Formulation of eye drops MCQs With Answer is a focused set of practice questions designed for B.Pharm students to deepen understanding of ophthalmic formulation principles. This collection emphasizes key topics such as ocular physiology, sterility, preservatives, tonicity, pH and buffering, viscosity enhancers, suspensions and emulsions, packaging, aseptic processing, and stability testing. Each question targets practical formulation challenges—selection of excipients, sterilization methods, container compatibility, drop size, and patient safety—so you gain clinically relevant knowledge and exam-ready detail. These MCQs with explanations help reinforce regulatory and quality-control considerations central to ophthalmic product development. ‘Now let’s test your knowledge with 30 MCQs on this topic.’
Q1. Which property is most important to match between an ophthalmic solution and tear fluid to avoid ocular irritation?
- Tonicity
- Color
- Density
- Surface tension
Correct Answer: Tonicity
Q2. What is the commonly accepted isotonic concentration of sodium chloride for ophthalmic solutions?
- 0.45% w/v
- 0.9% w/v
- 1.8% w/v
- 2.5% w/v
Correct Answer: 0.9% w/v
Q3. Which preservative is most widely used in multi-dose eye drop formulations?
- Benzalkonium chloride (BAK)
- Sodium chloride
- Sodium bicarbonate
Correct Answer: Benzalkonium chloride (BAK)
Q4. For heat-labile drugs intended for ophthalmic use, which sterilization method is preferred?
- Boiling
- Autoclaving at 121°C
- Steam under atmospheric pressure
- Sterile filtration through 0.22 µm membrane
Correct Answer: Sterile filtration through 0.22 µm membrane
Q5. Which excipient is commonly used to increase ocular residence time by raising viscosity?
- Carbomer
- Sodium chloride
- Propylene glycol
- Ethyl alcohol
Correct Answer: Carbomer
Q6. What is the principal role of a buffering system in an ophthalmic formulation?
- Enhance microbial growth
- Maintain pH for drug stability and comfort
- Increase viscosity
- Act as a preservative
Correct Answer: Maintain pH for drug stability and comfort
Q7. Which particle size is generally considered acceptable for ophthalmic suspensions to minimize corneal irritation?
- Greater than 100 µm
- 50–100 µm
- 10–50 µm
- Less than 10 µm
Correct Answer: Less than 10 µm
Q8. Which packaging material is commonly used for sterile eye drop containers because of squeezability and low cost?
- High-density polyethylene (HDPE)
- Polystyrene
- Low-density polyethylene (LDPE)
- Polyvinyl chloride (PVC)
Correct Answer: Low-density polyethylene (LDPE)
Q9. What is the typical volume of a single ophthalmic drop delivered from a standard dropper?
- 1–5 µL
- 7–10 µL
- 20–40 µL
- 100–200 µL
Correct Answer: 20–40 µL
Q10. Which preservative is contraindicated for many soft contact lens users due to adsorption and irritation?
- Sorbitol
- Benzalkonium chloride (BAK)
- Edetate disodium (EDTA)
- Glycerin
Correct Answer: Benzalkonium chloride (BAK)
Q11. Which agent is used as a chelating agent to potentiate preservative activity in ophthalmic formulations?
- EDTA (ethylenediaminetetraacetic acid)
- Carboxymethylcellulose
- Propylparaben
- Sodium chloride
Correct Answer: EDTA (ethylenediaminetetraacetic acid)
Q12. Which test is essential to confirm the absence of viable microorganisms in a sterile ophthalmic batch?
- pH measurement
- Sterility test (e.g., USP sterility test)
- Density measurement
- Viscosity profiling
Correct Answer: Sterility test (e.g., USP sterility test)
Q13. Which viscosity behavior is desirable for ocular comfort and reduced blurring immediately after instillation?
- Newtonian high viscosity
- Pseudoplastic (shear-thinning)
- Dilatant (shear-thickening)
- Thixotropic stable at high shear
Correct Answer: Pseudoplastic (shear-thinning)
Q14. Cyclodextrins are used in ophthalmic formulations primarily to:
- Act as preservatives
- Improve solubility of lipophilic drugs
- Increase tonicity
- Reduce pH
Correct Answer: Improve solubility of lipophilic drugs
Q15. What is the usual pore size of a sterilizing-grade membrane filter for ophthalmic solution filtration?
