Principles of formulation of skin care products MCQs With Answer

Principles of formulation of skin care products MCQs With Answer provides B.Pharm students a focused, practical review of topical formulation concepts including excipients, emulsions, rheology, preservatives, penetration enhancers, HLB theory, stability testing, and packaging. This concise introduction links pharmaceutical principles to cosmetic and therapeutic skin care design, emphasizing ingredient selection, skin physiology, pH considerations, and methods to improve delivery and stability. Questions target formulation strategy, troubleshooting common instabilities (creaming, coalescence, syneresis), and regulatory/safety aspects relevant to pharmacists. Mastery of these topics prepares students for formulation development, quality control, and clinical implications of topical products. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary function of an emulsifier in topical creams?

• Increase drug solubility in water
• Lower interfacial tension between oil and water phases
• Act as a preservative
• Increase the pH of the formulation

Correct Answer: Lower interfacial tension between oil and water phases

Q2. Which HLB value range is generally suitable for oil-in-water (O/W) emulsifiers?

• 1–4
• 5–9
• Approximately 10–18
• 20–30

Correct Answer: Approximately 10–18

Q3. What does phase inversion temperature (PIT) refer to in emulsion technology?

• The temperature at which an emulsion solidifies
• The temperature at which O/W and W/O emulsions interchange
• The melting point of the oil phase
• The cloud point of a surfactant

Correct Answer: The temperature at which O/W and W/O emulsions interchange

Q4. Which factor most strongly affects the efficacy of many commonly used preservatives?

• Color of the formulation
• pH of the formulation
• Viscosity of the product
• Packaging material

Correct Answer: pH of the formulation

Q5. What is the main role of humectants (e.g., glycerin) in skin care formulations?

• Provide UV protection
• Lower formulation viscosity
• Attract and retain water in the stratum corneum
• Act as emulsifying agents

Correct Answer: Attract and retain water in the stratum corneum

Q6. Which of the following is a classic occlusive agent used to reduce transepidermal water loss?

• Glycerin
• Petrolatum
• Ethanol
• Carbomer

Correct Answer: Petrolatum

Q7. Which rheology modifier is commonly used to form clear carbomer hydrogels in topical products?

• Xanthan gum
• Carbomer (carbopol)
• Cetyl alcohol
• Lanolin

Correct Answer: Carbomer (carbopol)

Q8. Which emulsion instability is typically reversible and results from migration of dispersed droplets?

• Creaming
• Coalescence
• Phase inversion
• Cracking

Correct Answer: Creaming

Q9. Which type of topical base is most suitable for very dry skin due to high occlusivity?

• Hydrophilic gel
• Ointment (oleaginous base)
• Alcoholic lotion
• Aqueous cream

Correct Answer: Ointment (oleaginous base)

Q10. What does SPF (Sun Protection Factor) quantify?

• The ratio of sunscreen absorption to reflection
• The ratio of minimal erythemal dose on protected skin to unprotected skin
• The percentage of UVA blocked
• The water resistance time of a sunscreen

Correct Answer: The ratio of minimal erythemal dose on protected skin to unprotected skin

Q11. How do liposomes improve topical delivery of active ingredients?

• By permanently changing skin pH
• By encapsulating actives and enhancing penetration into/through the skin
• By acting as strong preservatives
• By increasing formulation viscosity only

Correct Answer: By encapsulating actives and enhancing penetration into/through the skin

Q12. What is the typical surface pH of healthy human skin used as a guideline for topical formulations?

• 2.0–3.0
• 4.5–5.5
• 7.0–8.0
• 9.0–10.0

Correct Answer: 4.5–5.5

Q13. Which type of surfactant is generally considered the mildest for skin-contact products?

• Anionic surfactants
• Cationic surfactants
• Nonionic surfactants
• Zwitterionic surfactants

Correct Answer: Nonionic surfactants

Q14. What is the primary role of chelating agents (e.g., EDTA) in skin care formulations?

• Provide fragrance
• Bind metal ions to improve stability and preservative efficacy
• Act as primary emulsifiers
• Lower the pH drastically

Correct Answer: Bind metal ions to improve stability and preservative efficacy

Q15. Which test specifically evaluates the effectiveness of preservatives in a formulation?

