Ocular formulations and ocuserts – design and evaluation MCQs With Answer

Ocular formulations and ocuserts – design and evaluation explore principles of ophthalmic drug delivery, sustained-release ocusert systems, and critical evaluation methods for B.Pharm students. This introduction covers formulation strategies, polymers, rate-controlling membranes, mucoadhesion, sterilization, stability, in vitro release testing, and in vivo correlation to improve ocular bioavailability and patient compliance. Key topics include selection of biocompatible polymers (e.g., EVA, Carbopol, chitosan), release kinetics (Higuchi, Korsmeyer‑Peppas), analytical assays (HPLC, SEM, DSC), preservative considerations, and regulatory quality attributes such as sterility, content uniformity, and packaging. Emphasis is on practical design and robust evaluation for safe, effective ophthalmic products. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary purpose of an ocusert in ophthalmic therapy?

• Instantaneous drug bolus to the eye
• Sustained and controlled ocular drug release
• To replace topical eye drops permanently
• To act as a diagnostic device

Correct Answer: Sustained and controlled ocular drug release

Q2. Which formulation attribute most directly improves ocular bioavailability?

• Low viscosity
• Prolonged precorneal residence time
• Brightly colored formulation
• Large particle size

Correct Answer: Prolonged precorneal residence time

Q3. Which polymer is commonly used as a rate-controlling membrane in ocuserts?

• Polyethylene glycol (PEG 400)
• Ethylene-vinyl acetate (EVA)
• Polyvinylpyrrolidone (PVP K30)
• Sodium chloride

Correct Answer: Ethylene-vinyl acetate (EVA)

Q4. Which mathematical model is widely used to describe diffusion-controlled release from ocuserts?

• Michaelis-Menten model
• Higuchi model
• Arrhenius model
• Langmuir isotherm

Correct Answer: Higuchi model

Q5. Which test is essential to confirm that an ophthalmic product is free from viable microorganisms?

• Viscosity test
• Sterility test (pharmacopeial)
• pH measurement
• In vitro release

Correct Answer: Sterility test (pharmacopeial)

Q6. Which apparatus is commonly used for in vitro release testing of ocuserts?

• Franz diffusion cell
• Brookfield viscometer
• Atomic absorption spectrometer
• UV lamp

Correct Answer: Franz diffusion cell

Q7. What is the primary function of a rate-controlling membrane in a reservoir ocusert?

• Provide color to the device
• Control the rate of drug diffusion
• Act as a preservative
• Increase device buoyancy

Correct Answer: Control the rate of drug diffusion

Q8. Which polymer is frequently used for mucoadhesion in ocular formulations?

• Chitosan
• Sodium chloride
• Polytetrafluoroethylene (PTFE)
• Calcium carbonate

Correct Answer: Chitosan

Q9. What is the ideal pH target for most ocular formulations to match tear fluid?

• pH 4.0
• pH 5.5
• pH 7.4
• pH 9.0

Correct Answer: pH 7.4

Q10. Which in vivo test is a classical method for assessing ocular irritation?

• Draize eye test
• Higuchi test
• Ostwald viscometry
• Heamolysis assay

Correct Answer: Draize eye test

Q11. For preservative-free ophthalmic products, which packaging is preferred to maintain sterility?

• Multi-dose bottle without special features
• Single-dose sterile containers
• Open jars
• Metal tins

Correct Answer: Single-dose sterile containers

Q12. How are ocuserts commonly classified based on drug distribution?

• Solid and liquid
• Matrix and reservoir
• Hydrophobic and hydrophilic only
• Single-layer and double-layer without further distinction

Correct Answer: Matrix and reservoir

Q13. Which technique is used to evaluate surface morphology of ocuserts?

• High-performance liquid chromatography (HPLC)
• Scanning electron microscopy (SEM)
• pH meter
• UV-Visible spectroscopy

Correct Answer: Scanning electron microscopy (SEM)

Q14. The HET-CAM assay is used as an alternative to which ocular test?

