Formulation and preparation of sunscreens MCQs With Answer is a focused review for B. Pharm students covering key concepts in sunscreen formulation, UV filters, emulsion technology, photostability, safety, and regulatory testing. This introduction highlights important keywords: SPF, UVA/UVB filters, organic and inorganic filters (zinc oxide, titanium dioxide), emulsifiers, antioxidants, photodegradation, nano vs non‑nano particles, critical wavelength, in vivo/in vitro testing, water resistance, and packaging. The questions probe formulation strategy, excipient selection, analytical methods, and stability considerations to deepen understanding of practical sunscreen preparation and evaluation. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What does SPF (Sun Protection Factor) quantitatively represent?
- Percentage of UV rays blocked by the sunscreen
- Ratio of minimal erythemal dose (MED) of protected skin to unprotected skin
- Time in minutes until sunburn appears after application
- Critical wavelength of the sunscreen formulation
Correct Answer: Ratio of minimal erythemal dose (MED) of protected skin to unprotected skin
Q2. Which wavelength range defines UVA radiation relevant to sunscreen formulation?
- 100–280 nm
- 280–320 nm
- 320–400 nm
- 400–700 nm
Correct Answer: 320–400 nm
Q3. How do inorganic (physical) filters such as zinc oxide and titanium dioxide primarily protect skin?
- By chemically reacting with skin proteins
- By absorbing and converting UV into heat
- By scattering and reflecting UV radiation
- By increasing skin melanin production
Correct Answer: By scattering and reflecting UV radiation
Q4. What is the main mechanism of action for organic (chemical) UV filters?
- Acting as antioxidants to neutralize free radicals
- Absorbing UV photons and dissipating energy as heat
- Scattering visible light to reduce pigmentation
- Increasing skin barrier thickness to block UV
Correct Answer: Absorbing UV photons and dissipating energy as heat
Q5. Which criterion is commonly used to classify a sunscreen as ‘broad spectrum’?
- SPF greater than 30
- Critical wavelength ≥ 370 nm
- Contains both titanium dioxide and zinc oxide
- Has water resistance for 80 minutes
Correct Answer: Critical wavelength ≥ 370 nm
Q6. Avobenzone is an effective UVA filter but is photounstable; which ingredient is commonly used to stabilize avobenzone in formulations?
- PABA (para-aminobenzoic acid)
- Octocrylene
- Homosalate
- Isopropyl myristate
Correct Answer: Octocrylene
Q7. Standard water-resistance claims for sunscreens are typically validated for which exposure durations?
- 10 and 20 minutes
- 20 and 40 minutes
- 40 and 80 minutes
- 90 and 120 minutes
Correct Answer: 40 and 80 minutes
Q8. In vivo SPF testing is primarily based on which biological endpoint?
- Degree of tanning after 24 hours
- Minimal erythemal dose (MED)
- Skin hydration changes
- Trans-epidermal water loss (TEWL)
Correct Answer: Minimal erythemal dose (MED)
Q9. For an oil-in-water (O/W) sunscreen emulsion, which excipient selection is most critical to achieve long-term physical stability?
- Choice of preservative
- Type and HLB value of the emulsifier
- Amount of fragrance
- pH buffer selection
Correct Answer: Type and HLB value of the emulsifier
Q10. Why are antioxidants added to sunscreen formulations?
- To increase SPF numerically
- To quench free radicals and reduce photodegradation of filters
- To act as primary emulsifiers
- To neutralize skin pH
Correct Answer: To quench free radicals and reduce photodegradation of filters
Q11. What particle size threshold typically differentiates nanosized inorganic sunscreens from non‑nano particles?
- < 10 nm
- < 50 nm
- < 100 nm
- > 500 nm
Correct Answer: < 100 nm
Q12. Which UV filter is primarily used for UVA protection and is well known for photoinstability issues?
- Octisalate
- Homosalate
- Avobenzone (butyl methoxydibenzoylmethane)
- Octinoxate
Correct Answer: Avobenzone (butyl methoxydibenzoylmethane)
Q13. Which of the following filters is mainly used for UVB protection?
- Oxybenzone
- Octisalate
- Bemotrizinol (Tinosorb S)
- Mexoryl SX
Correct Answer: Octisalate
Q14. Sunscreen formulations generally maintain stability best at which pH range for most organic filters and emulsions?
- Highly acidic (pH 2–3)
- Moderately acidic (pH 4–5)
- Near neutral (pH 6–7)
- Alkaline (pH 9–10)
Correct Answer: Near neutral (pH 6–7)
Q15. Which emulsion type is usually preferred for cosmetically elegant sunscreen lotions with low greasiness?