• Viscosity test
• Preservative efficacy test (challenge test)
• Melting point determination
• Partition coefficient measurement

Correct Answer: Preservative efficacy test (challenge test)

Q16. Which packaging choice best minimizes photodegradation of light-sensitive actives?

• Clear polyethylene bottle
• Amber glass or opaque airless container
• Metal tube with transparent cap
• Open jar packaging

Correct Answer: Amber glass or opaque airless container

Q17. What is a common function of co-solvents like propylene glycol in topical formulations?

• Act as primary emulsifiers
• Enhance solubility of actives and act as penetration enhancers
• Raise the pH
• Provide SPF activity

Correct Answer: Enhance solubility of actives and act as penetration enhancers

Q18. How does spreadability typically relate to viscosity in topical formulations?

• Spreadability increases as viscosity increases
• Spreadability is independent of viscosity
• Spreadability decreases as viscosity increases (inverse relationship)
• Spreadability is only affected by pH

Correct Answer: Spreadability decreases as viscosity increases (inverse relationship)

Q19. Which emulsion type is generally more suitable for dry skin because of higher emolliency?

• Oil-in-water (O/W)
• Water-in-oil (W/O)
• Microemulsion only
• Hydroalcoholic solution

Correct Answer: Water-in-oil (W/O)

Q20. Which antioxidant is commonly used to prevent rancidity of unsaturated oils in creams?

• Sodium benzoate
• Butylated hydroxytoluene (BHT)
• Chlorhexidine
• Methylisothiazolinone

Correct Answer: Butylated hydroxytoluene (BHT)

Q21. What is the typical functional role of fatty alcohols such as cetyl alcohol in creams?

• Primary preservative
• Co-emulsifier and thickening/stabilizing agent
• Fragrance fixative
• Penetration enhancer

Correct Answer: Co-emulsifier and thickening/stabilizing agent

Q22. Which molecular characteristic most favors percutaneous penetration of an active ingredient?

• High molecular weight (>1000 Da)
• Low molecular weight (<500 Da)
• Highly charged molecule
• Extremely hydrophilic nature

Correct Answer: Low molecular weight (<500 Da)

Q23. Which of the following is a commonly used topical penetration enhancer?

• Sodium chloride
• Ethanol
• Sorbitol
• Magnesium stearate

Correct Answer: Ethanol

Q24. How do microemulsions differ from nanoemulsions in formulation terms?

• Microemulsions are thermodynamically stable; nanoemulsions are kinetically stable
• Microemulsions are always opaque; nanoemulsions are always clear
• Microemulsions contain no surfactant; nanoemulsions contain high surfactant
• There is no practical difference between them

Correct Answer: Microemulsions are thermodynamically stable; nanoemulsions are kinetically stable

Q25. Why is viscosity control important in topical formulations?

• Only to increase product color intensity
• Because it affects stability, spreadability, and release of actives
• Viscosity has no effect on product performance
• Only to determine pH

Correct Answer: Because it affects stability, spreadability, and release of actives

Q26. Which preservative is a commonly used paraben in cosmetic and topical products?

• Sodium lauryl sulfate
• Methylparaben
• EDTA
• Carbomer

Correct Answer: Methylparaben

Q27. At what water activity (aw) level is bacterial growth generally inhibited in formulations?

• aw > 0.95
• aw ≈ 0.8–0.9
• aw < 0.6
• aw = 1.0

Correct Answer: aw < 0.6

Q28. What is the purpose of adding co-emulsifiers like cetostearyl alcohol to an emulsion?

• Increase water activity
• Improve emulsion stability and consistency
• Act as the primary active ingredient
• Serve as the main preservative

Correct Answer: Improve emulsion stability and consistency

Q29. Which parameter is most directly measured to assess spreadability in the lab?

• pH
• Viscosity or diameter of spread under a standard weight
• Melting point
• Partition coefficient (log P)

Correct Answer: Viscosity or diameter of spread under a standard weight

Q30. If an oil phase requires an HLB of 12, and surfactants with HLB 4 and HLB 16 are available, what approximate ratio of HLB4:HLB16 gives the target HLB?

• 50:50
• 33:67 (HLB4 : HLB16)
• 10:90
• 67:33 (HLB4 : HLB16)

Correct Answer: 33:67 (HLB4 : HLB16)

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