• Microbial limit test
• Draize eye irritation test
• pH determination
• Content uniformity

Correct Answer: Draize eye irritation test

Q15. What tonicity is generally considered ideal for ocular comfort?

• Hypertonic (5% NaCl)
• Isotonic (~0.9% NaCl)
• Hypotonic (0.01% NaCl)
• Any tonicity has equal comfort

Correct Answer: Isotonic (~0.9% NaCl)

Q16. Which analytical method is most suitable for quantifying drug content in ocuserts?

• HPLC (High-performance liquid chromatography)
• Simple color comparison
• Microscopy
• Thermogravimetric analysis only

Correct Answer: HPLC (High-performance liquid chromatography)

Q17. Which parameter specifically measures the adhesive strength of an ocular insert to the mucosal surface?

• Viscosity alone
• Mucoadhesive strength
• pH
• Osmolarity

Correct Answer: Mucoadhesive strength

Q18. Which preservative is commonly used in multi-dose ophthalmic formulations?

• Benzalkonium chloride (BAK)
• Sucrose
• Magnesium stearate
• Silicone oil

Correct Answer: Benzalkonium chloride (BAK)

Q19. What are the main routes for corneal drug penetration?

• Gastrointestinal absorption
• Transcellular and paracellular pathways
• Transdermal only
• Systemic venous return

Correct Answer: Transcellular and paracellular pathways

Q20. Why is in vitro–in vivo correlation (IVIVC) important for ocular formulations?

• To replace stability testing
• To predict in vivo performance from in vitro release data
• To eliminate the need for analytical methods
• To assess color stability

Correct Answer: To predict in vivo performance from in vitro release data

Q21. Which polymer is commonly used to increase viscosity and enhance ocular residence time?

• Carbopol
• Sodium chloride
• Polyethylene glycol 6000 as lubricant only
• Calcium carbonate

Correct Answer: Carbopol

Q22. In the Korsmeyer–Peppas model, the release exponent n provides information about what?

• Drug molecular weight only
• Mechanism of drug release (diffusion, erosion, anomalous)
• pH of formulation
• Color stability

Correct Answer: Mechanism of drug release (diffusion, erosion, anomalous)

Q23. Which QC test assesses uniformity in ocusert thickness and dimension?

• Thickness measurement using micrometer
• pH testing
• Sterility test
• HET-CAM

Correct Answer: Thickness measurement using micrometer

Q24. Which sterilization method is frequently suitable for polymeric ocuserts that cannot tolerate heat?

• Autoclaving at 121°C
• Gamma irradiation
• Boiling in water
• Oven drying at 160°C

Correct Answer: Gamma irradiation

Q25. Why is content uniformity testing critical for ocuserts?

• To ensure consistent dosing between units
• To measure viscosity
• To determine color matching
• To assess microbial contamination only

Correct Answer: To ensure consistent dosing between units

Q26. What typically causes a burst release in ocusert release profiles?

• Complete absence of drug in formulation
• High proportion of surface-associated or loosely bound drug
• Perfectly uniform drug distribution
• Excessive membrane thickness

Correct Answer: High proportion of surface-associated or loosely bound drug

Q27. Which method is commonly used to determine low levels of moisture in ocusert materials?

• Karl Fischer titration
• Microscopy
• pH meter
• Franz cell only

Correct Answer: Karl Fischer titration

Q28. Which buffering system is commonly used to maintain physiological pH in ocular formulations?

• Phosphate buffer
• Sulfate buffer
• Hydrochloric acid alone
• Potassium permanganate

Correct Answer: Phosphate buffer

Q29. Which is a key clinical advantage of ocuserts over conventional eye drops?

• Require multiple daily administrations
• Prolonged drug release and reduced dosing frequency
• Increase systemic side effects
• Provide immediate high systemic absorption

Correct Answer: Prolonged drug release and reduced dosing frequency

Q30. Which pharmacopeia commonly provides official monographs and tests for ophthalmic preparations?

• Food Code
• United States Pharmacopeia (USP)
• ISO personal grooming standard
• National Building Code

Correct Answer: United States Pharmacopeia (USP)

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