- Water-in-oil (W/O)
- Oil-in-water (O/W)
- Microemulsion with high oil content
- Anhydrous ointment base
Correct Answer: Oil-in-water (O/W)
Q16. Which polymer is commonly used as a film former to improve water resistance and substantivity of sunscreen formulations?
- Carbomer
- PVP (polyvinylpyrrolidone)
- Cetyl alcohol
- Glycerin
Correct Answer: PVP (polyvinylpyrrolidone)
Q17. Which analytical method is routinely used in vitro to measure the spectral absorbance and calculate critical wavelength of a sunscreen?
- Dynamic light scattering (DLS)
- UV‑Vis spectrophotometry using a substrate or film
- High-performance liquid chromatography (HPLC)
- Gas chromatography-mass spectrometry (GC-MS)
Correct Answer: UV‑Vis spectrophotometry using a substrate or film
Q18. What is the main purpose of including a chelating agent (e.g., EDTA) in sunscreen formulations?
- Act as primary emulsifier
- Prevent metal-catalyzed oxidation and improve stability
- Increase SPF by absorbing UV light
- Serve as a fragrance enhancer
Correct Answer: Prevent metal-catalyzed oxidation and improve stability
Q19. For an O/W emulsifier intended to stabilize a sunscreen, the required HLB value is typically:
- Very low (1–4)
- Moderate (4–7)
- High (8–18)
- Does not depend on HLB
Correct Answer: High (8–18)
Q20. SPF labeling primarily communicates protection against which part of the UV spectrum?
- UVA only
- Both UVA and visible light
- UVB primarily
- Infrared radiation
Correct Answer: UVB primarily
Q21. Which organic UV filter has been restricted or banned in some regions due to environmental concerns such as coral bleaching?
- Octocrylene
- Homosalate
- Oxybenzone (benzophenone-3)
- Octisalate
Correct Answer: Oxybenzone (benzophenone-3)
Q22. Which analytical technique is most appropriate for quantifying photodegradation of organic filters in a formulation?
- FTIR spectroscopy on intact emulsion
- High-performance liquid chromatography (HPLC)
- Thermogravimetric analysis (TGA)
- pH titration
Correct Answer: High-performance liquid chromatography (HPLC)
Q23. Which technique is commonly used to measure particle size distribution of dispersed zinc oxide or titanium dioxide in sunscreen dispersions?
- Gas chromatography
- Dynamic light scattering (DLS)
- Atomic absorption spectroscopy
- Microwave resonance
Correct Answer: Dynamic light scattering (DLS)
Q24. Which manufacturing process is typically used to achieve small oil droplet size and uniform emulsions in sunscreen production?
- Magnetic stirring at room temperature
- High-pressure homogenization
- Simple hand-shaking
- Slow cooling without shear
Correct Answer: High-pressure homogenization
Q25. What is the purpose of performing a preservative efficacy (challenge) test on sunscreen formulations?
- To determine SPF value
- To evaluate emulsifier HLB
- To ensure microbiological stability and preservative effectiveness
- To measure viscosity
Correct Answer: To ensure microbiological stability and preservative effectiveness
Q26. Which historical UV filter is known for causing allergic reactions and is now rarely used or restricted in many products?
- Homosalate
- PABA (para-aminobenzoic acid)
- Octisalate
- Bemotrizinol
Correct Answer: PABA (para-aminobenzoic acid)
Q27. Which formulation strategy most increases sunscreen substantivity (ability to remain on skin) during sweat and water exposure?
- Increasing volatile solvent content
- Adding film-forming polymers
- Reducing UV filter concentration
- Adding a high percentage of humectants
Correct Answer: Adding film-forming polymers
Q28. Why are inorganic oxide particles often coated (e.g., silica or alumina-coated TiO2)?
- To increase photocatalytic activity
- To improve whitening effect
- To reduce photocatalysis and improve dispersion and photostability
- To make particles larger and more visible
Correct Answer: To reduce photocatalysis and improve dispersion and photostability
Q29. Which in vivo test is commonly used to assess UVA protective efficacy specifically (beyond SPF)?
- Minimal erythemal dose (MED) test
- Persistent pigment darkening (PPD) test
- Trans-epidermal water loss (TEWL)
- Patch test for irritation
Correct Answer: Persistent pigment darkening (PPD) test
Q30. Which excipient is generally considered non-comedogenic and is often used in sunscreen bases for acne-prone skin?
- Mineral oil
- Lanolin
- Isopropyl myristate
- Cyclomethicone
Correct Answer: Cyclomethicone
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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