dicalcium phosphate with mannitol

Q5. A directly compressed tablet shows markedly slower dissolution after extended lubrication. Which interaction best explains this?

• Formation of a eutectic mixture
• Complexation with povidone (PVP)
• Hydrophobic coating by magnesium stearate on particle surfaces
• Cocrystal formation between API and filler

Correct Answer: Hydrophobic coating by magnesium stearate on particle surfaces

Q6. A quaternary ammonium drug shows poor release from a matrix containing an anionic disintegrant. What is the most likely mechanism?

• Ionic complexation with the anionic polymer (e.g., croscarmellose/NaCMC)
• Hydrogen bonding to microcrystalline cellulose
• Oxidation by peroxides in PEG
• Partitioning into stearate lubricant

Correct Answer: Ionic complexation with the anionic polymer (e.g., croscarmellose/NaCMC)

Q7. Which pair is most likely to form an ion-pair/salt in the solid state, altering dissolution and stability?

• Ibuprofen with Eudragit EPO (cationic methacrylate copolymer)
• Metformin with Eudragit L100 (anionic methacrylate)
• Paracetamol with hydroxypropyl cellulose (HPC)
• Ranitidine hydrochloride with mannitol

Correct Answer: Ibuprofen with Eudragit EPO (cationic methacrylate copolymer)

Q8. To quantify adsorption of a cationic API onto colloidal silica, which experiment is most appropriate?

• Equilibrium adsorption isotherm measuring drug depletion from solution (UV/HPLC)
• Differential scanning calorimetry on binary mixture
• Powder X-ray diffraction of the blend
• pH–solubility profile determination

Correct Answer: Equilibrium adsorption isotherm measuring drug depletion from solution (UV/HPLC)

Q9. To minimize Maillard reaction risk in an amine-containing drug tablet, which diluent is preferred?

• Spray-dried lactose
• Alpha-lactose monohydrate
• Mannitol
• Anhydrous lactose

Correct Answer: Mannitol

Q10. Which commonly used excipient can contain peroxide impurities capable of oxidizing sensitive drugs?

• Microcrystalline cellulose
• Polyethylene glycol (PEG 400)
• Lactose monohydrate
• Dicalcium phosphate dihydrate

Correct Answer: Polyethylene glycol (PEG 400)

Q11. Which technique most directly evidences formation of a new crystalline salt/cocrystal phase between a drug and excipient?

• Solid-state 13C NMR chemical shift changes alone
• XRPD showing new diffraction peaks distinct from either component
• Karl Fischer titration indicating water uptake
• Optical microscopy of particle morphology

Correct Answer: XRPD showing new diffraction peaks distinct from either component

Q12. During wet granulation of a low-dose API, significant assay loss occurs due to surface binding. Which excipient is the most likely culprit?

• Microcrystalline cellulose
• Dicalcium phosphate dihydrate
• Colloidal silicon dioxide
• Pregelatinized starch

Correct Answer: Colloidal silicon dioxide

Q13. For a hydrophobic peptide prone to adsorption onto excipients and container surfaces, which excipient most effectively mitigates losses?

• Sodium chloride
• Polysorbate 80
• Lactose monohydrate
• Dicalcium phosphate

Correct Answer: Polysorbate 80

Q14. An API is unstable at alkaline pH but stable at pH 3–4. Which approach best controls microenvironmental pH in a tablet?

• Intragranular incorporation of citric acid as an acidifier
• Extra-granular addition of sodium carbonate
• Increase crospovidone concentration
• Replace disintegrant with talc

Correct Answer: Intragranular incorporation of citric acid as an acidifier

Q15. Which observation most strongly suggests a Maillard-type drug–excipient interaction during stability testing?

• Browning of tablets containing lactose with a primary amine drug under high humidity
• Increased tablet friability after compression
• Oil exudation on the tablet surface
• Faster disintegration but unchanged assay

Correct Answer: Browning of tablets containing lactose with a primary amine drug under high humidity

Q16. Which excipient is least likely to form ionic complexes with a weakly basic API?

• Croscarmellose sodium
• Sodium alginate
• Carbomer (crosslinked polyacrylic acid)
• Hypromellose (HPMC)

Correct Answer: Hypromellose (HPMC)

Q17. What is the most appropriate design for an accelerated drug–excipient compatibility study during preformulation?

• Evaluate API alone at 25°C/60% RH for 1 week
• Prepare and store binary mixtures (1:1 w/w) at elevated temperature/humidity with periodic DSC/FTIR/assay
• Test only final compressed tablets under ICH long-term conditions
• Perform photostability testing without excipients

Correct Answer: Prepare and store binary mixtures (1:1 w/w) at elevated temperature/humidity with periodic DSC/FTIR/assay

Q18. In amorphous solid dispersions with povidone (PVP), which interaction most commonly stabilizes the drug against recrystallization?

• Ionic bond formation
• Covalent bond formation
• Hydrogen bonding between API and PVP
• Metallic coordination

Correct Answer: Hydrogen bonding between API and PVP

Q19. A formulation suffers metal-catalyzed oxidation. Which excipient-based mitigation is most appropriate?

• Add disodium EDTA as a chelating agent
• Increase talc concentration
• Add citric acid only
• Raise tablet compression force

Correct Answer: Add disodium EDTA as a chelating agent

Q20. Which condition–excipient combination most likely promotes hydrate formation or solid-state transformation of an anhydrous API via moisture-induced plasticization?

• High humidity storage with microcrystalline cellulose
• Low humidity storage with mannitol
• Vacuum storage at 25°C
• Nitrogen-flushed packaging with desiccant

Correct Answer: High humidity storage with microcrystalline cellulose

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