- 1.2 µm
- 0.45 µm
- 0.22 µm
- 5.0 µm
Correct Answer: 0.22 µm
Q16. Which type of ophthalmic formulation is preferred for a poorly water-soluble drug that requires extended contact time?
- Simple aqueous solution
- Emulsion or suspension
- Oral tablet
- Inhalation aerosol
Correct Answer: Emulsion or suspension
Q17. Which of the following acts as an antioxidant commonly used in ophthalmic formulations?
- Sodium metabisulfite
- Cetyl alcohol
- Polyethylene glycol
- Sodium chloride
Correct Answer: Sodium metabisulfite
Q18. Which regulatory requirement is most relevant for labeling ophthalmic products?
- “For external use only” without further instructions
- “For ophthalmic use only” and storage/expiry details
- No labeling needed for sterile drops
- Only manufacturer address is required
Correct Answer: “For ophthalmic use only” and storage/expiry details
Q19. Which factor most increases the risk of preservative-induced corneal toxicity?
- Low drug potency
- High preservative concentration and frequent dosing
- Neutral pH
- Use of isotonic vehicle
Correct Answer: High preservative concentration and frequent dosing
Q20. What is the benefit of single-dose preservative-free eye drop units?
- Long-term multi-dose use without contamination
- Lower manufacturing cost than multi-dose
- Reduced risk of preservative-related toxicity and contamination
- They always provide sustained release
Correct Answer: Reduced risk of preservative-related toxicity and contamination
Q21. Which buffer system is frequently used in ophthalmic formulations for pH control?
- Phosphate buffer
- Formaldehyde buffer
- Hydrochloric acid buffer
- Chloride buffer
Correct Answer: Phosphate buffer
Q22. What is a chief advantage of using mucoadhesive polymers in eye drop formulations?
- They inactivate the drug
- They reduce corneal permeability
- They increase precorneal residence time and bioavailability
- They prevent sterilization
Correct Answer: They increase precorneal residence time and bioavailability
Q23. Which of the following is a common indicator of physical instability in ophthalmic emulsions?
- Clear solution appearance
- Phase separation or creaming
- Stable droplet size
- Constant viscosity
Correct Answer: Phase separation or creaming
Q24. During aseptic filling of eye drops, which cleanroom classification is typically required at the filling zone?
- ISO 9 / Grade D
- ISO 8 / Grade C
- ISO 5 / Grade A
- ISO 1 / Grade S
Correct Answer: ISO 5 / Grade A
Q25. Which measurement is used to assess the osmolarity of an ophthalmic solution?
- pH meter
- Refractometer or osmometer
- Viscometer
- Colorimeter
Correct Answer: Refractometer or osmometer
Q26. What is the main reason to include surfactants in ophthalmic emulsions?
- To increase tonicity
- To stabilize oil droplets and reduce interfacial tension
- To act as preservatives
- To change color
Correct Answer: To stabilize oil droplets and reduce interfacial tension
Q27. Which in-process test helps ensure correct dropper performance for consistent dosing?
- Drop count and drop size measurement
- pH aging assay
- Color comparison
- Odor evaluation only
Correct Answer: Drop count and drop size measurement
Q28. Which excipient can act both as a humectant and tonicity agent in ophthalmic solutions?
- Glycerin
- Paraffin
- Cellulose acetate
- Magnesium stearate
Correct Answer: Glycerin
Q29. Endotoxin testing in ophthalmic products is primarily performed to detect:
- Bacterial endotoxins (pyrogens) that can cause inflammation
- Fungal contamination only
- Color impurities
- Viscosity changes
Correct Answer: Bacterial endotoxins (pyrogens) that can cause inflammation
Q30. Which approach improves the solubility and ocular penetration of a weakly basic drug in an eye drop?
- Formulate at a pH well above physiological pH
- Use cyclodextrin complexation or adjust pH to increase unionized fraction carefully
- Remove buffer completely
- Add high concentrations of preservative
Correct Answer: Use cyclodextrin complexation or adjust pH to increase unionized fraction carefully
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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